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src/hotspot/share/runtime/mutexLocker.hpp

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  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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_RUNTIME_MUTEXLOCKER_HPP
  26 #define SHARE_RUNTIME_MUTEXLOCKER_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "runtime/flags/flagSetting.hpp"
  30 #include "runtime/mutex.hpp"
  31 
  32 // Mutexes used in the VM.
  33 
  34 extern Mutex*   Patching_lock;                   // a lock used to guard code patching of compiled code
  35 extern Mutex*   CompiledMethod_lock;             // a lock used to guard a compiled method
  36 extern Monitor* SystemDictionary_lock;           // a lock on the system dictionary
  37 extern Mutex*   ProtectionDomainSet_lock;        // a lock on the pd_set list in the system dictionary
  38 extern Mutex*   SharedDictionary_lock;           // a lock on the CDS shared dictionary
  39 extern Mutex*   Module_lock;                     // a lock on module and package related data structures
  40 extern Mutex*   CompiledIC_lock;                 // a lock used to guard compiled IC patching and access
  41 extern Mutex*   InlineCacheBuffer_lock;          // a lock used to guard the InlineCacheBuffer
  42 extern Mutex*   VMStatistic_lock;                // a lock used to guard statistics count increment
  43 extern Mutex*   JNIGlobalAlloc_lock;             // JNI global storage allocate list lock
  44 extern Mutex*   JNIGlobalActive_lock;            // JNI global storage active list lock
  45 extern Mutex*   JNIWeakAlloc_lock;               // JNI weak storage allocate list lock
  46 extern Mutex*   JNIWeakActive_lock;              // JNI weak storage active list lock
  47 extern Mutex*   StringTableWeakAlloc_lock;       // StringTable weak storage allocate list lock
  48 extern Mutex*   StringTableWeakActive_lock;      // STringTable weak storage active list lock
  49 extern Mutex*   JNIHandleBlockFreeList_lock;     // a lock on the JNI handle block free list
  50 extern Mutex*   VMWeakAlloc_lock;                // VM Weak Handles storage allocate list lock
  51 extern Mutex*   VMWeakActive_lock;               // VM Weak Handles storage active list lock
  52 extern Mutex*   ResolvedMethodTableWeakAlloc_lock;  // ResolvedMethodTable weak storage allocate list
  53 extern Mutex*   ResolvedMethodTableWeakActive_lock; // ResolvedMethodTable weak storage active list
  54 extern Mutex*   JmethodIdCreation_lock;          // a lock on creating JNI method identifiers
  55 extern Mutex*   JfieldIdCreation_lock;           // a lock on creating JNI static field identifiers
  56 extern Monitor* JNICritical_lock;                // a lock used while entering and exiting JNI critical regions, allows GC to sometimes get in
  57 extern Mutex*   JvmtiThreadState_lock;           // a lock on modification of JVMTI thread data
  58 extern Monitor* Heap_lock;                       // a lock on the heap
  59 extern Mutex*   ExpandHeap_lock;                 // a lock on expanding the heap
  60 extern Mutex*   AdapterHandlerLibrary_lock;      // a lock on the AdapterHandlerLibrary
  61 extern Mutex*   SignatureHandlerLibrary_lock;    // a lock on the SignatureHandlerLibrary
  62 extern Mutex*   VtableStubs_lock;                // a lock on the VtableStubs
  63 extern Mutex*   SymbolArena_lock;                // a lock on the symbol table arena
  64 extern Monitor* StringDedupQueue_lock;           // a lock on the string deduplication queue
  65 extern Mutex*   StringDedupTable_lock;           // a lock on the string deduplication table
  66 extern Monitor* CodeCache_lock;                  // a lock on the CodeCache, rank is special
  67 extern Mutex*   MethodData_lock;                 // a lock on installation of method data
  68 extern Mutex*   TouchedMethodLog_lock;           // a lock on allocation of LogExecutedMethods info
  69 extern Mutex*   RetData_lock;                    // a lock on installation of RetData inside method data

  70 extern Monitor* CGCPhaseManager_lock;            // a lock to protect a concurrent GC's phase management
  71 extern Monitor* VMOperationQueue_lock;           // a lock on queue of vm_operations waiting to execute
  72 extern Monitor* VMOperationRequest_lock;         // a lock on Threads waiting for a vm_operation to terminate
  73 extern Monitor* Threads_lock;                    // a lock on the Threads table of active Java threads
  74                                                  // (also used by Safepoints too to block threads creation/destruction)
  75 extern Mutex*   NonJavaThreadsList_lock;         // a lock on the NonJavaThreads list
  76 extern Mutex*   NonJavaThreadsListSync_lock;     // a lock for NonJavaThreads list synchronization
  77 extern Monitor* CGC_lock;                        // used for coordination between
  78                                                  // fore- & background GC threads.
  79 extern Monitor* STS_lock;                        // used for joining/leaving SuspendibleThreadSet.
  80 extern Monitor* FullGCCount_lock;                // in support of "concurrent" full gc
  81 extern Monitor* SATB_Q_CBL_mon;                  // Protects SATB Q
  82                                                  // completed buffer queue.
  83 extern Monitor* DirtyCardQ_CBL_mon;              // Protects dirty card Q
  84                                                  // completed buffer queue.
  85 extern Mutex*   Shared_DirtyCardQ_lock;          // Lock protecting dirty card
  86                                                  // queue shared by
  87                                                  // non-Java threads.
  88 extern Mutex*   MarkStackFreeList_lock;          // Protects access to the global mark stack free list.
  89 extern Mutex*   MarkStackChunkList_lock;         // Protects access to the global mark stack chunk list.


 116 extern Mutex*   RawMonitor_lock;
 117 extern Mutex*   PerfDataMemAlloc_lock;           // a lock on the allocator for PerfData memory for performance data
 118 extern Mutex*   PerfDataManager_lock;            // a long on access to PerfDataManager resources
 119 extern Mutex*   ParkerFreeList_lock;
 120 extern Mutex*   OopMapCacheAlloc_lock;           // protects allocation of oop_map caches
 121 
 122 extern Mutex*   FreeList_lock;                   // protects the free region list during safepoints
 123 extern Mutex*   OldSets_lock;                    // protects the old region sets
 124 extern Monitor* RootRegionScan_lock;             // used to notify that the CM threads have finished scanning the IM snapshot regions
 125 
 126 extern Mutex*   Management_lock;                 // a lock used to serialize JVM management
 127 extern Monitor* Service_lock;                    // a lock used for service thread operation
 128 extern Monitor* PeriodicTask_lock;               // protects the periodic task structure
 129 extern Monitor* RedefineClasses_lock;            // locks classes from parallel redefinition
 130 extern Monitor* ThreadsSMRDelete_lock;           // Used by ThreadsSMRSupport to take pressure off the Threads_lock
 131 extern Mutex*   SharedDecoder_lock;              // serializes access to the decoder during normal (not error reporting) use
 132 extern Mutex*   DCmdFactory_lock;                // serialize access to DCmdFactory information
 133 #if INCLUDE_NMT
 134 extern Mutex*   NMTQuery_lock;                   // serialize NMT Dcmd queries
 135 #endif
 136 #if INCLUDE_CDS
 137 #if INCLUDE_JVMTI
 138 extern Mutex*   CDSClassFileStream_lock;         // FileMapInfo::open_stream_for_jvmti
 139 #endif
 140 extern Mutex*   DumpTimeTable_lock;              // SystemDictionaryShared::find_or_allocate_info_for
 141 #endif // INCLUDE_CDS
 142 #if INCLUDE_JFR
 143 extern Mutex*   JfrStacktrace_lock;              // used to guard access to the JFR stacktrace table
 144 extern Monitor* JfrMsg_lock;                     // protects JFR messaging
 145 extern Mutex*   JfrBuffer_lock;                  // protects JFR buffer operations
 146 extern Mutex*   JfrStream_lock;                  // protects JFR stream access
 147 extern Monitor* JfrThreadSampler_lock;           // used to suspend/resume JFR thread sampler
 148 #endif
 149 
 150 #ifndef SUPPORTS_NATIVE_CX8
 151 extern Mutex*   UnsafeJlong_lock;                // provides Unsafe atomic updates to jlongs on platforms that don't support cx8
 152 #endif
 153 
 154 extern Mutex*   MetaspaceExpand_lock;            // protects Metaspace virtualspace and chunk expansions
 155 extern Mutex*   ClassLoaderDataGraph_lock;       // protects CLDG list, needed for concurrent unloading
 156 
 157 
 158 extern Monitor* CodeHeapStateAnalytics_lock;     // lock print functions against concurrent analyze functions.
 159                                                  // Only used locally in PrintCodeCacheLayout processing.
 160 
 161 #if INCLUDE_JVMCI
 162 extern Monitor* JVMCI_lock;                      // Monitor to control initialization of JVMCI
 163 extern Mutex*   JVMCIGlobalAlloc_lock;           // JVMCI global storage allocate list lock
 164 extern Mutex*   JVMCIGlobalActive_lock;          // JVMCI global storage active list lock
 165 #endif
 166 
 167 // A MutexLocker provides mutual exclusion with respect to a given mutex
 168 // for the scope which contains the locker.  The lock is an OS lock, not
 169 // an object lock, and the two do not interoperate.  Do not use Mutex-based
 170 // locks to lock on Java objects, because they will not be respected if a
 171 // that object is locked using the Java locking mechanism.
 172 //
 173 //                NOTE WELL!!
 174 //
 175 // See orderAccess.hpp.  We assume throughout the VM that MutexLocker's
 176 // and friends constructors do a fence, a lock and an acquire *in that
 177 // order*.  And that their destructors do a release and unlock, in *that*
 178 // order.  If their implementations change such that these assumptions
 179 // are violated, a whole lot of code will break.
 180 
 181 // Print all mutexes/monitors that are currently owned by a thread; called
 182 // by fatal error handler.
 183 void print_owned_locks_on_error(outputStream* st);
 184 
 185 char *lock_name(Mutex *mutex);
 186 

























 187 // for debugging: check that we're already owning this lock (or are at a safepoint)
 188 #ifdef ASSERT
 189 void assert_locked_or_safepoint(const Monitor * lock);
 190 void assert_locked_or_safepoint_weak(const Monitor * lock);
 191 void assert_lock_strong(const Monitor * lock);
 192 #else
 193 #define assert_locked_or_safepoint(lock)
 194 #define assert_locked_or_safepoint_weak(lock)
 195 #define assert_lock_strong(lock)
 196 #endif
 197 
 198 class MutexLocker: public StackObj {
 199  protected:
 200   Monitor* _mutex;





 201  private:

 202  public:
 203   MutexLocker(Monitor* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
 204     _mutex(mutex) {
 205     bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
 206     if (_mutex != NULL) {
 207       assert(_mutex->rank() > Mutex::special || no_safepoint_check,
 208              "Mutexes with rank special or lower should not do safepoint checks");
 209       if (no_safepoint_check) {
 210         _mutex->lock_without_safepoint_check();
 211       } else {
 212         _mutex->lock();
 213       }
 214     }
 215   }
 216 
 217   MutexLocker(Monitor* mutex, Thread* thread, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
 218     _mutex(mutex) {
 219     bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
 220     if (_mutex != NULL) {
 221       assert(_mutex->rank() > Mutex::special || no_safepoint_check,
 222              "Mutexes with rank special or lower should not do safepoint checks");
 223       if (no_safepoint_check) {
 224         _mutex->lock_without_safepoint_check(thread);
 225       } else {
 226         _mutex->lock(thread);
 227       }
 228     }
 229   }
 230 
 231   ~MutexLocker() {
 232     if (_mutex != NULL) {
 233       assert_lock_strong(_mutex);
 234       _mutex->unlock();
 235     }
 236   }
 237 };
 238 
 239 // A MonitorLocker is like a MutexLocker above, except it allows
 240 // wait/notify as well which are delegated to the underlying Monitor.
 241 // It also disallows NULL.
 242 
 243 class MonitorLocker: public MutexLocker {
 244   Mutex::SafepointCheckFlag _flag;

 245  public:
 246   MonitorLocker(Monitor* monitor, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
 247     MutexLocker(monitor, flag), _flag(flag) {


 248     // Superclass constructor did locking
 249     assert(_mutex != NULL, "NULL monitor not allowed");
 250   }
 251 
 252   MonitorLocker(Monitor* monitor, Thread* thread, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
 253     MutexLocker(monitor, thread, flag), _flag(flag)  {
 254     // Superclass constructor did locking
 255     assert(_mutex != NULL, "NULL monitor not allowed");



 256   }
 257 
 258   bool wait(long timeout = 0,

 259             bool as_suspend_equivalent = !Mutex::_as_suspend_equivalent_flag) {
 260     if (_flag == Mutex::_safepoint_check_flag) {
 261       return _mutex->wait(timeout, as_suspend_equivalent);
 262     } else {
 263       return _mutex->wait_without_safepoint_check(timeout);
 264     }
 265     return false;
 266   }
 267 
 268   void notify_all() {
 269     _mutex->notify_all();


 270   }
 271 
 272   void notify() {
 273     _mutex->notify();


 274   }
 275 };
 276 
 277 

 278 // A GCMutexLocker is usually initialized with a mutex that is
 279 // automatically acquired in order to do GC.  The function that
 280 // synchronizes using a GCMutexLocker may be called both during and between
 281 // GC's.  Thus, it must acquire the mutex if GC is not in progress, but not
 282 // if GC is in progress (since the mutex is already held on its behalf.)
 283 
 284 class GCMutexLocker: public StackObj {
 285 private:
 286   Monitor* _mutex;
 287   bool _locked;
 288 public:
 289   GCMutexLocker(Monitor* mutex);
 290   ~GCMutexLocker() { if (_locked) _mutex->unlock(); }
 291 };
 292 


 293 // A MutexUnlocker temporarily exits a previously
 294 // entered mutex for the scope which contains the unlocker.
 295 
 296 class MutexUnlocker: StackObj {
 297  private:
 298   Monitor* _mutex;
 299   bool _no_safepoint_check;
 300 
 301  public:
 302   MutexUnlocker(Monitor* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
 303     _mutex(mutex),
 304     _no_safepoint_check(flag) {
 305     _mutex->unlock();
 306   }
 307 
 308   ~MutexUnlocker() {
 309     if (_no_safepoint_check) {




















 310       _mutex->lock_without_safepoint_check();
 311     } else {
 312       _mutex->lock();
 313     }
 314   }
 315 };
 316 
 317 #endif // SHARE_RUNTIME_MUTEXLOCKER_HPP


  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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_RUNTIME_MUTEXLOCKER_HPP
  26 #define SHARE_RUNTIME_MUTEXLOCKER_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "runtime/flags/flagSetting.hpp"
  30 #include "runtime/mutex.hpp"
  31 
  32 // Mutexes used in the VM.
  33 
  34 extern Mutex*   Patching_lock;                   // a lock used to guard code patching of compiled code

  35 extern Monitor* SystemDictionary_lock;           // a lock on the system dictionary
  36 extern Mutex*   ProtectionDomainSet_lock;        // a lock on the pd_set list in the system dictionary
  37 extern Mutex*   SharedDictionary_lock;           // a lock on the CDS shared dictionary
  38 extern Mutex*   Module_lock;                     // a lock on module and package related data structures
  39 extern Mutex*   CompiledIC_lock;                 // a lock used to guard compiled IC patching and access
  40 extern Mutex*   InlineCacheBuffer_lock;          // a lock used to guard the InlineCacheBuffer
  41 extern Mutex*   VMStatistic_lock;                // a lock used to guard statistics count increment
  42 extern Mutex*   JNIGlobalAlloc_lock;             // JNI global storage allocate list lock
  43 extern Mutex*   JNIGlobalActive_lock;            // JNI global storage active list lock
  44 extern Mutex*   JNIWeakAlloc_lock;               // JNI weak storage allocate list lock
  45 extern Mutex*   JNIWeakActive_lock;              // JNI weak storage active list lock
  46 extern Mutex*   StringTableWeakAlloc_lock;       // StringTable weak storage allocate list lock
  47 extern Mutex*   StringTableWeakActive_lock;      // STringTable weak storage active list lock
  48 extern Mutex*   JNIHandleBlockFreeList_lock;     // a lock on the JNI handle block free list
  49 extern Mutex*   VMWeakAlloc_lock;                // VM Weak Handles storage allocate list lock
  50 extern Mutex*   VMWeakActive_lock;               // VM Weak Handles storage active list lock
  51 extern Mutex*   ResolvedMethodTable_lock;        // a lock on the ResolvedMethodTable updates

  52 extern Mutex*   JmethodIdCreation_lock;          // a lock on creating JNI method identifiers
  53 extern Mutex*   JfieldIdCreation_lock;           // a lock on creating JNI static field identifiers
  54 extern Monitor* JNICritical_lock;                // a lock used while entering and exiting JNI critical regions, allows GC to sometimes get in
  55 extern Mutex*   JvmtiThreadState_lock;           // a lock on modification of JVMTI thread data
  56 extern Monitor* Heap_lock;                       // a lock on the heap
  57 extern Mutex*   ExpandHeap_lock;                 // a lock on expanding the heap
  58 extern Mutex*   AdapterHandlerLibrary_lock;      // a lock on the AdapterHandlerLibrary
  59 extern Mutex*   SignatureHandlerLibrary_lock;    // a lock on the SignatureHandlerLibrary
  60 extern Mutex*   VtableStubs_lock;                // a lock on the VtableStubs
  61 extern Mutex*   SymbolArena_lock;                // a lock on the symbol table arena
  62 extern Monitor* StringDedupQueue_lock;           // a lock on the string deduplication queue
  63 extern Mutex*   StringDedupTable_lock;           // a lock on the string deduplication table
  64 extern Monitor* CodeCache_lock;                  // a lock on the CodeCache, rank is special, use MutexLockerEx
  65 extern Mutex*   MethodData_lock;                 // a lock on installation of method data
  66 extern Mutex*   TouchedMethodLog_lock;           // a lock on allocation of LogExecutedMethods info
  67 extern Mutex*   RetData_lock;                    // a lock on installation of RetData inside method data
  68 extern Mutex*   DerivedPointerTableGC_lock;      // a lock to protect the derived pointer table
  69 extern Monitor* CGCPhaseManager_lock;            // a lock to protect a concurrent GC's phase management
  70 extern Monitor* VMOperationQueue_lock;           // a lock on queue of vm_operations waiting to execute
  71 extern Monitor* VMOperationRequest_lock;         // a lock on Threads waiting for a vm_operation to terminate
  72 extern Monitor* Threads_lock;                    // a lock on the Threads table of active Java threads
  73                                                  // (also used by Safepoints too to block threads creation/destruction)
  74 extern Mutex*   NonJavaThreadsList_lock;         // a lock on the NonJavaThreads list
  75 extern Mutex*   NonJavaThreadsListSync_lock;     // a lock for NonJavaThreads list synchronization
  76 extern Monitor* CGC_lock;                        // used for coordination between
  77                                                  // fore- & background GC threads.
  78 extern Monitor* STS_lock;                        // used for joining/leaving SuspendibleThreadSet.
  79 extern Monitor* FullGCCount_lock;                // in support of "concurrent" full gc
  80 extern Monitor* SATB_Q_CBL_mon;                  // Protects SATB Q
  81                                                  // completed buffer queue.
  82 extern Monitor* DirtyCardQ_CBL_mon;              // Protects dirty card Q
  83                                                  // completed buffer queue.
  84 extern Mutex*   Shared_DirtyCardQ_lock;          // Lock protecting dirty card
  85                                                  // queue shared by
  86                                                  // non-Java threads.
  87 extern Mutex*   MarkStackFreeList_lock;          // Protects access to the global mark stack free list.
  88 extern Mutex*   MarkStackChunkList_lock;         // Protects access to the global mark stack chunk list.


 115 extern Mutex*   RawMonitor_lock;
 116 extern Mutex*   PerfDataMemAlloc_lock;           // a lock on the allocator for PerfData memory for performance data
 117 extern Mutex*   PerfDataManager_lock;            // a long on access to PerfDataManager resources
 118 extern Mutex*   ParkerFreeList_lock;
 119 extern Mutex*   OopMapCacheAlloc_lock;           // protects allocation of oop_map caches
 120 
 121 extern Mutex*   FreeList_lock;                   // protects the free region list during safepoints
 122 extern Mutex*   OldSets_lock;                    // protects the old region sets
 123 extern Monitor* RootRegionScan_lock;             // used to notify that the CM threads have finished scanning the IM snapshot regions
 124 
 125 extern Mutex*   Management_lock;                 // a lock used to serialize JVM management
 126 extern Monitor* Service_lock;                    // a lock used for service thread operation
 127 extern Monitor* PeriodicTask_lock;               // protects the periodic task structure
 128 extern Monitor* RedefineClasses_lock;            // locks classes from parallel redefinition
 129 extern Monitor* ThreadsSMRDelete_lock;           // Used by ThreadsSMRSupport to take pressure off the Threads_lock
 130 extern Mutex*   SharedDecoder_lock;              // serializes access to the decoder during normal (not error reporting) use
 131 extern Mutex*   DCmdFactory_lock;                // serialize access to DCmdFactory information
 132 #if INCLUDE_NMT
 133 extern Mutex*   NMTQuery_lock;                   // serialize NMT Dcmd queries
 134 #endif
 135 #if INCLUDE_CDS && INCLUDE_JVMTI

 136 extern Mutex*   CDSClassFileStream_lock;         // FileMapInfo::open_stream_for_jvmti
 137 #endif


 138 #if INCLUDE_JFR
 139 extern Mutex*   JfrStacktrace_lock;              // used to guard access to the JFR stacktrace table
 140 extern Monitor* JfrMsg_lock;                     // protects JFR messaging
 141 extern Mutex*   JfrBuffer_lock;                  // protects JFR buffer operations
 142 extern Mutex*   JfrStream_lock;                  // protects JFR stream access
 143 extern Monitor* JfrThreadSampler_lock;           // used to suspend/resume JFR thread sampler
 144 #endif
 145 
 146 #ifndef SUPPORTS_NATIVE_CX8
 147 extern Mutex*   UnsafeJlong_lock;                // provides Unsafe atomic updates to jlongs on platforms that don't support cx8
 148 #endif
 149 
 150 extern Mutex*   MetaspaceExpand_lock;            // protects Metaspace virtualspace and chunk expansions
 151 extern Mutex*   ClassLoaderDataGraph_lock;       // protects CLDG list, needed for concurrent unloading
 152 
 153 
 154 extern Monitor* CodeHeapStateAnalytics_lock;     // lock print functions against concurrent analyze functions.
 155                                                  // Only used locally in PrintCodeCacheLayout processing.
 156 






 157 // A MutexLocker provides mutual exclusion with respect to a given mutex
 158 // for the scope which contains the locker.  The lock is an OS lock, not
 159 // an object lock, and the two do not interoperate.  Do not use Mutex-based
 160 // locks to lock on Java objects, because they will not be respected if a
 161 // that object is locked using the Java locking mechanism.
 162 //
 163 //                NOTE WELL!!
 164 //
 165 // See orderAccess.hpp.  We assume throughout the VM that MutexLocker's
 166 // and friends constructors do a fence, a lock and an acquire *in that
 167 // order*.  And that their destructors do a release and unlock, in *that*
 168 // order.  If their implementations change such that these assumptions
 169 // are violated, a whole lot of code will break.
 170 
 171 // Print all mutexes/monitors that are currently owned by a thread; called
 172 // by fatal error handler.
 173 void print_owned_locks_on_error(outputStream* st);
 174 
 175 char *lock_name(Mutex *mutex);
 176 
 177 class MutexLocker: StackObj {
 178  private:
 179   Monitor * _mutex;
 180  public:
 181   MutexLocker(Monitor * mutex) {
 182     assert(mutex->rank() != Mutex::special,
 183       "Special ranked mutex should only use MutexLockerEx");
 184     _mutex = mutex;
 185     _mutex->lock();
 186   }
 187 
 188   // Overloaded constructor passing current thread
 189   MutexLocker(Monitor * mutex, Thread *thread) {
 190     assert(mutex->rank() != Mutex::special,
 191       "Special ranked mutex should only use MutexLockerEx");
 192     _mutex = mutex;
 193     _mutex->lock(thread);
 194   }
 195 
 196   ~MutexLocker() {
 197     _mutex->unlock();
 198   }
 199 
 200 };
 201 
 202 // for debugging: check that we're already owning this lock (or are at a safepoint)
 203 #ifdef ASSERT
 204 void assert_locked_or_safepoint(const Monitor * lock);
 205 void assert_locked_or_safepoint_weak(const Monitor * lock);
 206 void assert_lock_strong(const Monitor * lock);
 207 #else
 208 #define assert_locked_or_safepoint(lock)
 209 #define assert_locked_or_safepoint_weak(lock)
 210 #define assert_lock_strong(lock)
 211 #endif
 212 
 213 // A MutexLockerEx behaves like a MutexLocker when its constructor is
 214 // called with a Mutex.  Unlike a MutexLocker, its constructor can also be
 215 // called with NULL, in which case the MutexLockerEx is a no-op.  There
 216 // is also a corresponding MutexUnlockerEx.  We want to keep the
 217 // basic MutexLocker as fast as possible.  MutexLockerEx can also lock
 218 // without safepoint check.
 219 
 220 class MutexLockerEx: public StackObj {
 221  private:
 222   Monitor * _mutex;
 223  public:
 224   MutexLockerEx(Monitor * mutex, bool no_safepoint_check = !Mutex::_no_safepoint_check_flag) {
 225     _mutex = mutex;

 226     if (_mutex != NULL) {
 227       assert(mutex->rank() > Mutex::special || no_safepoint_check,
 228         "Mutexes with rank special or lower should not do safepoint checks");
 229       if (no_safepoint_check)
 230         _mutex->lock_without_safepoint_check();
 231       else
 232         _mutex->lock();

 233     }
 234   }
 235 
 236   ~MutexLockerEx() {














 237     if (_mutex != NULL) {

 238       _mutex->unlock();
 239     }
 240   }
 241 };
 242 
 243 // A MonitorLockerEx is like a MutexLockerEx above, except it takes
 244 // a possibly null Monitor, and allows wait/notify as well which are
 245 // delegated to the underlying Monitor.
 246 
 247 class MonitorLockerEx: public MutexLockerEx {
 248  private:
 249   Monitor * _monitor;
 250  public:
 251   MonitorLockerEx(Monitor* monitor,
 252                   bool no_safepoint_check = !Mutex::_no_safepoint_check_flag):
 253     MutexLockerEx(monitor, no_safepoint_check),
 254     _monitor(monitor) {
 255     // Superclass constructor did locking

 256   }
 257 
 258   ~MonitorLockerEx() {
 259     #ifdef ASSERT
 260       if (_monitor != NULL) {
 261         assert_lock_strong(_monitor);
 262       }
 263     #endif  // ASSERT
 264     // Superclass destructor will do unlocking
 265   }
 266 
 267   bool wait(bool no_safepoint_check = !Mutex::_no_safepoint_check_flag,
 268             long timeout = 0,
 269             bool as_suspend_equivalent = !Mutex::_as_suspend_equivalent_flag) {
 270     if (_monitor != NULL) {
 271       return _monitor->wait(no_safepoint_check, timeout, as_suspend_equivalent);


 272     }
 273     return false;
 274   }
 275 
 276   void notify_all() {
 277     if (_monitor != NULL) {
 278       _monitor->notify_all();
 279     }
 280   }
 281 
 282   void notify() {
 283     if (_monitor != NULL) {
 284       _monitor->notify();
 285     }
 286   }
 287 };
 288 
 289 
 290 
 291 // A GCMutexLocker is usually initialized with a mutex that is
 292 // automatically acquired in order to do GC.  The function that
 293 // synchronizes using a GCMutexLocker may be called both during and between
 294 // GC's.  Thus, it must acquire the mutex if GC is not in progress, but not
 295 // if GC is in progress (since the mutex is already held on its behalf.)
 296 
 297 class GCMutexLocker: public StackObj {
 298 private:
 299   Monitor * _mutex;
 300   bool _locked;
 301 public:
 302   GCMutexLocker(Monitor * mutex);
 303   ~GCMutexLocker() { if (_locked) _mutex->unlock(); }
 304 };
 305 
 306 
 307 
 308 // A MutexUnlocker temporarily exits a previously
 309 // entered mutex for the scope which contains the unlocker.
 310 
 311 class MutexUnlocker: StackObj {
 312  private:
 313   Monitor * _mutex;

 314 
 315  public:
 316   MutexUnlocker(Monitor * mutex) {
 317     _mutex = mutex;

 318     _mutex->unlock();
 319   }
 320 
 321   ~MutexUnlocker() {
 322     _mutex->lock();
 323   }
 324 };
 325 
 326 // A MutexUnlockerEx temporarily exits a previously
 327 // entered mutex for the scope which contains the unlocker.
 328 
 329 class MutexUnlockerEx: StackObj {
 330  private:
 331   Monitor * _mutex;
 332   bool _no_safepoint_check;
 333 
 334  public:
 335   MutexUnlockerEx(Monitor * mutex, bool no_safepoint_check = !Mutex::_no_safepoint_check_flag) {
 336     _mutex = mutex;
 337     _no_safepoint_check = no_safepoint_check;
 338     _mutex->unlock();
 339   }
 340 
 341   ~MutexUnlockerEx() {
 342     if (_no_safepoint_check == Mutex::_no_safepoint_check_flag) {
 343       _mutex->lock_without_safepoint_check();
 344     } else {
 345       _mutex->lock();
 346     }
 347   }
 348 };
 349 
 350 #endif // SHARE_RUNTIME_MUTEXLOCKER_HPP
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