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package mount
import "sync/atomic"
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) {
lastOffset := atomic.SwapInt64(&rp.lastWriteStopOffset, offset+int64(size))
counter := atomic.LoadInt64(&rp.isSequentialCounter)
if lastOffset == offset {
if counter < ModeChangeLimit {
atomic.AddInt64(&rp.isSequentialCounter, 1)
}
} else {
if counter > -ModeChangeLimit {
atomic.AddInt64(&rp.isSequentialCounter, -1)
}
}
}
func (rp *WriterPattern) IsSequentialMode() bool {
return atomic.LoadInt64(&rp.isSequentialCounter) >= 0
}
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