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package filer
type ReaderPattern struct {
isSequentialCounter int64
lastReadStopOffset int64
}
const ModeChangeLimit = 3
// For streaming read: only cache the first chunk
// For random read: only fetch the requested range, instead of the whole chunk
func NewReaderPattern() *ReaderPattern {
return &ReaderPattern{
isSequentialCounter: 0,
lastReadStopOffset: 0,
}
}
func (rp *ReaderPattern) MonitorReadAt(offset int64, size int) {
if rp.lastReadStopOffset == offset {
if rp.isSequentialCounter < ModeChangeLimit {
rp.isSequentialCounter++
}
} else {
if rp.isSequentialCounter > -ModeChangeLimit {
rp.isSequentialCounter--
}
}
rp.lastReadStopOffset = offset + int64(size)
}
func (rp *ReaderPattern) IsRandomMode() bool {
return rp.isSequentialCounter < 0
}
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