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1 /*
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2 * Copyright 2002-2005 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_cmsLockVerifier.cpp.incl"
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27
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28 ///////////// Locking verification specific to CMS //////////////
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29 // Much like "assert_lock_strong()", except that it relaxes the
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30 // assertion somewhat for the parallel GC case, where VM thread
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31 // or the CMS thread might hold the lock on behalf of the parallel
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32 // threads. The second argument is in support of an extra locking
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33 // check for CFL spaces' free list locks.
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34 #ifndef PRODUCT
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35 void CMSLockVerifier::assert_locked(const Mutex* lock, const Mutex* p_lock) {
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36 if (!Universe::is_fully_initialized()) {
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37 return;
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38 }
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39
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40 Thread* myThread = Thread::current();
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41
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42 if (lock == NULL) { // a "lock-free" structure, e.g. MUT, protected by CMS token
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43 assert(p_lock == NULL, "Unexpected state");
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44 if (myThread->is_ConcurrentGC_thread()) {
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45 // This test might have to change in the future, if there can be
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46 // multiple peer CMS threads. But for now, if we're testing the CMS
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47 assert(myThread == ConcurrentMarkSweepThread::cmst(),
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48 "In CMS, CMS thread is the only Conc GC thread.");
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49 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
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50 "CMS thread should have CMS token");
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51 } else if (myThread->is_VM_thread()) {
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52 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),
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53 "VM thread should have CMS token");
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54 } else {
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55 // Token should be held on our behalf by one of the other
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56 // of CMS or VM thread; not enough easily testable
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57 // state info to test which here.
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58 assert(myThread->is_GC_task_thread(), "Unexpected thread type");
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59 }
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60 return;
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61 }
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62
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63 if (ParallelGCThreads == 0) {
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64 assert_lock_strong(lock);
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65 } else {
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66 if (myThread->is_VM_thread()
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67 || myThread->is_ConcurrentGC_thread()
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68 || myThread->is_Java_thread()) {
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69 // Make sure that we are holding the associated lock.
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70 assert_lock_strong(lock);
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71 // The checking of p_lock is a spl case for CFLS' free list
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72 // locks: we make sure that none of the parallel GC work gang
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73 // threads are holding "sub-locks" of freeListLock(). We check only
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74 // the parDictionaryAllocLock because the others are too numerous.
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75 // This spl case code is somewhat ugly and any improvements
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76 // are welcome XXX FIX ME!!
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77 if (p_lock != NULL) {
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78 assert(!p_lock->is_locked() || p_lock->owned_by_self(),
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79 "Possible race between this and parallel GC threads");
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80 }
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81 } else if (myThread->is_GC_task_thread()) {
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82 // Make sure that the VM or CMS thread holds lock on our behalf
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83 // XXX If there were a concept of a gang_master for a (set of)
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84 // gang_workers, we could have used the identity of that thread
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85 // for checking ownership here; for now we just disjunct.
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86 assert(lock->owner() == VMThread::vm_thread() ||
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87 lock->owner() == ConcurrentMarkSweepThread::cmst(),
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88 "Should be locked by VM thread or CMS thread on my behalf");
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89 } else {
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90 // Make sure we didn't miss some obscure corner case
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91 ShouldNotReachHere();
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92 }
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93 }
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94 }
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95 #endif
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