mirror of git://gcc.gnu.org/git/gcc.git
95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"os"
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"runtime"
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"time"
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)
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var mainTID int
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func init() {
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registerInit("LockOSThreadMain", func() {
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// init is guaranteed to run on the main thread.
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mainTID = gettid()
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})
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register("LockOSThreadMain", LockOSThreadMain)
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registerInit("LockOSThreadAlt", func() {
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// Lock the OS thread now so main runs on the main thread.
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runtime.LockOSThread()
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})
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register("LockOSThreadAlt", LockOSThreadAlt)
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}
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func LockOSThreadMain() {
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// gettid only works on Linux, so on other platforms this just
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// checks that the runtime doesn't do anything terrible.
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// This requires GOMAXPROCS=1 from the beginning to reliably
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// start a goroutine on the main thread.
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if runtime.GOMAXPROCS(-1) != 1 {
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println("requires GOMAXPROCS=1")
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os.Exit(1)
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}
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ready := make(chan bool, 1)
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go func() {
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// Because GOMAXPROCS=1, this *should* be on the main
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// thread. Stay there.
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runtime.LockOSThread()
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if mainTID != 0 && gettid() != mainTID {
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println("failed to start goroutine on main thread")
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os.Exit(1)
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}
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// Exit with the thread locked, which should exit the
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// main thread.
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ready <- true
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}()
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<-ready
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time.Sleep(1 * time.Millisecond)
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// Check that this goroutine is still running on a different
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// thread.
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if mainTID != 0 && gettid() == mainTID {
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println("goroutine migrated to locked thread")
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os.Exit(1)
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}
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println("OK")
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}
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func LockOSThreadAlt() {
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// This is running locked to the main OS thread.
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var subTID int
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ready := make(chan bool, 1)
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go func() {
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// This goroutine must be running on a new thread.
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runtime.LockOSThread()
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subTID = gettid()
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ready <- true
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// Exit with the thread locked.
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}()
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<-ready
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runtime.UnlockOSThread()
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for i := 0; i < 100; i++ {
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time.Sleep(1 * time.Millisecond)
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// Check that this goroutine is running on a different thread.
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if subTID != 0 && gettid() == subTID {
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println("locked thread reused")
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os.Exit(1)
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}
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exists, supported := tidExists(subTID)
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if !supported || !exists {
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goto ok
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}
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}
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println("sub thread", subTID, "still running")
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return
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ok:
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println("OK")
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}
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