Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1997, 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 "memory/gcLocker.inline.hpp"

 #include "memory/resourceArea.hpp"

 #include "memory/sharedHeap.hpp"

 volatile jint GC_locker::_jni_lock_count = 0;

 volatile jint GC_locker::_lock_count     = 0;

 volatile bool GC_locker::_needs_gc       = false;

 volatile bool GC_locker::_doing_gc       = false;

 void GC_locker::stall_until_clear() {

   assert(!JavaThread::current()->in_critical(), "Would deadlock");

   if (PrintJNIGCStalls && PrintGCDetails) {

     ResourceMark rm; // JavaThread::name() allocates to convert to UTF8

     gclog_or_tty->print_cr(

       "Allocation failed. Thread \"%s\" is stalled by JNI critical section.",

       JavaThread::current()->name());

   }

   MutexLocker   ml(JNICritical_lock);

   // Wait for _needs_gc  to be cleared

   while (GC_locker::needs_gc()) {

     JNICritical_lock->wait();

   }

 }

 void GC_locker::jni_lock_slow() {

   MutexLocker mu(JNICritical_lock);

   // Block entering threads if we know at least one thread is in a

   // JNI critical region and we need a GC.

   // We check that at least one thread is in a critical region before

   // blocking because blocked threads are woken up by a thread exiting

   // a JNI critical region.

   while ((is_jni_active() && needs_gc()) || _doing_gc) {

     JNICritical_lock->wait();

   }

   jni_lock();

 }

 void GC_locker::jni_unlock_slow() {

   MutexLocker mu(JNICritical_lock);

   jni_unlock();

   if (needs_gc() && !is_jni_active()) {

     // We're the last thread out. Cause a GC to occur.

     // GC will also check is_active, so this check is not

     // strictly needed. It's added here to make it clear that

     // the GC will NOT be performed if any other caller

     // of GC_locker::lock() still needs GC locked.

     if (!is_active()) {

       _doing_gc = true;

       {

         // Must give up the lock while at a safepoint

         MutexUnlocker munlock(JNICritical_lock);

         Universe::heap()->collect(GCCause::_gc_locker);

       }

       _doing_gc = false;

     }

     clear_needs_gc();

     JNICritical_lock->notify_all();

   }

 }

 // Implementation of No_GC_Verifier

 #ifdef ASSERT

 No_GC_Verifier::No_GC_Verifier(bool verifygc) {

   _verifygc = verifygc;

   if (_verifygc) {

     CollectedHeap* h = Universe::heap();

     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");

     _old_invocations = h->total_collections();

   }

 }

 No_GC_Verifier::~No_GC_Verifier() {

   if (_verifygc) {

     CollectedHeap* h = Universe::heap();

     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");

     if (_old_invocations != h->total_collections()) {

       fatal("collection in a No_GC_Verifier secured function");

     }

   }

 }

 Pause_No_GC_Verifier::Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {

   _ngcv = ngcv;

   if (_ngcv->_verifygc) {

     // if we were verifying, then make sure that nothing is

     // wrong before we "pause" verification

     CollectedHeap* h = Universe::heap();

     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");

     if (_ngcv->_old_invocations != h->total_collections()) {

       fatal("collection in a No_GC_Verifier secured function");

     }

   }

 }

 Pause_No_GC_Verifier::~Pause_No_GC_Verifier() {

   if (_ngcv->_verifygc) {

     // if we were verifying before, then reenable verification

     CollectedHeap* h = Universe::heap();

     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");

     _ngcv->_old_invocations = h->total_collections();

   }

 }

 // JRT_LEAF rules:

 // A JRT_LEAF method may not interfere with safepointing by

 //   1) acquiring or blocking on a Mutex or JavaLock - checked

 //   2) allocating heap memory - checked

 //   3) executing a VM operation - checked

 //   4) executing a system call (including malloc) that could block or grab a lock

 //   5) invoking GC

 //   6) reaching a safepoint

 //   7) running too long

 // Nor may any method it calls.

 JRT_Leaf_Verifier::JRT_Leaf_Verifier()

   : No_Safepoint_Verifier(true, JRT_Leaf_Verifier::should_verify_GC())

 {

 }

 JRT_Leaf_Verifier::~JRT_Leaf_Verifier()

 {

 }

 bool JRT_Leaf_Verifier::should_verify_GC() {

   switch (JavaThread::current()->thread_state()) {

   case _thread_in_Java:

     // is in a leaf routine, there must be no safepoint.

     return true;

   case _thread_in_native:

     // A native thread is not subject to safepoints.

     // Even while it is in a leaf routine, GC is ok

     return false;

   default:

     // Leaf routines cannot be called from other contexts.

     ShouldNotReachHere();

     return false;

   }

 }

 #endif