| /* |
| * Copyright (c) 1998, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |
| #define SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |
| |
| #include "runtime/os.hpp" |
| #include "runtime/park.hpp" |
| #include "runtime/perfData.hpp" |
| |
| // ObjectWaiter serves as a "proxy" or surrogate thread. |
| // TODO-FIXME: Eliminate ObjectWaiter and use the thread-specific |
| // ParkEvent instead. Beware, however, that the JVMTI code |
| // knows about ObjectWaiters, so we'll have to reconcile that code. |
| // See next_waiter(), first_waiter(), etc. |
| |
| class ObjectWaiter : public StackObj { |
| public: |
| enum TStates { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER, TS_CXQ } ; |
| enum Sorted { PREPEND, APPEND, SORTED } ; |
| ObjectWaiter * volatile _next; |
| ObjectWaiter * volatile _prev; |
| Thread* _thread; |
| jlong _notifier_tid; |
| ParkEvent * _event; |
| volatile int _notified ; |
| volatile TStates TState ; |
| Sorted _Sorted ; // List placement disposition |
| bool _active ; // Contention monitoring is enabled |
| public: |
| ObjectWaiter(Thread* thread); |
| |
| void wait_reenter_begin(ObjectMonitor *mon); |
| void wait_reenter_end(ObjectMonitor *mon); |
| }; |
| |
| // forward declaration to avoid include tracing.hpp |
| class EventJavaMonitorWait; |
| |
| // WARNING: |
| // This is a very sensitive and fragile class. DO NOT make any |
| // change unless you are fully aware of the underlying semantics. |
| |
| // This class can not inherit from any other class, because I have |
| // to let the displaced header be the very first word. Otherwise I |
| // have to let markOop include this file, which would export the |
| // monitor data structure to everywhere. |
| // |
| // The ObjectMonitor class is used to implement JavaMonitors which have |
| // transformed from the lightweight structure of the thread stack to a |
| // heavy weight lock due to contention |
| |
| // It is also used as RawMonitor by the JVMTI |
| |
| |
| class ObjectMonitor { |
| public: |
| enum { |
| OM_OK, // no error |
| OM_SYSTEM_ERROR, // operating system error |
| OM_ILLEGAL_MONITOR_STATE, // IllegalMonitorStateException |
| OM_INTERRUPTED, // Thread.interrupt() |
| OM_TIMED_OUT // Object.wait() timed out |
| }; |
| |
| public: |
| // TODO-FIXME: the "offset" routines should return a type of off_t instead of int ... |
| // ByteSize would also be an appropriate type. |
| static int header_offset_in_bytes() { return offset_of(ObjectMonitor, _header); } |
| static int object_offset_in_bytes() { return offset_of(ObjectMonitor, _object); } |
| static int owner_offset_in_bytes() { return offset_of(ObjectMonitor, _owner); } |
| static int count_offset_in_bytes() { return offset_of(ObjectMonitor, _count); } |
| static int recursions_offset_in_bytes() { return offset_of(ObjectMonitor, _recursions); } |
| static int cxq_offset_in_bytes() { return offset_of(ObjectMonitor, _cxq) ; } |
| static int succ_offset_in_bytes() { return offset_of(ObjectMonitor, _succ) ; } |
| static int EntryList_offset_in_bytes() { return offset_of(ObjectMonitor, _EntryList); } |
| static int FreeNext_offset_in_bytes() { return offset_of(ObjectMonitor, FreeNext); } |
| static int WaitSet_offset_in_bytes() { return offset_of(ObjectMonitor, _WaitSet) ; } |
| static int Responsible_offset_in_bytes() { return offset_of(ObjectMonitor, _Responsible);} |
| static int Spinner_offset_in_bytes() { return offset_of(ObjectMonitor, _Spinner); } |
| |
| public: |
| // Eventaully we'll make provisions for multiple callbacks, but |
| // now one will suffice. |
| static int (*SpinCallbackFunction)(intptr_t, int) ; |
| static intptr_t SpinCallbackArgument ; |
| |
| |
| public: |
| markOop header() const; |
| void set_header(markOop hdr); |
| |
| intptr_t is_busy() const { |
| // TODO-FIXME: merge _count and _waiters. |
| // TODO-FIXME: assert _owner == null implies _recursions = 0 |
| // TODO-FIXME: assert _WaitSet != null implies _count > 0 |
| return _count|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList ) ; |
| } |
| |
| intptr_t is_entered(Thread* current) const; |
| |
| void* owner() const; |
| void set_owner(void* owner); |
| |
| intptr_t waiters() const; |
| |
| intptr_t count() const; |
| void set_count(intptr_t count); |
| intptr_t contentions() const ; |
| intptr_t recursions() const { return _recursions; } |
| |
| // JVM/DI GetMonitorInfo() needs this |
| ObjectWaiter* first_waiter() { return _WaitSet; } |
| ObjectWaiter* next_waiter(ObjectWaiter* o) { return o->_next; } |
| Thread* thread_of_waiter(ObjectWaiter* o) { return o->_thread; } |
| |
| // initialize the monitor, exception the semaphore, all other fields |
| // are simple integers or pointers |
| ObjectMonitor() { |
| _header = NULL; |
| _count = 0; |
| _waiters = 0, |
| _recursions = 0; |
| _object = NULL; |
| _owner = NULL; |
| _WaitSet = NULL; |
| _WaitSetLock = 0 ; |
| _Responsible = NULL ; |
| _succ = NULL ; |
| _cxq = NULL ; |
| FreeNext = NULL ; |
| _EntryList = NULL ; |
| _SpinFreq = 0 ; |
| _SpinClock = 0 ; |
| OwnerIsThread = 0 ; |
| _previous_owner_tid = 0; |
| } |
| |
| ~ObjectMonitor() { |
| // TODO: Add asserts ... |
| // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0 |
| // _count == 0 _EntryList == NULL etc |
| } |
| |
| private: |
| void Recycle () { |
| // TODO: add stronger asserts ... |
| // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0 |
| // _count == 0 EntryList == NULL |
| // _recursions == 0 _WaitSet == NULL |
| // TODO: assert (is_busy()|_recursions) == 0 |
| _succ = NULL ; |
| _EntryList = NULL ; |
| _cxq = NULL ; |
| _WaitSet = NULL ; |
| _recursions = 0 ; |
| _SpinFreq = 0 ; |
| _SpinClock = 0 ; |
| OwnerIsThread = 0 ; |
| } |
| |
| public: |
| |
| void* object() const; |
| void* object_addr(); |
| void set_object(void* obj); |
| |
| bool check(TRAPS); // true if the thread owns the monitor. |
| void check_slow(TRAPS); |
| void clear(); |
| static void sanity_checks(); // public for -XX:+ExecuteInternalVMTests |
| // in PRODUCT for -XX:SyncKnobs=Verbose=1 |
| #ifndef PRODUCT |
| void verify(); |
| void print(); |
| #endif |
| |
| bool try_enter (TRAPS) ; |
| void enter(TRAPS); |
| void exit(bool not_suspended, TRAPS); |
| void wait(jlong millis, bool interruptable, TRAPS); |
| void notify(TRAPS); |
| void notifyAll(TRAPS); |
| |
| // Use the following at your own risk |
| intptr_t complete_exit(TRAPS); |
| void reenter(intptr_t recursions, TRAPS); |
| |
| private: |
| void AddWaiter (ObjectWaiter * waiter) ; |
| static void DeferredInitialize(); |
| |
| ObjectWaiter * DequeueWaiter () ; |
| void DequeueSpecificWaiter (ObjectWaiter * waiter) ; |
| void EnterI (TRAPS) ; |
| void ReenterI (Thread * Self, ObjectWaiter * SelfNode) ; |
| void UnlinkAfterAcquire (Thread * Self, ObjectWaiter * SelfNode) ; |
| int TryLock (Thread * Self) ; |
| int NotRunnable (Thread * Self, Thread * Owner) ; |
| int TrySpin_Fixed (Thread * Self) ; |
| int TrySpin_VaryFrequency (Thread * Self) ; |
| int TrySpin_VaryDuration (Thread * Self) ; |
| void ctAsserts () ; |
| void ExitEpilog (Thread * Self, ObjectWaiter * Wakee) ; |
| bool ExitSuspendEquivalent (JavaThread * Self) ; |
| void post_monitor_wait_event(EventJavaMonitorWait * event, |
| jlong notifier_tid, |
| jlong timeout, |
| bool timedout); |
| |
| private: |
| friend class ObjectSynchronizer; |
| friend class ObjectWaiter; |
| friend class VMStructs; |
| |
| // WARNING: this must be the very first word of ObjectMonitor |
| // This means this class can't use any virtual member functions. |
| |
| volatile markOop _header; // displaced object header word - mark |
| void* volatile _object; // backward object pointer - strong root |
| |
| double SharingPad [1] ; // temp to reduce false sharing |
| |
| // All the following fields must be machine word aligned |
| // The VM assumes write ordering wrt these fields, which can be |
| // read from other threads. |
| |
| protected: // protected for jvmtiRawMonitor |
| void * volatile _owner; // pointer to owning thread OR BasicLock |
| volatile jlong _previous_owner_tid; // thread id of the previous owner of the monitor |
| volatile intptr_t _recursions; // recursion count, 0 for first entry |
| private: |
| int OwnerIsThread ; // _owner is (Thread *) vs SP/BasicLock |
| ObjectWaiter * volatile _cxq ; // LL of recently-arrived threads blocked on entry. |
| // The list is actually composed of WaitNodes, acting |
| // as proxies for Threads. |
| protected: |
| ObjectWaiter * volatile _EntryList ; // Threads blocked on entry or reentry. |
| private: |
| Thread * volatile _succ ; // Heir presumptive thread - used for futile wakeup throttling |
| Thread * volatile _Responsible ; |
| int _PromptDrain ; // rqst to drain cxq into EntryList ASAP |
| |
| volatile int _Spinner ; // for exit->spinner handoff optimization |
| volatile int _SpinFreq ; // Spin 1-out-of-N attempts: success rate |
| volatile int _SpinClock ; |
| volatile int _SpinDuration ; |
| volatile intptr_t _SpinState ; // MCS/CLH list of spinners |
| |
| // TODO-FIXME: _count, _waiters and _recursions should be of |
| // type int, or int32_t but not intptr_t. There's no reason |
| // to use 64-bit fields for these variables on a 64-bit JVM. |
| |
| volatile intptr_t _count; // reference count to prevent reclaimation/deflation |
| // at stop-the-world time. See deflate_idle_monitors(). |
| // _count is approximately |_WaitSet| + |_EntryList| |
| protected: |
| volatile intptr_t _waiters; // number of waiting threads |
| private: |
| protected: |
| ObjectWaiter * volatile _WaitSet; // LL of threads wait()ing on the monitor |
| private: |
| volatile int _WaitSetLock; // protects Wait Queue - simple spinlock |
| |
| public: |
| int _QMix ; // Mixed prepend queue discipline |
| ObjectMonitor * FreeNext ; // Free list linkage |
| intptr_t StatA, StatsB ; |
| |
| 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 int Knob_Verbose; |
| static int Knob_SpinLimit; |
| void* operator new (size_t size) throw() { |
| return AllocateHeap(size, mtInternal); |
| } |
| void* operator new[] (size_t size) throw() { |
| return operator new (size); |
| } |
| void operator delete(void* p) { |
| FreeHeap(p, mtInternal); |
| } |
| void operator delete[] (void *p) { |
| operator delete(p); |
| } |
| }; |
| |
| #undef TEVENT |
| #define TEVENT(nom) {if (SyncVerbose) FEVENT(nom); } |
| |
| #define FEVENT(nom) { static volatile int ctr = 0 ; int v = ++ctr ; if ((v & (v-1)) == 0) { ::printf (#nom " : %d \n", v); ::fflush(stdout); }} |
| |
| #undef TEVENT |
| #define TEVENT(nom) {;} |
| |
| |
| #endif // SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |