ebiten/internal/buffered/command.go
Hajime Hoshi b08b740914 internal/buffered: bug fix: functions were not concurrent-safe
Before this change, `delayedCommandsFlushed` was set as 1 BEFORE
buffered commands were flushed. This meant that a function call and
a command being flushed were not concurrent-safe.

This change fixes this issue by changing the timing of setting
`delayedCommandsFlushed` as 1 to the later time after flushing the
buffered commands.

Closes #2580
2023-02-21 20:38:06 +09:00

75 lines
2.1 KiB
Go

// Copyright 2019 The Ebiten 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 buffered
import (
"sync"
"sync/atomic"
)
var (
// delayedCommands represents a queue for image operations that are ordered before the game starts
// (BeginFrame). Before the game starts, the package shareable doesn't determine the minimum/maximum texture
// sizes (#879).
delayedCommands = []func(){}
delayedCommandsM sync.Mutex
delayedCommandsFlushed uint32
)
func flushDelayedCommands() {
if atomic.LoadUint32(&delayedCommandsFlushed) == 0 {
// Outline the slow-path to expect the fast-path is inlined.
flushDelayedCommandsSlow()
}
}
func flushDelayedCommandsSlow() {
delayedCommandsM.Lock()
defer delayedCommandsM.Unlock()
if delayedCommandsFlushed == 0 {
for _, f := range delayedCommands {
f()
}
delayedCommandsFlushed = 1
}
}
// maybeCanAddDelayedCommand returns false if the delayed commands cannot be added.
// Otherwise, maybeCanAddDelayedCommand's returning value is not determined.
// For example, maybeCanAddDelayedCommand can return true even when flushing is being processed.
func maybeCanAddDelayedCommand() bool {
return atomic.LoadUint32(&delayedCommandsFlushed) == 0
}
func tryAddDelayedCommand(f func()) bool {
delayedCommandsM.Lock()
defer delayedCommandsM.Unlock()
if delayedCommandsFlushed == 0 {
delayedCommands = append(delayedCommands, f)
return true
}
return false
}
func checkDelayedCommandsFlushed(fname string) {
if atomic.LoadUint32(&delayedCommandsFlushed) == 0 {
panic("buffered: the command queue is not available yet at " + fname)
}
}