seaweedfs/weed/mount/page_writer_pattern.go
2022-08-07 11:35:33 -07:00

38 lines
849 B
Go

package mount
type WriterPattern struct {
isSequentialCounter int64
lastWriteStopOffset int64
chunkSize int64
}
const ModeChangeLimit = 3
// For streaming write: only cache the first chunk
// For random write: fall back to temp file approach
func NewWriterPattern(chunkSize int64) *WriterPattern {
return &WriterPattern{
isSequentialCounter: 0,
lastWriteStopOffset: 0,
chunkSize: chunkSize,
}
}
func (rp *WriterPattern) MonitorWriteAt(offset int64, size int) {
if rp.lastWriteStopOffset == offset {
if rp.isSequentialCounter < ModeChangeLimit {
rp.isSequentialCounter++
}
} else {
if rp.isSequentialCounter > -ModeChangeLimit {
rp.isSequentialCounter--
}
}
rp.lastWriteStopOffset = offset + int64(size)
}
func (rp *WriterPattern) IsSequentialMode() bool {
return rp.isSequentialCounter >= 0
}