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//go:build !appengine && !windows
// +build !appengine,!windows
package fastcache
import (
"fmt"
"sync"
"unsafe"
"golang.org/x/sys/unix"
)
const chunksPerAlloc = 1024
var (
freeChunks []*[chunkSize]byte
freeChunksLock sync.Mutex
)
func getChunk() []byte {
freeChunksLock.Lock()
if len(freeChunks) == 0 {
// Allocate offheap memory, so GOGC won't take into account cache size.
// This should reduce free memory waste.
data, err := unix.Mmap(-1, 0, chunkSize*chunksPerAlloc, unix.PROT_READ|unix.PROT_WRITE, unix.MAP_ANON|unix.MAP_PRIVATE)
if err != nil {
panic(fmt.Errorf("cannot allocate %d bytes via mmap: %s", chunkSize*chunksPerAlloc, err))
}
for len(data) > 0 {
p := (*[chunkSize]byte)(unsafe.Pointer(&data[0]))
freeChunks = append(freeChunks, p)
data = data[chunkSize:]
}
}
n := len(freeChunks) - 1
p := freeChunks[n]
freeChunks[n] = nil
freeChunks = freeChunks[:n]
freeChunksLock.Unlock()
return p[:]
}
func putChunk(chunk []byte) {
if chunk == nil {
return
}
chunk = chunk[:chunkSize]
p := (*[chunkSize]byte)(unsafe.Pointer(&chunk[0]))
freeChunksLock.Lock()
freeChunks = append(freeChunks, p)
freeChunksLock.Unlock()
}
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