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src/os/windows/vm/threadCritical_windows.cpp@cd3d6a6b95d9 (annotated)

src/os/windows/vm/threadCritical_windows.cpp

Fri, 30 Nov 2012 15:23:16 -0800

author

twisti

date

Fri, 30 Nov 2012 15:23:16 -0800

changeset 4318

cd3d6a6b95d9

parent 2314

f95d63e2154a

child 4299

f34d701e952e

permissions

-rw-r--r--

8003240: x86: move MacroAssembler into separate file
Reviewed-by: kvn

duke@435	1	/*
stefank@2314	2	* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
stefank@2314	25	#include "precompiled.hpp"
stefank@2314	26	#include "runtime/threadCritical.hpp"
stefank@2314	27	#include "thread_windows.inline.hpp"
duke@435	28
duke@435	29	// OS-includes here
duke@435	30	# include <windows.h>
duke@435	31	# include <winbase.h>
duke@435	32
duke@435	33	//
duke@435	34	// See threadCritical.hpp for details of this class.
duke@435	35	//
duke@435	36
duke@435	37	static bool initialized = false;
duke@435	38	static volatile jint lock_count = -1;
duke@435	39	static HANDLE lock_event;
duke@435	40	static DWORD lock_owner = -1;
duke@435	41
duke@435	42	//
duke@435	43	// Note that Microsoft's critical region code contains a race
duke@435	44	// condition, and is not suitable for use. A thread holding the
duke@435	45	// critical section cannot safely suspend a thread attempting
duke@435	46	// to enter the critical region. The failure mode is that both
duke@435	47	// threads are permanently suspended.
duke@435	48	//
duke@435	49	// I experiemented with the use of ordinary windows mutex objects
duke@435	50	// and found them ~30 times slower than the critical region code.
duke@435	51	//
duke@435	52
duke@435	53	void ThreadCritical::initialize() {
duke@435	54	}
duke@435	55
duke@435	56	void ThreadCritical::release() {
duke@435	57	assert(lock_owner == -1, "Mutex being deleted while owned.");
duke@435	58	assert(lock_count == -1, "Mutex being deleted while recursively locked");
duke@435	59	assert(lock_event != NULL, "Sanity check");
duke@435	60	CloseHandle(lock_event);
duke@435	61	}
duke@435	62
duke@435	63	ThreadCritical::ThreadCritical() {
duke@435	64	DWORD current_thread = GetCurrentThreadId();
duke@435	65
duke@435	66	if (lock_owner != current_thread) {
duke@435	67	// Grab the lock before doing anything.
duke@435	68	while (Atomic::cmpxchg(0, &lock_count, -1) != -1) {
duke@435	69	if (initialized) {
duke@435	70	DWORD ret = WaitForSingleObject(lock_event, INFINITE);
duke@435	71	assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject");
duke@435	72	}
duke@435	73	}
duke@435	74
duke@435	75	// Make sure the event object is allocated.
duke@435	76	if (!initialized) {
duke@435	77	// Locking will not work correctly unless this is autoreset.
duke@435	78	lock_event = CreateEvent(NULL, false, false, NULL);
duke@435	79	initialized = true;
duke@435	80	}
duke@435	81
duke@435	82	assert(lock_owner == -1, "Lock acquired illegally.");
duke@435	83	lock_owner = current_thread;
duke@435	84	} else {
duke@435	85	// Atomicity isn't required. Bump the recursion count.
duke@435	86	lock_count++;
duke@435	87	}
duke@435	88
duke@435	89	assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally.");
duke@435	90	}
duke@435	91
duke@435	92	ThreadCritical::~ThreadCritical() {
duke@435	93	assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread");
duke@435	94	assert(lock_count >= 0, "Attempt to unlock when already unlocked");
duke@435	95
duke@435	96	if (lock_count == 0) {
duke@435	97	// We're going to unlock
duke@435	98	lock_owner = -1;
duke@435	99	lock_count = -1;
duke@435	100	// No lost wakeups, lock_event stays signaled until reset.
duke@435	101	DWORD ret = SetEvent(lock_event);
duke@435	102	assert(ret != 0, "unexpected return value from SetEvent");
duke@435	103	} else {
duke@435	104	// Just unwinding a recursive lock;
duke@435	105	lock_count--;
duke@435	106	}
duke@435	107	}