1 /*

     2  * Copyright 1998-2007 Sun Microsystems, Inc.  All Rights Reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 class BasicLock VALUE_OBJ_CLASS_SPEC {

    26   friend class VMStructs;

    27  private:

    28   volatile markOop _displaced_header;

    29  public:

    30   markOop      displaced_header() const               { return _displaced_header; }

    31   void         set_displaced_header(markOop header)   { _displaced_header = header; }

    32 

    33   void print_on(outputStream* st) const;

    34 

    35   // move a basic lock (used during deoptimization

    36   void move_to(oop obj, BasicLock* dest);

    37 

    38   static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }

    39 };

    40 

    41 // A BasicObjectLock associates a specific Java object with a BasicLock.

    42 // It is currently embedded in an interpreter frame.

    43 

    44 // Because some machines have alignment restrictions on the control stack,

    45 // the actual space allocated by the interpreter may include padding words

    46 // after the end of the BasicObjectLock.  Also, in order to guarantee

    47 // alignment of the embedded BasicLock objects on such machines, we

    48 // put the embedded BasicLock at the beginning of the struct.

    49 

    50 class BasicObjectLock VALUE_OBJ_CLASS_SPEC {

    51   friend class VMStructs;

    52  private:

    53   BasicLock _lock;                                    // the lock, must be double word aligned

    54   oop       _obj;                                     // object holds the lock;

    55 

    56  public:

    57   // Manipulation

    58   oop      obj() const                                { return _obj;  }

    59   void set_obj(oop obj)                               { _obj = obj; }

    60   BasicLock* lock()                                   { return &_lock; }

    61 

    62   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks

    63   //       in interpreter activation frames since it includes machine-specific padding.

    64   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }

    65 

    66   // GC support

    67   void oops_do(OopClosure* f) { f->do_oop(&_obj); }

    68 

    69   static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }

    70   static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }

    71 };

    72 

    73 class ObjectMonitor;

    74 

    75 class ObjectSynchronizer : AllStatic {

    76   friend class VMStructs;

    77  public:

    78   typedef enum {

    79     owner_self,

    80     owner_none,

    81     owner_other

    82   } LockOwnership;

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

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

    85 

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

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

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

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

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

    91   //

    92   // attempt_rebias flag is used by UseBiasedLocking implementation

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

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

    95 

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

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

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

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

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

   101 

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

   103   // Internally they will use heavy weight monitor.

   104   static void jni_enter   (Handle obj, TRAPS);

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

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

   107 

   108   // Handle all interpreter, compiler and jni cases

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

   110   static void notify             (Handle obj,               TRAPS);

   111   static void notifyall          (Handle obj,               TRAPS);

   112 

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

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

   115   // throwing unexpected InterruptedExecutionExceptions.

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

   117 

   118   // used by classloading to free classloader object lock,

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

   120   // with original recursion count

   121   static intptr_t complete_exit  (Handle obj,                TRAPS);

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

   123 

   124   // thread-specific and global objectMonitor free list accessors

   125   static ObjectMonitor * omAlloc (Thread * Self) ;

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

   127   static void omFlush   (Thread * Self) ;

   128 

   129   // Inflate light weight monitor to heavy weight monitor

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

   131   // This version is only for internal use

   132   static ObjectMonitor* inflate_helper(oop obj);

   133 

   134   // Returns the identity hash value for an oop

   135   // NOTE: It may cause monitor inflation

   136   static intptr_t identity_hash_value_for(Handle obj);

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

   138 

   139   // java.lang.Thread support

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

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

   142 

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

   144 

   145   // JNI detach support

   146   static void release_monitors_owned_by_thread(TRAPS);

   147   static void monitors_iterate(MonitorClosure* m);

   148 

   149   // GC: we current use aggressive monitor deflation policy

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

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

   152   static void deflate_idle_monitors();

   153   static void oops_do(OopClosure* f);

   154 

   155   // debugging

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

   157   static void verify() PRODUCT_RETURN;

   158   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;

   159 

   160  private:

   161   enum { _BLOCKSIZE = 128 };

   162   static ObjectMonitor* gBlockList;

   163   static ObjectMonitor * volatile gFreeList;

   164 

   165  public:

   166   static void Initialize () ;

   167   static PerfCounter * _sync_ContendedLockAttempts ;

   168   static PerfCounter * _sync_FutileWakeups ;

   169   static PerfCounter * _sync_Parks ;

   170   static PerfCounter * _sync_EmptyNotifications ;

   171   static PerfCounter * _sync_Notifications ;

   172   static PerfCounter * _sync_SlowEnter ;

   173   static PerfCounter * _sync_SlowExit ;

   174   static PerfCounter * _sync_SlowNotify ;

   175   static PerfCounter * _sync_SlowNotifyAll ;

   176   static PerfCounter * _sync_FailedSpins ;

   177   static PerfCounter * _sync_SuccessfulSpins ;

   178   static PerfCounter * _sync_PrivateA ;

   179   static PerfCounter * _sync_PrivateB ;

   180   static PerfCounter * _sync_MonInCirculation ;

   181   static PerfCounter * _sync_MonScavenged ;

   182   static PerfCounter * _sync_Inflations ;

   183   static PerfCounter * _sync_Deflations ;

   184   static PerfLongVariable * _sync_MonExtant ;

   185 

   186  public:

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

   188 

   189 };

   190 

   191 // ObjectLocker enforced balanced locking and can never thrown an

   192 // IllegalMonitorStateException. However, a pending exception may

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

   194 // asynchronous exceptions. The caller is responsible for checking

   195 // the threads pending exception if needed.

   196 // doLock was added to support classloading with UnsyncloadClass which

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

   198 class ObjectLocker : public StackObj {

   199  private:

   200   Thread*   _thread;

   201   Handle    _obj;

   202   BasicLock _lock;

   203   bool      _dolock;   // default true

   204  public:

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

   206   ~ObjectLocker();

   207 

   208   // Monitor behavior

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

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

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

   212   // complete_exit gives up lock completely, returning recursion count

   213   // reenter reclaims lock with original recursion count

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

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

   216 };