Documentation ¶
Index ¶
- Variables
- type Batch
- type CRC
- type Log
- func (l *Log) ClearCache() error
- func (l *Log) Close() error
- func (l *Log) FirstIndex() (index uint64, err error)
- func (l *Log) LastIndex() (index uint64, err error)
- func (l *Log) Read(index uint64) (data []byte, err error)
- func (l *Log) Sync() error
- func (l *Log) TruncateBack(index uint64) error
- func (l *Log) TruncateFront(index uint64) error
- func (l *Log) Write(index uint64, data []byte) error
- func (l *Log) WriteBatch(b *Batch) error
- type LogFormat
- type Options
Constants ¶
This section is empty.
Variables ¶
var ( // ErrCorrupt is returns when the log is corrupt. ErrCorrupt = errors.New("log corrupt") // ErrClosed is returned when an operation cannot be completed because // the log is closed. ErrClosed = errors.New("log closed") // ErrNotFound is returned when an entry is not found. ErrNotFound = errors.New("not found") // ErrOutOfOrder is returned from Write() when the index is not equal to // LastIndex()+1. It's required that log monotonically grows by one and has // no gaps. Thus, the series 10,11,12,13,14 is valid, but 10,11,13,14 is // not because there's a gap between 11 and 13. Also, 10,12,11,13 is not // valid because 12 and 11 are out of order. ErrOutOfOrder = errors.New("out of order") // ErrOutOfRange is returned from TruncateFront() and TruncateBack() when // the index not in the range of the log's first and last index. Or, this // may be returned when the caller is attempting to remove *all* entries; // The log requires that at least one entry exists following a truncate. ErrOutOfRange = errors.New("out of range") )
var DefaultOptions = &Options{ NoSync: false, SegmentSize: 20971520, LogFormat: Binary, SegmentCacheSize: 2, NoCopy: false, }
DefaultOptions for Open().
Functions ¶
This section is empty.
Types ¶
type Batch ¶
type Batch struct {
// contains filtered or unexported fields
}
Batch of entries. Used to write multiple entries at once using WriteBatch().
type Log ¶
type Log struct {
// contains filtered or unexported fields
}
Log represents a write ahead log
func (*Log) FirstIndex ¶
FirstIndex returns the index of the first entry in the log. Returns zero when log has no entries.
func (*Log) LastIndex ¶
LastIndex returns the index of the last entry in the log. Returns zero when log has no entries.
func (*Log) Sync ¶
Sync performs an fsync on the log. This is not necessary when the NoSync option is set to false.
func (*Log) TruncateBack ¶
TruncateBack truncates the back of the log by removing all entries that are after the provided `index`. In other words the entry at `index` becomes the last entry in the log.
func (*Log) TruncateFront ¶
TruncateFront truncates the front of the log by removing all entries that are before the provided `index`. In other words the entry at `index` becomes the first entry in the log.
func (*Log) WriteBatch ¶
WriteBatch writes the entries in the batch to the log in the order that they were added to the batch. The batch is cleared upon a successful return.
type Options ¶
type Options struct { // NoSync disables fsync after writes. This is less durable and puts the // log at risk of data loss when there's a server crash. NoSync bool // SegmentSize of each segment. This is just a target value, actual size // may differ. Default is 20 MB. SegmentSize int // LogFormat is the format of the log files. Default is Binary. LogFormat LogFormat // SegmentCacheSize is the maximum number of segments that will be held in // memory for caching. Increasing this value may enhance performance for // concurrent read operations. Default is 1 SegmentCacheSize int // NoCopy allows for the Read() operation to return the raw underlying data // slice. This is an optimization to help minimize allocations. When this // option is set, do not modify the returned data because it may affect // other Read calls. Default false NoCopy bool }
Options for Log