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-rw-r--r--vendor/github.com/etcd-io/bbolt/db.go1164
1 files changed, 1164 insertions, 0 deletions
diff --git a/vendor/github.com/etcd-io/bbolt/db.go b/vendor/github.com/etcd-io/bbolt/db.go
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+++ b/vendor/github.com/etcd-io/bbolt/db.go
@@ -0,0 +1,1164 @@
+package bbolt
+
+import (
+ "errors"
+ "fmt"
+ "hash/fnv"
+ "log"
+ "os"
+ "runtime"
+ "sort"
+ "sync"
+ "time"
+ "unsafe"
+)
+
+// The largest step that can be taken when remapping the mmap.
+const maxMmapStep = 1 << 30 // 1GB
+
+// The data file format version.
+const version = 2
+
+// Represents a marker value to indicate that a file is a Bolt DB.
+const magic uint32 = 0xED0CDAED
+
+const pgidNoFreelist pgid = 0xffffffffffffffff
+
+// IgnoreNoSync specifies whether the NoSync field of a DB is ignored when
+// syncing changes to a file. This is required as some operating systems,
+// such as OpenBSD, do not have a unified buffer cache (UBC) and writes
+// must be synchronized 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
+ DefaultAllocSize = 16 * 1024 * 1024
+)
+
+// default page size for db is set to the OS page size.
+var defaultPageSize = os.Getpagesize()
+
+// The time elapsed between consecutive file locking attempts.
+const flockRetryTimeout = 50 * time.Millisecond
+
+// FreelistType is the type of the freelist backend
+type FreelistType string
+
+const (
+ // FreelistArrayType indicates backend freelist type is array
+ FreelistArrayType = FreelistType("array")
+ // FreelistMapType indicates backend freelist type is hashmap
+ FreelistMapType = FreelistType("hashmap")
+)
+
+// 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.
+type DB struct {
+ // When enabled, the database will perform a Check() after every commit.
+ // A panic is issued if the database is in an inconsistent state. This
+ // flag has a large performance impact so it should only be used for
+ // debugging purposes.
+ StrictMode bool
+
+ // Setting the NoSync flag will cause the database to skip fsync()
+ // calls after each commit. This can be useful when bulk loading data
+ // into a database and you can restart the bulk load in the event of
+ // a system failure or database corruption. Do not set this flag for
+ // normal use.
+ //
+ // If the package global IgnoreNoSync constant is true, this value is
+ // ignored. See the comment on that constant for more details.
+ //
+ // THIS IS UNSAFE. PLEASE USE WITH CAUTION.
+ NoSync bool
+
+ // When true, skips syncing freelist to disk. This improves the database
+ // write performance under normal operation, but requires a full database
+ // re-sync during recovery.
+ NoFreelistSync bool
+
+ // FreelistType sets the backend freelist type. There are two options. Array which is simple but endures
+ // dramatic performance degradation if database is large and framentation in freelist is common.
+ // The alternative one is using hashmap, it is faster in almost all circumstances
+ // but it doesn't guarantee that it offers the smallest page id available. In normal case it is safe.
+ // The default type is array
+ FreelistType FreelistType
+
+ // 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
+
+ // If you want to read the entire database fast, you can set MmapFlag to
+ // syscall.MAP_POPULATE on Linux 2.6.23+ for sequential read-ahead.
+ MmapFlags int
+
+ // 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
+
+ // AllocSize is the amount of space allocated when the database
+ // needs to create new pages. This is done to amortize the cost
+ // of truncate() and fsync() when growing the data file.
+ AllocSize int
+
+ path string
+ file *os.File
+ dataref []byte // mmap'ed readonly, write throws SEGV
+ data *[maxMapSize]byte
+ datasz int
+ filesz int // current on disk file size
+ meta0 *meta
+ meta1 *meta
+ pageSize int
+ opened bool
+ rwtx *Tx
+ txs []*Tx
+ stats Stats
+
+ freelist *freelist
+ freelistLoad sync.Once
+
+ pagePool sync.Pool
+
+ 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.
+ statlock sync.RWMutex // Protects stats access.
+
+ 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.
+func (db *DB) Path() string {
+ return db.path
+}
+
+// GoString returns the Go string representation of the database.
+func (db *DB) GoString() string {
+ return fmt.Sprintf("bolt.DB{path:%q}", db.path)
+}
+
+// String returns the string representation of the database.
+func (db *DB) String() string {
+ return fmt.Sprintf("DB<%q>", db.path)
+}
+
+// Open creates and opens a database at the given path.
+// If the file does not exist then it will be created automatically.
+// Passing in nil options will cause Bolt to open the database with the default options.
+func Open(path string, mode os.FileMode, options *Options) (*DB, error) {
+ db := &DB{
+ opened: true,
+ }
+ // Set default options if no options are provided.
+ if options == nil {
+ options = DefaultOptions
+ }
+ db.NoSync = options.NoSync
+ db.NoGrowSync = options.NoGrowSync
+ db.MmapFlags = options.MmapFlags
+ db.NoFreelistSync = options.NoFreelistSync
+ db.FreelistType = options.FreelistType
+
+ // Set default values for later DB operations.
+ db.MaxBatchSize = DefaultMaxBatchSize
+ db.MaxBatchDelay = DefaultMaxBatchDelay
+ db.AllocSize = DefaultAllocSize
+
+ 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, flag|os.O_CREATE, mode); err != nil {
+ _ = db.close()
+ return nil, err
+ }
+
+ // 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, !db.readOnly, options.Timeout); err != nil {
+ _ = db.close()
+ return nil, err
+ }
+
+ // Default values for test hooks
+ db.ops.writeAt = db.file.WriteAt
+
+ if db.pageSize = options.PageSize; db.pageSize == 0 {
+ // Set the default page size to the OS page size.
+ db.pageSize = defaultPageSize
+ }
+
+ // Initialize the database if it doesn't exist.
+ if info, err := db.file.Stat(); err != nil {
+ _ = db.close()
+ return nil, err
+ } else if info.Size() == 0 {
+ // Initialize new files with meta pages.
+ if err := db.init(); err != nil {
+ // clean up file descriptor on initialization fail
+ _ = db.close()
+ return nil, err
+ }
+ } else {
+ // Read the first meta page to determine the page size.
+ var buf [0x1000]byte
+ // If we can't read the page size, but can read a page, assume
+ // it's the same as the OS or one given -- since that's how the
+ // page size was chosen in the first place.
+ //
+ // If the first page is invalid and this OS uses a different
+ // page size than what the database was created with then we
+ // are out of luck and cannot access the database.
+ //
+ // TODO: scan for next page
+ if bw, err := db.file.ReadAt(buf[:], 0); err == nil && bw == len(buf) {
+ if m := db.pageInBuffer(buf[:], 0).meta(); m.validate() == nil {
+ db.pageSize = int(m.pageSize)
+ }
+ } else {
+ _ = db.close()
+ return nil, ErrInvalid
+ }
+ }
+
+ // Initialize page pool.
+ db.pagePool = sync.Pool{
+ New: func() interface{} {
+ return make([]byte, db.pageSize)
+ },
+ }
+
+ // Memory map the data file.
+ if err := db.mmap(options.InitialMmapSize); err != nil {
+ _ = db.close()
+ return nil, err
+ }
+
+ if db.readOnly {
+ return db, nil
+ }
+
+ db.loadFreelist()
+
+ // Flush freelist when transitioning from no sync to sync so
+ // NoFreelistSync unaware boltdb can open the db later.
+ if !db.NoFreelistSync && !db.hasSyncedFreelist() {
+ tx, err := db.Begin(true)
+ if tx != nil {
+ err = tx.Commit()
+ }
+ if err != nil {
+ _ = db.close()
+ return nil, err
+ }
+ }
+
+ // Mark the database as opened and return.
+ return db, nil
+}
+
+// loadFreelist reads the freelist if it is synced, or reconstructs it
+// by scanning the DB if it is not synced. It assumes there are no
+// concurrent accesses being made to the freelist.
+func (db *DB) loadFreelist() {
+ db.freelistLoad.Do(func() {
+ db.freelist = newFreelist(db.FreelistType)
+ if !db.hasSyncedFreelist() {
+ // Reconstruct free list by scanning the DB.
+ db.freelist.readIDs(db.freepages())
+ } else {
+ // Read free list from freelist page.
+ db.freelist.read(db.page(db.meta().freelist))
+ }
+ db.stats.FreePageN = db.freelist.free_count()
+ })
+}
+
+func (db *DB) hasSyncedFreelist() bool {
+ return db.meta().freelist != pgidNoFreelist
+}
+
+// mmap opens the underlying memory-mapped file and initializes the meta references.
+// minsz is the minimum size that the new mmap can be.
+func (db *DB) mmap(minsz int) error {
+ db.mmaplock.Lock()
+ defer db.mmaplock.Unlock()
+
+ info, err := db.file.Stat()
+ if err != nil {
+ return fmt.Errorf("mmap stat error: %s", err)
+ } else if int(info.Size()) < db.pageSize*2 {
+ return fmt.Errorf("file size too small")
+ }
+
+ // Ensure the size is at least the minimum size.
+ var size = int(info.Size())
+ if size < minsz {
+ size = minsz
+ }
+ 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 {
+ return err
+ }
+
+ // Save references to the meta pages.
+ db.meta0 = db.page(0).meta()
+ db.meta1 = db.page(1).meta()
+
+ // Validate the meta pages. We only return an error if both meta pages fail
+ // validation, since meta0 failing validation means that it wasn't saved
+ // properly -- but we can recover using meta1. And vice-versa.
+ err0 := db.meta0.validate()
+ err1 := db.meta1.validate()
+ if err0 != nil && err1 != nil {
+ return err0
+ }
+
+ return nil
+}
+
+// munmap unmaps the data file from memory.
+func (db *DB) munmap() error {
+ if err := munmap(db); err != nil {
+ return fmt.Errorf("unmap error: " + err.Error())
+ }
+ return nil
+}
+
+// mmapSize determines the appropriate size for the mmap given the current size
+// of the database. The minimum size is 32KB 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.
+ // 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 int(sz), nil
+}
+
+// init creates a new database file and initializes its meta pages.
+func (db *DB) init() error {
+ // Create two meta pages on a buffer.
+ buf := make([]byte, db.pageSize*4)
+ for i := 0; i < 2; i++ {
+ p := db.pageInBuffer(buf[:], pgid(i))
+ p.id = pgid(i)
+ p.flags = metaPageFlag
+
+ // Initialize the meta page.
+ m := p.meta()
+ m.magic = magic
+ m.version = version
+ m.pageSize = uint32(db.pageSize)
+ m.freelist = 2
+ m.root = bucket{root: 3}
+ m.pgid = 4
+ m.txid = txid(i)
+ m.checksum = m.sum64()
+ }
+
+ // Write an empty freelist at page 3.
+ p := db.pageInBuffer(buf[:], pgid(2))
+ p.id = pgid(2)
+ p.flags = freelistPageFlag
+ p.count = 0
+
+ // Write an empty leaf page at page 4.
+ p = db.pageInBuffer(buf[:], pgid(3))
+ p.id = pgid(3)
+ p.flags = leafPageFlag
+ p.count = 0
+
+ // Write the buffer to our data file.
+ if _, err := db.ops.writeAt(buf, 0); err != nil {
+ return err
+ }
+ if err := fdatasync(db); err != nil {
+ return err
+ }
+
+ return nil
+}
+
+// Close releases all database resources.
+// It will block waiting for any open transactions to finish
+// before closing the database and returning.
+func (db *DB) Close() error {
+ db.rwlock.Lock()
+ defer db.rwlock.Unlock()
+
+ db.metalock.Lock()
+ defer db.metalock.Unlock()
+
+ db.mmaplock.Lock()
+ defer db.mmaplock.Unlock()
+
+ return db.close()
+}
+
+func (db *DB) close() error {
+ if !db.opened {
+ return nil
+ }
+
+ db.opened = false
+
+ db.freelist = nil
+
+ // Clear ops.
+ db.ops.writeAt = nil
+
+ // Close the mmap.
+ if err := db.munmap(); err != nil {
+ return err
+ }
+
+ // Close file handles.
+ if db.file != nil {
+ // No need to unlock read-only file.
+ if !db.readOnly {
+ // Unlock the file.
+ if err := funlock(db); err != nil {
+ log.Printf("bolt.Close(): funlock error: %s", err)
+ }
+ }
+
+ // Close the file descriptor.
+ if err := db.file.Close(); err != nil {
+ return fmt.Errorf("db file close: %s", err)
+ }
+ db.file = nil
+ }
+
+ db.path = ""
+ return nil
+}
+
+// Begin starts a new transaction.
+// Multiple read-only transactions can be used concurrently but only one
+// write transaction can be used at a time. Starting multiple write transactions
+// will cause the calls to block and be serialized until the current write
+// transaction finishes.
+//
+// Transactions should not be dependent 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.
+//
+// If a long running read transaction (for example, a snapshot transaction) is
+// needed, you might want to set DB.InitialMmapSize to a large enough value
+// to avoid potential blocking of write transaction.
+//
+// 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) {
+ if writable {
+ return db.beginRWTx()
+ }
+ return db.beginTx()
+}
+
+func (db *DB) beginTx() (*Tx, error) {
+ // Lock the meta pages while we initialize the transaction. We obtain
+ // the meta lock before the mmap lock because that's the order that the
+ // write transaction will obtain them.
+ db.metalock.Lock()
+
+ // Obtain a read-only lock on the mmap. When the mmap is remapped it will
+ // obtain a write lock so all transactions must finish before it can be
+ // remapped.
+ db.mmaplock.RLock()
+
+ // Exit if the database is not open yet.
+ if !db.opened {
+ db.mmaplock.RUnlock()
+ db.metalock.Unlock()
+ return nil, ErrDatabaseNotOpen
+ }
+
+ // Create a transaction associated with the database.
+ t := &Tx{}
+ t.init(db)
+
+ // Keep track of transaction until it closes.
+ db.txs = append(db.txs, t)
+ n := len(db.txs)
+
+ // Unlock the meta pages.
+ db.metalock.Unlock()
+
+ // Update the transaction stats.
+ db.statlock.Lock()
+ db.stats.TxN++
+ db.stats.OpenTxN = n
+ db.statlock.Unlock()
+
+ return t, nil
+}
+
+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()
+
+ // Once we have the writer lock then we can lock the meta pages so that
+ // we can set up the transaction.
+ db.metalock.Lock()
+ defer db.metalock.Unlock()
+
+ // Exit if the database is not open yet.
+ if !db.opened {
+ db.rwlock.Unlock()
+ return nil, ErrDatabaseNotOpen
+ }
+
+ // Create a transaction associated with the database.
+ t := &Tx{writable: true}
+ t.init(db)
+ db.rwtx = t
+ db.freePages()
+ return t, nil
+}
+
+// freePages releases any pages associated with closed read-only transactions.
+func (db *DB) freePages() {
+ // Free all pending pages prior to earliest open transaction.
+ sort.Sort(txsById(db.txs))
+ minid := txid(0xFFFFFFFFFFFFFFFF)
+ if len(db.txs) > 0 {
+ minid = db.txs[0].meta.txid
+ }
+ if minid > 0 {
+ db.freelist.release(minid - 1)
+ }
+ // Release unused txid extents.
+ for _, t := range db.txs {
+ db.freelist.releaseRange(minid, t.meta.txid-1)
+ minid = t.meta.txid + 1
+ }
+ db.freelist.releaseRange(minid, txid(0xFFFFFFFFFFFFFFFF))
+ // Any page both allocated and freed in an extent is safe to release.
+}
+
+type txsById []*Tx
+
+func (t txsById) Len() int { return len(t) }
+func (t txsById) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
+func (t txsById) Less(i, j int) bool { return t[i].meta.txid < t[j].meta.txid }
+
+// removeTx removes a transaction from the database.
+func (db *DB) removeTx(tx *Tx) {
+ // Release the read lock on the mmap.
+ db.mmaplock.RUnlock()
+
+ // Use the meta lock to restrict access to the DB object.
+ db.metalock.Lock()
+
+ // Remove the transaction.
+ for i, t := range db.txs {
+ if t == tx {
+ last := len(db.txs) - 1
+ db.txs[i] = db.txs[last]
+ db.txs[last] = nil
+ db.txs = db.txs[:last]
+ break
+ }
+ }
+ n := len(db.txs)
+
+ // Unlock the meta pages.
+ db.metalock.Unlock()
+
+ // Merge statistics.
+ db.statlock.Lock()
+ db.stats.OpenTxN = n
+ db.stats.TxStats.add(&tx.stats)
+ db.statlock.Unlock()
+}
+
+// Update executes a function within the context of a read-write managed transaction.
+// If no error is returned from the function then the transaction is committed.
+// If an error is returned then the entire transaction is rolled back.
+// Any error that is returned from the function or returned from the commit is
+// returned from the Update() method.
+//
+// Attempting to manually commit or rollback within the function will cause a panic.
+func (db *DB) Update(fn func(*Tx) error) error {
+ t, err := db.Begin(true)
+ if err != nil {
+ return err
+ }
+
+ // Make sure the transaction rolls back in the event of a panic.
+ defer func() {
+ if t.db != nil {
+ t.rollback()
+ }
+ }()
+
+ // Mark as a managed tx so that the inner function cannot manually commit.
+ t.managed = true
+
+ // If an error is returned from the function then rollback and return error.
+ err = fn(t)
+ t.managed = false
+ if err != nil {
+ _ = t.Rollback()
+ return err
+ }
+
+ return t.Commit()
+}
+
+// View executes a function within the context of a managed read-only transaction.
+// Any error that is returned from the function is returned from the View() method.
+//
+// Attempting to manually rollback within the function will cause a panic.
+func (db *DB) View(fn func(*Tx) error) error {
+ t, err := db.Begin(false)
+ if err != nil {
+ return err
+ }
+
+ // Make sure the transaction rolls back in the event of a panic.
+ defer func() {
+ if t.db != nil {
+ t.rollback()
+ }
+ }()
+
+ // Mark as a managed tx so that the inner function cannot manually rollback.
+ t.managed = true
+
+ // If an error is returned from the function then pass it through.
+ err = fn(t)
+ t.managed = false
+ if err != nil {
+ _ = t.Rollback()
+ return err
+ }
+
+ return t.Rollback()
+}
+
+// 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 {
+ 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)
+}
+
+// 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 {
+ db.statlock.RLock()
+ defer db.statlock.RUnlock()
+ return db.stats
+}
+
+// This is for internal access to the raw data bytes from the C cursor, use
+// carefully, or not at all.
+func (db *DB) Info() *Info {
+ return &Info{uintptr(unsafe.Pointer(&db.data[0])), db.pageSize}
+}
+
+// page retrieves a page reference from the mmap based on the current page size.
+func (db *DB) page(id pgid) *page {
+ pos := id * pgid(db.pageSize)
+ return (*page)(unsafe.Pointer(&db.data[pos]))
+}
+
+// pageInBuffer retrieves a page reference from a given byte array based on the current page size.
+func (db *DB) pageInBuffer(b []byte, id pgid) *page {
+ return (*page)(unsafe.Pointer(&b[id*pgid(db.pageSize)]))
+}
+
+// meta retrieves the current meta page reference.
+func (db *DB) meta() *meta {
+ // We have to return the meta with the highest txid which doesn't fail
+ // validation. Otherwise, we can cause errors when in fact the database is
+ // in a consistent state. metaA is the one with the higher txid.
+ metaA := db.meta0
+ metaB := db.meta1
+ if db.meta1.txid > db.meta0.txid {
+ metaA = db.meta1
+ metaB = db.meta0
+ }
+
+ // Use higher meta page if valid. Otherwise fallback to previous, if valid.
+ if err := metaA.validate(); err == nil {
+ return metaA
+ } else if err := metaB.validate(); err == nil {
+ return metaB
+ }
+
+ // This should never be reached, because both meta1 and meta0 were validated
+ // on mmap() and we do fsync() on every write.
+ panic("bolt.DB.meta(): invalid meta pages")
+}
+
+// allocate returns a contiguous block of memory starting at a given page.
+func (db *DB) allocate(txid txid, count int) (*page, error) {
+ // Allocate a temporary buffer for the page.
+ var buf []byte
+ if count == 1 {
+ buf = db.pagePool.Get().([]byte)
+ } else {
+ buf = make([]byte, count*db.pageSize)
+ }
+ p := (*page)(unsafe.Pointer(&buf[0]))
+ p.overflow = uint32(count - 1)
+
+ // Use pages from the freelist if they are available.
+ if p.id = db.freelist.allocate(txid, count); p.id != 0 {
+ return p, nil
+ }
+
+ // Resize mmap() if we're at the end.
+ p.id = db.rwtx.meta.pgid
+ var minsz = int((p.id+pgid(count))+1) * db.pageSize
+ if minsz >= db.datasz {
+ if err := db.mmap(minsz); err != nil {
+ return nil, fmt.Errorf("mmap allocate error: %s", err)
+ }
+ }
+
+ // Move the page id high water mark.
+ db.rwtx.meta.pgid += pgid(count)
+
+ return p, nil
+}
+
+// grow grows the size of the database to the given sz.
+func (db *DB) grow(sz int) error {
+ // Ignore if the new size is less than available file size.
+ if sz <= db.filesz {
+ return nil
+ }
+
+ // If the data is smaller than the alloc size then only allocate what's needed.
+ // Once it goes over the allocation size then allocate in chunks.
+ if db.datasz < db.AllocSize {
+ sz = db.datasz
+ } else {
+ sz += db.AllocSize
+ }
+
+ // Truncate and fsync to ensure file size metadata is flushed.
+ // https://github.com/boltdb/bolt/issues/284
+ if !db.NoGrowSync && !db.readOnly {
+ if runtime.GOOS != "windows" {
+ 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)
+ }
+ }
+
+ db.filesz = sz
+ return nil
+}
+
+func (db *DB) IsReadOnly() bool {
+ return db.readOnly
+}
+
+func (db *DB) freepages() []pgid {
+ tx, err := db.beginTx()
+ defer func() {
+ err = tx.Rollback()
+ if err != nil {
+ panic("freepages: failed to rollback tx")
+ }
+ }()
+ if err != nil {
+ panic("freepages: failed to open read only tx")
+ }
+
+ reachable := make(map[pgid]*page)
+ nofreed := make(map[pgid]bool)
+ ech := make(chan error)
+ go func() {
+ for e := range ech {
+ panic(fmt.Sprintf("freepages: failed to get all reachable pages (%v)", e))
+ }
+ }()
+ tx.checkBucket(&tx.root, reachable, nofreed, ech)
+ close(ech)
+
+ var fids []pgid
+ for i := pgid(2); i < db.meta().pgid; i++ {
+ if _, ok := reachable[i]; !ok {
+ fids = append(fids, i)
+ }
+ }
+ return fids
+}
+
+// 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
+
+ // Do not sync freelist to disk. This improves the database write performance
+ // under normal operation, but requires a full database re-sync during recovery.
+ NoFreelistSync bool
+
+ // FreelistType sets the backend freelist type. There are two options. Array which is simple but endures
+ // dramatic performance degradation if database is large and framentation in freelist is common.
+ // The alternative one is using hashmap, it is faster in almost all circumstances
+ // but it doesn't guarantee that it offers the smallest page id available. In normal case it is safe.
+ // The default type is array
+ FreelistType FreelistType
+
+ // Open database in read-only mode. Uses flock(..., LOCK_SH |LOCK_NB) to
+ // grab a shared lock (UNIX).
+ ReadOnly bool
+
+ // Sets the DB.MmapFlags flag before memory mapping the file.
+ MmapFlags int
+
+ // InitialMmapSize is the initial mmap size of the database
+ // in bytes. Read transactions won't block write transaction
+ // if the InitialMmapSize is large enough to hold database mmap
+ // size. (See DB.Begin for more information)
+ //
+ // If <=0, the initial map size is 0.
+ // If initialMmapSize is smaller than the previous database size,
+ // it takes no effect.
+ InitialMmapSize int
+
+ // PageSize overrides the default OS page size.
+ PageSize int
+
+ // NoSync sets the initial value of DB.NoSync. Normally this can just be
+ // set directly on the DB itself when returned from Open(), but this option
+ // is useful in APIs which expose Options but not the underlying DB.
+ NoSync 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,
+ NoGrowSync: false,
+ FreelistType: FreelistArrayType,
+}
+
+// Stats represents statistics about the database.
+type Stats struct {
+ // Freelist stats
+ FreePageN int // total number of free pages on the freelist
+ PendingPageN int // total number of pending pages on the freelist
+ FreeAlloc int // total bytes allocated in free pages
+ FreelistInuse int // total bytes used by the freelist
+
+ // Transaction stats
+ TxN int // total number of started read transactions
+ OpenTxN int // number of currently open read transactions
+
+ TxStats TxStats // global, ongoing stats.
+}
+
+// Sub calculates and returns the difference between two sets of database stats.
+// This is useful when obtaining stats at two different points and time and
+// you need the performance counters that occurred within that time span.
+func (s *Stats) Sub(other *Stats) Stats {
+ if other == nil {
+ return *s
+ }
+ var diff Stats
+ diff.FreePageN = s.FreePageN
+ diff.PendingPageN = s.PendingPageN
+ diff.FreeAlloc = s.FreeAlloc
+ diff.FreelistInuse = s.FreelistInuse
+ diff.TxN = s.TxN - other.TxN
+ diff.TxStats = s.TxStats.Sub(&other.TxStats)
+ return diff
+}
+
+type Info struct {
+ Data uintptr
+ PageSize int
+}
+
+type meta struct {
+ magic uint32
+ version uint32
+ pageSize uint32
+ flags uint32
+ root bucket
+ freelist pgid
+ pgid pgid
+ txid txid
+ checksum uint64
+}
+
+// validate checks the marker bytes and version of the meta page to ensure it matches this binary.
+func (m *meta) validate() error {
+ if m.magic != magic {
+ return ErrInvalid
+ } else if m.version != version {
+ return ErrVersionMismatch
+ } else if m.checksum != 0 && m.checksum != m.sum64() {
+ return ErrChecksum
+ }
+ return nil
+}
+
+// copy copies one meta object to another.
+func (m *meta) copy(dest *meta) {
+ *dest = *m
+}
+
+// write writes the meta onto a page.
+func (m *meta) write(p *page) {
+ 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 && m.freelist != pgidNoFreelist {
+ // TODO: reject pgidNoFreeList if !NoFreelistSync
+ 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)
+ p.flags |= metaPageFlag
+
+ // Calculate the checksum.
+ m.checksum = m.sum64()
+
+ m.copy(p.meta())
+}
+
+// generates the checksum for the meta.
+func (m *meta) sum64() uint64 {
+ var h = fnv.New64a()
+ _, _ = h.Write((*[unsafe.Offsetof(meta{}.checksum)]byte)(unsafe.Pointer(m))[:])
+ return h.Sum64()
+}
+
+// _assert will panic with a given formatted message if the given condition is false.
+func _assert(condition bool, msg string, v ...interface{}) {
+ if !condition {
+ panic(fmt.Sprintf("assertion failed: "+msg, v...))
+ }
+}
generated by cgit v1.2.3-54-g00ecf (git 2.39.0) at 2024-11-16 18:35:03 +0000