synchronizer.hpp revision 6687:da4514678bcf 
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24
25#ifndef SHARE_VM_RUNTIME_SYNCHRONIZER_HPP
26#define SHARE_VM_RUNTIME_SYNCHRONIZER_HPP
27
28#include "oops/markOop.hpp"
29#include "runtime/basicLock.hpp"
30#include "runtime/handles.hpp"
31#include "runtime/perfData.hpp"
32#include "utilities/top.hpp"
33
34
35class ObjectMonitor;
36
37class ObjectSynchronizer : AllStatic {
38  friend class VMStructs;
39 public:
40  typedef enum {
41    owner_self,
42    owner_none,
43    owner_other
44  } LockOwnership;
45  // exit must be implemented non-blocking, since the compiler cannot easily handle
46  // deoptimization at monitor exit. Hence, it does not take a Handle argument.
47
48  // This is full version of monitor enter and exit. I choose not
49  // to use enter() and exit() in order to make sure user be ware
50  // of the performance and semantics difference. They are normally
51  // used by ObjectLocker etc. The interpreter and compiler use
52  // assembly copies of these routines. Please keep them synchronized.
53  //
54  // attempt_rebias flag is used by UseBiasedLocking implementation
55  static void fast_enter  (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
56  static void fast_exit   (oop obj,    BasicLock* lock, Thread* THREAD);
57
58  // WARNING: They are ONLY used to handle the slow cases. They should
59  // only be used when the fast cases failed. Use of these functions
60  // without previous fast case check may cause fatal error.
61  static void slow_enter  (Handle obj, BasicLock* lock, TRAPS);
62  static void slow_exit   (oop obj,    BasicLock* lock, Thread* THREAD);
63
64  // Used only to handle jni locks or other unmatched monitor enter/exit
65  // Internally they will use heavy weight monitor.
66  static void jni_enter   (Handle obj, TRAPS);
67  static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
68  static void jni_exit    (oop obj,    Thread* THREAD);
69
70  // Handle all interpreter, compiler and jni cases
71  static int  wait               (Handle obj, jlong millis, TRAPS);
72  static void notify             (Handle obj,               TRAPS);
73  static void notifyall          (Handle obj,               TRAPS);
74
75  // Special internal-use-only method for use by JVM infrastructure
76  // that needs to wait() on a java-level object but that can't risk
77  // throwing unexpected InterruptedExecutionExceptions.
78  static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
79
80  // used by classloading to free classloader object lock,
81  // wait on an internal lock, and reclaim original lock
82  // with original recursion count
83  static intptr_t complete_exit  (Handle obj,                TRAPS);
84  static void reenter            (Handle obj, intptr_t recursion, TRAPS);
85
86  // thread-specific and global objectMonitor free list accessors
87  static void verifyInUse(Thread * Self);
88  static ObjectMonitor * omAlloc(Thread * Self);
89  static void omRelease(Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc);
90  static void omFlush(Thread * Self);
91
92  // Inflate light weight monitor to heavy weight monitor
93  static ObjectMonitor* inflate(Thread * Self, oop obj);
94  // This version is only for internal use
95  static ObjectMonitor* inflate_helper(oop obj);
96
97  // Returns the identity hash value for an oop
98  // NOTE: It may cause monitor inflation
99  static intptr_t identity_hash_value_for(Handle obj);
100  static intptr_t FastHashCode(Thread * Self, oop obj);
101
102  // java.lang.Thread support
103  static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
104  static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
105
106  static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
107
108  // JNI detach support
109  static void release_monitors_owned_by_thread(TRAPS);
110  static void monitors_iterate(MonitorClosure* m);
111
112  // GC: we current use aggressive monitor deflation policy
113  // Basically we deflate all monitors that are not busy.
114  // An adaptive profile-based deflation policy could be used if needed
115  static void deflate_idle_monitors();
116  static int walk_monitor_list(ObjectMonitor** listheadp,
117                               ObjectMonitor** freeHeadp,
118                               ObjectMonitor** freeTailp);
119  static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** freeHeadp,
120                              ObjectMonitor** freeTailp);
121  static void oops_do(OopClosure* f);
122
123  // debugging
124  static void verify() PRODUCT_RETURN;
125  static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
126
127  static void RegisterSpinCallback(int(*)(intptr_t, int), intptr_t);
128
129 private:
130  enum { _BLOCKSIZE = 128 };
131  static ObjectMonitor* gBlockList;
132  static ObjectMonitor * volatile gFreeList;
133  // global monitor in use list, for moribund threads,
134  // monitors they inflated need to be scanned for deflation
135  static ObjectMonitor * volatile gOmInUseList;
136  // count of entries in gOmInUseList
137  static int gOmInUseCount;
138
139};
140
141// ObjectLocker enforced balanced locking and can never thrown an
142// IllegalMonitorStateException. However, a pending exception may
143// have to pass through, and we must also be able to deal with
144// asynchronous exceptions. The caller is responsible for checking
145// the threads pending exception if needed.
146// doLock was added to support classloading with UnsyncloadClass which
147// requires flag based choice of locking the classloader lock.
148class ObjectLocker : public StackObj {
149 private:
150  Thread*   _thread;
151  Handle    _obj;
152  BasicLock _lock;
153  bool      _dolock;   // default true
154 public:
155  ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
156  ~ObjectLocker();
157
158  // Monitor behavior
159  void wait      (TRAPS)      { ObjectSynchronizer::wait     (_obj, 0, CHECK); } // wait forever
160  void notify_all(TRAPS)      { ObjectSynchronizer::notifyall(_obj,    CHECK); }
161  void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK); }
162  // complete_exit gives up lock completely, returning recursion count
163  // reenter reclaims lock with original recursion count
164  intptr_t complete_exit(TRAPS) { return  ObjectSynchronizer::complete_exit(_obj, CHECK_0); }
165  void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
166};
167
168#endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP
169