mirror of
https://github.com/hajimehoshi/ebiten.git
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d9cf1095d4
This CL fixes the race condtion on delayedCommands, which can be accessed and set to nil at the same time. This CL separates some operations for delayedCommands into slow- paths and fast-paths, and use mutex only at slow-paths for performance. The implementation is based on sync.Once. Fixes #1195
97 lines
2.4 KiB
Go
97 lines
2.4 KiB
Go
// Copyright 2019 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package buffered
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import (
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"sync"
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"sync/atomic"
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)
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var (
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// delayedCommands represents a queue for image operations that are ordered before the game starts
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// (BeginFrame). Before the game starts, the package shareable doesn't determine the minimum/maximum texture
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// sizes (#879).
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delayedCommands = []func() error{}
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delayedCommandsM sync.Mutex
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delayedCommandsFlushed uint32
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)
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func flushDelayedCommands() error {
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fs := getDelayedFuncsAndClear()
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for _, f := range fs {
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if err := f(); err != nil {
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return err
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}
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}
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return nil
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}
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func getDelayedFuncsAndClear() []func() error {
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if atomic.LoadUint32(&delayedCommandsFlushed) == 0 {
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// Outline the slow-path to expect the fast-path is inlined.
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return getDelayedFuncsAndClearSlow()
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}
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return nil
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}
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func getDelayedFuncsAndClearSlow() []func() error {
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delayedCommandsM.Lock()
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defer delayedCommandsM.Unlock()
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if delayedCommandsFlushed == 0 {
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defer atomic.StoreUint32(&delayedCommandsFlushed, 1)
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fs := make([]func() error, len(delayedCommands))
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copy(fs, delayedCommands)
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delayedCommands = nil
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return fs
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}
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return nil
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}
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func tryAddDelayedCommand(f func(obj interface{}) error, ondelayed func() interface{}) bool {
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if atomic.LoadUint32(&delayedCommandsFlushed) == 0 {
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// Outline the slow-path to expect the fast-path is inlined.
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tryAddDelayedCommandSlow(f, ondelayed)
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return true
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}
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return false
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}
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func tryAddDelayedCommandSlow(f func(obj interface{}) error, ondelayed func() interface{}) {
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delayedCommandsM.Lock()
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defer delayedCommandsM.Unlock()
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if delayedCommandsFlushed == 0 {
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var obj interface{}
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if ondelayed != nil {
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obj = ondelayed()
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}
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delayedCommands = append(delayedCommands, func() error {
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return f(obj)
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})
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}
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}
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func checkDelayedCommandsNil(fname string) {
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if delayedCommands != nil {
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panic("buffered: the command queue is not available yet at " + fname)
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}
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}
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