1 /* 2 * Copyright (c) 1998, 2018, 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 "memory/padded.hpp" 29 #include "oops/markOop.hpp" 30 #include "runtime/basicLock.hpp" 31 #include "runtime/handles.hpp" 32 #include "runtime/perfData.hpp" 33 34 class ObjectMonitor; 35 class ThreadsList; 36 37 38 class ParallelObjectSynchronizerIterator { 39 friend class ObjectSynchronizer; 40 41 private: 42 PaddedEnd<ObjectMonitor>* volatile _cur; 43 44 private: 45 ParallelObjectSynchronizerIterator(PaddedEnd<ObjectMonitor>* head); 46 ObjectMonitor* claim(); 47 48 public: 49 bool parallel_oops_do(OopClosure* f); 50 }; 51 52 struct DeflateMonitorCounters { 53 int nInuse; // currently associated with objects 54 int nInCirculation; // extant 55 int nScavenged; // reclaimed 56 }; 57 58 class ObjectSynchronizer : AllStatic { 59 friend class VMStructs; 60 friend class ParallelObjectSynchronizerIterator; 61 public: 62 typedef enum { 63 owner_self, 64 owner_none, 65 owner_other 66 } LockOwnership; 67 68 typedef enum { 69 inflate_cause_vm_internal = 0, 70 inflate_cause_monitor_enter = 1, 71 inflate_cause_wait = 2, 72 inflate_cause_notify = 3, 73 inflate_cause_hash_code = 4, 74 inflate_cause_jni_enter = 5, 75 inflate_cause_jni_exit = 6, 76 inflate_cause_nof = 7 // Number of causes 77 } InflateCause; 78 79 // exit must be implemented non-blocking, since the compiler cannot easily handle 80 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 81 82 // This is full version of monitor enter and exit. I choose not 83 // to use enter() and exit() in order to make sure user be ware 84 // of the performance and semantics difference. They are normally 85 // used by ObjectLocker etc. The interpreter and compiler use 86 // assembly copies of these routines. Please keep them synchronized. 87 // 88 // attempt_rebias flag is used by UseBiasedLocking implementation 89 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 90 TRAPS); 91 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 92 93 // WARNING: They are ONLY used to handle the slow cases. They should 94 // only be used when the fast cases failed. Use of these functions 95 // without previous fast case check may cause fatal error. 96 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 97 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 98 99 // Used only to handle jni locks or other unmatched monitor enter/exit 100 // Internally they will use heavy weight monitor. 101 static void jni_enter(Handle obj, TRAPS); 102 static void jni_exit(oop obj, Thread* THREAD); 103 104 // Handle all interpreter, compiler and jni cases 105 static int wait(Handle obj, jlong millis, TRAPS); 106 static void notify(Handle obj, TRAPS); 107 static void notifyall(Handle obj, TRAPS); 108 109 static bool quick_notify(oopDesc* obj, Thread* Self, bool All); 110 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); 111 112 // Special internal-use-only method for use by JVM infrastructure 113 // that needs to wait() on a java-level object but that can't risk 114 // throwing unexpected InterruptedExecutionExceptions. 115 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); 116 117 // used by classloading to free classloader object lock, 118 // wait on an internal lock, and reclaim original lock 119 // with original recursion count 120 static intptr_t complete_exit(Handle obj, TRAPS); 121 static void reenter (Handle obj, intptr_t recursion, TRAPS); 122 123 // thread-specific and global objectMonitor free list accessors 124 static void verifyInUse(Thread * Self); 125 static ObjectMonitor * omAlloc(Thread * Self); 126 static void omRelease(Thread * Self, ObjectMonitor * m, 127 bool FromPerThreadAlloc); 128 static void omFlush(Thread * Self); 129 130 // Inflate light weight monitor to heavy weight monitor 131 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause); 132 // This version is only for internal use 133 static ObjectMonitor* inflate_helper(oop obj); 134 static const char* inflate_cause_name(const InflateCause cause); 135 136 // Returns the identity hash value for an oop 137 // NOTE: It may cause monitor inflation 138 static intptr_t identity_hash_value_for(Handle obj); 139 static intptr_t FastHashCode(Thread * Self, oop obj); 140 141 // java.lang.Thread support 142 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 143 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 144 145 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 146 147 // JNI detach support 148 static void release_monitors_owned_by_thread(TRAPS); 149 static void monitors_iterate(MonitorClosure* m); 150 151 // GC: we current use aggressive monitor deflation policy 152 // Basically we deflate all monitors that are not busy. 153 // An adaptive profile-based deflation policy could be used if needed 154 static void deflate_idle_monitors(DeflateMonitorCounters* counters); 155 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters, OopClosure* cl); 156 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); 157 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); 158 159 // For a given monitor list: global or per-thread, deflate idle monitors 160 static int deflate_monitor_list(ObjectMonitor** listheadp, 161 ObjectMonitor** freeHeadp, 162 ObjectMonitor** freeTailp, 163 OopClosure* cl = NULL); 164 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 165 ObjectMonitor** freeHeadp, 166 ObjectMonitor** freeTailp); 167 static bool is_cleanup_needed(); 168 static void oops_do(OopClosure* f); 169 // Process oops in thread local used monitors 170 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 171 172 // Parallel GC support 173 static ParallelObjectSynchronizerIterator parallel_iterator(); 174 175 // debugging 176 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 177 178 private: 179 friend class SynchronizerTest; 180 181 enum { _BLOCKSIZE = 128 }; 182 // global list of blocks of monitors 183 static PaddedEnd<ObjectMonitor> * volatile gBlockList; 184 // global monitor free list 185 static ObjectMonitor * volatile gFreeList; 186 // global monitor in-use list, for moribund threads, 187 // monitors they inflated need to be scanned for deflation 188 static ObjectMonitor * volatile gOmInUseList; 189 // count of entries in gOmInUseList 190 static int gOmInUseCount; 191 192 // Process oops in all monitors 193 static void global_oops_do(OopClosure* f); 194 // Process oops in all global used monitors (i.e. moribund thread's monitors) 195 static void global_used_oops_do(OopClosure* f); 196 // Process oops in monitors on the given list 197 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 198 199 // Support for SynchronizerTest access to GVars fields: 200 static u_char* get_gvars_addr(); 201 static u_char* get_gvars_hcSequence_addr(); 202 static size_t get_gvars_size(); 203 static u_char* get_gvars_stwRandom_addr(); 204 }; 205 206 // ObjectLocker enforced balanced locking and can never thrown an 207 // IllegalMonitorStateException. However, a pending exception may 208 // have to pass through, and we must also be able to deal with 209 // asynchronous exceptions. The caller is responsible for checking 210 // the threads pending exception if needed. 211 class ObjectLocker : public StackObj { 212 private: 213 Thread* _thread; 214 Handle _obj; 215 BasicLock _lock; 216 bool _dolock; // default true 217 public: 218 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 219 ~ObjectLocker(); 220 221 // Monitor behavior 222 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 223 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 224 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } 225 // complete_exit gives up lock completely, returning recursion count 226 // reenter reclaims lock with original recursion count 227 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 228 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 229 }; 230 231 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP