mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-26 19:58:54 +01:00
135 lines
3.1 KiB
Go
135 lines
3.1 KiB
Go
// Copyright 2023 The Ebitengine Authors
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package graphics
|
|
|
|
import (
|
|
"runtime"
|
|
"sync"
|
|
)
|
|
|
|
// ManagedBytes is a managed byte slice.
|
|
// The internal byte alice are managed in a pool.
|
|
// ManagedBytes is useful when its lifetime is explicit, as the underlying byte slice can be reused for another ManagedBytes later.
|
|
// This can reduce allocations and GCs.
|
|
type ManagedBytes struct {
|
|
bytes []byte
|
|
pool *bytesPool
|
|
}
|
|
|
|
// Len returns the length of the slice.
|
|
func (m *ManagedBytes) Len() int {
|
|
return len(m.bytes)
|
|
}
|
|
|
|
// Read reads the byte slice's content to dst.
|
|
func (m *ManagedBytes) Read(dst []byte, from, to int) {
|
|
copy(dst, m.bytes[from:to])
|
|
}
|
|
|
|
// Clone creates a new ManagedBytes with the same content.
|
|
func (m *ManagedBytes) Clone() *ManagedBytes {
|
|
return NewManagedBytes(len(m.bytes), func(bs []byte) {
|
|
copy(bs, m.bytes)
|
|
})
|
|
}
|
|
|
|
// GetAndRelease returns the raw byte slice and a finalizer.
|
|
// A finalizer should be called when you can ensure that the slice is no longer used,
|
|
// e.g. when a graphics command using this slice is sent and executed.
|
|
//
|
|
// After GetAndRelease is called, the underlying byte slice is no longer available.
|
|
func (m *ManagedBytes) GetAndRelease() ([]byte, func()) {
|
|
bs := m.bytes
|
|
m.bytes = nil
|
|
return bs, func() {
|
|
m.pool.put(bs)
|
|
runtime.SetFinalizer(m, nil)
|
|
}
|
|
}
|
|
|
|
// NewManagedBytes returns a managed byte slice initialized by the given constructor f.
|
|
//
|
|
// The byte slice is not zero-cleared at the constructor.
|
|
func NewManagedBytes(size int, f func([]byte)) *ManagedBytes {
|
|
bs := theBytesPool.get(size)
|
|
f(bs.bytes)
|
|
return bs
|
|
}
|
|
|
|
type bytesPool struct {
|
|
pool [][]byte
|
|
|
|
m sync.Mutex
|
|
}
|
|
|
|
var theBytesPool bytesPool
|
|
|
|
func (b *bytesPool) get(size int) *ManagedBytes {
|
|
bs := b.getFromCache(size)
|
|
if bs == nil {
|
|
bs = make([]byte, size)
|
|
}
|
|
m := &ManagedBytes{
|
|
bytes: bs,
|
|
pool: b,
|
|
}
|
|
runtime.SetFinalizer(m, func(m *ManagedBytes) {
|
|
b.put(m.bytes)
|
|
})
|
|
return m
|
|
}
|
|
|
|
func (b *bytesPool) getFromCache(size int) []byte {
|
|
b.m.Lock()
|
|
defer b.m.Unlock()
|
|
|
|
for i, bs := range b.pool {
|
|
if cap(bs) < size {
|
|
continue
|
|
}
|
|
|
|
copy(b.pool[i:], b.pool[i+1:])
|
|
b.pool[len(b.pool)-1] = nil
|
|
b.pool = b.pool[:len(b.pool)-1]
|
|
return bs[:size]
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func (b *bytesPool) put(bs []byte) {
|
|
if len(bs) == 0 {
|
|
return
|
|
}
|
|
|
|
b.m.Lock()
|
|
defer b.m.Unlock()
|
|
|
|
b.pool = append(b.pool, bs)
|
|
|
|
// GC the pool. The size limitation is arbitrary.
|
|
for len(b.pool) >= 32 || b.totalSize() >= 1024*1024*1024 {
|
|
b.pool = b.pool[1:]
|
|
}
|
|
}
|
|
|
|
func (b *bytesPool) totalSize() int {
|
|
var s int
|
|
for _, bs := range b.pool {
|
|
s += len(bs)
|
|
}
|
|
return s
|
|
}
|