src/hotspot/share/runtime/mutexLocker.hpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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#ifndef SHARE_RUNTIME_MUTEXLOCKER_HPP
#define SHARE_RUNTIME_MUTEXLOCKER_HPP

#include "memory/allocation.hpp"
#include "runtime/flags/flagSetting.hpp"
#include "runtime/mutex.hpp"

// Mutexes used in the VM.

extern Mutex*   Patching_lock;                   // a lock used to guard code patching of compiled code
extern Monitor* SystemDictionary_lock;           // a lock on the system dictionary
extern Mutex*   ProtectionDomainSet_lock;        // a lock on the pd_set list in the system dictionary
extern Mutex*   SharedDictionary_lock;           // a lock on the CDS shared dictionary
extern Mutex*   Module_lock;                     // a lock on module and package related data structures
extern Mutex*   CompiledIC_lock;                 // a lock used to guard compiled IC patching and access
extern Mutex*   InlineCacheBuffer_lock;          // a lock used to guard the InlineCacheBuffer
extern Mutex*   VMStatistic_lock;                // a lock used to guard statistics count increment
extern Mutex*   JNIGlobalAlloc_lock;             // JNI global storage allocate list lock
extern Mutex*   JNIGlobalActive_lock;            // JNI global storage active list lock
extern Mutex*   JNIWeakAlloc_lock;               // JNI weak storage allocate list lock
extern Mutex*   JNIWeakActive_lock;              // JNI weak storage active list lock
extern Mutex*   StringTableWeakAlloc_lock;       // StringTable weak storage allocate list lock
extern Mutex*   StringTableWeakActive_lock;      // STringTable weak storage active list lock
extern Mutex*   JNIHandleBlockFreeList_lock;     // a lock on the JNI handle block free list
extern Mutex*   VMWeakAlloc_lock;                // VM Weak Handles storage allocate list lock
extern Mutex*   VMWeakActive_lock;               // VM Weak Handles storage active list lock
extern Mutex*   ResolvedMethodTableWeakAlloc_lock;  // ResolvedMethodTable weak storage allocate list
extern Mutex*   ResolvedMethodTableWeakActive_lock; // ResolvedMethodTable weak storage active list
extern Mutex*   JmethodIdCreation_lock;          // a lock on creating JNI method identifiers
extern Mutex*   JfieldIdCreation_lock;           // a lock on creating JNI static field identifiers
extern Monitor* JNICritical_lock;                // a lock used while entering and exiting JNI critical regions, allows GC to sometimes get in
extern Mutex*   JvmtiThreadState_lock;           // a lock on modification of JVMTI thread data
extern Monitor* Heap_lock;                       // a lock on the heap
extern Mutex*   ExpandHeap_lock;                 // a lock on expanding the heap
extern Mutex*   AdapterHandlerLibrary_lock;      // a lock on the AdapterHandlerLibrary
extern Mutex*   SignatureHandlerLibrary_lock;    // a lock on the SignatureHandlerLibrary
extern Mutex*   VtableStubs_lock;                // a lock on the VtableStubs
extern Mutex*   SymbolArena_lock;                // a lock on the symbol table arena
extern Monitor* StringDedupQueue_lock;           // a lock on the string deduplication queue
extern Mutex*   StringDedupTable_lock;           // a lock on the string deduplication table
extern Monitor* CodeCache_lock;                  // a lock on the CodeCache, rank is special
extern Mutex*   MethodData_lock;                 // a lock on installation of method data
extern Mutex*   TouchedMethodLog_lock;           // a lock on allocation of LogExecutedMethods info
extern Mutex*   RetData_lock;                    // a lock on installation of RetData inside method data
extern Monitor* CGCPhaseManager_lock;            // a lock to protect a concurrent GC's phase management
extern Monitor* VMOperationQueue_lock;           // a lock on queue of vm_operations waiting to execute
extern Monitor* VMOperationRequest_lock;         // a lock on Threads waiting for a vm_operation to terminate
extern Monitor* Threads_lock;                    // a lock on the Threads table of active Java threads
                                                 // (also used by Safepoints too to block threads creation/destruction)
extern Mutex*   NonJavaThreadsList_lock;         // a lock on the NonJavaThreads list
extern Mutex*   NonJavaThreadsListSync_lock;     // a lock for NonJavaThreads list synchronization
extern Monitor* CGC_lock;                        // used for coordination between
                                                 // fore- & background GC threads.
extern Monitor* STS_lock;                        // used for joining/leaving SuspendibleThreadSet.
extern Monitor* FullGCCount_lock;                // in support of "concurrent" full gc
extern Monitor* SATB_Q_CBL_mon;                  // Protects SATB Q
                                                 // completed buffer queue.
extern Monitor* DirtyCardQ_CBL_mon;              // Protects dirty card Q
                                                 // completed buffer queue.
extern Mutex*   Shared_DirtyCardQ_lock;          // Lock protecting dirty card
                                                 // queue shared by
                                                 // non-Java threads.
extern Mutex*   MarkStackFreeList_lock;          // Protects access to the global mark stack free list.
extern Mutex*   MarkStackChunkList_lock;         // Protects access to the global mark stack chunk list.
extern Mutex*   MonitoringSupport_lock;          // Protects updates to the serviceability memory pools.
extern Mutex*   ParGCRareEvent_lock;             // Synchronizes various (rare) parallel GC ops.
extern Mutex*   Compile_lock;                    // a lock held when Compilation is updating code (used to block CodeCache traversal, CHA updates, etc)
extern Monitor* MethodCompileQueue_lock;         // a lock held when method compilations are enqueued, dequeued
extern Monitor* CompileThread_lock;              // a lock held by compile threads during compilation system initialization
extern Monitor* Compilation_lock;                // a lock used to pause compilation
extern Mutex*   CompileTaskAlloc_lock;           // a lock held when CompileTasks are allocated
extern Mutex*   CompileStatistics_lock;          // a lock held when updating compilation statistics
extern Mutex*   DirectivesStack_lock;            // a lock held when mutating the dirstack and ref counting directives
extern Mutex*   MultiArray_lock;                 // a lock used to guard allocation of multi-dim arrays
extern Monitor* Terminator_lock;                 // a lock used to guard termination of the vm
extern Monitor* InitCompleted_lock;              // a lock used to signal threads waiting on init completed
extern Monitor* BeforeExit_lock;                 // a lock used to guard cleanups and shutdown hooks
extern Monitor* Notify_lock;                     // a lock used to synchronize the start-up of the vm
extern Mutex*   ProfilePrint_lock;               // a lock used to serialize the printing of profiles
extern Mutex*   ExceptionCache_lock;             // a lock used to synchronize exception cache updates
extern Mutex*   OsrList_lock;                    // a lock used to serialize access to OSR queues
extern Mutex*   NMethodSweeperStats_lock;        // a lock used to serialize access to sweeper statistics

#ifndef PRODUCT
extern Mutex*   FullGCALot_lock;                 // a lock to make FullGCALot MT safe
#endif // PRODUCT
extern Mutex*   Debug1_lock;                     // A bunch of pre-allocated locks that can be used for tracing
extern Mutex*   Debug2_lock;                     // down synchronization related bugs!
extern Mutex*   Debug3_lock;

extern Mutex*   RawMonitor_lock;
extern Mutex*   PerfDataMemAlloc_lock;           // a lock on the allocator for PerfData memory for performance data
extern Mutex*   PerfDataManager_lock;            // a long on access to PerfDataManager resources
extern Mutex*   ParkerFreeList_lock;
extern Mutex*   OopMapCacheAlloc_lock;           // protects allocation of oop_map caches

extern Mutex*   FreeList_lock;                   // protects the free region list during safepoints
extern Mutex*   OldSets_lock;                    // protects the old region sets
extern Monitor* RootRegionScan_lock;             // used to notify that the CM threads have finished scanning the IM snapshot regions

extern Mutex*   Management_lock;                 // a lock used to serialize JVM management
extern Monitor* Service_lock;                    // a lock used for service thread operation
extern Monitor* PeriodicTask_lock;               // protects the periodic task structure
extern Monitor* RedefineClasses_lock;            // locks classes from parallel redefinition
extern Monitor* ThreadsSMRDelete_lock;           // Used by ThreadsSMRSupport to take pressure off the Threads_lock
extern Mutex*   SharedDecoder_lock;              // serializes access to the decoder during normal (not error reporting) use
extern Mutex*   DCmdFactory_lock;                // serialize access to DCmdFactory information
#if INCLUDE_NMT
extern Mutex*   NMTQuery_lock;                   // serialize NMT Dcmd queries
#endif
#if INCLUDE_CDS
#if INCLUDE_JVMTI
extern Mutex*   CDSClassFileStream_lock;         // FileMapInfo::open_stream_for_jvmti
#endif
extern Mutex*   DumpTimeTable_lock;              // SystemDictionaryShared::find_or_allocate_info_for
#endif // INCLUDE_CDS
#if INCLUDE_JFR
extern Mutex*   JfrStacktrace_lock;              // used to guard access to the JFR stacktrace table
extern Monitor* JfrMsg_lock;                     // protects JFR messaging
extern Mutex*   JfrBuffer_lock;                  // protects JFR buffer operations
extern Mutex*   JfrStream_lock;                  // protects JFR stream access
extern Monitor* JfrThreadSampler_lock;           // used to suspend/resume JFR thread sampler
#endif

#ifndef SUPPORTS_NATIVE_CX8
extern Mutex*   UnsafeJlong_lock;                // provides Unsafe atomic updates to jlongs on platforms that don't support cx8
#endif

extern Mutex*   MetaspaceExpand_lock;            // protects Metaspace virtualspace and chunk expansions
extern Mutex*   ClassLoaderDataGraph_lock;       // protects CLDG list, needed for concurrent unloading


extern Monitor* CodeHeapStateAnalytics_lock;     // lock print functions against concurrent analyze functions.
                                                 // Only used locally in PrintCodeCacheLayout processing.

#if INCLUDE_JVMCI
extern Monitor* JVMCI_lock;                      // Monitor to control initialization of JVMCI
extern Mutex*   JVMCIGlobalAlloc_lock;           // JVMCI global storage allocate list lock
extern Mutex*   JVMCIGlobalActive_lock;          // JVMCI global storage active list lock
#endif

// A MutexLocker provides mutual exclusion with respect to a given mutex
// for the scope which contains the locker.  The lock is an OS lock, not
// an object lock, and the two do not interoperate.  Do not use Mutex-based
// locks to lock on Java objects, because they will not be respected if a
// that object is locked using the Java locking mechanism.
//
//                NOTE WELL!!
//
// See orderAccess.hpp.  We assume throughout the VM that MutexLocker's
// and friends constructors do a fence, a lock and an acquire *in that
// order*.  And that their destructors do a release and unlock, in *that*
// order.  If their implementations change such that these assumptions
// are violated, a whole lot of code will break.

// Print all mutexes/monitors that are currently owned by a thread; called
// by fatal error handler.
void print_owned_locks_on_error(outputStream* st);

char *lock_name(Mutex *mutex);

// for debugging: check that we're already owning this lock (or are at a safepoint)
#ifdef ASSERT
void assert_locked_or_safepoint(const Monitor * lock);
void assert_locked_or_safepoint_weak(const Monitor * lock);
void assert_lock_strong(const Monitor * lock);
#else
#define assert_locked_or_safepoint(lock)
#define assert_locked_or_safepoint_weak(lock)
#define assert_lock_strong(lock)
#endif

class MutexLocker: public StackObj {
 protected:
  Monitor* _mutex;
 private:
 public:
  MutexLocker(Monitor* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
    _mutex(mutex) {
    bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
    if (_mutex != NULL) {
      assert(_mutex->rank() > Mutex::special || no_safepoint_check,
             "Mutexes with rank special or lower should not do safepoint checks");
      if (no_safepoint_check) {
        _mutex->lock_without_safepoint_check();
      } else {
        _mutex->lock();
      }
    }
  }

  MutexLocker(Monitor* mutex, Thread* thread, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
    _mutex(mutex) {
    bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
    if (_mutex != NULL) {
      assert(_mutex->rank() > Mutex::special || no_safepoint_check,
             "Mutexes with rank special or lower should not do safepoint checks");
      if (no_safepoint_check) {
        _mutex->lock_without_safepoint_check(thread);
      } else {
        _mutex->lock(thread);
      }
    }
  }

  ~MutexLocker() {
    if (_mutex != NULL) {
      assert_lock_strong(_mutex);
      _mutex->unlock();
    }
  }
};

// A MonitorLocker is like a MutexLocker above, except it allows
// wait/notify as well which are delegated to the underlying Monitor.
// It also disallows NULL.

class MonitorLocker: public MutexLocker {
  Mutex::SafepointCheckFlag _flag;
 public:
  MonitorLocker(Monitor* monitor, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
    MutexLocker(monitor, flag), _flag(flag) {
    // Superclass constructor did locking
    assert(_mutex != NULL, "NULL monitor not allowed");
  }

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

  bool wait(long timeout = 0,
            bool as_suspend_equivalent = !Mutex::_as_suspend_equivalent_flag) {
    if (_flag == Mutex::_safepoint_check_flag) {
      return _mutex->wait(timeout, as_suspend_equivalent);
    } else {
      return _mutex->wait_without_safepoint_check(timeout);
    }
    return false;
  }

  void notify_all() {
    _mutex->notify_all();
  }

  void notify() {
    _mutex->notify();
  }
};


// A GCMutexLocker is usually initialized with a mutex that is
// automatically acquired in order to do GC.  The function that
// synchronizes using a GCMutexLocker may be called both during and between
// GC's.  Thus, it must acquire the mutex if GC is not in progress, but not
// if GC is in progress (since the mutex is already held on its behalf.)

class GCMutexLocker: public StackObj {
private:
  Monitor* _mutex;
  bool _locked;
public:
  GCMutexLocker(Monitor* mutex);
  ~GCMutexLocker() { if (_locked) _mutex->unlock(); }
};

// A MutexUnlocker temporarily exits a previously
// entered mutex for the scope which contains the unlocker.

class MutexUnlocker: StackObj {
 private:
  Monitor* _mutex;
  bool _no_safepoint_check;

 public:
  MutexUnlocker(Monitor* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
    _mutex(mutex),
    _no_safepoint_check(flag) {
    _mutex->unlock();
  }

  ~MutexUnlocker() {
    if (_no_safepoint_check) {
      _mutex->lock_without_safepoint_check();
    } else {
      _mutex->lock();
    }
  }
};

#endif // SHARE_RUNTIME_MUTEXLOCKER_HPP