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Custom allocator.

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This commit is contained in:
Nuno Cruces
2024-05-17 17:23:54 +01:00
parent bdaf77a657
commit 3d30a561f0
6 changed files with 39 additions and 34 deletions
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19
internal/util/alloc_windows.go
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@@ -3,7 +3,6 @@
package util
import (
"context"
"math"
"reflect"
"unsafe"
@@ -12,14 +11,6 @@ import (
"golang.org/x/sys/windows"
)
func withAllocator(ctx context.Context) context.Context {
if math.MaxInt != math.MaxInt64 {
return ctx
}
return experimental.WithMemoryAllocator(ctx,
experimental.MemoryAllocatorFunc(newAllocator))
}
func newAllocator(cap, max uint64) experimental.LinearMemory {
// Round up to the page size.
rnd := uint64(windows.Getpagesize() - 1)
@@ -27,12 +18,12 @@ func newAllocator(cap, max uint64) experimental.LinearMemory {
cap = (cap + rnd) &^ rnd
if max > math.MaxInt {
// This ensures int(max) overflows to a negative value,
// and unix.Mmap returns EINVAL.
// This ensures uintptr(max) overflows to a large value,
// and windows.VirtualAlloc returns an error.
max = math.MaxUint64
}
// Reserve max bytes of address space, to ensure we won't need to move it.
// A protected, private, anonymous mapping should not commit memory.
// This does not commit memory.
r, err := windows.VirtualAlloc(0, uintptr(max), windows.MEM_RESERVE, windows.PAGE_READWRITE)
if err != nil {
panic(err)
@@ -61,7 +52,9 @@ type virtualMemory struct {
}
func (m *virtualMemory) Reallocate(size uint64) []byte {
if com := uint64(len(m.buf)); com < size {
com := uint64(len(m.buf))
res := uint64(cap(m.buf))
if com < size && size < res {
// Round up to the page size.
rnd := uint64(windows.Getpagesize() - 1)
new := (size + rnd) &^ rnd