README
¶
wal
A fast write ahead log for Go, all writes wait for sync and all functions are thread safe.
Getting Started
// open a write ahead log file
w, err := Open("testlog")
// write some records
pos, err = w.Write("first record")
pos, err = w.Write("second record")
pos, err = w.Write("third record")
// read all records from head
r, err = w.NewReader(0)
for {
pos, data, err = r.Next()
if pos == -1{
break
}
}
// truncate the log from position before 100
err = w.TruncateBefore(100)
// truncate the log from position after 200
err = w.TruncateAfter(200)
// backup
name, err = w.Backup()
// recover the write ahead log from the backup file
err = w.RecoverFromBackup(name)
// close the log
w.Close()
License
wal source code is available under the MIT License.
Documentation
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Index ¶
- Constants
- type Reader
- type Wal
- func (w *Wal) Backup() (string, error)
- func (w *Wal) Close() error
- func (w *Wal) NewReader(pos int64) (*Reader, error)
- func (w *Wal) RecoverFromBackup(name string) error
- func (w *Wal) TruncateAfter(pos int64) error
- func (w *Wal) TruncateBefore(pos int64) error
- func (w *Wal) Write(p []byte) (int64, error)
Constants ¶
const ( // MaxRecordSize is the maximum size of a record MaxRecordSize = 1<<32 - 1 // SyncConcurrency is the number of concurrent syncs SyncConcurrency = 1 << 10 // RecordHeaderSize is the size of the record header RecordHeaderSize = 8 )
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Reader ¶
type Reader struct {
// contains filtered or unexported fields
}
Reader represents a reader for the write ahead log, Reader is thread-unsafe
type Wal ¶
WAL represents a write ahead log that provides durability and fault-tolerance for incoming writes
func (*Wal) Backup ¶
Backup backup the write ahead log, return the backup file name this operation is mutually exclusive with all read and write operations
func (*Wal) NewReader ¶
NewReader returns a new reader for the write ahead log, the created reader traverses the current point snapshot to read all the records in the current write ahead log
func (*Wal) RecoverFromBackup ¶
RecoverFromBackup recover the write ahead log from the backup this operation is mutually exclusive with all read and write operations
func (*Wal) TruncateAfter ¶
TruncateAfter truncates the back of the write ahead log by removing all records after the provided pos this operation is mutually exclusive with all read and write operations
func (*Wal) TruncateBefore ¶
TruncateBefore truncates the front of the write ahead log by removing all records that are before the provided pos this operation is mutually exclusive with all read and write operations
Source Files