/* * Copyright (c) 1998, 2010, 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_SYNCHRONIZER_HPP #define SHARE_VM_RUNTIME_SYNCHRONIZER_HPP #include "oops/markOop.hpp" #include "runtime/handles.hpp" #include "runtime/perfData.hpp" #include "utilities/top.hpp" class BasicLock VALUE_OBJ_CLASS_SPEC { friend class VMStructs; private: volatile markOop _displaced_header; public: markOop displaced_header() const { return _displaced_header; } void set_displaced_header(markOop header) { _displaced_header = header; } void print_on(outputStream* st) const; // move a basic lock (used during deoptimization void move_to(oop obj, BasicLock* dest); static int displaced_header_offset_in_bytes() { return offset_of(BasicLock, _displaced_header); } }; // A BasicObjectLock associates a specific Java object with a BasicLock. // It is currently embedded in an interpreter frame. // Because some machines have alignment restrictions on the control stack, // the actual space allocated by the interpreter may include padding words // after the end of the BasicObjectLock. Also, in order to guarantee // alignment of the embedded BasicLock objects on such machines, we // put the embedded BasicLock at the beginning of the struct. class BasicObjectLock VALUE_OBJ_CLASS_SPEC { friend class VMStructs; private: BasicLock _lock; // the lock, must be double word aligned oop _obj; // object holds the lock; public: // Manipulation oop obj() const { return _obj; } void set_obj(oop obj) { _obj = obj; } BasicLock* lock() { return &_lock; } // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks // in interpreter activation frames since it includes machine-specific padding. static int size() { return sizeof(BasicObjectLock)/wordSize; } // GC support void oops_do(OopClosure* f) { f->do_oop(&_obj); } static int obj_offset_in_bytes() { return offset_of(BasicObjectLock, _obj); } static int lock_offset_in_bytes() { return offset_of(BasicObjectLock, _lock); } }; class ObjectMonitor; class ObjectSynchronizer : AllStatic { friend class VMStructs; public: typedef enum { owner_self, owner_none, owner_other } LockOwnership; // exit must be implemented non-blocking, since the compiler cannot easily handle // deoptimization at monitor exit. Hence, it does not take a Handle argument. // This is full version of monitor enter and exit. I choose not // to use enter() and exit() in order to make sure user be ware // of the performance and semantics difference. They are normally // used by ObjectLocker etc. The interpreter and compiler use // assembly copies of these routines. Please keep them synchornized. // // attempt_rebias flag is used by UseBiasedLocking implementation static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS); static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD); // WARNING: They are ONLY used to handle the slow cases. They should // only be used when the fast cases failed. Use of these functions // without previous fast case check may cause fatal error. static void slow_enter (Handle obj, BasicLock* lock, TRAPS); static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD); // Used only to handle jni locks or other unmatched monitor enter/exit // Internally they will use heavy weight monitor. static void jni_enter (Handle obj, TRAPS); static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter static void jni_exit (oop obj, Thread* THREAD); // Handle all interpreter, compiler and jni cases static void wait (Handle obj, jlong millis, TRAPS); static void notify (Handle obj, TRAPS); static void notifyall (Handle obj, TRAPS); // Special internal-use-only method for use by JVM infrastructure // that needs to wait() on a java-level object but that can't risk // throwing unexpected InterruptedExecutionExceptions. static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ; // used by classloading to free classloader object lock, // wait on an internal lock, and reclaim original lock // with original recursion count static intptr_t complete_exit (Handle obj, TRAPS); static void reenter (Handle obj, intptr_t recursion, TRAPS); // thread-specific and global objectMonitor free list accessors // static void verifyInUse (Thread * Self) ; too slow for general assert/debug static ObjectMonitor * omAlloc (Thread * Self) ; static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ; static void omFlush (Thread * Self) ; // Inflate light weight monitor to heavy weight monitor static ObjectMonitor* inflate(Thread * Self, oop obj); // This version is only for internal use static ObjectMonitor* inflate_helper(oop obj); // Returns the identity hash value for an oop // NOTE: It may cause monitor inflation static intptr_t identity_hash_value_for(Handle obj); static intptr_t FastHashCode (Thread * Self, oop obj) ; // java.lang.Thread support static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); static JavaThread* get_lock_owner(Handle h_obj, bool doLock); // JNI detach support static void release_monitors_owned_by_thread(TRAPS); static void monitors_iterate(MonitorClosure* m); // GC: we current use aggressive monitor deflation policy // Basically we deflate all monitors that are not busy. // An adaptive profile-based deflation policy could be used if needed static void deflate_idle_monitors(); static int walk_monitor_list(ObjectMonitor** listheadp, ObjectMonitor** FreeHeadp, ObjectMonitor** FreeTailp); static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp, ObjectMonitor** FreeTailp); static void oops_do(OopClosure* f); // debugging static void trace_locking(Handle obj, bool is_compiled, bool is_method, bool is_locking) PRODUCT_RETURN; static void verify() PRODUCT_RETURN; static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; private: enum { _BLOCKSIZE = 128 }; static ObjectMonitor* gBlockList; static ObjectMonitor * volatile gFreeList; static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned static int gOmInUseCount; 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 void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ; }; // ObjectLocker enforced balanced locking and can never thrown an // IllegalMonitorStateException. However, a pending exception may // have to pass through, and we must also be able to deal with // asynchronous exceptions. The caller is responsible for checking // the threads pending exception if needed. // doLock was added to support classloading with UnsyncloadClass which // requires flag based choice of locking the classloader lock. class ObjectLocker : public StackObj { private: Thread* _thread; Handle _obj; BasicLock _lock; bool _dolock; // default true public: ObjectLocker(Handle obj, Thread* thread, bool doLock = true); ~ObjectLocker(); // Monitor behavior void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);} // complete_exit gives up lock completely, returning recursion count // reenter reclaims lock with original recursion count intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, CHECK_0); } void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } }; #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP