cmsLockVerifier.cpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
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#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