1 /* 2 * Copyright (c) 1998, 2017, 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 struct DeflateMonitorCounters { 38 int nInuse; // currently associated with objects 39 int nInCirculation; // extant 40 int nScavenged; // reclaimed 41 }; 42 43 class ObjectSynchronizer : AllStatic { 44 friend class VMStructs; 45 public: 46 typedef enum { 47 owner_self, 48 owner_none, 49 owner_other 50 } LockOwnership; 51 52 typedef enum { 53 inflate_cause_vm_internal = 0, 54 inflate_cause_monitor_enter = 1, 55 inflate_cause_wait = 2, 56 inflate_cause_notify = 3, 57 inflate_cause_hash_code = 4, 58 inflate_cause_jni_enter = 5, 59 inflate_cause_jni_exit = 6, 60 inflate_cause_nof = 7 // Number of causes 61 } InflateCause; 62 63 // exit must be implemented non-blocking, since the compiler cannot easily handle 64 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 65 66 // This is full version of monitor enter and exit. I choose not 67 // to use enter() and exit() in order to make sure user be ware 68 // of the performance and semantics difference. They are normally 69 // used by ObjectLocker etc. The interpreter and compiler use 70 // assembly copies of these routines. Please keep them synchronized. 71 // 72 // attempt_rebias flag is used by UseBiasedLocking implementation 73 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 74 TRAPS); 75 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 76 77 // WARNING: They are ONLY used to handle the slow cases. They should 78 // only be used when the fast cases failed. Use of these functions 79 // without previous fast case check may cause fatal error. 80 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 81 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 82 83 // Used only to handle jni locks or other unmatched monitor enter/exit 84 // Internally they will use heavy weight monitor. 85 static void jni_enter(Handle obj, TRAPS); 86 static void jni_exit(oop obj, Thread* THREAD); 87 88 // Handle all interpreter, compiler and jni cases 89 static int wait(Handle obj, jlong millis, TRAPS); 90 static void notify(Handle obj, TRAPS); 91 static void notifyall(Handle obj, TRAPS); 92 93 static bool quick_notify(oopDesc* obj, Thread* Self, bool All); 94 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); 95 96 // Special internal-use-only method for use by JVM infrastructure 97 // that needs to wait() on a java-level object but that can't risk 98 // throwing unexpected InterruptedExecutionExceptions. 99 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); 100 101 // used by classloading to free classloader object lock, 102 // wait on an internal lock, and reclaim original lock 103 // with original recursion count 104 static intptr_t complete_exit(Handle obj, TRAPS); 105 static void reenter (Handle obj, intptr_t recursion, TRAPS); 106 107 // thread-specific and global objectMonitor free list accessors 108 static void verifyInUse(Thread * Self); 109 static ObjectMonitor * omAlloc(Thread * Self); 110 static void omRelease(Thread * Self, ObjectMonitor * m, 111 bool FromPerThreadAlloc); 112 static void omFlush(Thread * Self); 113 114 // Inflate light weight monitor to heavy weight monitor 115 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause); 116 // This version is only for internal use 117 static ObjectMonitor* inflate_helper(oop obj); 118 static const char* inflate_cause_name(const InflateCause cause); 119 120 // Returns the identity hash value for an oop 121 // NOTE: It may cause monitor inflation 122 static intptr_t identity_hash_value_for(Handle obj); 123 static intptr_t FastHashCode(Thread * Self, oop obj); 124 125 // java.lang.Thread support 126 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 127 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 128 129 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 130 131 // JNI detach support 132 static void release_monitors_owned_by_thread(TRAPS); 133 static void monitors_iterate(MonitorClosure* m); 134 135 // GC: we current use aggressive monitor deflation policy 136 // Basically we deflate all monitors that are not busy. 137 // An adaptive profile-based deflation policy could be used if needed 138 static void deflate_idle_monitors(DeflateMonitorCounters* counters); 139 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters); 140 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); 141 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); 142 143 // For a given monitor list: global or per-thread, deflate idle monitors 144 static int deflate_monitor_list(ObjectMonitor** listheadp, 145 ObjectMonitor** freeHeadp, 146 ObjectMonitor** freeTailp); 147 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 148 ObjectMonitor** freeHeadp, 149 ObjectMonitor** freeTailp); 150 static bool is_cleanup_needed(); 151 static void oops_do(OopClosure* f); 152 // Process oops in thread local used monitors 153 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 154 155 // debugging 156 static void sanity_checks(const bool verbose, 157 const unsigned int cache_line_size, 158 int *error_cnt_ptr, int *warning_cnt_ptr); 159 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 160 161 private: 162 enum { _BLOCKSIZE = 128 }; 163 // global list of blocks of monitors 164 static PaddedEnd<ObjectMonitor> * volatile gBlockList; 165 // global monitor free list 166 static ObjectMonitor * volatile gFreeList; 167 // global monitor in-use list, for moribund threads, 168 // monitors they inflated need to be scanned for deflation 169 static ObjectMonitor * volatile gOmInUseList; 170 // count of entries in gOmInUseList 171 static int gOmInUseCount; 172 173 // Process oops in all monitors 174 static void global_oops_do(OopClosure* f); 175 // Process oops in all global used monitors (i.e. moribund thread's monitors) 176 static void global_used_oops_do(OopClosure* f); 177 // Process oops in monitors on the given list 178 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 179 180 }; 181 182 // ObjectLocker enforced balanced locking and can never thrown an 183 // IllegalMonitorStateException. However, a pending exception may 184 // have to pass through, and we must also be able to deal with 185 // asynchronous exceptions. The caller is responsible for checking 186 // the threads pending exception if needed. 187 // doLock was added to support classloading with UnsyncloadClass which 188 // requires flag based choice of locking the classloader lock. 189 class ObjectLocker : public StackObj { 190 private: 191 Thread* _thread; 192 Handle _obj; 193 BasicLock _lock; 194 bool _dolock; // default true 195 public: 196 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 197 ~ObjectLocker(); 198 199 // Monitor behavior 200 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 201 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 202 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } 203 // complete_exit gives up lock completely, returning recursion count 204 // reenter reclaims lock with original recursion count 205 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 206 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 207 }; 208 209 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP