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

 /*

  * Copyright (c) 1998, 2007, 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.

  *

  */

 class ObjectMonitor;

 class ObjectSynchronizer : AllStatic {

   friend class VMStructs;

  public:

   typedef enum {

     owner_self,

     owner_none,

     owner_other

   } LockOwnership;

   // exit must be implemented non-blocking, since the compiler cannot easily handle

   // deoptimization at monitor exit. Hence, it does not take a Handle argument.

   // This is full version of monitor enter and exit. I choose not

   // to use enter() and exit() in order to make sure user be ware

   // of the performance and semantics difference. They are normally

   // used by ObjectLocker etc. The interpreter and compiler use

   // assembly copies of these routines. Please keep them synchornized.

   //

   // attempt_rebias flag is used by UseBiasedLocking implementation

   static void fast_enter  (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);

   static void fast_exit   (oop obj,    BasicLock* lock, Thread* THREAD);

   // WARNING: They are ONLY used to handle the slow cases. They should

   // only be used when the fast cases failed. Use of these functions

   // without previous fast case check may cause fatal error.

   static void slow_enter  (Handle obj, BasicLock* lock, TRAPS);

   static void slow_exit   (oop obj,    BasicLock* lock, Thread* THREAD);

   // Used only to handle jni locks or other unmatched monitor enter/exit

   // Internally they will use heavy weight monitor.

   static void jni_enter   (Handle obj, TRAPS);

   static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter

   static void jni_exit    (oop obj,    Thread* THREAD);

   // Handle all interpreter, compiler and jni cases

   static void wait               (Handle obj, jlong millis, TRAPS);

   static void notify             (Handle obj,               TRAPS);

   static void notifyall          (Handle obj,               TRAPS);

   // Special internal-use-only method for use by JVM infrastructure

   // that needs to wait() on a java-level object but that can't risk

   // throwing unexpected InterruptedExecutionExceptions.

   static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;

   // used by classloading to free classloader object lock,

   // wait on an internal lock, and reclaim original lock

   // with original recursion count

   static intptr_t complete_exit  (Handle obj,                TRAPS);

   static void reenter            (Handle obj, intptr_t recursion, TRAPS);

   // thread-specific and global objectMonitor free list accessors

 //  static void verifyInUse (Thread * Self) ; too slow for general assert/debug

   static ObjectMonitor * omAlloc (Thread * Self) ;

   static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;

   static void omFlush   (Thread * Self) ;

   // Inflate light weight monitor to heavy weight monitor

   static ObjectMonitor* inflate(Thread * Self, oop obj);

   // This version is only for internal use

   static ObjectMonitor* inflate_helper(oop obj);

   // Returns the identity hash value for an oop

   // NOTE: It may cause monitor inflation

   static intptr_t identity_hash_value_for(Handle obj);

   static intptr_t FastHashCode (Thread * Self, oop obj) ;

   // java.lang.Thread support

   static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);

   static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);

   static JavaThread* get_lock_owner(Handle h_obj, bool doLock);

   // JNI detach support

   static void release_monitors_owned_by_thread(TRAPS);

   static void monitors_iterate(MonitorClosure* m);

   // GC: we current use aggressive monitor deflation policy

   // Basically we deflate all monitors that are not busy.

   // An adaptive profile-based deflation policy could be used if needed

   static void deflate_idle_monitors();

   static int walk_monitor_list(ObjectMonitor** listheadp,

                                ObjectMonitor** FreeHeadp,

                                ObjectMonitor** FreeTailp);

   static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,

                               ObjectMonitor** FreeTailp);

   static void oops_do(OopClosure* f);

   // debugging

   static void trace_locking(Handle obj, bool is_compiled, bool is_method, bool is_locking) PRODUCT_RETURN;

   static void verify() PRODUCT_RETURN;

   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;

   static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;

  private:

   enum { _BLOCKSIZE = 128 };

   static ObjectMonitor* gBlockList;

   static ObjectMonitor * volatile gFreeList;

   static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned

   static int gOmInUseCount;

 };

 // ObjectLocker enforced balanced locking and can never thrown an

 // IllegalMonitorStateException. However, a pending exception may

 // have to pass through, and we must also be able to deal with

 // asynchronous exceptions. The caller is responsible for checking

 // the threads pending exception if needed.

 // doLock was added to support classloading with UnsyncloadClass which

 // requires flag based choice of locking the classloader lock.

 class ObjectLocker : public StackObj {

  private:

   Thread*   _thread;

   Handle    _obj;

   BasicLock _lock;

   bool      _dolock;   // default true

  public:

   ObjectLocker(Handle obj, Thread* thread, bool doLock = true);

   ~ObjectLocker();

   // Monitor behavior

   void wait      (TRAPS)      { ObjectSynchronizer::wait     (_obj, 0, CHECK); } // wait forever

   void notify_all(TRAPS)      { ObjectSynchronizer::notifyall(_obj,    CHECK); }

   void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}

   // complete_exit gives up lock completely, returning recursion count

   // reenter reclaims lock with original recursion count

   intptr_t complete_exit(TRAPS) { return  ObjectSynchronizer::complete_exit(_obj, CHECK_0); }

   void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }

 };