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hotspot/src/share/vm/runtime/synchronizer.hpp

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+/*
+ * Copyright 1998-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+class BasicLock VALUE_OBJ_CLASS_SPEC {
+  friend class VMStructs;
+ private:
+  volatile markOop _displaced_header;
+ public:
+  markOop      displaced_header() const               { return _displaced_header; }
+  void         set_displaced_header(markOop header)   { _displaced_header = header; }
+
+  void print_on(outputStream* st) const;
+
+  // move a basic lock (used during deoptimization
+  void move_to(oop obj, BasicLock* dest);
+
+  static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }
+};
+
+// A BasicObjectLock associates a specific Java object with a BasicLock.
+// It is currently embedded in an interpreter frame.
+
+// Because some machines have alignment restrictions on the control stack,
+// the actual space allocated by the interpreter may include padding words
+// after the end of the BasicObjectLock.  Also, in order to guarantee
+// alignment of the embedded BasicLock objects on such machines, we
+// put the embedded BasicLock at the beginning of the struct.
+
+class BasicObjectLock VALUE_OBJ_CLASS_SPEC {
+  friend class VMStructs;
+ private:
+  BasicLock _lock;                                    // the lock, must be double word aligned
+  oop       _obj;                                     // object holds the lock;
+
+ public:
+  // Manipulation
+  oop      obj() const                                { return _obj;  }
+  void set_obj(oop obj)                               { _obj = obj; }
+  BasicLock* lock()                                   { return &_lock; }
+
+  // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
+  //       in interpreter activation frames since it includes machine-specific padding.
+  static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
+
+  // GC support
+  void oops_do(OopClosure* f) { f->do_oop(&_obj); }
+
+  static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }
+  static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }
+};
+
+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 ObjectMonitor * omAlloc (Thread * Self) ;
+  static void omRelease (Thread * Self, ObjectMonitor * m) ;
+  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 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;
+
+ private:
+  enum { _BLOCKSIZE = 128 };
+  static ObjectMonitor* gBlockList;
+  static ObjectMonitor * volatile gFreeList;
+
+ public:
+  static void Initialize () ;
+  static PerfCounter * _sync_ContendedLockAttempts ;
+  static PerfCounter * _sync_FutileWakeups ;
+  static PerfCounter * _sync_Parks ;
+  static PerfCounter * _sync_EmptyNotifications ;
+  static PerfCounter * _sync_Notifications ;
+  static PerfCounter * _sync_SlowEnter ;
+  static PerfCounter * _sync_SlowExit ;
+  static PerfCounter * _sync_SlowNotify ;
+  static PerfCounter * _sync_SlowNotifyAll ;
+  static PerfCounter * _sync_FailedSpins ;
+  static PerfCounter * _sync_SuccessfulSpins ;
+  static PerfCounter * _sync_PrivateA ;
+  static PerfCounter * _sync_PrivateB ;
+  static PerfCounter * _sync_MonInCirculation ;
+  static PerfCounter * _sync_MonScavenged ;
+  static PerfCounter * _sync_Inflations ;
+  static PerfCounter * _sync_Deflations ;
+  static PerfLongVariable * _sync_MonExtant ;
+
+ public:
+  static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
+
+};
+
+// 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); }
+};