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