1 /* 2 * Copyright (c) 1998, 2015, 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 synchronized. 53 // 54 // attempt_rebias flag is used by UseBiasedLocking implementation 55 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 56 TRAPS); 57 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 58 59 // WARNING: They are ONLY used to handle the slow cases. They should 60 // only be used when the fast cases failed. Use of these functions 61 // without previous fast case check may cause fatal error. 62 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 63 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 64 65 // Used only to handle jni locks or other unmatched monitor enter/exit 66 // Internally they will use heavy weight monitor. 67 static void jni_enter(Handle obj, TRAPS); 68 static void jni_exit(oop obj, Thread* THREAD); 69 70 // Handle all interpreter, compiler and jni cases 71 static int wait(Handle obj, jlong millis, TRAPS); 72 static void notify(Handle obj, TRAPS); 73 static void notifyall(Handle obj, TRAPS); 74 75 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); 76 77 // Special internal-use-only method for use by JVM infrastructure 78 // that needs to wait() on a java-level object but that can't risk 79 // throwing unexpected InterruptedExecutionExceptions. 80 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); 81 82 // used by classloading to free classloader object lock, 83 // wait on an internal lock, and reclaim original lock 84 // with original recursion count 85 static intptr_t complete_exit(Handle obj, TRAPS); 86 static void reenter (Handle obj, intptr_t recursion, TRAPS); 87 88 // thread-specific and global objectMonitor free list accessors 89 static void verifyInUse(Thread * Self); 90 static ObjectMonitor * omAlloc(Thread * Self); 91 static void omRelease(Thread * Self, ObjectMonitor * m, 92 bool FromPerThreadAlloc); 93 static void omFlush(Thread * Self); 94 95 // Inflate light weight monitor to heavy weight monitor 96 static ObjectMonitor* inflate(Thread * Self, oop obj); 97 // This version is only for internal use 98 static ObjectMonitor* inflate_helper(oop obj); 99 100 // Returns the identity hash value for an oop 101 // NOTE: It may cause monitor inflation 102 static intptr_t identity_hash_value_for(Handle obj); 103 static intptr_t FastHashCode(Thread * Self, oop obj); 104 105 // java.lang.Thread support 106 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 107 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 108 109 static JavaThread* get_lock_owner(Handle h_obj, bool doLock); 110 111 // JNI detach support 112 static void release_monitors_owned_by_thread(TRAPS); 113 static void monitors_iterate(MonitorClosure* m); 114 115 // GC: we current use aggressive monitor deflation policy 116 // Basically we deflate all monitors that are not busy. 117 // An adaptive profile-based deflation policy could be used if needed 118 static void deflate_idle_monitors(); 119 // For a given monitor list: global or per-thread, deflate idle monitors 120 static int deflate_monitor_list(ObjectMonitor** listheadp, 121 ObjectMonitor** freeHeadp, 122 ObjectMonitor** freeTailp); 123 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 124 ObjectMonitor** freeHeadp, 125 ObjectMonitor** freeTailp); 126 static void oops_do(OopClosure* f); 127 128 // debugging 129 static void sanity_checks(const bool verbose, 130 const unsigned int cache_line_size, 131 int *error_cnt_ptr, int *warning_cnt_ptr); 132 static void verify() PRODUCT_RETURN; 133 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 134 135 static void RegisterSpinCallback(int(*)(intptr_t, int), intptr_t); 136 137 private: 138 enum { _BLOCKSIZE = 128 }; 139 // global list of blocks of monitors 140 // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't 141 // want to expose the PaddedEnd template more than necessary. 142 static ObjectMonitor * gBlockList; 143 // global monitor free list 144 static ObjectMonitor * volatile gFreeList; 145 // global monitor in-use list, for moribund threads, 146 // monitors they inflated need to be scanned for deflation 147 static ObjectMonitor * volatile gOmInUseList; 148 // count of entries in gOmInUseList 149 static int gOmInUseCount; 150 }; 151 152 // ObjectLocker enforced balanced locking and can never thrown an 153 // IllegalMonitorStateException. However, a pending exception may 154 // have to pass through, and we must also be able to deal with 155 // asynchronous exceptions. The caller is responsible for checking 156 // the threads pending exception if needed. 157 // doLock was added to support classloading with UnsyncloadClass which 158 // requires flag based choice of locking the classloader lock. 159 class ObjectLocker : public StackObj { 160 private: 161 Thread* _thread; 162 Handle _obj; 163 BasicLock _lock; 164 bool _dolock; // default true 165 public: 166 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 167 ~ObjectLocker(); 168 169 // Monitor behavior 170 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 171 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 172 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } 173 // complete_exit gives up lock completely, returning recursion count 174 // reenter reclaims lock with original recursion count 175 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 176 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 177 }; 178 179 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP