1 /* 2 * Copyright (c) 1998, 2016, 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 33 class ObjectMonitor; 34 35 class ObjectSynchronizer : AllStatic { 36 friend class VMStructs; 37 public: 38 typedef enum { 39 owner_self, 40 owner_none, 41 owner_other 42 } LockOwnership; 43 44 typedef enum { 45 inflate_cause_vm_internal = 0, 46 inflate_cause_monitor_enter = 1, 47 inflate_cause_wait = 2, 48 inflate_cause_notify = 3, 49 inflate_cause_hash_code = 4, 50 inflate_cause_jni_enter = 5, 51 inflate_cause_jni_exit = 6, 52 inflate_cause_nof = 7 // Number of causes 53 } InflateCause; 54 55 // exit must be implemented non-blocking, since the compiler cannot easily handle 56 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 57 58 // This is full version of monitor enter and exit. I choose not 59 // to use enter() and exit() in order to make sure user be ware 60 // of the performance and semantics difference. They are normally 61 // used by ObjectLocker etc. The interpreter and compiler use 62 // assembly copies of these routines. Please keep them synchronized. 63 // 64 // attempt_rebias flag is used by UseBiasedLocking implementation 65 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 66 TRAPS); 67 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 68 69 // WARNING: They are ONLY used to handle the slow cases. They should 70 // only be used when the fast cases failed. Use of these functions 71 // without previous fast case check may cause fatal error. 72 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 73 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 74 75 // Used only to handle jni locks or other unmatched monitor enter/exit 76 // Internally they will use heavy weight monitor. 77 static void jni_enter(Handle obj, TRAPS); 78 static void jni_exit(oop obj, Thread* THREAD); 79 80 // Handle all interpreter, compiler and jni cases 81 static int wait(Handle obj, jlong millis, TRAPS); 82 static void notify(Handle obj, TRAPS); 83 static void notifyall(Handle obj, TRAPS); 84 85 static bool quick_notify(oopDesc* obj, Thread* Self, bool All); 86 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); 87 88 // Special internal-use-only method for use by JVM infrastructure 89 // that needs to wait() on a java-level object but that can't risk 90 // throwing unexpected InterruptedExecutionExceptions. 91 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); 92 93 // used by classloading to free classloader object lock, 94 // wait on an internal lock, and reclaim original lock 95 // with original recursion count 96 static intptr_t complete_exit(Handle obj, TRAPS); 97 static void reenter (Handle obj, intptr_t recursion, TRAPS); 98 99 // thread-specific and global objectMonitor free list accessors 100 static void verifyInUse(Thread * Self); 101 static ObjectMonitor * omAlloc(Thread * Self); 102 static void omRelease(Thread * Self, ObjectMonitor * m, 103 bool FromPerThreadAlloc); 104 static void omFlush(Thread * Self); 105 106 // Inflate light weight monitor to heavy weight monitor 107 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause); 108 // This version is only for internal use 109 static ObjectMonitor* inflate_helper(oop obj); 110 static const char* inflate_cause_name(const InflateCause cause); 111 112 // Returns the identity hash value for an oop 113 // NOTE: It may cause monitor inflation 114 static intptr_t identity_hash_value_for(Handle obj); 115 static intptr_t FastHashCode(Thread * Self, oop obj); 116 117 // java.lang.Thread support 118 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 119 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 120 121 static JavaThread* get_lock_owner(Handle h_obj, bool doLock); 122 123 // JNI detach support 124 static void release_monitors_owned_by_thread(TRAPS); 125 static void monitors_iterate(MonitorClosure* m); 126 127 // GC: we current use aggressive monitor deflation policy 128 // Basically we deflate all monitors that are not busy. 129 // An adaptive profile-based deflation policy could be used if needed 130 static void deflate_idle_monitors(); 131 // For a given monitor list: global or per-thread, deflate idle monitors 132 static int deflate_monitor_list(ObjectMonitor** listheadp, 133 ObjectMonitor** freeHeadp, 134 ObjectMonitor** freeTailp); 135 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 136 ObjectMonitor** freeHeadp, 137 ObjectMonitor** freeTailp); 138 static void oops_do(OopClosure* f); 139 // Process oops in thread local used monitors 140 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 141 142 // debugging 143 static void sanity_checks(const bool verbose, 144 const unsigned int cache_line_size, 145 int *error_cnt_ptr, int *warning_cnt_ptr); 146 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 147 148 private: 149 enum { _BLOCKSIZE = 128 }; 150 // global list of blocks of monitors 151 // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't 152 // want to expose the PaddedEnd template more than necessary. 153 static ObjectMonitor * volatile gBlockList; 154 // global monitor free list 155 static ObjectMonitor * volatile gFreeList; 156 // global monitor in-use list, for moribund threads, 157 // monitors they inflated need to be scanned for deflation 158 static ObjectMonitor * volatile gOmInUseList; 159 // count of entries in gOmInUseList 160 static int gOmInUseCount; 161 162 // Process oops in all monitors 163 static void global_oops_do(OopClosure* f); 164 // Process oops in all global used monitors (i.e. moribund thread's monitors) 165 static void global_used_oops_do(OopClosure* f); 166 // Process oops in monitors on the given list 167 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 168 169 }; 170 171 // ObjectLocker enforced balanced locking and can never thrown an 172 // IllegalMonitorStateException. However, a pending exception may 173 // have to pass through, and we must also be able to deal with 174 // asynchronous exceptions. The caller is responsible for checking 175 // the threads pending exception if needed. 176 // doLock was added to support classloading with UnsyncloadClass which 177 // requires flag based choice of locking the classloader lock. 178 class ObjectLocker : public StackObj { 179 private: 180 Thread* _thread; 181 Handle _obj; 182 BasicLock _lock; 183 bool _dolock; // default true 184 public: 185 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 186 ~ObjectLocker(); 187 188 // Monitor behavior 189 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 190 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 191 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } 192 // complete_exit gives up lock completely, returning recursion count 193 // reenter reclaims lock with original recursion count 194 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 195 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 196 }; 197 198 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP