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c05b06a12d
This changes the os package to use the runtime poller for file I/O where possible. When a system call blocks on a pollable descriptor, the goroutine will be blocked on the poller but the thread will be released to run other goroutines. When using a non-pollable descriptor, the os package will continue to use thread-blocking system calls as before. For example, on GNU/Linux, the runtime poller uses epoll. epoll does not support ordinary disk files, so they will continue to use blocking I/O as before. The poller will be used for pipes. Since this means that the poller is used for many more programs, this modifies the runtime to only block waiting for the poller if there is some goroutine that is waiting on the poller. Otherwise, there is no point, as the poller will never make any goroutine ready. This preserves the runtime's current simple deadlock detection. This seems to crash FreeBSD systems, so it is disabled on FreeBSD. This is issue 19093. Using the poller on Windows requires opening the file with FILE_FLAG_OVERLAPPED. We should only do that if we can remove that flag if the program calls the Fd method. This is issue 19098. Update #6817. Update #7903. Update #15021. Update #18507. Update #19093. Update #19098. Change-Id: Ia5197dcefa7c6fbcca97d19a6f8621b2abcbb1fe Reviewed-on: https://go-review.googlesource.com/36800 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
31 lines
583 B
Go
31 lines
583 B
Go
// Copyright 2013 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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// Fake network poller for NaCl.
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// Should never be used, because NaCl network connections do not honor "SetNonblock".
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package runtime
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func netpollinit() {
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}
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func netpolldescriptor() uintptr {
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return ^uintptr(0)
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}
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func netpollopen(fd uintptr, pd *pollDesc) int32 {
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return 0
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}
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func netpollclose(fd uintptr) int32 {
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return 0
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}
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func netpollarm(pd *pollDesc, mode int) {
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}
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func netpoll(block bool) *g {
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return nil
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}
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