/
thread.go
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/
thread.go
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// Copyright 2018 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 thread
import (
"context"
"runtime"
)
type Thread interface {
Loop(ctx context.Context) error
Call(f func())
CallAsync(f func())
private()
}
type queueItem struct {
f func()
sync bool
}
// OSThread represents an OS thread.
type OSThread struct {
funcs chan queueItem
done chan struct{}
}
// NewOSThread creates a new thread.
//
// queueSize indicates the function queue size. This matters when you use CallAsync.
func NewOSThread() *OSThread {
return &OSThread{
funcs: make(chan queueItem),
done: make(chan struct{}),
}
}
// Loop starts the thread loop until Stop is called on the current OS thread.
//
// Loop must be called on the OS thread.
func (t *OSThread) Loop(ctx context.Context) error {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
for {
select {
case item := <-t.funcs:
func() {
if item.sync {
defer func() {
t.done <- struct{}{}
}()
}
item.f()
}()
case <-ctx.Done():
return ctx.Err()
}
}
}
// Call calls f on the thread.
//
// Do not call Call from the same thread. Call would block forever.
//
// Call blocks if Loop is not called.
func (t *OSThread) Call(f func()) {
t.funcs <- queueItem{f: f, sync: true}
<-t.done
}
func (t *OSThread) private() {
}
// CallAsync tries to queue f.
// CallAsync returns immediately if f can be queued.
// CallAsync blocks if f cannot be queued.
//
// Do not call CallAsync from the same thread. CallAsync would block forever.
func (t *OSThread) CallAsync(f func()) {
t.funcs <- queueItem{f: f, sync: false}
}
// NoopThread is used to disable threading.
type NoopThread struct{}
// NewNoopThread creates a new thread that does no threading.
func NewNoopThread() *NoopThread {
return &NoopThread{}
}
// Loop does nothing.
func (t *NoopThread) Loop(ctx context.Context) error {
return nil
}
// Call executes the func immediately.
func (t *NoopThread) Call(f func()) {
f()
}
// CallAsync executes the func immediately.
func (t *NoopThread) CallAsync(f func()) {
f()
}
func (t *NoopThread) private() {
}