Merge pull request #16898 from hqhq/hq_bump_bolt

Bump bolt to v1.1.0

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

vendor/src/github.com/boltdb/bolt/.gitignore

@@ -1,3 +1,4 @@
 *.prof
 *.test
+*.swp
 /bin/

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.
-

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)
+}

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

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

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

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

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

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

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
+}

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
+}

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.

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
 		}

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)

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")

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.

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.

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

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
+}

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