diff options
Diffstat (limited to 'db.go')
| -rw-r--r-- | db.go | 42 |
1 files changed, 40 insertions, 2 deletions
@@ -26,13 +26,14 @@ const magic uint32 = 0xED0CDAED // 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 synchronzied using the msync(2) syscall. +// 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 ) // DB represents a collection of buckets persisted to a file on disk. @@ -85,11 +86,17 @@ type DB struct { // 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 @@ -147,6 +154,7 @@ func Open(path string, mode os.FileMode, options *Options) (*DB, error) { // Set default values for later DB operations. db.MaxBatchSize = DefaultMaxBatchSize db.MaxBatchDelay = DefaultMaxBatchDelay + db.AllocSize = DefaultAllocSize flag := os.O_RDWR if options.ReadOnly { @@ -410,7 +418,7 @@ 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 +// 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. @@ -798,6 +806,36 @@ func (db *DB) allocate(count int) (*page, error) { 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 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 } |