Mercurial > hg > truffle
annotate src/os/windows/vm/threadCritical_windows.cpp @ 21947:9f70fc90169d
Truffle: remove expensive assertion
| author | Andreas Woess <andreas.woess@oracle.com> |
|---|---|
| date | Wed, 17 Jun 2015 04:09:30 +0200 |
| parents | f34d701e952e |
| children |
| rev | line source |
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| 0 | 1 /* |
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| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
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| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
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26 #include "runtime/thread.inline.hpp" |
| 1972 | 27 #include "runtime/threadCritical.hpp" |
| 0 | 28 |
| 29 // OS-includes here | |
| 30 # include <windows.h> | |
| 31 # include <winbase.h> | |
| 32 | |
| 33 // | |
| 34 // See threadCritical.hpp for details of this class. | |
| 35 // | |
| 36 | |
| 37 static bool initialized = false; | |
| 38 static volatile jint lock_count = -1; | |
| 39 static HANDLE lock_event; | |
| 40 static DWORD lock_owner = -1; | |
| 41 | |
| 42 // | |
| 43 // Note that Microsoft's critical region code contains a race | |
| 44 // condition, and is not suitable for use. A thread holding the | |
| 45 // critical section cannot safely suspend a thread attempting | |
| 46 // to enter the critical region. The failure mode is that both | |
| 47 // threads are permanently suspended. | |
| 48 // | |
| 49 // I experiemented with the use of ordinary windows mutex objects | |
| 50 // and found them ~30 times slower than the critical region code. | |
| 51 // | |
| 52 | |
| 53 void ThreadCritical::initialize() { | |
| 54 } | |
| 55 | |
| 56 void ThreadCritical::release() { | |
| 57 assert(lock_owner == -1, "Mutex being deleted while owned."); | |
| 58 assert(lock_count == -1, "Mutex being deleted while recursively locked"); | |
| 59 assert(lock_event != NULL, "Sanity check"); | |
| 60 CloseHandle(lock_event); | |
| 61 } | |
| 62 | |
| 63 ThreadCritical::ThreadCritical() { | |
| 64 DWORD current_thread = GetCurrentThreadId(); | |
| 65 | |
| 66 if (lock_owner != current_thread) { | |
| 67 // Grab the lock before doing anything. | |
| 68 while (Atomic::cmpxchg(0, &lock_count, -1) != -1) { | |
| 69 if (initialized) { | |
| 70 DWORD ret = WaitForSingleObject(lock_event, INFINITE); | |
| 71 assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject"); | |
| 72 } | |
| 73 } | |
| 74 | |
| 75 // Make sure the event object is allocated. | |
| 76 if (!initialized) { | |
| 77 // Locking will not work correctly unless this is autoreset. | |
| 78 lock_event = CreateEvent(NULL, false, false, NULL); | |
| 79 initialized = true; | |
| 80 } | |
| 81 | |
| 82 assert(lock_owner == -1, "Lock acquired illegally."); | |
| 83 lock_owner = current_thread; | |
| 84 } else { | |
| 85 // Atomicity isn't required. Bump the recursion count. | |
| 86 lock_count++; | |
| 87 } | |
| 88 | |
| 89 assert(lock_owner == GetCurrentThreadId(), "Lock acquired illegally."); | |
| 90 } | |
| 91 | |
| 92 ThreadCritical::~ThreadCritical() { | |
| 93 assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread"); | |
| 94 assert(lock_count >= 0, "Attempt to unlock when already unlocked"); | |
| 95 | |
| 96 if (lock_count == 0) { | |
| 97 // We're going to unlock | |
| 98 lock_owner = -1; | |
| 99 lock_count = -1; | |
| 100 // No lost wakeups, lock_event stays signaled until reset. | |
| 101 DWORD ret = SetEvent(lock_event); | |
| 102 assert(ret != 0, "unexpected return value from SetEvent"); | |
| 103 } else { | |
| 104 // Just unwinding a recursive lock; | |
| 105 lock_count--; | |
| 106 } | |
| 107 } |