Mercurial > hg > truffle
diff agent/src/os/win32/Monitor.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
parents | |
children | c18cbe5936b8 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/agent/src/os/win32/Monitor.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,176 @@ +/* + * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +#include <stdio.h> +#include <assert.h> +#include "Monitor.hpp" + +Monitor::Monitor() { + _lock_count = -1; // No threads have entered the critical section + _owner = NULL; + _lock_event = CreateEvent(NULL, false, false, NULL); + _wait_event = CreateEvent(NULL, true, false, NULL); + _counter = 0; + _tickets = 0; + _waiters = 0; +} + +Monitor::~Monitor() { + assert(_owner == NULL); // Otherwise, owned monitor being deleted + assert(_lock_count == -1); // Otherwise, monitor being deleted with non -1 lock count + CloseHandle(_lock_event); + CloseHandle(_wait_event); +} + +void +Monitor::lock() { + if (InterlockedIncrement(&_lock_count) == 0) { + // Success, we now own the lock + } else { + DWORD dwRet = WaitForSingleObject((HANDLE)_lock_event, INFINITE); + assert(dwRet == WAIT_OBJECT_0); // Unexpected return value from WaitForSingleObject + } + assert(owner() == NULL); // Otherwise, lock count and owner are inconsistent + setOwner(GetCurrentThread()); +} + +void +Monitor::unlock() { + setOwner(NULL); + if (InterlockedDecrement(&_lock_count) >= 0) { + // Wake a waiting thread up + DWORD dwRet = SetEvent(_lock_event); + assert(dwRet != 0); // Unexpected return value from SetEvent + } +} + +bool +Monitor::wait(long timeout) { + assert(owner() != NULL); + assert(owner() == GetCurrentThread()); + + // 0 means forever. Convert to Windows specific code. + DWORD timeout_value = (timeout == 0) ? INFINITE : timeout; + DWORD which; + + long c = _counter; + bool retry = false; + + _waiters++; + // Loop until condition variable is signaled. The event object is + // set whenever the condition variable is signaled, and tickets will + // reflect the number of threads which have been notified. The counter + // field is used to make sure we don't respond to notifications that + // have occurred *before* we started waiting, and is incremented each + // time the condition variable is signaled. + + while (true) { + + // Leave critical region + unlock(); + + // If this is a retry, let other low-priority threads have a chance + // to run. Make sure that we sleep outside of the critical section. + if (retry) { + Sleep(1); + } else { + retry = true; + } + + which = WaitForSingleObject(_wait_event, timeout_value); + // Enter critical section + lock(); + + if (_tickets != 0 && _counter != c) break; + + if (which == WAIT_TIMEOUT) { + --_waiters; + return true; + } + } + _waiters--; + + // If this was the last thread to be notified, then we need to reset + // the event object. + if (--_tickets == 0) { + ResetEvent(_wait_event); + } + + return false; +} + +// Notify a single thread waiting on this monitor +bool +Monitor::notify() { + assert(ownedBySelf()); // Otherwise, notify on unknown thread + + if (_waiters > _tickets) { + if (!SetEvent(_wait_event)) { + return false; + } + _tickets++; + _counter++; + } + + return true; +} + +// Notify all threads waiting on this monitor +bool +Monitor::notifyAll() { + assert(ownedBySelf()); // Otherwise, notifyAll on unknown thread + + if (_waiters > 0) { + if (!SetEvent(_wait_event)) { + return false; + } + _tickets = _waiters; + _counter++; + } + + return true; +} + +HANDLE +Monitor::owner() { + return _owner; +} + +void +Monitor::setOwner(HANDLE owner) { + if (owner != NULL) { + assert(_owner == NULL); // Setting owner thread of already owned monitor + assert(owner == GetCurrentThread()); // Else should not be doing this + } else { + HANDLE oldOwner = _owner; + assert(oldOwner != NULL); // Removing the owner thread of an unowned mutex + assert(oldOwner == GetCurrentThread()); + } + _owner = owner; +} + +bool +Monitor::ownedBySelf() { + return (_owner == GetCurrentThread()); +}