/*

 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc_implementation/concurrentMarkSweep/cmsLockVerifier.hpp"

#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"

#include "runtime/vmThread.hpp"

///////////// Locking verification specific to CMS //////////////

// Much like "assert_lock_strong()", except that it relaxes the

// assertion somewhat for the parallel GC case, where VM thread

// or the CMS thread might hold the lock on behalf of the parallel

// threads. The second argument is in support of an extra locking

// check for CFL spaces' free list locks.

#ifndef PRODUCT

void CMSLockVerifier::assert_locked(const Mutex* lock,

                                    const Mutex* p_lock1,

                                    const Mutex* p_lock2) {

  if (!Universe::is_fully_initialized()) {

    return;

  }

  Thread* myThread = Thread::current();

  if (lock == NULL) { // a "lock-free" structure, e.g. MUT, protected by CMS token

    assert(p_lock1 == NULL && p_lock2 == NULL, "Unexpected caller error");

    if (myThread->is_ConcurrentGC_thread()) {

      // This test might have to change in the future, if there can be

      // multiple peer CMS threads.  But for now, if we're testing the CMS

      assert(myThread == ConcurrentMarkSweepThread::cmst(),

             "In CMS, CMS thread is the only Conc GC thread.");

      assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(),

             "CMS thread should have CMS token");

    } else if (myThread->is_VM_thread()) {

      assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),

             "VM thread should have CMS token");

    } else {

      // Token should be held on our behalf by one of the other

      // of CMS or VM thread; not enough easily testable

      // state info to test which here.

      assert(myThread->is_GC_task_thread(), "Unexpected thread type");

    }

    return;

  }

  if (myThread->is_VM_thread()

      || myThread->is_ConcurrentGC_thread()

      || myThread->is_Java_thread()) {

    // Make sure that we are holding the associated lock.

    assert_lock_strong(lock);

    // The checking of p_lock is a spl case for CFLS' free list

    // locks: we make sure that none of the parallel GC work gang

    // threads are holding "sub-locks" of freeListLock(). We check only

    // the parDictionaryAllocLock because the others are too numerous.

    // This spl case code is somewhat ugly and any improvements

    // are welcome.

    assert(p_lock1 == NULL || !p_lock1->is_locked() || p_lock1->owned_by_self(),

           "Possible race between this and parallel GC threads");

    assert(p_lock2 == NULL || !p_lock2->is_locked() || p_lock2->owned_by_self(),

           "Possible race between this and parallel GC threads");

  } else if (myThread->is_GC_task_thread()) {

    // Make sure that the VM or CMS thread holds lock on our behalf

    // XXX If there were a concept of a gang_master for a (set of)

    // gang_workers, we could have used the identity of that thread

    // for checking ownership here; for now we just disjunct.

    assert(lock->owner() == VMThread::vm_thread() ||

           lock->owner() == ConcurrentMarkSweepThread::cmst(),

           "Should be locked by VM thread or CMS thread on my behalf");

    if (p_lock1 != NULL) {

      assert_lock_strong(p_lock1);

    }

    if (p_lock2 != NULL) {

      assert_lock_strong(p_lock2);

    }

  } else {

    // Make sure we didn't miss some other thread type calling into here;

    // perhaps as a result of future VM evolution.

    ShouldNotReachHere();

  }

}

#endif