mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-01 14:47:38 +00:00
34 lines
1 KiB
Go
34 lines
1 KiB
Go
// +build cgo
|
|
|
|
package fs
|
|
|
|
// #cgo CFLAGS: -O3
|
|
//
|
|
// #include <stdint.h> // for uintptr_t
|
|
// #include <string.h> // for memcpy
|
|
//
|
|
// // The memcpy_wrapper allows avoiding memory allocations during calls from Go.
|
|
// // See https://github.com/golang/go/issues/24450 .
|
|
// static void memcpy_wrapper(uintptr_t dst, uintptr_t src, size_t n) {
|
|
// memcpy((void*)dst, (void*)src, n);
|
|
// }
|
|
import "C"
|
|
|
|
import (
|
|
"runtime"
|
|
"unsafe"
|
|
)
|
|
|
|
// copyMmap copies len(dst) bytes from src to dst.
|
|
func copyMmap(dst, src []byte) {
|
|
// Copy data from mmap'ed src via cgo call in order to protect from goroutine stalls
|
|
// when the copied data isn't available in RAM, so the OS triggers reading the data from file.
|
|
// See https://medium.com/@valyala/mmap-in-go-considered-harmful-d92a25cb161d for details.
|
|
dstPtr := C.uintptr_t(uintptr(unsafe.Pointer(&dst[0])))
|
|
srcPtr := C.uintptr_t(uintptr(unsafe.Pointer(&src[0])))
|
|
C.memcpy_wrapper(dstPtr, srcPtr, C.size_t(len(dst)))
|
|
|
|
// Prevent from GC'ing src or dst during C.memcpy_wrapper call.
|
|
runtime.KeepAlive(src)
|
|
runtime.KeepAlive(dst)
|
|
}
|