[meta-virtualization] [PATCH][v2] docker: uprev to 1.9.0

Bruce Ashfield bruce.ashfield at gmail.com
Wed Apr 20 13:47:14 PDT 2016


On Tue, Apr 19, 2016 at 3:30 PM, Bruce Ashfield <bruce.ashfield at gmail.com>
wrote:

>
>
> On Tue, Apr 19, 2016 at 3:29 AM, Wei Lu <W.Lu at nxp.com> wrote:
>
>> Hello,
>>
>>
>>
>
> Thanks. I've queued this locally. If my testing passes, I'll follow up
> when it has been
> pushed.
>

I had to fix some other go 1.x applications, but I can confirm that this
also worked for
x86-64.

The changes are now pushed.

Bruce


>
> Bruce
>
>
>> For Docker running on ARM64, we need enable below configures, these extra
>> configures are not enabled in default kernel, so we need open it manually.
>>
>> CONFIG_CGROUP_DEBUG=y
>>
>> CONFIG_CGROUP_FREEZER=y
>>
>> CONFIG_CGROUP_DEVICE=y
>>
>> CONFIG_CPUSETS=y
>>
>> CONFIG_CGROUP_CPUACCT=y
>>
>> CONFIG_CGROUP_PERF=y
>>
>> CONFIG_BLK_CGROUP=y
>>
>> CONFIG_DEBUG_BLK_CGROUP=y
>>
>> CONFIG_UTS_NS=y
>>
>> CONFIG_IPC_NS=y
>>
>> CONFIG_USER_NS=y
>>
>> CONFIG_IPV6=y
>>
>> CONFIG_BRIDGE=y
>>
>> CONFIG_VLAN_8021Q=y
>>
>> CONFIG_VLAN_8021Q_GVRP=y
>>
>> CONFIG_VLAN_8021Q_MVRP=y
>>
>> CONFIG_MACVLAN=y
>>
>> CONFIG_MACVTAP=y
>>
>> CONFIG_VETH=y
>>
>> CONFIG_DEVPTS_MULTIPLE_INSTANCES=y
>>
>> CONFIG_EXT2_FS_XATTR=y
>>
>> CONFIG_EXT2_FS_POSIX_ACL=y
>>
>> CONFIG_EXT3_FS_POSIX_ACL=y
>>
>> CONFIG_EXT4_FS_POSIX_ACL=y
>>
>> CONFIG_TMPFS_POSIX_ACL=y
>>
>> CONFIG_SECCOMP=y
>>
>> CONFIG_BLK_DEV_THROTTLING=y
>>
>> CONFIG_CFQ_GROUP_IOSCHED=y
>>
>> CONFIG_OVERLAY_FS=y
>>
>> CONFIG_TMPFS_POSIX_ACL=y
>>
>> CONFIG_TMPFS_XATTR=y
>>
>> CONFIG_NETFILTER=y
>>
>> CONFIG_NETFILTER_ADVANCED=y
>>
>> CONFIG_BRIDGE_NETFILTER=m
>>
>> CONFIG_NETFILTER_NETLINK=y
>>
>> CONFIG_NF_CONNTRACK=y
>>
>> CONFIG_NF_CONNTRACK_MARK=y
>>
>> CONFIG_NF_CONNTRACK_PROCFS=y
>>
>> CONFIG_NF_NAT=y
>>
>> CONFIG_NF_NAT_NEEDED=y
>>
>> CONFIG_NF_TABLES=y
>>
>> CONFIG_NFT_CT=y
>>
>> CONFIG_NFT_RBTREE=y
>>
>> CONFIG_NFT_MASQ=y
>>
>> CONFIG_NFT_NAT=y
>>
>> CONFIG_NFT_COMPAT=y
>>
>> CONFIG_NETFILTER_XTABLES=y
>>
>> CONFIG_NETFILTER_XT_CONNMARK=y
>>
>> CONFIG_NETFILTER_XT_TARGET_CONNMARK=y
>>
>> CONFIG_NETFILTER_XT_NAT=y
>>
>> CONFIG_NETFILTER_XT_MATCH_ADDRTYPE=y
>>
>> CONFIG_NETFILTER_XT_MATCH_CONNMARK=y
>>
>> CONFIG_NETFILTER_XT_MATCH_CONNTRACK=y
>>
>> CONFIG_NF_DEFRAG_IPV4=y
>>
>> CONFIG_NF_CONNTRACK_IPV4=y
>>
>> CONFIG_NF_CONNTRACK_PROC_COMPAT=y
>>
>> CONFIG_NF_TABLES_IPV4=y
>>
>> CONFIG_NF_NAT_IPV4=y
>>
>> CONFIG_NF_NAT_MASQUERADE_IPV4=y
>>
>> CONFIG_IP_NF_IPTABLES=y
>>
>> CONFIG_IP_NF_FILTER=y
>>
>> CONFIG_IP_NF_NAT=y
>>
>> CONFIG_IP_NF_TARGET_MASQUERADE=y
>>
>> CONFIG_IP_NF_MANGLE=y
>>
>> CONFIG_NF_TABLES_BRIDGE=y
>>
>> CONFIG_BRIDGE_NF_EBTABLES=y
>>
>> CONFIG_BRIDGE_EBT_T_NAT=y
>>
>> CONFIG_BRIDGE_EBT_DNAT=y
>>
>> CONFIG_BRIDGE_EBT_SNAT=y
>>
>>
>>
>> Test steps on ARM64:
>>
>> docker daemon &
>>
>> docker  login docker hub
>>
>> docker search arm64
>>
>> docker pull $ARM64_images
>>
>> docker run -d -p 30081:80 --name=sandbox1 -h sandbox1 $ARM64_images bash
>> -c "lighttpd -f /etc/lighttpd/lighttpd.conf -D"
>>
>> docker logout
>>
>> docker ps –a
>>
>> docker images
>>
>> docker stop sandbox1
>>
>> docker rm sandbox1
>>
>>
>>
>>
>>
>> Regards
>>
>> Lu Wei
>>
>>
>>
>> *From:* Zongchun Yu
>> *Sent:* Tuesday, April 19, 2016 11:18 AM
>> *To:* Bruce Ashfield <bruce.ashfield at gmail.com>; Wei Lu <W.Lu at nxp.com>
>> *Cc:* meta-virtualization at yoctoproject.org
>> *Subject:* RE: [meta-virtualization][PATCH][v2] docker: uprev to 1.9.0
>>
>>
>>
>> Okay.  Let me add Lu wei.
>>
>>
>>
>> Hi Lu wei.
>>
>>
>>
>> Can you help to provide the arm64 test and configure message to Bruce?
>>
>>
>>
>>
>>
>> Thank you.
>>
>>
>>
>> Best Regards
>>
>> Zongchun
>>
>> *From:* Bruce Ashfield [mailto:bruce.ashfield at gmail.com
>> <bruce.ashfield at gmail.com>]
>> *Sent:* Tuesday, April 19, 2016 11:10 AM
>> *To:* Zongchun Yu
>> *Cc:* meta-virtualization at yoctoproject.org
>> *Subject:* Re: [meta-virtualization][PATCH][v2] docker: uprev to 1.9.0
>>
>>
>>
>>
>>
>>
>>
>> On Mon, Apr 18, 2016 at 10:26 PM, Zongchun Yu <zongchun.yu at nxp.com>
>> wrote:
>>
>> Hi Bruce.
>>
>> May I know if you have comments about this v2 patch? If not. Can you help
>> to apply the patch?
>>
>>
>>
>>
>>
>> I'm waiting to hear from Bogdan P: .. you said the following:
>>
>>
>>
>> ------------
>>
>>
>>
>> Hi Bogdan P.
>>
>>
>>
>> Can you help to provide the arm64 test and configure messages to Bruce?
>>
>>
>>
>> -----------
>>
>>
>>
>> And I see no other email on the subject .. so I'm not sure why I'd have
>> started to merge a new version.
>>
>>
>>
>> Bruce
>>
>>
>>
>>
>> Thanks.
>>
>> Best Regards
>> Zongchun
>>
>> -----Original Message-----
>> From: zongchun.yu at nxp.com [mailto:zongchun.yu at nxp.com]
>> Sent: Tuesday, April 12, 2016 4:36 PM
>> To: meta-virtualization at yoctoproject.org
>> Cc: bruce.ashfield at gmail.com; Zongchun Yu
>> Subject: [meta-virtualization][PATCH][v2] docker: uprev to 1.9.0
>>
>> From: Zongchun Yu <zongchun.yu at nxp.com>
>>
>> Uprev to 1.9.0.
>> Enable build support for arm64.
>> The libcontainer is removed from the source in the new version. drop the
>> nsinit install lines.
>>
>> Signed-off-by: Zongchun Yu <zongchun.yu at nxp.com>
>> ---
>>  recipes-containers/docker/docker_git.bb            |   38 +-
>>  .../docker/files/Bump-bolt-to-v1.1.0.patch         | 1828
>> ++++++++++++++++++++
>>  .../docker/files/disable_sha1sum_startup.patch     |   21 +-
>>  3 files changed, 1855 insertions(+), 32 deletions(-)
>>  create mode 100644
>> recipes-containers/docker/files/Bump-bolt-to-v1.1.0.patch
>>
>> diff --git a/recipes-containers/docker/docker_git.bb
>> b/recipes-containers/docker/docker_git.bb
>> index 2672b22..19fdef0 100644
>> --- a/recipes-containers/docker/docker_git.bb
>> +++ b/recipes-containers/docker/docker_git.bb
>> @@ -18,23 +18,23 @@ DESCRIPTION = "Linux container runtime \
>>   subtle and/or glaring issues. \
>>   "
>>
>> -SRCREV = "7c8fca2ddb58c8d2c4fb4df31c242886df7dd257"
>> -SRCBRANCH = "v1.6.2"
>> +SRCREV = "76d6bc9a9f1690e16f3721ba165364688b626de2"
>>  SRC_URI = "\
>> -       git://github.com/docker/docker.git;branch=${SRCBRANCH};nobranch=1
>> <http://github.com/docker/docker.git;branch=$%7bSRCBRANCH%7d;nobranch=1>
>> \
>> +       git://github.com/docker/docker.git;nobranch=1 \
>>         file://docker.service \
>>         file://docker.init \
>>         file://hi.Dockerfile \
>>         file://disable_sha1sum_startup.patch \
>> +       file://Bump-bolt-to-v1.1.0.patch \
>>         "
>>
>>  # Apache-2.0 for docker
>>  LICENSE = "Apache-2.0"
>> -LIC_FILES_CHKSUM = "file://LICENSE;md5=1cc0497778922bfd6cb48721deb80dc7"
>> +LIC_FILES_CHKSUM = "file://LICENSE;md5=cc2221abf0b96ea39dd68141b70f7937"
>>
>>  S = "${WORKDIR}/git"
>>
>> -DOCKER_VERSION = "1.6.2"
>> +DOCKER_VERSION = "1.9.0"
>>  PV = "${DOCKER_VERSION}+git${SRCREV}"
>>
>>  DEPENDS = "go-cross \
>> @@ -62,17 +62,17 @@ RRECOMMENDS_${PN} = "lxc docker-registry rt-tests"
>>  RRECOMMENDS_${PN} += " kernel-module-dm-thin-pool kernel-module-nf-nat"
>>  DOCKER_PKG="github.com/docker/docker"
>>
>> -do_configure() {
>> -}
>> +do_configure[noexec] = "1"
>>
>>  do_compile() {
>> -       export PATH=${STAGING_BINDIR_NATIVE}/${HOST_SYS}/go-1.3:$PATH
>> -
>>         export GOARCH="${TARGET_ARCH}"
>> -       # supported amd64, 386, arm
>> +       # supported amd64, 386, arm arm64
>>         if [ "${TARGET_ARCH}" = "x86_64" ]; then
>>                 export GOARCH="amd64"
>>         fi
>> +       if [ "${TARGET_ARCH}" = "aarch64" ]; then
>> +               export GOARCH="arm64"
>> +       fi
>>
>>         # Set GOPATH. See 'PACKAGERS.md'. Don't rely on
>>         # docker to download its dependencies but rather
>> @@ -84,21 +84,19 @@ do_compile() {
>>         export
>> GOPATH="${S}/.gopath:${S}/vendor:${STAGING_DIR_TARGET}/${prefix}/local/go"
>>         cd -
>>
>> -       export CGO_ENABLED="1"
>> -
>>         # Pass the needed cflags/ldflags so that cgo
>>         # can find the needed headers files and libraries
>> -       export CGO_CFLAGS="${BUILDSDK_CFLAGS}"
>> -       export CGO_LDFLAGS="${BUILDSDK_LDFLAGS}"
>> +       export CGO_ENABLED="1"
>> +       export CGO_CFLAGS="${BUILDSDK_CFLAGS}
>> --sysroot=${STAGING_DIR_TARGET}"
>> +       export CGO_LDFLAGS="${BUILDSDK_LDFLAGS}
>> --sysroot=${STAGING_DIR_TARGET}"
>> +       # in order to exclude devicemapper and btrfs -
>> https://github.com/docker/docker/issues/14056
>> +       export DOCKER_BUILDTAGS='exclude_graphdriver_btrfs
>> exclude_graphdriver_devicemapper'
>>
>>         # this is the unsupported built structure
>>         # that doesn't rely on an existing docker
>>         # to build this:
>>         DOCKER_GITCOMMIT="${SRCREV}" \
>>           ./hack/make.sh dynbinary
>> -
>> -       # make nsinit from libcontainer
>> -       go install github.com/docker/libcontainer/nsinit/
>>  }
>>
>>  inherit systemd update-rc.d
>> @@ -127,12 +125,6 @@ do_install() {
>>              install -m 0755 ${WORKDIR}/docker.init
>> ${D}${sysconfdir}/init.d/docker.init
>>         fi
>>
>> -       if [ -d ${S}/vendor/bin/linux_* ]; then
>> -               cp ${S}/vendor/bin/linux_*/* ${D}/${bindir}
>> -       else
>> -               cp ${S}/vendor/bin/* ${D}/${bindir}
>> -       fi
>> -
>>         mkdir -p ${D}/usr/share/docker/
>>         cp ${WORKDIR}/hi.Dockerfile ${D}/usr/share/docker/
>>  }
>> diff --git a/recipes-containers/docker/files/Bump-bolt-to-v1.1.0.patch
>> b/recipes-containers/docker/files/Bump-bolt-to-v1.1.0.patch
>> new file mode 100644
>> index 0000000..ca4ad81
>> --- /dev/null
>> +++ b/recipes-containers/docker/files/Bump-bolt-to-v1.1.0.patch
>> @@ -0,0 +1,1828 @@
>> +From a41917c2c88bd7f694d141ac67f4a194aaa16fa1 Mon Sep 17 00:00:00 2001
>> +From: Qiang Huang <h.huangqiang at huawei.com>
>> +Date: Wed, 28 Oct 2015 08:49:45 +0800
>> +Subject: [PATCH] Bump bolt to v1.1.0
>> +
>> +It adds ARM64, ppc64le, s390x, solaris support, and a bunch of
>> +bugfixs.
>> +
>> +Signed-off-by: Qiang Huang <h.huangqiang at huawei.com>
>> +---
>> + hack/vendor.sh                                     |   2 +-
>> + vendor/src/github.com/boltdb/bolt/.gitignore       |   1 +
>> + vendor/src/github.com/boltdb/bolt/README.md        | 250
>> +++++++++++++++++++--
>> + vendor/src/github.com/boltdb/bolt/batch.go         | 138 ++++++++++++
>> + vendor/src/github.com/boltdb/bolt/bolt_386.go      |   5 +-
>> + vendor/src/github.com/boltdb/bolt/bolt_amd64.go    |   3 +
>> + vendor/src/github.com/boltdb/bolt/bolt_arm.go      |   5 +-
>> + vendor/src/github.com/boltdb/bolt/bolt_arm64.go    |   9 +
>> + vendor/src/github.com/boltdb/bolt/bolt_ppc64le.go  |   9 +
>> + vendor/src/github.com/boltdb/bolt/bolt_s390x.go    |   9 +
>> + vendor/src/github.com/boltdb/bolt/bolt_unix.go     |  37 ++-
>> + .../github.com/boltdb/bolt/bolt_unix_solaris.go    | 101 +++++++++
>> + vendor/src/github.com/boltdb/bolt/bolt_windows.go  |  10 +-
>> + vendor/src/github.com/boltdb/bolt/bucket.go        |  29 ++-
>> + vendor/src/github.com/boltdb/bolt/cursor.go        |  12 +-
>> + vendor/src/github.com/boltdb/bolt/db.go            | 195
>> ++++++++++++----
>> + vendor/src/github.com/boltdb/bolt/errors.go        |   4 +
>> + vendor/src/github.com/boltdb/bolt/freelist.go      |  28 ++-
>> + vendor/src/github.com/boltdb/bolt/node.go          |  36 ++-
>> + vendor/src/github.com/boltdb/bolt/page.go          |  45 +++-
>> + vendor/src/github.com/boltdb/bolt/tx.go            |  80 +++++--
>> + 21 files changed, 886 insertions(+), 122 deletions(-)
>> + create mode 100644 vendor/src/github.com/boltdb/bolt/batch.go
>> + create mode 100644 vendor/src/github.com/boltdb/bolt/bolt_arm64.go
>> + create mode 100644 vendor/src/github.com/boltdb/bolt/bolt_ppc64le.go
>> + create mode 100644 vendor/src/github.com/boltdb/bolt/bolt_s390x.go
>> + create mode 100644 vendor/src/
>> github.com/boltdb/bolt/bolt_unix_solaris.go
>> +
>> +diff --git a/hack/vendor.sh b/hack/vendor.sh
>> +index d872d4a..c28e677 100755
>> +--- a/hack/vendor.sh
>> ++++ b/hack/vendor.sh
>> +@@ -36,7 +36,7 @@ clone git github.com/coreos/etcd v2.2.0
>> + fix_rewritten_imports github.com/coreos/etcd
>> + clone git github.com/ugorji/go 5abd4e96a45c386928ed2ca2a7ef63e2533e18ec
>> + clone git github.com/hashicorp/consul v0.5.2
>> +-clone git github.com/boltdb/bolt v1.0
>> ++clone git github.com/boltdb/bolt v1.1.0
>> +
>> + # get graph and distribution packages
>> + clone git github.com/docker/distribution
>> 20c4b7a1805a52753dfd593ee1cc35558722a0ce # docker/1.9 branch
>> +diff --git a/vendor/src/github.com/boltdb/bolt/.gitignore b/vendor/src/
>> github.com/boltdb/bolt/.gitignore
>> +index b2bb382..c7bd2b7 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/.gitignore
>> ++++ b/vendor/src/github.com/boltdb/bolt/.gitignore
>> +@@ -1,3 +1,4 @@
>> + *.prof
>> + *.test
>> ++*.swp
>> + /bin/
>> +diff --git a/vendor/src/github.com/boltdb/bolt/README.md b/vendor/src/
>> github.com/boltdb/bolt/README.md
>> +index 727e977..0a33ebc 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/README.md
>> ++++ b/vendor/src/github.com/boltdb/bolt/README.md
>> +@@ -16,7 +16,7 @@ and setting values. That's it.
>> +
>> + ## Project Status
>> +
>> +-Bolt is stable and the API is fixed. Full unit test coverage and
>> randomized
>> ++Bolt is stable and the API is fixed. Full unit test coverage and
>> randomized
>> + black box testing are used to ensure database consistency and thread
>> safety.
>> + Bolt is currently in high-load production environments serving
>> databases as
>> + large as 1TB. Many companies such as Shopify and Heroku use Bolt-backed
>> +@@ -87,6 +87,11 @@ are not thread safe. To work with data in multiple
>> goroutines you must start
>> + a transaction for each one or use locking to ensure only one goroutine
>> accesses
>> + a transaction at a time. Creating transaction from the `DB` is thread
>> safe.
>> +
>> ++Read-only transactions and read-write transactions should not depend on
>> one
>> ++another and generally shouldn't be opened simultaneously in the same
>> goroutine.
>> ++This can cause a deadlock as the read-write transaction needs to
>> periodically
>> ++re-map the data file but it cannot do so while a read-only transaction
>> is open.
>> ++
>> +
>> + #### Read-write transactions
>> +
>> +@@ -120,12 +125,88 @@ err := db.View(func(tx *bolt.Tx) error {
>> + })
>> + ```
>> +
>> +-You also get a consistent view of the database within this closure,
>> however,
>> ++You also get a consistent view of the database within this closure,
>> however,
>> + no mutating operations are allowed within a read-only transaction. You
>> can only
>> + retrieve buckets, retrieve values, and copy the database within a
>> read-only
>> + transaction.
>> +
>> +
>> ++#### Batch read-write transactions
>> ++
>> ++Each `DB.Update()` waits for disk to commit the writes. This overhead
>> ++can be minimized by combining multiple updates with the `DB.Batch()`
>> ++function:
>> ++
>> ++```go
>> ++err := db.Batch(func(tx *bolt.Tx) error {
>> ++      ...
>> ++      return nil
>> ++})
>> ++```
>> ++
>> ++Concurrent Batch calls are opportunistically combined into larger
>> ++transactions. Batch is only useful when there are multiple goroutines
>> ++calling it.
>> ++
>> ++The trade-off is that `Batch` can call the given
>> ++function multiple times, if parts of the transaction fail. The
>> ++function must be idempotent and side effects must take effect only
>> ++after a successful return from `DB.Batch()`.
>> ++
>> ++For example: don't display messages from inside the function, instead
>> ++set variables in the enclosing scope:
>> ++
>> ++```go
>> ++var id uint64
>> ++err := db.Batch(func(tx *bolt.Tx) error {
>> ++      // Find last key in bucket, decode as bigendian uint64, increment
>> ++      // by one, encode back to []byte, and add new key.
>> ++      ...
>> ++      id = newValue
>> ++      return nil
>> ++})
>> ++if err != nil {
>> ++      return ...
>> ++}
>> ++fmt.Println("Allocated ID %d", id)
>> ++```
>> ++
>> ++
>> ++#### Managing transactions manually
>> ++
>> ++The `DB.View()` and `DB.Update()` functions are wrappers around the
>> `DB.Begin()`
>> ++function. These helper functions will start the transaction, execute a
>> function,
>> ++and then safely close your transaction if an error is returned. This is
>> the
>> ++recommended way to use Bolt transactions.
>> ++
>> ++However, sometimes you may want to manually start and end your
>> transactions.
>> ++You can use the `Tx.Begin()` function directly but _please_ be sure to
>> close the
>> ++transaction.
>> ++
>> ++```go
>> ++// Start a writable transaction.
>> ++tx, err := db.Begin(true)
>> ++if err != nil {
>> ++    return err
>> ++}
>> ++defer tx.Rollback()
>> ++
>> ++// Use the transaction...
>> ++_, err := tx.CreateBucket([]byte("MyBucket"))
>> ++if err != nil {
>> ++    return err
>> ++}
>> ++
>> ++// Commit the transaction and check for error.
>> ++if err := tx.Commit(); err != nil {
>> ++    return err
>> ++}
>> ++```
>> ++
>> ++The first argument to `DB.Begin()` is a boolean stating if the
>> transaction
>> ++should be writable.
>> ++
>> ++
>> + ### Using buckets
>> +
>> + Buckets are collections of key/value pairs within the database. All
>> keys in a
>> +@@ -175,13 +256,61 @@ db.View(func(tx *bolt.Tx) error {
>> + ```
>> +
>> + The `Get()` function does not return an error because its operation is
>> +-guarenteed to work (unless there is some kind of system failure). If
>> the key
>> ++guaranteed to work (unless there is some kind of system failure). If
>> the key
>> + exists then it will return its byte slice value. If it doesn't exist
>> then it
>> + will return `nil`. It's important to note that you can have a
>> zero-length value
>> + set to a key which is different than the key not existing.
>> +
>> + Use the `Bucket.Delete()` function to delete a key from the bucket.
>> +
>> ++Please note that values returned from `Get()` are only valid while the
>> ++transaction is open. If you need to use a value outside of the
>> transaction
>> ++then you must use `copy()` to copy it to another byte slice.
>> ++
>> ++
>> ++### Autoincrementing integer for the bucket
>> ++By using the NextSequence() function, you can let Bolt determine a
>> sequence
>> ++which can be used as the unique identifier for your key/value pairs.
>> See the
>> ++example below.
>> ++
>> ++```go
>> ++// CreateUser saves u to the store. The new user ID is set on u once
>> the data is persisted.
>> ++func (s *Store) CreateUser(u *User) error {
>> ++    return s.db.Update(func(tx *bolt.Tx) error {
>> ++        // Retrieve the users bucket.
>> ++        // This should be created when the DB is first opened.
>> ++        b := tx.Bucket([]byte("users"))
>> ++
>> ++        // Generate ID for the user.
>> ++        // This returns an error only if the Tx is closed or not
>> writeable.
>> ++        // That can't happen in an Update() call so I ignore the error
>> check.
>> ++        id, _ = b.NextSequence()
>> ++        u.ID = int(id)
>> ++
>> ++        // Marshal user data into bytes.
>> ++        buf, err := json.Marshal(u)
>> ++        if err != nil {
>> ++            return err
>> ++        }
>> ++
>> ++        // Persist bytes to users bucket.
>> ++        return b.Put(itob(u.ID), buf)
>> ++    })
>> ++}
>> ++
>> ++// itob returns an 8-byte big endian representation of v.
>> ++func itob(v int) []byte {
>> ++    b := make([]byte, 8)
>> ++    binary.BigEndian.PutUint64(b, uint64(v))
>> ++    return b
>> ++}
>> ++
>> ++type User struct {
>> ++    ID int
>> ++    ...
>> ++}
>> ++
>> ++```
>> +
>> + ### Iterating over keys
>> +
>> +@@ -254,7 +383,7 @@ db.View(func(tx *bolt.Tx) error {
>> +       max := []byte("2000-01-01T00:00:00Z")
>> +
>> +       // Iterate over the 90's.
>> +-      for k, v := c.Seek(min); k != nil && bytes.Compare(k, max) != -1;
>> k, v = c.Next() {
>> ++      for k, v := c.Seek(min); k != nil && bytes.Compare(k, max) <= 0;
>> k, v = c.Next() {
>> +               fmt.Printf("%s: %s\n", k, v)
>> +       }
>> +
>> +@@ -294,7 +423,7 @@ func (*Bucket) DeleteBucket(key []byte) error
>> +
>> + ### Database backups
>> +
>> +-Bolt is a single file so it's easy to backup. You can use the
>> `Tx.Copy()`
>> ++Bolt is a single file so it's easy to backup. You can use the
>> `Tx.WriteTo()`
>> + function to write a consistent view of the database to a writer. If you
>> call
>> + this from a read-only transaction, it will perform a hot backup and not
>> block
>> + your other database reads and writes. It will also use `O_DIRECT` when
>> available
>> +@@ -305,11 +434,12 @@ do database backups:
>> +
>> + ```go
>> + func BackupHandleFunc(w http.ResponseWriter, req *http.Request) {
>> +-      err := db.View(func(tx bolt.Tx) error {
>> ++      err := db.View(func(tx *bolt.Tx) error {
>> +               w.Header().Set("Content-Type", "application/octet-stream")
>> +               w.Header().Set("Content-Disposition", `attachment;
>> filename="my.db"`)
>> +               w.Header().Set("Content-Length",
>> strconv.Itoa(int(tx.Size())))
>> +-              return tx.Copy(w)
>> ++              _, err := tx.WriteTo(w)
>> ++              return err
>> +       })
>> +       if err != nil {
>> +               http.Error(w, err.Error(), http.StatusInternalServerError)
>> +@@ -351,14 +481,13 @@ go func() {
>> +               // Grab the current stats and diff them.
>> +               stats := db.Stats()
>> +               diff := stats.Sub(&prev)
>> +-
>> ++
>> +               // Encode stats to JSON and print to STDERR.
>> +               json.NewEncoder(os.Stderr).Encode(diff)
>> +
>> +               // Save stats for the next loop.
>> +               prev = stats
>> +       }
>> +-}
>> + }()
>> + ```
>> +
>> +@@ -366,25 +495,83 @@ It's also useful to pipe these stats to a service
>> such as statsd for monitoring
>> + or to provide an HTTP endpoint that will perform a fixed-length sample.
>> +
>> +
>> ++### Read-Only Mode
>> ++
>> ++Sometimes it is useful to create a shared, read-only Bolt database. To
>> this,
>> ++set the `Options.ReadOnly` flag when opening your database. Read-only
>> mode
>> ++uses a shared lock to allow multiple processes to read from the
>> database but
>> ++it will block any processes from opening the database in read-write
>> mode.
>> ++
>> ++```go
>> ++db, err := bolt.Open("my.db", 0666, &bolt.Options{ReadOnly: true})
>> ++if err != nil {
>> ++      log.Fatal(err)
>> ++}
>> ++```
>> ++
>> ++
>> + ## Resources
>> +
>> + For more information on getting started with Bolt, check out the
>> following articles:
>> +
>> + * [Intro to BoltDB: Painless Performant Persistence](
>> http://npf.io/2014/07/intro-to-boltdb-painless-performant-persistence/)
>> by [Nate Finch](https://github.com/natefinch).
>> ++* [Bolt -- an embedded key/value database for Go](
>> https://www.progville.com/go/bolt-embedded-db-golang/) by Progville
>> ++
>> ++
>> ++## Comparison with other databases
>> ++
>> ++### Postgres, MySQL, & other relational databases
>> ++
>> ++Relational databases structure data into rows and are only accessible
>> through
>> ++the use of SQL. This approach provides flexibility in how you store and
>> query
>> ++your data but also incurs overhead in parsing and planning SQL
>> statements. Bolt
>> ++accesses all data by a byte slice key. This makes Bolt fast to read and
>> write
>> ++data by key but provides no built-in support for joining values
>> together.
>> ++
>> ++Most relational databases (with the exception of SQLite) are standalone
>> servers
>> ++that run separately from your application. This gives your systems
>> ++flexibility to connect multiple application servers to a single database
>> ++server but also adds overhead in serializing and transporting data over
>> the
>> ++network. Bolt runs as a library included in your application so all
>> data access
>> ++has to go through your application's process. This brings data closer
>> to your
>> ++application but limits multi-process access to the data.
>> ++
>> ++
>> ++### LevelDB, RocksDB
>> +
>> ++LevelDB and its derivatives (RocksDB, HyperLevelDB) are similar to Bolt
>> in that
>> ++they are libraries bundled into the application, however, their
>> underlying
>> ++structure is a log-structured merge-tree (LSM tree). An LSM tree
>> optimizes
>> ++random writes by using a write ahead log and multi-tiered, sorted files
>> called
>> ++SSTables. Bolt uses a B+tree internally and only a single file. Both
>> approaches
>> ++have trade offs.
>> +
>> ++If you require a high random write throughput (>10,000 w/sec) or you
>> need to use
>> ++spinning disks then LevelDB could be a good choice. If your application
>> is
>> ++read-heavy or does a lot of range scans then Bolt could be a good
>> choice.
>> +
>> +-## Comparing Bolt to LMDB
>> ++One other important consideration is that LevelDB does not have
>> transactions.
>> ++It supports batch writing of key/values pairs and it supports read
>> snapshots
>> ++but it will not give you the ability to do a compare-and-swap operation
>> safely.
>> ++Bolt supports fully serializable ACID transactions.
>> ++
>> ++
>> ++### LMDB
>> +
>> + Bolt was originally a port of LMDB so it is architecturally similar.
>> Both use
>> +-a B+tree, have ACID semanetics with fully serializable transactions,
>> and support
>> ++a B+tree, have ACID semantics with fully serializable transactions, and
>> support
>> + lock-free MVCC using a single writer and multiple readers.
>> +
>> + The two projects have somewhat diverged. LMDB heavily focuses on raw
>> performance
>> + while Bolt has focused on simplicity and ease of use. For example, LMDB
>> allows
>> +-several unsafe actions such as direct writes and append writes for the
>> sake of
>> +-performance. Bolt opts to disallow actions which can leave the database
>> in a
>> +-corrupted state. The only exception to this in Bolt is `DB.NoSync`.
>> ++several unsafe actions such as direct writes for the sake of
>> performance. Bolt
>> ++opts to disallow actions which can leave the database in a corrupted
>> state. The
>> ++only exception to this in Bolt is `DB.NoSync`.
>> ++
>> ++There are also a few differences in API. LMDB requires a maximum mmap
>> size when
>> ++opening an `mdb_env` whereas Bolt will handle incremental mmap resizing
>> ++automatically. LMDB overloads the getter and setter functions with
>> multiple
>> ++flags whereas Bolt splits these specialized cases into their own
>> functions.
>> +
>> +
>> + ## Caveats & Limitations
>> +@@ -425,14 +612,33 @@ Here are a few things to note when evaluating and
>> using Bolt:
>> +   can in memory and will release memory as needed to other processes.
>> This means
>> +   that Bolt can show very high memory usage when working with large
>> databases.
>> +   However, this is expected and the OS will release memory as needed.
>> Bolt can
>> +-  handle databases much larger than the available physical RAM.
>> ++  handle databases much larger than the available physical RAM,
>> provided its
>> ++  memory-map fits in the process virtual address space. It may be
>> problematic
>> ++  on 32-bits systems.
>> ++
>> ++* The data structures in the Bolt database are memory mapped so the
>> data file
>> ++  will be endian specific. This means that you cannot copy a Bolt file
>> from a
>> ++  little endian machine to a big endian machine and have it work. For
>> most
>> ++  users this is not a concern since most modern CPUs are little endian.
>> ++
>> ++* Because of the way pages are laid out on disk, Bolt cannot truncate
>> data files
>> ++  and return free pages back to the disk. Instead, Bolt maintains a
>> free list
>> ++  of unused pages within its data file. These free pages can be reused
>> by later
>> ++  transactions. This works well for many use cases as databases
>> generally tend
>> ++  to grow. However, it's important to note that deleting large chunks
>> of data
>> ++  will not allow you to reclaim that space on disk.
>> ++
>> ++  For more information on page allocation, [see this
>> comment][page-allocation].
>> ++
>> ++[page-allocation]:
>> https://github.com/boltdb/bolt/issues/308#issuecomment-74811638
>> +
>> +
>> + ## Other Projects Using Bolt
>> +
>> + Below is a list of public, open source projects that use Bolt:
>> +
>> +-* [Bazil](https://github.com/bazillion/bazil) - A file system that
>> lets your data reside where it is most convenient for it to reside.
>> ++* [Operation Go: A Routine Mission](http://gocode.io) - An online
>> programming game for Golang using Bolt for user accounts and a leaderboard.
>> ++* [Bazil](https://bazil.org/) - A file system that lets your data
>> reside where it is most convenient for it to reside.
>> + * [DVID](https://github.com/janelia-flyem/dvid) - Added Bolt as
>> optional storage engine and testing it against Basho-tuned leveldb.
>> + * [Skybox Analytics](https://github.com/skybox/skybox) - A standalone
>> funnel analysis tool for web analytics.
>> + * [Scuttlebutt](https://github.com/benbjohnson/scuttlebutt) - Uses
>> Bolt to store and process all Twitter mentions of GitHub projects.
>> +@@ -450,6 +656,16 @@ Below is a list of public, open source projects
>> that use Bolt:
>> + * [bleve](http://www.blevesearch.com/) - A pure Go search engine
>> similar to ElasticSearch that uses Bolt as the default storage backend.
>> + * [tentacool](https://github.com/optiflows/tentacool) - REST api
>> server to manage system stuff (IP, DNS, Gateway...) on a linux server.
>> + * [SkyDB](https://github.com/skydb/sky) - Behavioral analytics
>> database.
>> ++* [Seaweed File System](https://github.com/chrislusf/weed-fs) - Highly
>> scalable distributed key~file system with O(1) disk read.
>> ++* [InfluxDB](http://influxdb.com) - Scalable datastore for metrics,
>> events, and real-time analytics.
>> ++* [Freehold](http://tshannon.bitbucket.org/freehold/) - An open,
>> secure, and lightweight platform for your files and data.
>> ++* [Prometheus Annotation Server](
>> https://github.com/oliver006/prom_annotation_server) - Annotation server
>> for PromDash & Prometheus service monitoring system.
>> ++* [Consul](https://github.com/hashicorp/consul) - Consul is service
>> discovery and configuration made easy. Distributed, highly available, and
>> datacenter-aware.
>> ++* [Kala](https://github.com/ajvb/kala) - Kala is a modern job
>> scheduler optimized to run on a single node. It is persistent, JSON over
>> HTTP API, ISO 8601 duration notation, and dependent jobs.
>> ++* [drive](https://github.com/odeke-em/drive) - drive is an unofficial
>> Google Drive command line client for \*NIX operating systems.
>> ++* [stow](https://github.com/djherbis/stow) -  a persistence manager
>> for objects
>> ++  backed by boltdb.
>> ++* [buckets](https://github.com/joyrexus/buckets) - a bolt wrapper
>> streamlining
>> ++  simple tx and key scans.
>> +
>> + If you are using Bolt in a project please send a pull request to add it
>> to the list.
>> +-
>> +diff --git a/vendor/src/github.com/boltdb/bolt/batch.go b/vendor/src/
>> github.com/boltdb/bolt/batch.go
>> +new file mode 100644
>> +index 0000000..84acae6
>> +--- /dev/null
>> ++++ b/vendor/src/github.com/boltdb/bolt/batch.go
>> +@@ -0,0 +1,138 @@
>> ++package bolt
>> ++
>> ++import (
>> ++      "errors"
>> ++      "fmt"
>> ++      "sync"
>> ++      "time"
>> ++)
>> ++
>> ++// Batch calls fn as part of a batch. It behaves similar to Update,
>> ++// except:
>> ++//
>> ++// 1. concurrent Batch calls can be combined into a single Bolt
>> ++// transaction.
>> ++//
>> ++// 2. the function passed to Batch may be called multiple times,
>> ++// regardless of whether it returns error or not.
>> ++//
>> ++// This means that Batch function side effects must be idempotent and
>> ++// take permanent effect only after a successful return is seen in
>> ++// caller.
>> ++//
>> ++// The maximum batch size and delay can be adjusted with DB.MaxBatchSize
>> ++// and DB.MaxBatchDelay, respectively.
>> ++//
>> ++// Batch is only useful when there are multiple goroutines calling it.
>> ++func (db *DB) Batch(fn func(*Tx) error) error {
>> ++      errCh := make(chan error, 1)
>> ++
>> ++      db.batchMu.Lock()
>> ++      if (db.batch == nil) || (db.batch != nil && len(db.batch.calls)
>> >= db.MaxBatchSize) {
>> ++              // There is no existing batch, or the existing batch is
>> full; start a new one.
>> ++              db.batch = &batch{
>> ++                      db: db,
>> ++              }
>> ++              db.batch.timer = time.AfterFunc(db.MaxBatchDelay,
>> db.batch.trigger)
>> ++      }
>> ++      db.batch.calls = append(db.batch.calls, call{fn: fn, err: errCh})
>> ++      if len(db.batch.calls) >= db.MaxBatchSize {
>> ++              // wake up batch, it's ready to run
>> ++              go db.batch.trigger()
>> ++      }
>> ++      db.batchMu.Unlock()
>> ++
>> ++      err := <-errCh
>> ++      if err == trySolo {
>> ++              err = db.Update(fn)
>> ++      }
>> ++      return err
>> ++}
>> ++
>> ++type call struct {
>> ++      fn  func(*Tx) error
>> ++      err chan<- error
>> ++}
>> ++
>> ++type batch struct {
>> ++      db    *DB
>> ++      timer *time.Timer
>> ++      start sync.Once
>> ++      calls []call
>> ++}
>> ++
>> ++// trigger runs the batch if it hasn't already been run.
>> ++func (b *batch) trigger() {
>> ++      b.start.Do(b.run)
>> ++}
>> ++
>> ++// run performs the transactions in the batch and communicates results
>> ++// back to DB.Batch.
>> ++func (b *batch) run() {
>> ++      b.db.batchMu.Lock()
>> ++      b.timer.Stop()
>> ++      // Make sure no new work is added to this batch, but don't break
>> ++      // other batches.
>> ++      if b.db.batch == b {
>> ++              b.db.batch = nil
>> ++      }
>> ++      b.db.batchMu.Unlock()
>> ++
>> ++retry:
>> ++      for len(b.calls) > 0 {
>> ++              var failIdx = -1
>> ++              err := b.db.Update(func(tx *Tx) error {
>> ++                      for i, c := range b.calls {
>> ++                              if err := safelyCall(c.fn, tx); err !=
>> nil {
>> ++                                      failIdx = i
>> ++                                      return err
>> ++                              }
>> ++                      }
>> ++                      return nil
>> ++              })
>> ++
>> ++              if failIdx >= 0 {
>> ++                      // take the failing transaction out of the batch.
>> it's
>> ++                      // safe to shorten b.calls here because db.batch
>> no longer
>> ++                      // points to us, and we hold the mutex anyway.
>> ++                      c := b.calls[failIdx]
>> ++                      b.calls[failIdx], b.calls =
>> b.calls[len(b.calls)-1], b.calls[:len(b.calls)-1]
>> ++                      // tell the submitter re-run it solo, continue
>> with the rest of the batch
>> ++                      c.err <- trySolo
>> ++                      continue retry
>> ++              }
>> ++
>> ++              // pass success, or bolt internal errors, to all callers
>> ++              for _, c := range b.calls {
>> ++                      if c.err != nil {
>> ++                              c.err <- err
>> ++                      }
>> ++              }
>> ++              break retry
>> ++      }
>> ++}
>> ++
>> ++// trySolo is a special sentinel error value used for signaling that a
>> ++// transaction function should be re-run. It should never be seen by
>> ++// callers.
>> ++var trySolo = errors.New("batch function returned an error and should
>> be re-run solo")
>> ++
>> ++type panicked struct {
>> ++      reason interface{}
>> ++}
>> ++
>> ++func (p panicked) Error() string {
>> ++      if err, ok := p.reason.(error); ok {
>> ++              return err.Error()
>> ++      }
>> ++      return fmt.Sprintf("panic: %v", p.reason)
>> ++}
>> ++
>> ++func safelyCall(fn func(*Tx) error, tx *Tx) (err error) {
>> ++      defer func() {
>> ++              if p := recover(); p != nil {
>> ++                      err = panicked{p}
>> ++              }
>> ++      }()
>> ++      return fn(tx)
>> ++}
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_386.go b/vendor/src/
>> github.com/boltdb/bolt/bolt_386.go
>> +index 856f401..e659bfb 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bolt_386.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_386.go
>> +@@ -1,4 +1,7 @@
>> + package bolt
>> +
>> + // maxMapSize represents the largest mmap size supported by Bolt.
>> +-const maxMapSize = 0xFFFFFFF // 256MB
>> ++const maxMapSize = 0x7FFFFFFF // 2GB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0xFFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_amd64.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_amd64.go
>> +index 4262932..cca6b7e 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bolt_amd64.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_amd64.go
>> +@@ -2,3 +2,6 @@ package bolt
>> +
>> + // maxMapSize represents the largest mmap size supported by Bolt.
>> + const maxMapSize = 0xFFFFFFFFFFFF // 256TB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0x7FFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_arm.go b/vendor/src/
>> github.com/boltdb/bolt/bolt_arm.go
>> +index 856f401..e659bfb 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bolt_arm.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_arm.go
>> +@@ -1,4 +1,7 @@
>> + package bolt
>> +
>> + // maxMapSize represents the largest mmap size supported by Bolt.
>> +-const maxMapSize = 0xFFFFFFF // 256MB
>> ++const maxMapSize = 0x7FFFFFFF // 2GB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0xFFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_arm64.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_arm64.go
>> +new file mode 100644
>> +index 0000000..6d23093
>> +--- /dev/null
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_arm64.go
>> +@@ -0,0 +1,9 @@
>> ++// +build arm64
>> ++
>> ++package bolt
>> ++
>> ++// maxMapSize represents the largest mmap size supported by Bolt.
>> ++const maxMapSize = 0xFFFFFFFFFFFF // 256TB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0x7FFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_ppc64le.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_ppc64le.go
>> +new file mode 100644
>> +index 0000000..8351e12
>> +--- /dev/null
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_ppc64le.go
>> +@@ -0,0 +1,9 @@
>> ++// +build ppc64le
>> ++
>> ++package bolt
>> ++
>> ++// maxMapSize represents the largest mmap size supported by Bolt.
>> ++const maxMapSize = 0xFFFFFFFFFFFF // 256TB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0x7FFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_s390x.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_s390x.go
>> +new file mode 100644
>> +index 0000000..f4dd26b
>> +--- /dev/null
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_s390x.go
>> +@@ -0,0 +1,9 @@
>> ++// +build s390x
>> ++
>> ++package bolt
>> ++
>> ++// maxMapSize represents the largest mmap size supported by Bolt.
>> ++const maxMapSize = 0xFFFFFFFFFFFF // 256TB
>> ++
>> ++// maxAllocSize is the size used when creating array pointers.
>> ++const maxAllocSize = 0x7FFFFFFF
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_unix.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_unix.go
>> +index 95647a7..6eef6b2 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bolt_unix.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_unix.go
>> +@@ -1,8 +1,9 @@
>> +-// +build !windows,!plan9
>> ++// +build !windows,!plan9,!solaris
>> +
>> + package bolt
>> +
>> + import (
>> ++      "fmt"
>> +       "os"
>> +       "syscall"
>> +       "time"
>> +@@ -10,7 +11,7 @@ import (
>> + )
>> +
>> + // flock acquires an advisory lock on a file descriptor.
>> +-func flock(f *os.File, timeout time.Duration) error {
>> ++func flock(f *os.File, exclusive bool, timeout time.Duration) error {
>> +       var t time.Time
>> +       for {
>> +               // If we're beyond our timeout then return an error.
>> +@@ -20,9 +21,13 @@ func flock(f *os.File, timeout time.Duration) error {
>> +               } else if timeout > 0 && time.Since(t) > timeout {
>> +                       return ErrTimeout
>> +               }
>> ++              flag := syscall.LOCK_SH
>> ++              if exclusive {
>> ++                      flag = syscall.LOCK_EX
>> ++              }
>> +
>> +               // Otherwise attempt to obtain an exclusive lock.
>> +-              err := syscall.Flock(int(f.Fd()),
>> syscall.LOCK_EX|syscall.LOCK_NB)
>> ++              err := syscall.Flock(int(f.Fd()), flag|syscall.LOCK_NB)
>> +               if err == nil {
>> +                       return nil
>> +               } else if err != syscall.EWOULDBLOCK {
>> +@@ -41,11 +46,28 @@ func funlock(f *os.File) error {
>> +
>> + // mmap memory maps a DB's data file.
>> + func mmap(db *DB, sz int) error {
>> ++      // Truncate and fsync to ensure file size metadata is flushed.
>> ++      // https://github.com/boltdb/bolt/issues/284
>> ++      if !db.NoGrowSync && !db.readOnly {
>> ++              if err := db.file.Truncate(int64(sz)); err != nil {
>> ++                      return fmt.Errorf("file resize error: %s", err)
>> ++              }
>> ++              if err := db.file.Sync(); err != nil {
>> ++                      return fmt.Errorf("file sync error: %s", err)
>> ++              }
>> ++      }
>> ++
>> ++      // Map the data file to memory.
>> +       b, err := syscall.Mmap(int(db.file.Fd()), 0, sz,
>> syscall.PROT_READ, syscall.MAP_SHARED)
>> +       if err != nil {
>> +               return err
>> +       }
>> +
>> ++      // Advise the kernel that the mmap is accessed randomly.
>> ++      if err := madvise(b, syscall.MADV_RANDOM); err != nil {
>> ++              return fmt.Errorf("madvise: %s", err)
>> ++      }
>> ++
>> +       // Save the original byte slice and convert to a byte array
>> pointer.
>> +       db.dataref = b
>> +       db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
>> +@@ -67,3 +89,12 @@ func munmap(db *DB) error {
>> +       db.datasz = 0
>> +       return err
>> + }
>> ++
>> ++// NOTE: This function is copied from stdlib because it is not
>> available on darwin.
>> ++func madvise(b []byte, advice int) (err error) {
>> ++      _, _, e1 := syscall.Syscall(syscall.SYS_MADVISE,
>> uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)), uintptr(advice))
>> ++      if e1 != 0 {
>> ++              err = e1
>> ++      }
>> ++      return
>> ++}
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_unix_solaris.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_unix_solaris.go
>> +new file mode 100644
>> +index 0000000..f480ee7
>> +--- /dev/null
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_unix_solaris.go
>> +@@ -0,0 +1,101 @@
>> ++
>> ++package bolt
>> ++
>> ++import (
>> ++      "fmt"
>> ++      "os"
>> ++      "syscall"
>> ++      "time"
>> ++      "unsafe"
>> ++      "golang.org/x/sys/unix"
>> ++)
>> ++
>> ++// flock acquires an advisory lock on a file descriptor.
>> ++func flock(f *os.File, exclusive bool, timeout time.Duration) error {
>> ++      var t time.Time
>> ++      for {
>> ++              // If we're beyond our timeout then return an error.
>> ++              // This can only occur after we've attempted a flock once.
>> ++              if t.IsZero() {
>> ++                      t = time.Now()
>> ++              } else if timeout > 0 && time.Since(t) > timeout {
>> ++                      return ErrTimeout
>> ++              }
>> ++              var lock syscall.Flock_t
>> ++              lock.Start = 0
>> ++              lock.Len = 0
>> ++              lock.Pid = 0
>> ++              lock.Whence = 0
>> ++              lock.Pid = 0
>> ++              if exclusive {
>> ++                      lock.Type = syscall.F_WRLCK
>> ++              } else {
>> ++                      lock.Type = syscall.F_RDLCK
>> ++              }
>> ++              err := syscall.FcntlFlock(f.Fd(), syscall.F_SETLK, &lock)
>> ++              if err == nil {
>> ++                      return nil
>> ++              } else if err != syscall.EAGAIN {
>> ++                      return err
>> ++              }
>> ++
>> ++              // Wait for a bit and try again.
>> ++              time.Sleep(50 * time.Millisecond)
>> ++      }
>> ++}
>> ++
>> ++// funlock releases an advisory lock on a file descriptor.
>> ++func funlock(f *os.File) error {
>> ++      var lock syscall.Flock_t
>> ++      lock.Start = 0
>> ++      lock.Len = 0
>> ++      lock.Type = syscall.F_UNLCK
>> ++      lock.Whence = 0
>> ++      return syscall.FcntlFlock(uintptr(f.Fd()), syscall.F_SETLK, &lock)
>> ++}
>> ++
>> ++// mmap memory maps a DB's data file.
>> ++func mmap(db *DB, sz int) error {
>> ++      // Truncate and fsync to ensure file size metadata is flushed.
>> ++      // https://github.com/boltdb/bolt/issues/284
>> ++      if !db.NoGrowSync && !db.readOnly {
>> ++              if err := db.file.Truncate(int64(sz)); err != nil {
>> ++                      return fmt.Errorf("file resize error: %s", err)
>> ++              }
>> ++              if err := db.file.Sync(); err != nil {
>> ++                      return fmt.Errorf("file sync error: %s", err)
>> ++              }
>> ++      }
>> ++
>> ++      // Map the data file to memory.
>> ++      b, err := unix.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ,
>> syscall.MAP_SHARED)
>> ++      if err != nil {
>> ++              return err
>> ++      }
>> ++
>> ++      // Advise the kernel that the mmap is accessed randomly.
>> ++      if err := unix.Madvise(b, syscall.MADV_RANDOM); err != nil {
>> ++              return fmt.Errorf("madvise: %s", err)
>> ++      }
>> ++
>> ++      // Save the original byte slice and convert to a byte array
>> pointer.
>> ++      db.dataref = b
>> ++      db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
>> ++      db.datasz = sz
>> ++      return nil
>> ++}
>> ++
>> ++// munmap unmaps a DB's data file from memory.
>> ++func munmap(db *DB) error {
>> ++      // Ignore the unmap if we have no mapped data.
>> ++      if db.dataref == nil {
>> ++              return nil
>> ++      }
>> ++
>> ++      // Unmap using the original byte slice.
>> ++      err := unix.Munmap(db.dataref)
>> ++      db.dataref = nil
>> ++      db.data = nil
>> ++      db.datasz = 0
>> ++      return err
>> ++}
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bolt_windows.go
>> b/vendor/src/github.com/boltdb/bolt/bolt_windows.go
>> +index c8539d4..8b782be 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bolt_windows.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bolt_windows.go
>> +@@ -16,7 +16,7 @@ func fdatasync(db *DB) error {
>> + }
>> +
>> + // flock acquires an advisory lock on a file descriptor.
>> +-func flock(f *os.File, _ time.Duration) error {
>> ++func flock(f *os.File, _ bool, _ time.Duration) error {
>> +       return nil
>> + }
>> +
>> +@@ -28,9 +28,11 @@ func funlock(f *os.File) error {
>> + // mmap memory maps a DB's data file.
>> + // Based on: https://github.com/edsrzf/mmap-go
>> + func mmap(db *DB, sz int) error {
>> +-      // Truncate the database to the size of the mmap.
>> +-      if err := db.file.Truncate(int64(sz)); err != nil {
>> +-              return fmt.Errorf("truncate: %s", err)
>> ++      if !db.readOnly {
>> ++              // Truncate the database to the size of the mmap.
>> ++              if err := db.file.Truncate(int64(sz)); err != nil {
>> ++                      return fmt.Errorf("truncate: %s", err)
>> ++              }
>> +       }
>> +
>> +       // Open a file mapping handle.
>> +diff --git a/vendor/src/github.com/boltdb/bolt/bucket.go b/vendor/src/
>> github.com/boltdb/bolt/bucket.go
>> +index 2630800..2925288 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/bucket.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/bucket.go
>> +@@ -99,6 +99,7 @@ func (b *Bucket) Cursor() *Cursor {
>> +
>> + // Bucket retrieves a nested bucket by name.
>> + // Returns nil if the bucket does not exist.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (b *Bucket) Bucket(name []byte) *Bucket {
>> +       if b.buckets != nil {
>> +               if child := b.buckets[string(name)]; child != nil {
>> +@@ -148,6 +149,7 @@ func (b *Bucket) openBucket(value []byte) *Bucket {
>> +
>> + // CreateBucket creates a new bucket at the given key and returns the
>> new bucket.
>> + // Returns an error if the key already exists, if the bucket name is
>> blank, or if the bucket name is too long.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (b *Bucket) CreateBucket(key []byte) (*Bucket, error) {
>> +       if b.tx.db == nil {
>> +               return nil, ErrTxClosed
>> +@@ -192,6 +194,7 @@ func (b *Bucket) CreateBucket(key []byte) (*Bucket,
>> error) {
>> +
>> + // CreateBucketIfNotExists creates a new bucket if it doesn't already
>> exist and returns a reference to it.
>> + // Returns an error if the bucket name is blank, or if the bucket name
>> is too long.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (b *Bucket) CreateBucketIfNotExists(key []byte) (*Bucket, error) {
>> +       child, err := b.CreateBucket(key)
>> +       if err == ErrBucketExists {
>> +@@ -252,6 +255,7 @@ func (b *Bucket) DeleteBucket(key []byte) error {
>> +
>> + // Get retrieves the value for a key in the bucket.
>> + // Returns a nil value if the key does not exist or if the key is a
>> nested bucket.
>> ++// The returned value is only valid for the life of the transaction.
>> + func (b *Bucket) Get(key []byte) []byte {
>> +       k, v, flags := b.Cursor().seek(key)
>> +
>> +@@ -332,6 +336,12 @@ func (b *Bucket) NextSequence() (uint64, error) {
>> +               return 0, ErrTxNotWritable
>> +       }
>> +
>> ++      // Materialize the root node if it hasn't been already so that the
>> ++      // bucket will be saved during commit.
>> ++      if b.rootNode == nil {
>> ++              _ = b.node(b.root, nil)
>> ++      }
>> ++
>> +       // Increment and return the sequence.
>> +       b.bucket.sequence++
>> +       return b.bucket.sequence, nil
>> +@@ -339,7 +349,8 @@ func (b *Bucket) NextSequence() (uint64, error) {
>> +
>> + // ForEach executes a function for each key/value pair in a bucket.
>> + // If the provided function returns an error then the iteration is
>> stopped and
>> +-// the error is returned to the caller.
>> ++// the error is returned to the caller. The provided function must not
>> modify
>> ++// the bucket; this will result in undefined behavior.
>> + func (b *Bucket) ForEach(fn func(k, v []byte) error) error {
>> +       if b.tx.db == nil {
>> +               return ErrTxClosed
>> +@@ -511,8 +522,12 @@ func (b *Bucket) spill() error {
>> +               // Update parent node.
>> +               var c = b.Cursor()
>> +               k, _, flags := c.seek([]byte(name))
>> +-              _assert(bytes.Equal([]byte(name), k), "misplaced bucket
>> header: %x -> %x", []byte(name), k)
>> +-              _assert(flags&bucketLeafFlag != 0, "unexpected bucket
>> header flag: %x", flags)
>> ++              if !bytes.Equal([]byte(name), k) {
>> ++                      panic(fmt.Sprintf("misplaced bucket header: %x ->
>> %x", []byte(name), k))
>> ++              }
>> ++              if flags&bucketLeafFlag == 0 {
>> ++                      panic(fmt.Sprintf("unexpected bucket header flag:
>> %x", flags))
>> ++              }
>> +               c.node().put([]byte(name), []byte(name), value, 0,
>> bucketLeafFlag)
>> +       }
>> +
>> +@@ -528,7 +543,9 @@ func (b *Bucket) spill() error {
>> +       b.rootNode = b.rootNode.root()
>> +
>> +       // Update the root node for this bucket.
>> +-      _assert(b.rootNode.pgid < b.tx.meta.pgid, "pgid (%d) above high
>> water mark (%d)", b.rootNode.pgid, b.tx.meta.pgid)
>> ++      if b.rootNode.pgid >= b.tx.meta.pgid {
>> ++              panic(fmt.Sprintf("pgid (%d) above high water mark (%d)",
>> b.rootNode.pgid, b.tx.meta.pgid))
>> ++      }
>> +       b.root = b.rootNode.pgid
>> +
>> +       return nil
>> +@@ -659,7 +676,9 @@ func (b *Bucket) pageNode(id pgid) (*page, *node) {
>> +       // Inline buckets have a fake page embedded in their value so
>> treat them
>> +       // differently. We'll return the rootNode (if available) or the
>> fake page.
>> +       if b.root == 0 {
>> +-              _assert(id == 0, "inline bucket non-zero page access(2):
>> %d != 0", id)
>> ++              if id != 0 {
>> ++                      panic(fmt.Sprintf("inline bucket non-zero page
>> access(2): %d != 0", id))
>> ++              }
>> +               if b.rootNode != nil {
>> +                       return nil, b.rootNode
>> +               }
>> +diff --git a/vendor/src/github.com/boltdb/bolt/cursor.go b/vendor/src/
>> github.com/boltdb/bolt/cursor.go
>> +index 3bfc2f1..006c548 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/cursor.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/cursor.go
>> +@@ -2,6 +2,7 @@ package bolt
>> +
>> + import (
>> +       "bytes"
>> ++      "fmt"
>> +       "sort"
>> + )
>> +
>> +@@ -9,6 +10,8 @@ import (
>> + // Cursors see nested buckets with value == nil.
>> + // Cursors can be obtained from a transaction and are valid as long as
>> the transaction is open.
>> + //
>> ++// Keys and values returned from the cursor are only valid for the life
>> of the transaction.
>> ++//
>> + // Changing data while traversing with a cursor may cause it to be
>> invalidated
>> + // and return unexpected keys and/or values. You must reposition your
>> cursor
>> + // after mutating data.
>> +@@ -24,6 +27,7 @@ func (c *Cursor) Bucket() *Bucket {
>> +
>> + // First moves the cursor to the first item in the bucket and returns
>> its key and value.
>> + // If the bucket is empty then a nil key and value are returned.
>> ++// The returned key and value are only valid for the life of the
>> transaction.
>> + func (c *Cursor) First() (key []byte, value []byte) {
>> +       _assert(c.bucket.tx.db != nil, "tx closed")
>> +       c.stack = c.stack[:0]
>> +@@ -40,6 +44,7 @@ func (c *Cursor) First() (key []byte, value []byte) {
>> +
>> + // Last moves the cursor to the last item in the bucket and returns its
>> key and value.
>> + // If the bucket is empty then a nil key and value are returned.
>> ++// The returned key and value are only valid for the life of the
>> transaction.
>> + func (c *Cursor) Last() (key []byte, value []byte) {
>> +       _assert(c.bucket.tx.db != nil, "tx closed")
>> +       c.stack = c.stack[:0]
>> +@@ -57,6 +62,7 @@ func (c *Cursor) Last() (key []byte, value []byte) {
>> +
>> + // Next moves the cursor to the next item in the bucket and returns its
>> key and value.
>> + // If the cursor is at the end of the bucket then a nil key and value
>> are returned.
>> ++// The returned key and value are only valid for the life of the
>> transaction.
>> + func (c *Cursor) Next() (key []byte, value []byte) {
>> +       _assert(c.bucket.tx.db != nil, "tx closed")
>> +       k, v, flags := c.next()
>> +@@ -68,6 +74,7 @@ func (c *Cursor) Next() (key []byte, value []byte) {
>> +
>> + // Prev moves the cursor to the previous item in the bucket and returns
>> its key and value.
>> + // If the cursor is at the beginning of the bucket then a nil key and
>> value are returned.
>> ++// The returned key and value are only valid for the life of the
>> transaction.
>> + func (c *Cursor) Prev() (key []byte, value []byte) {
>> +       _assert(c.bucket.tx.db != nil, "tx closed")
>> +
>> +@@ -99,6 +106,7 @@ func (c *Cursor) Prev() (key []byte, value []byte) {
>> + // Seek moves the cursor to a given key and returns it.
>> + // If the key does not exist then the next key is used. If no keys
>> + // follow, a nil key is returned.
>> ++// The returned key and value are only valid for the life of the
>> transaction.
>> + func (c *Cursor) Seek(seek []byte) (key []byte, value []byte) {
>> +       k, v, flags := c.seek(seek)
>> +
>> +@@ -228,8 +236,8 @@ func (c *Cursor) next() (key []byte, value []byte,
>> flags uint32) {
>> + // search recursively performs a binary search against a given
>> page/node until it finds a given key.
>> + func (c *Cursor) search(key []byte, pgid pgid) {
>> +       p, n := c.bucket.pageNode(pgid)
>> +-      if p != nil {
>> +-              _assert((p.flags&(branchPageFlag|leafPageFlag)) != 0,
>> "invalid page type: %d: %x", p.id, p.flags)
>> ++      if p != nil && (p.flags&(branchPageFlag|leafPageFlag)) == 0 {
>> ++              panic(fmt.Sprintf("invalid page type: %d: %x", p.id,
>> p.flags))
>> +       }
>> +       e := elemRef{page: p, node: n}
>> +       c.stack = append(c.stack, e)
>> +diff --git a/vendor/src/github.com/boltdb/bolt/db.go b/vendor/src/
>> github.com/boltdb/bolt/db.go
>> +index 6c45736..d39c4aa 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/db.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/db.go
>> +@@ -12,9 +12,6 @@ import (
>> +       "unsafe"
>> + )
>> +
>> +-// The smallest size that the mmap can be.
>> +-const minMmapSize = 1 << 22 // 4MB
>> +-
>> + // The largest step that can be taken when remapping the mmap.
>> + const maxMmapStep = 1 << 30 // 1GB
>> +
>> +@@ -30,6 +27,12 @@ const magic uint32 = 0xED0CDAED
>> + // must be synchronzied using the msync(2) syscall.
>> + const IgnoreNoSync = runtime.GOOS == "openbsd"
>> +
>> ++// Default values if not set in a DB instance.
>> ++const (
>> ++      DefaultMaxBatchSize  int = 1000
>> ++      DefaultMaxBatchDelay     = 10 * time.Millisecond
>> ++)
>> ++
>> + // DB represents a collection of buckets persisted to a file on disk.
>> + // All data access is performed through transactions which can be
>> obtained through the DB.
>> + // All the functions on DB will return a ErrDatabaseNotOpen if accessed
>> before Open() is called.
>> +@@ -52,9 +55,33 @@ type DB struct {
>> +       // THIS IS UNSAFE. PLEASE USE WITH CAUTION.
>> +       NoSync bool
>> +
>> ++      // When true, skips the truncate call when growing the database.
>> ++      // Setting this to true is only safe on non-ext3/ext4 systems.
>> ++      // Skipping truncation avoids preallocation of hard drive space
>> and
>> ++      // bypasses a truncate() and fsync() syscall on remapping.
>> ++      //
>> ++      // https://github.com/boltdb/bolt/issues/284
>> ++      NoGrowSync bool
>> ++
>> ++      // MaxBatchSize is the maximum size of a batch. Default value is
>> ++      // copied from DefaultMaxBatchSize in Open.
>> ++      //
>> ++      // If <=0, disables batching.
>> ++      //
>> ++      // Do not change concurrently with calls to Batch.
>> ++      MaxBatchSize int
>> ++
>> ++      // MaxBatchDelay is the maximum delay before a batch starts.
>> ++      // Default value is copied from DefaultMaxBatchDelay in Open.
>> ++      //
>> ++      // If <=0, effectively disables batching.
>> ++      //
>> ++      // Do not change concurrently with calls to Batch.
>> ++      MaxBatchDelay time.Duration
>> ++
>> +       path     string
>> +       file     *os.File
>> +-      dataref  []byte
>> ++      dataref  []byte // mmap'ed readonly, write throws SEGV
>> +       data     *[maxMapSize]byte
>> +       datasz   int
>> +       meta0    *meta
>> +@@ -66,6 +93,9 @@ type DB struct {
>> +       freelist *freelist
>> +       stats    Stats
>> +
>> ++      batchMu sync.Mutex
>> ++      batch   *batch
>> ++
>> +       rwlock   sync.Mutex   // Allows only one writer at a time.
>> +       metalock sync.Mutex   // Protects meta page access.
>> +       mmaplock sync.RWMutex // Protects mmap access during remapping.
>> +@@ -74,6 +104,10 @@ type DB struct {
>> +       ops struct {
>> +               writeAt func(b []byte, off int64) (n int, err error)
>> +       }
>> ++
>> ++      // Read only mode.
>> ++      // When true, Update() and Begin(true) return ErrDatabaseReadOnly
>> immediately.
>> ++      readOnly bool
>> + }
>> +
>> + // Path returns the path to currently open database file.
>> +@@ -101,20 +135,34 @@ func Open(path string, mode os.FileMode, options
>> *Options) (*DB, error) {
>> +       if options == nil {
>> +               options = DefaultOptions
>> +       }
>> ++      db.NoGrowSync = options.NoGrowSync
>> ++
>> ++      // Set default values for later DB operations.
>> ++      db.MaxBatchSize = DefaultMaxBatchSize
>> ++      db.MaxBatchDelay = DefaultMaxBatchDelay
>> ++
>> ++      flag := os.O_RDWR
>> ++      if options.ReadOnly {
>> ++              flag = os.O_RDONLY
>> ++              db.readOnly = true
>> ++      }
>> +
>> +       // Open data file and separate sync handler for metadata writes.
>> +       db.path = path
>> +-
>> +       var err error
>> +-      if db.file, err = os.OpenFile(db.path, os.O_RDWR|os.O_CREATE,
>> mode); err != nil {
>> ++      if db.file, err = os.OpenFile(db.path, flag|os.O_CREATE, mode);
>> err != nil {
>> +               _ = db.close()
>> +               return nil, err
>> +       }
>> +
>> +-      // Lock file so that other processes using Bolt cannot use the
>> database
>> +-      // at the same time. This would cause corruption since the two
>> processes
>> +-      // would write meta pages and free pages separately.
>> +-      if err := flock(db.file, options.Timeout); err != nil {
>> ++      // Lock file so that other processes using Bolt in read-write
>> mode cannot
>> ++      // use the database  at the same time. This would cause
>> corruption since
>> ++      // the two processes would write meta pages and free pages
>> separately.
>> ++      // The database file is locked exclusively (only one process can
>> grab the lock)
>> ++      // if !options.ReadOnly.
>> ++      // The database file is locked using the shared lock (more than
>> one process may
>> ++      // hold a lock at the same time) otherwise (options.ReadOnly is
>> set).
>> ++      if err := flock(db.file, !db.readOnly, options.Timeout); err !=
>> nil {
>> +               _ = db.close()
>> +               return nil, err
>> +       }
>> +@@ -162,16 +210,6 @@ func (db *DB) mmap(minsz int) error {
>> +       db.mmaplock.Lock()
>> +       defer db.mmaplock.Unlock()
>> +
>> +-      // Dereference all mmap references before unmapping.
>> +-      if db.rwtx != nil {
>> +-              db.rwtx.root.dereference()
>> +-      }
>> +-
>> +-      // Unmap existing data before continuing.
>> +-      if err := db.munmap(); err != nil {
>> +-              return err
>> +-      }
>> +-
>> +       info, err := db.file.Stat()
>> +       if err != nil {
>> +               return fmt.Errorf("mmap stat error: %s", err)
>> +@@ -184,7 +222,20 @@ func (db *DB) mmap(minsz int) error {
>> +       if size < minsz {
>> +               size = minsz
>> +       }
>> +-      size = db.mmapSize(size)
>> ++      size, err = db.mmapSize(size)
>> ++      if err != nil {
>> ++              return err
>> ++      }
>> ++
>> ++      // Dereference all mmap references before unmapping.
>> ++      if db.rwtx != nil {
>> ++              db.rwtx.root.dereference()
>> ++      }
>> ++
>> ++      // Unmap existing data before continuing.
>> ++      if err := db.munmap(); err != nil {
>> ++              return err
>> ++      }
>> +
>> +       // Memory-map the data file as a byte slice.
>> +       if err := mmap(db, size); err != nil {
>> +@@ -215,22 +266,40 @@ func (db *DB) munmap() error {
>> + }
>> +
>> + // mmapSize determines the appropriate size for the mmap given the
>> current size
>> +-// of the database. The minimum size is 4MB and doubles until it
>> reaches 1GB.
>> +-func (db *DB) mmapSize(size int) int {
>> +-      if size <= minMmapSize {
>> +-              return minMmapSize
>> +-      } else if size < maxMmapStep {
>> +-              size *= 2
>> +-      } else {
>> +-              size += maxMmapStep
>> ++// of the database. The minimum size is 1MB and doubles until it
>> reaches 1GB.
>> ++// Returns an error if the new mmap size is greater than the max
>> allowed.
>> ++func (db *DB) mmapSize(size int) (int, error) {
>> ++      // Double the size from 32KB until 1GB.
>> ++      for i := uint(15); i <= 30; i++ {
>> ++              if size <= 1<<i {
>> ++                      return 1 << i, nil
>> ++              }
>> ++      }
>> ++
>> ++      // Verify the requested size is not above the maximum allowed.
>> ++      if size > maxMapSize {
>> ++              return 0, fmt.Errorf("mmap too large")
>> ++      }
>> ++
>> ++      // If larger than 1GB then grow by 1GB at a time.
>> ++      sz := int64(size)
>> ++      if remainder := sz % int64(maxMmapStep); remainder > 0 {
>> ++              sz += int64(maxMmapStep) - remainder
>> +       }
>> +
>> +       // Ensure that the mmap size is a multiple of the page size.
>> +-      if (size % db.pageSize) != 0 {
>> +-              size = ((size / db.pageSize) + 1) * db.pageSize
>> ++      // This should always be true since we're incrementing in MBs.
>> ++      pageSize := int64(db.pageSize)
>> ++      if (sz % pageSize) != 0 {
>> ++              sz = ((sz / pageSize) + 1) * pageSize
>> ++      }
>> ++
>> ++      // If we've exceeded the max size then only grow up to the max
>> size.
>> ++      if sz > maxMapSize {
>> ++              sz = maxMapSize
>> +       }
>> +
>> +-      return size
>> ++      return int(sz), nil
>> + }
>> +
>> + // init creates a new database file and initializes its meta pages.
>> +@@ -250,7 +319,6 @@ func (db *DB) init() error {
>> +               m.magic = magic
>> +               m.version = version
>> +               m.pageSize = uint32(db.pageSize)
>> +-              m.version = version
>> +               m.freelist = 2
>> +               m.root = bucket{root: 3}
>> +               m.pgid = 4
>> +@@ -283,8 +351,15 @@ func (db *DB) init() error {
>> + // Close releases all database resources.
>> + // All transactions must be closed before closing the database.
>> + func (db *DB) Close() error {
>> ++      db.rwlock.Lock()
>> ++      defer db.rwlock.Unlock()
>> ++
>> +       db.metalock.Lock()
>> +       defer db.metalock.Unlock()
>> ++
>> ++      db.mmaplock.RLock()
>> ++      defer db.mmaplock.RUnlock()
>> ++
>> +       return db.close()
>> + }
>> +
>> +@@ -304,8 +379,11 @@ func (db *DB) close() error {
>> +
>> +       // Close file handles.
>> +       if db.file != nil {
>> +-              // Unlock the file.
>> +-              _ = funlock(db.file)
>> ++              // No need to unlock read-only file.
>> ++              if !db.readOnly {
>> ++                      // Unlock the file.
>> ++                      _ = funlock(db.file)
>> ++              }
>> +
>> +               // Close the file descriptor.
>> +               if err := db.file.Close(); err != nil {
>> +@@ -323,6 +401,11 @@ func (db *DB) close() error {
>> + // will cause the calls to block and be serialized until the current
>> write
>> + // transaction finishes.
>> + //
>> ++// Transactions should not be depedent on one another. Opening a read
>> ++// transaction and a write transaction in the same goroutine can cause
>> the
>> ++// writer to deadlock because the database periodically needs to
>> re-mmap itself
>> ++// as it grows and it cannot do that while a read transaction is open.
>> ++//
>> + // IMPORTANT: You must close read-only transactions after you are
>> finished or
>> + // else the database will not reclaim old pages.
>> + func (db *DB) Begin(writable bool) (*Tx, error) {
>> +@@ -371,6 +454,11 @@ func (db *DB) beginTx() (*Tx, error) {
>> + }
>> +
>> + func (db *DB) beginRWTx() (*Tx, error) {
>> ++      // If the database was opened with Options.ReadOnly, return an
>> error.
>> ++      if db.readOnly {
>> ++              return nil, ErrDatabaseReadOnly
>> ++      }
>> ++
>> +       // Obtain writer lock. This is released by the transaction when
>> it closes.
>> +       // This enforces only one writer transaction at a time.
>> +       db.rwlock.Lock()
>> +@@ -501,6 +589,12 @@ func (db *DB) View(fn func(*Tx) error) error {
>> +       return nil
>> + }
>> +
>> ++// Sync executes fdatasync() against the database file handle.
>> ++//
>> ++// This is not necessary under normal operation, however, if you use
>> NoSync
>> ++// then it allows you to force the database file to sync against the
>> disk.
>> ++func (db *DB) Sync() error { return fdatasync(db) }
>> ++
>> + // Stats retrieves ongoing performance stats for the database.
>> + // This is only updated when a transaction closes.
>> + func (db *DB) Stats() Stats {
>> +@@ -561,18 +655,30 @@ func (db *DB) allocate(count int) (*page, error) {
>> +       return p, nil
>> + }
>> +
>> ++func (db *DB) IsReadOnly() bool {
>> ++      return db.readOnly
>> ++}
>> ++
>> + // Options represents the options that can be set when opening a
>> database.
>> + type Options struct {
>> +       // Timeout is the amount of time to wait to obtain a file lock.
>> +       // When set to zero it will wait indefinitely. This option is only
>> +       // available on Darwin and Linux.
>> +       Timeout time.Duration
>> ++
>> ++      // Sets the DB.NoGrowSync flag before memory mapping the file.
>> ++      NoGrowSync bool
>> ++
>> ++      // Open database in read-only mode. Uses flock(..., LOCK_SH
>> |LOCK_NB) to
>> ++      // grab a shared lock (UNIX).
>> ++      ReadOnly bool
>> + }
>> +
>> + // DefaultOptions represent the options used if nil options are passed
>> into Open().
>> + // No timeout is used which will cause Bolt to wait indefinitely for a
>> lock.
>> + var DefaultOptions = &Options{
>> +-      Timeout: 0,
>> ++      Timeout:    0,
>> ++      NoGrowSync: false,
>> + }
>> +
>> + // Stats represents statistics about the database.
>> +@@ -647,9 +753,11 @@ func (m *meta) copy(dest *meta) {
>> +
>> + // write writes the meta onto a page.
>> + func (m *meta) write(p *page) {
>> +-
>> +-      _assert(m.root.root < m.pgid, "root bucket pgid (%d) above high
>> water mark (%d)", m.root.root, m.pgid)
>> +-      _assert(m.freelist < m.pgid, "freelist pgid (%d) above high water
>> mark (%d)", m.freelist, m.pgid)
>> ++      if m.root.root >= m.pgid {
>> ++              panic(fmt.Sprintf("root bucket pgid (%d) above high water
>> mark (%d)", m.root.root, m.pgid))
>> ++      } else if m.freelist >= m.pgid {
>> ++              panic(fmt.Sprintf("freelist pgid (%d) above high water
>> mark (%d)", m.freelist, m.pgid))
>> ++      }
>> +
>> +       // Page id is either going to be 0 or 1 which we can determine by
>> the transaction ID.
>> +       p.id = pgid(m.txid % 2)
>> +@@ -675,13 +783,8 @@ func _assert(condition bool, msg string, v
>> ...interface{}) {
>> +       }
>> + }
>> +
>> +-func warn(v ...interface{}) {
>> +-      fmt.Fprintln(os.Stderr, v...)
>> +-}
>> +-
>> +-func warnf(msg string, v ...interface{}) {
>> +-      fmt.Fprintf(os.Stderr, msg+"\n", v...)
>> +-}
>> ++func warn(v ...interface{})              { fmt.Fprintln(os.Stderr,
>> v...) }
>> ++func warnf(msg string, v ...interface{}) { fmt.Fprintf(os.Stderr,
>> msg+"\n", v...) }
>> +
>> + func printstack() {
>> +       stack := strings.Join(strings.Split(string(debug.Stack()),
>> "\n")[2:], "\n")
>> +diff --git a/vendor/src/github.com/boltdb/bolt/errors.go b/vendor/src/
>> github.com/boltdb/bolt/errors.go
>> +index aa504f1..6883786 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/errors.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/errors.go
>> +@@ -36,6 +36,10 @@ var (
>> +       // ErrTxClosed is returned when committing or rolling back a
>> transaction
>> +       // that has already been committed or rolled back.
>> +       ErrTxClosed = errors.New("tx closed")
>> ++
>> ++      // ErrDatabaseReadOnly is returned when a mutating transaction is
>> started on a
>> ++      // read-only database.
>> ++      ErrDatabaseReadOnly = errors.New("database is in read-only mode")
>> + )
>> +
>> + // These errors can occur when putting or deleting a value or a bucket.
>> +diff --git a/vendor/src/github.com/boltdb/bolt/freelist.go b/vendor/src/
>> github.com/boltdb/bolt/freelist.go
>> +index 150e3e6..0161948 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/freelist.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/freelist.go
>> +@@ -1,6 +1,7 @@
>> + package bolt
>> +
>> + import (
>> ++      "fmt"
>> +       "sort"
>> +       "unsafe"
>> + )
>> +@@ -47,15 +48,14 @@ func (f *freelist) pending_count() int {
>> +
>> + // all returns a list of all free ids and all pending ids in one sorted
>> list.
>> + func (f *freelist) all() []pgid {
>> +-      ids := make([]pgid, len(f.ids))
>> +-      copy(ids, f.ids)
>> ++      m := make(pgids, 0)
>> +
>> +       for _, list := range f.pending {
>> +-              ids = append(ids, list...)
>> ++              m = append(m, list...)
>> +       }
>> +
>> +-      sort.Sort(pgids(ids))
>> +-      return ids
>> ++      sort.Sort(m)
>> ++      return pgids(f.ids).merge(m)
>> + }
>> +
>> + // allocate returns the starting page id of a contiguous list of pages
>> of a given size.
>> +@@ -67,7 +67,9 @@ func (f *freelist) allocate(n int) pgid {
>> +
>> +       var initial, previd pgid
>> +       for i, id := range f.ids {
>> +-              _assert(id > 1, "invalid page allocation: %d", id)
>> ++              if id <= 1 {
>> ++                      panic(fmt.Sprintf("invalid page allocation: %d",
>> id))
>> ++              }
>> +
>> +               // Reset initial page if this is not contiguous.
>> +               if previd == 0 || id-previd != 1 {
>> +@@ -103,13 +105,17 @@ func (f *freelist) allocate(n int) pgid {
>> + // free releases a page and its overflow for a given transaction id.
>> + // If the page is already free then a panic will occur.
>> + func (f *freelist) free(txid txid, p *page) {
>> +-      _assert(p.id > 1, "cannot free page 0 or 1: %d", p.id)
>> ++      if p.id <= 1 {
>> ++              panic(fmt.Sprintf("cannot free page 0 or 1: %d", p.id))
>> ++      }
>> +
>> +       // Free page and all its overflow pages.
>> +       var ids = f.pending[txid]
>> +       for id := p.id; id <= p.id+pgid(p.overflow); id++ {
>> +               // Verify that page is not already free.
>> +-              _assert(!f.cache[id], "page %d already freed", id)
>> ++              if f.cache[id] {
>> ++                      panic(fmt.Sprintf("page %d already freed", id))
>> ++              }
>> +
>> +               // Add to the freelist and cache.
>> +               ids = append(ids, id)
>> +@@ -120,15 +126,17 @@ func (f *freelist) free(txid txid, p *page) {
>> +
>> + // release moves all page ids for a transaction id (or older) to the
>> freelist.
>> + func (f *freelist) release(txid txid) {
>> ++      m := make(pgids, 0)
>> +       for tid, ids := range f.pending {
>> +               if tid <= txid {
>> +                       // Move transaction's pending pages to the
>> available freelist.
>> +                       // Don't remove from the cache since the page is
>> still free.
>> +-                      f.ids = append(f.ids, ids...)
>> ++                      m = append(m, ids...)
>> +                       delete(f.pending, tid)
>> +               }
>> +       }
>> +-      sort.Sort(pgids(f.ids))
>> ++      sort.Sort(m)
>> ++      f.ids = pgids(f.ids).merge(m)
>> + }
>> +
>> + // rollback removes the pages from a given pending tx.
>> +diff --git a/vendor/src/github.com/boltdb/bolt/node.go b/vendor/src/
>> github.com/boltdb/bolt/node.go
>> +index c204c39..c9fb21c 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/node.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/node.go
>> +@@ -2,6 +2,7 @@ package bolt
>> +
>> + import (
>> +       "bytes"
>> ++      "fmt"
>> +       "sort"
>> +       "unsafe"
>> + )
>> +@@ -70,7 +71,9 @@ func (n *node) pageElementSize() int {
>> +
>> + // childAt returns the child node at a given index.
>> + func (n *node) childAt(index int) *node {
>> +-      _assert(!n.isLeaf, "invalid childAt(%d) on a leaf node", index)
>> ++      if n.isLeaf {
>> ++              panic(fmt.Sprintf("invalid childAt(%d) on a leaf node",
>> index))
>> ++      }
>> +       return n.bucket.node(n.inodes[index].pgid, n)
>> + }
>> +
>> +@@ -111,9 +114,13 @@ func (n *node) prevSibling() *node {
>> +
>> + // put inserts a key/value.
>> + func (n *node) put(oldKey, newKey, value []byte, pgid pgid, flags
>> uint32) {
>> +-      _assert(pgid < n.bucket.tx.meta.pgid, "pgid (%d) above high water
>> mark (%d)", pgid, n.bucket.tx.meta.pgid)
>> +-      _assert(len(oldKey) > 0, "put: zero-length old key")
>> +-      _assert(len(newKey) > 0, "put: zero-length new key")
>> ++      if pgid >= n.bucket.tx.meta.pgid {
>> ++              panic(fmt.Sprintf("pgid (%d) above high water mark (%d)",
>> pgid, n.bucket.tx.meta.pgid))
>> ++      } else if len(oldKey) <= 0 {
>> ++              panic("put: zero-length old key")
>> ++      } else if len(newKey) <= 0 {
>> ++              panic("put: zero-length new key")
>> ++      }
>> +
>> +       // Find insertion index.
>> +       index := sort.Search(len(n.inodes), func(i int) bool { return
>> bytes.Compare(n.inodes[i].key, oldKey) != -1 })
>> +@@ -189,7 +196,9 @@ func (n *node) write(p *page) {
>> +               p.flags |= branchPageFlag
>> +       }
>> +
>> +-      _assert(len(n.inodes) < 0xFFFF, "inode overflow: %d (pgid=%d)",
>> len(n.inodes), p.id)
>> ++      if len(n.inodes) >= 0xFFFF {
>> ++              panic(fmt.Sprintf("inode overflow: %d (pgid=%d)",
>> len(n.inodes), p.id))
>> ++      }
>> +       p.count = uint16(len(n.inodes))
>> +
>> +       // Loop over each item and write it to the page.
>> +@@ -212,11 +221,20 @@ func (n *node) write(p *page) {
>> +                       _assert(elem.pgid != p.id, "write: circular
>> dependency occurred")
>> +               }
>> +
>> ++              // If the length of key+value is larger than the max
>> allocation size
>> ++              // then we need to reallocate the byte array pointer.
>> ++              //
>> ++              // See: https://github.com/boltdb/bolt/pull/335
>> ++              klen, vlen := len(item.key), len(item.value)
>> ++              if len(b) < klen+vlen {
>> ++                      b =
>> (*[maxAllocSize]byte)(unsafe.Pointer(&b[0]))[:]
>> ++              }
>> ++
>> +               // Write data for the element to the end of the page.
>> +               copy(b[0:], item.key)
>> +-              b = b[len(item.key):]
>> ++              b = b[klen:]
>> +               copy(b[0:], item.value)
>> +-              b = b[len(item.value):]
>> ++              b = b[vlen:]
>> +       }
>> +
>> +       // DEBUG ONLY: n.dump()
>> +@@ -348,7 +366,9 @@ func (n *node) spill() error {
>> +               }
>> +
>> +               // Write the node.
>> +-              _assert(p.id < tx.meta.pgid, "pgid (%d) above high water
>> mark (%d)", p.id, tx.meta.pgid)
>> ++              if p.id >= tx.meta.pgid {
>> ++                      panic(fmt.Sprintf("pgid (%d) above high water
>> mark (%d)", p.id, tx.meta.pgid))
>> ++              }
>> +               node.pgid = p.id
>> +               node.write(p)
>> +               node.spilled = true
>> +diff --git a/vendor/src/github.com/boltdb/bolt/page.go b/vendor/src/
>> github.com/boltdb/bolt/page.go
>> +index b3dc473..818aa1b 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/page.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/page.go
>> +@@ -3,12 +3,12 @@ package bolt
>> + import (
>> +       "fmt"
>> +       "os"
>> ++      "sort"
>> +       "unsafe"
>> + )
>> +
>> + const pageHeaderSize = int(unsafe.Offsetof(((*page)(nil)).ptr))
>> +
>> +-const maxAllocSize = 0xFFFFFFF
>> + const minKeysPerPage = 2
>> +
>> + const branchPageElementSize = int(unsafe.Sizeof(branchPageElement{}))
>> +@@ -97,7 +97,7 @@ type branchPageElement struct {
>> + // key returns a byte slice of the node key.
>> + func (n *branchPageElement) key() []byte {
>> +       buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
>> +-      return buf[n.pos : n.pos+n.ksize]
>> ++      return
>> (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
>> + }
>> +
>> + // leafPageElement represents a node on a leaf page.
>> +@@ -111,13 +111,13 @@ type leafPageElement struct {
>> + // key returns a byte slice of the node key.
>> + func (n *leafPageElement) key() []byte {
>> +       buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
>> +-      return buf[n.pos : n.pos+n.ksize]
>> ++      return
>> (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
>> + }
>> +
>> + // value returns a byte slice of the node value.
>> + func (n *leafPageElement) value() []byte {
>> +       buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
>> +-      return buf[n.pos+n.ksize : n.pos+n.ksize+n.vsize]
>> ++      return
>> (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos+n.ksize]))[:n.vsize]
>> + }
>> +
>> + // PageInfo represents human readable information about a page.
>> +@@ -133,3 +133,40 @@ type pgids []pgid
>> + func (s pgids) Len() int           { return len(s) }
>> + func (s pgids) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
>> + func (s pgids) Less(i, j int) bool { return s[i] < s[j] }
>> ++
>> ++// merge returns the sorted union of a and b.
>> ++func (a pgids) merge(b pgids) pgids {
>> ++      // Return the opposite slice if one is nil.
>> ++      if len(a) == 0 {
>> ++              return b
>> ++      } else if len(b) == 0 {
>> ++              return a
>> ++      }
>> ++
>> ++      // Create a list to hold all elements from both lists.
>> ++      merged := make(pgids, 0, len(a)+len(b))
>> ++
>> ++      // Assign lead to the slice with a lower starting value, follow
>> to the higher value.
>> ++      lead, follow := a, b
>> ++      if b[0] < a[0] {
>> ++              lead, follow = b, a
>> ++      }
>> ++
>> ++      // Continue while there are elements in the lead.
>> ++      for len(lead) > 0 {
>> ++              // Merge largest prefix of lead that is ahead of
>> follow[0].
>> ++              n := sort.Search(len(lead), func(i int) bool { return
>> lead[i] > follow[0] })
>> ++              merged = append(merged, lead[:n]...)
>> ++              if n >= len(lead) {
>> ++                      break
>> ++              }
>> ++
>> ++              // Swap lead and follow.
>> ++              lead, follow = follow, lead[n:]
>> ++      }
>> ++
>> ++      // Append what's left in follow.
>> ++      merged = append(merged, follow...)
>> ++
>> ++      return merged
>> ++}
>> +diff --git a/vendor/src/github.com/boltdb/bolt/tx.go b/vendor/src/
>> github.com/boltdb/bolt/tx.go
>> +index c041d73..fe6c287 100644
>> +--- a/vendor/src/github.com/boltdb/bolt/tx.go
>> ++++ b/vendor/src/github.com/boltdb/bolt/tx.go
>> +@@ -87,18 +87,21 @@ func (tx *Tx) Stats() TxStats {
>> +
>> + // Bucket retrieves a bucket by name.
>> + // Returns nil if the bucket does not exist.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (tx *Tx) Bucket(name []byte) *Bucket {
>> +       return tx.root.Bucket(name)
>> + }
>> +
>> + // CreateBucket creates a new bucket.
>> + // Returns an error if the bucket already exists, if the bucket name is
>> blank, or if the bucket name is too long.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) {
>> +       return tx.root.CreateBucket(name)
>> + }
>> +
>> + // CreateBucketIfNotExists creates a new bucket if it doesn't already
>> exist.
>> + // Returns an error if the bucket name is blank, or if the bucket name
>> is too long.
>> ++// The bucket instance is only valid for the lifetime of the
>> transaction.
>> + func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) {
>> +       return tx.root.CreateBucketIfNotExists(name)
>> + }
>> +@@ -127,7 +130,8 @@ func (tx *Tx) OnCommit(fn func()) {
>> + }
>> +
>> + // Commit writes all changes to disk and updates the meta page.
>> +-// Returns an error if a disk write error occurs.
>> ++// Returns an error if a disk write error occurs, or if Commit is
>> ++// called on a read-only transaction.
>> + func (tx *Tx) Commit() error {
>> +       _assert(!tx.managed, "managed tx commit not allowed")
>> +       if tx.db == nil {
>> +@@ -203,7 +207,8 @@ func (tx *Tx) Commit() error {
>> +       return nil
>> + }
>> +
>> +-// Rollback closes the transaction and ignores all previous updates.
>> ++// Rollback closes the transaction and ignores all previous updates.
>> Read-only
>> ++// transactions must be rolled back and not committed.
>> + func (tx *Tx) Rollback() error {
>> +       _assert(!tx.managed, "managed tx rollback not allowed")
>> +       if tx.db == nil {
>> +@@ -234,7 +239,8 @@ func (tx *Tx) close() {
>> +               var freelistPendingN = tx.db.freelist.pending_count()
>> +               var freelistAlloc = tx.db.freelist.size()
>> +
>> +-              // Remove writer lock.
>> ++              // Remove transaction ref & writer lock.
>> ++              tx.db.rwtx = nil
>> +               tx.db.rwlock.Unlock()
>> +
>> +               // Merge statistics.
>> +@@ -248,41 +254,51 @@ func (tx *Tx) close() {
>> +       } else {
>> +               tx.db.removeTx(tx)
>> +       }
>> ++
>> ++      // Clear all references.
>> +       tx.db = nil
>> ++      tx.meta = nil
>> ++      tx.root = Bucket{tx: tx}
>> ++      tx.pages = nil
>> + }
>> +
>> + // Copy writes the entire database to a writer.
>> +-// A reader transaction is maintained during the copy so it is safe to
>> continue
>> +-// using the database while a copy is in progress.
>> +-// Copy will write exactly tx.Size() bytes into the writer.
>> ++// This function exists for backwards compatibility. Use WriteTo() in
>> + func (tx *Tx) Copy(w io.Writer) error {
>> +-      var f *os.File
>> +-      var err error
>> ++      _, err := tx.WriteTo(w)
>> ++      return err
>> ++}
>> +
>> ++// WriteTo writes the entire database to a writer.
>> ++// If err == nil then exactly tx.Size() bytes will be written into the
>> writer.
>> ++func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) {
>> +       // Attempt to open reader directly.
>> ++      var f *os.File
>> +       if f, err = os.OpenFile(tx.db.path, os.O_RDONLY|odirect, 0); err
>> != nil {
>> +               // Fallback to a regular open if that doesn't work.
>> +               if f, err = os.OpenFile(tx.db.path, os.O_RDONLY, 0); err
>> != nil {
>> +-                      return err
>> ++                      return 0, err
>> +               }
>> +       }
>> +
>> +       // Copy the meta pages.
>> +       tx.db.metalock.Lock()
>> +-      _, err = io.CopyN(w, f, int64(tx.db.pageSize*2))
>> ++      n, err = io.CopyN(w, f, int64(tx.db.pageSize*2))
>> +       tx.db.metalock.Unlock()
>> +       if err != nil {
>> +               _ = f.Close()
>> +-              return fmt.Errorf("meta copy: %s", err)
>> ++              return n, fmt.Errorf("meta copy: %s", err)
>> +       }
>> +
>> +       // Copy data pages.
>> +-      if _, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2));
>> err != nil {
>> ++      wn, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2))
>> ++      n += wn
>> ++      if err != nil {
>> +               _ = f.Close()
>> +-              return err
>> ++              return n, err
>> +       }
>> +
>> +-      return f.Close()
>> ++      return n, f.Close()
>> + }
>> +
>> + // CopyFile copies the entire database to file at the given path.
>> +@@ -416,15 +432,39 @@ func (tx *Tx) write() error {
>> +       // Write pages to disk in order.
>> +       for _, p := range pages {
>> +               size := (int(p.overflow) + 1) * tx.db.pageSize
>> +-              buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:size]
>> +               offset := int64(p.id) * int64(tx.db.pageSize)
>> +-              if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
>> +-                      return err
>> +-              }
>> +
>> +-              // Update statistics.
>> +-              tx.stats.Write++
>> ++              // Write out page in "max allocation" sized chunks.
>> ++              ptr := (*[maxAllocSize]byte)(unsafe.Pointer(p))
>> ++              for {
>> ++                      // Limit our write to our max allocation size.
>> ++                      sz := size
>> ++                      if sz > maxAllocSize-1 {
>> ++                              sz = maxAllocSize - 1
>> ++                      }
>> ++
>> ++                      // Write chunk to disk.
>> ++                      buf := ptr[:sz]
>> ++                      if _, err := tx.db.ops.writeAt(buf, offset); err
>> != nil {
>> ++                              return err
>> ++                      }
>> ++
>> ++                      // Update statistics.
>> ++                      tx.stats.Write++
>> ++
>> ++                      // Exit inner for loop if we've written all the
>> chunks.
>> ++                      size -= sz
>> ++                      if size == 0 {
>> ++                              break
>> ++                      }
>> ++
>> ++                      // Otherwise move offset forward and move pointer
>> to next chunk.
>> ++                      offset += int64(sz)
>> ++                      ptr =
>> (*[maxAllocSize]byte)(unsafe.Pointer(&ptr[sz]))
>> ++              }
>> +       }
>> ++
>> ++      // Ignore file sync if flag is set on DB.
>> +       if !tx.db.NoSync || IgnoreNoSync {
>> +               if err := fdatasync(tx.db); err != nil {
>> +                       return err
>> +--
>> +1.9.1
>> +
>> diff --git
>> a/recipes-containers/docker/files/disable_sha1sum_startup.patch
>> b/recipes-containers/docker/files/disable_sha1sum_startup.patch
>> index 580ca23..cafd83d 100644
>> --- a/recipes-containers/docker/files/disable_sha1sum_startup.patch
>> +++ b/recipes-containers/docker/files/disable_sha1sum_startup.patch
>> @@ -12,20 +12,23 @@ of the binary instead.
>>
>>  Signed-off-by: Amy Fong <amy.fong at windriver.com>
>>  ---
>> - utils/utils.go |   17 +----------------
>> - 1 file changed, 1 insertion(+), 16 deletions(-)
>> + utils/utils.go | 18 +-----------------
>> + 1 file changed, 1 insertion(+), 17 deletions(-)
>>
>> +diff --git a/utils/utils.go b/utils/utils.go
>> +index a17ab9d..3fc514a 100644
>>  --- a/utils/utils.go
>>  +++ b/utils/utils.go
>> -@@ -3,7 +3,6 @@
>> +@@ -2,8 +2,6 @@ package utils
>> +
>>   import (
>>         "bufio"
>> -       "bytes"
>>  -      "crypto/sha1"
>> -       "crypto/sha256"
>> -       "encoding/hex"
>> +-      "encoding/hex"
>>         "fmt"
>> -@@ -75,20 +74,6 @@
>> +       "io"
>> +       "io/ioutil"
>> +@@ -42,20 +40,6 @@ func SelfPath() string {
>>         return path
>>   }
>>
>> @@ -46,7 +49,7 @@ Signed-off-by: Amy Fong <amy.fong at windriver.com>
>>   func isValidDockerInitPath(target string, selfPath string) bool { //
>> target and selfPath should be absolute (InitPath and SelfPath already do
>> this)
>>         if target == "" {
>>                 return false
>> -@@ -110,7 +95,7 @@
>> +@@ -77,7 +61,7 @@ func isValidDockerInitPath(target string, selfPath
>> string) bool { // target and
>>                 }
>>                 return os.SameFile(targetFileInfo, selfPathFileInfo)
>>         }
>> @@ -54,4 +57,4 @@ Signed-off-by: Amy Fong <amy.fong at windriver.com>
>>  +      return true
>>   }
>>
>> - // Figure out the path of our dockerinit (which may be SelfPath())
>> + // DockerInitPath figures out the path of our dockerinit (which may be
>> SelfPath())
>> --
>> 1.8.3.2
>>
>>
>>
>>
>>
>> --
>>
>> "Thou shalt not follow the NULL pointer, for chaos and madness await thee
>> at its end"
>>
>
>
>
> --
> "Thou shalt not follow the NULL pointer, for chaos and madness await thee
> at its end"
>



-- 
"Thou shalt not follow the NULL pointer, for chaos and madness await thee
at its end"
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