1 /* 2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 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_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 35 class ObjectMonitor; 36 37 class 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 synchornized. 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 void 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 void complete_exit(Handle obj, intptr_t *saved_recursions, intptr_t *saved_trace_exit_stack, TRAPS); 84 static void reenter (Handle obj, intptr_t saved_recursions, intptr_t saved_trace_exit_stack, TRAPS); 85 86 // thread-specific and global objectMonitor free list accessors 87 // static void verifyInUse (Thread * Self) ; too slow for general assert/debug 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 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned 134 static int gOmInUseCount; 135 136 }; 137 138 // ObjectLocker enforced balanced locking and can never thrown an 139 // IllegalMonitorStateException. However, a pending exception may 140 // have to pass through, and we must also be able to deal with 141 // asynchronous exceptions. The caller is responsible for checking 142 // the threads pending exception if needed. 143 // doLock was added to support classloading with UnsyncloadClass which 144 // requires flag based choice of locking the classloader lock. 145 class ObjectLocker : public StackObj { 146 private: 147 Thread* _thread; 148 Handle _obj; 149 BasicLock _lock; 150 bool _dolock; // default true 151 public: 152 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 153 ~ObjectLocker(); 154 155 // Monitor behavior 156 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever 157 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 158 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);} 159 }; 160 161 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP