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package bigcache
import (
"encoding/binary"
)
const (
timestampSizeInBytes = 8 // Number of bytes used for timestamp
hashSizeInBytes = 8 // Number of bytes used for hash
keySizeInBytes = 2 // Number of bytes used for size of entry key
headersSizeInBytes = timestampSizeInBytes + hashSizeInBytes + keySizeInBytes // Number of bytes used for all headers
)
func wrapEntry(timestamp uint64, hash uint64, key string, entry []byte, buffer *[]byte) []byte {
keyLength := len(key)
blobLength := len(entry) + headersSizeInBytes + keyLength
if blobLength > len(*buffer) {
*buffer = make([]byte, blobLength)
}
blob := *buffer
binary.LittleEndian.PutUint64(blob, timestamp)
binary.LittleEndian.PutUint64(blob[timestampSizeInBytes:], hash)
binary.LittleEndian.PutUint16(blob[timestampSizeInBytes+hashSizeInBytes:], uint16(keyLength))
copy(blob[headersSizeInBytes:], key)
copy(blob[headersSizeInBytes+keyLength:], entry)
return blob[:blobLength]
}
func readEntry(data []byte) []byte {
length := binary.LittleEndian.Uint16(data[timestampSizeInBytes+hashSizeInBytes:])
// copy on read
dst := make([]byte, len(data)-int(headersSizeInBytes+length))
copy(dst, data[headersSizeInBytes+length:])
return dst
}
func readTimestampFromEntry(data []byte) uint64 {
return binary.LittleEndian.Uint64(data)
}
func readKeyFromEntry(data []byte) string {
length := binary.LittleEndian.Uint16(data[timestampSizeInBytes+hashSizeInBytes:])
// copy on read
dst := make([]byte, length)
copy(dst, data[headersSizeInBytes:headersSizeInBytes+length])
return bytesToString(dst)
}
func readHashFromEntry(data []byte) uint64 {
return binary.LittleEndian.Uint64(data[timestampSizeInBytes:])
}
func resetKeyFromEntry(data []byte) {
binary.LittleEndian.PutUint64(data[timestampSizeInBytes:], 0)
}