synchronizer.hpp revision 1472:c18cbe5936b8 
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24
25class 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
50class 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
73class ObjectMonitor;
74
75class 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.
198class 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};
217