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