1 /* 2 * Copyright (c) 1998, 2019, 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_RUNTIME_SYNCHRONIZER_HPP 26 #define SHARE_RUNTIME_SYNCHRONIZER_HPP 27 28 #include "memory/padded.hpp" 29 #include "oops/markWord.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 (global and per-thread) 41 int perThreadScavenged; // per-thread scavenge total 42 double perThreadTimes; // per-thread scavenge times 43 }; 44 45 class ObjectSynchronizer : AllStatic { 46 friend class VMStructs; 47 public: 48 typedef enum { 49 owner_self, 50 owner_none, 51 owner_other 52 } LockOwnership; 53 54 typedef enum { 55 inflate_cause_vm_internal = 0, 56 inflate_cause_monitor_enter = 1, 57 inflate_cause_wait = 2, 58 inflate_cause_notify = 3, 59 inflate_cause_hash_code = 4, 60 inflate_cause_jni_enter = 5, 61 inflate_cause_jni_exit = 6, 62 inflate_cause_nof = 7 // Number of causes 63 } InflateCause; 64 65 // exit must be implemented non-blocking, since the compiler cannot easily handle 66 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 67 68 // This is full version of monitor enter and exit. I choose not 69 // to use enter() and exit() in order to make sure user be ware 70 // of the performance and semantics difference. They are normally 71 // used by ObjectLocker etc. The interpreter and compiler use 72 // assembly copies of these routines. Please keep them synchronized. 73 // 74 // attempt_rebias flag is used by UseBiasedLocking implementation 75 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 76 TRAPS); 77 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 78 79 // WARNING: They are ONLY used to handle the slow cases. They should 80 // only be used when the fast cases failed. Use of these functions 81 // without previous fast case check may cause fatal error. 82 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 83 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 84 85 // Used only to handle jni locks or other unmatched monitor enter/exit 86 // Internally they will use heavy weight monitor. 87 static void jni_enter(Handle obj, TRAPS); 88 static void jni_exit(oop obj, Thread* THREAD); 89 90 // Handle all interpreter, compiler and jni cases 91 static int wait(Handle obj, jlong millis, TRAPS); 92 static void notify(Handle obj, TRAPS); 93 static void notifyall(Handle obj, TRAPS); 94 95 static bool quick_notify(oopDesc* obj, Thread* Self, bool All); 96 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); 97 98 // Special internal-use-only method for use by JVM infrastructure 99 // that needs to wait() on a java-level object but that can't risk 100 // throwing unexpected InterruptedExecutionExceptions. 101 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); 102 103 // used by classloading to free classloader object lock, 104 // wait on an internal lock, and reclaim original lock 105 // with original recursion count 106 static intptr_t complete_exit(Handle obj, TRAPS); 107 static void reenter (Handle obj, intptr_t recursion, TRAPS); 108 109 // thread-specific and global objectMonitor free list accessors 110 static ObjectMonitor * omAlloc(Thread * Self); 111 static void omRelease(Thread * Self, ObjectMonitor * m, 112 bool FromPerThreadAlloc); 113 static void omFlush(Thread * Self); 114 115 // Inflate light weight monitor to heavy weight monitor 116 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause); 117 // This version is only for internal use 118 static void inflate_helper(oop obj); 119 static const char* inflate_cause_name(const InflateCause cause); 120 121 // Returns the identity hash value for an oop 122 // NOTE: It may cause monitor inflation 123 static intptr_t identity_hash_value_for(Handle obj); 124 static intptr_t FastHashCode(Thread * Self, oop obj); 125 126 // java.lang.Thread support 127 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 128 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 129 130 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 131 132 // JNI detach support 133 static void release_monitors_owned_by_thread(TRAPS); 134 static void monitors_iterate(MonitorClosure* m); 135 136 // GC: we current use aggressive monitor deflation policy 137 // Basically we deflate all monitors that are not busy. 138 // An adaptive profile-based deflation policy could be used if needed 139 static void deflate_idle_monitors(DeflateMonitorCounters* counters); 140 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters); 141 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); 142 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); 143 144 // For a given monitor list: global or per-thread, deflate idle monitors 145 static int deflate_monitor_list(ObjectMonitor** listheadp, 146 ObjectMonitor** freeHeadp, 147 ObjectMonitor** freeTailp); 148 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 149 ObjectMonitor** freeHeadp, 150 ObjectMonitor** freeTailp); 151 static bool is_cleanup_needed(); 152 static void oops_do(OopClosure* f); 153 // Process oops in thread local used monitors 154 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 155 156 // debugging 157 static void audit_and_print_stats(bool on_exit); 158 static void chk_free_entry(JavaThread * jt, ObjectMonitor * n, 159 outputStream * out, int *error_cnt_p); 160 static void chk_global_free_list_and_count(outputStream * out, 161 int *error_cnt_p); 162 static void chk_global_in_use_list_and_count(outputStream * out, 163 int *error_cnt_p); 164 static void chk_in_use_entry(JavaThread * jt, ObjectMonitor * n, 165 outputStream * out, int *error_cnt_p); 166 static void chk_per_thread_in_use_list_and_count(JavaThread *jt, 167 outputStream * out, 168 int *error_cnt_p); 169 static void chk_per_thread_free_list_and_count(JavaThread *jt, 170 outputStream * out, 171 int *error_cnt_p); 172 static void log_in_use_monitor_details(outputStream * out, bool on_exit); 173 static int log_monitor_list_counts(outputStream * out); 174 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 175 176 private: 177 friend class SynchronizerTest; 178 179 enum { _BLOCKSIZE = 128 }; 180 // global list of blocks of monitors 181 static PaddedEnd<ObjectMonitor> * volatile gBlockList; 182 // global monitor free list 183 static ObjectMonitor * volatile gFreeList; 184 // global monitor in-use list, for moribund threads, 185 // monitors they inflated need to be scanned for deflation 186 static ObjectMonitor * volatile gOmInUseList; 187 // count of entries in gOmInUseList 188 static int gOmInUseCount; 189 190 // Process oops in all global used monitors (i.e. moribund thread's monitors) 191 static void global_used_oops_do(OopClosure* f); 192 // Process oops in monitors on the given list 193 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 194 195 // Support for SynchronizerTest access to GVars fields: 196 static u_char* get_gvars_addr(); 197 static u_char* get_gvars_hcSequence_addr(); 198 static size_t get_gvars_size(); 199 static u_char* get_gvars_stwRandom_addr(); 200 }; 201 202 // ObjectLocker enforces balanced locking and can never throw an 203 // IllegalMonitorStateException. However, a pending exception may 204 // have to pass through, and we must also be able to deal with 205 // asynchronous exceptions. The caller is responsible for checking 206 // the thread's pending exception if needed. 207 class ObjectLocker : public StackObj { 208 private: 209 Thread* _thread; 210 Handle _obj; 211 BasicLock _lock; 212 bool _dolock; // default true 213 public: 214 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 215 ~ObjectLocker(); 216 217 // Monitor behavior 218 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 219 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 220 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } 221 // complete_exit gives up lock completely, returning recursion count 222 // reenter reclaims lock with original recursion count 223 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 224 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 225 }; 226 227 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP