diff options
Diffstat (limited to 'tx.go')
| -rw-r--r-- | tx.go | 27 |
1 files changed, 17 insertions, 10 deletions
@@ -29,6 +29,14 @@ type Tx struct { pages map[pgid]*page stats TxStats commitHandlers []func() + + // WriteFlag specifies the flag for write-related methods like WriteTo(). + // Tx opens the database file with the specified flag to copy the data. + // + // By default, the flag is unset, which works well for mostly in-memory + // workloads. For databases that are much larger than available RAM, + // set the flag to syscall.O_DIRECT to avoid trashing the page cache. + WriteFlag int } // init initializes the transaction. @@ -87,18 +95,21 @@ 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) } @@ -266,7 +277,7 @@ func (tx *Tx) close() { } // Copy writes the entire database to a writer. -// This function exists for backwards compatibility. Use WriteTo() in +// This function exists for backwards compatibility. Use WriteTo() instead. func (tx *Tx) Copy(w io.Writer) error { _, err := tx.WriteTo(w) return err @@ -275,21 +286,18 @@ func (tx *Tx) Copy(w io.Writer) error { // 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 0, err - } + // Attempt to open reader with WriteFlag + f, err := os.OpenFile(tx.db.path, os.O_RDONLY|tx.WriteFlag, 0) + if err != nil { + return 0, err } + defer func() { _ = f.Close() }() // Copy the meta pages. tx.db.metalock.Lock() n, err = io.CopyN(w, f, int64(tx.db.pageSize*2)) tx.db.metalock.Unlock() if err != nil { - _ = f.Close() return n, fmt.Errorf("meta copy: %s", err) } @@ -297,7 +305,6 @@ func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) { wn, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2)) n += wn if err != nil { - _ = f.Close() return n, err } |