113 lines
2.6 KiB
Go
113 lines
2.6 KiB
Go
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// 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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//go:build !plan9 && !windows
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// +build !plan9,!windows
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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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"sync/atomic"
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"time"
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"unsafe"
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)
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/*
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#include <pthread.h>
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#include <stdint.h>
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extern uint32_t threadExited;
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void setExited(void *x);
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*/
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import "C"
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var mainThread C.pthread_t
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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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mainThread = C.pthread_self()
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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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// 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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self := C.pthread_self()
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if C.pthread_equal(mainThread, self) == 0 {
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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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self := C.pthread_self()
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if C.pthread_equal(mainThread, self) != 0 {
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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 subThread C.pthread_t
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ready := make(chan bool, 1)
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C.threadExited = 0
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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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subThread = C.pthread_self()
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// Register a pthread destructor so we can tell this
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// thread has exited.
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var key C.pthread_key_t
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C.pthread_key_create(&key, (*[0]byte)(unsafe.Pointer(C.setExited)))
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C.pthread_setspecific(key, unsafe.Pointer(new(int)))
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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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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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self := C.pthread_self()
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if C.pthread_equal(subThread, self) != 0 {
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println("locked thread reused")
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os.Exit(1)
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}
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if atomic.LoadUint32((*uint32)(&C.threadExited)) != 0 {
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println("OK")
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return
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}
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}
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println("sub thread still running")
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os.Exit(1)
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}
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