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 ObjectMonitorHandle; 36 class ThreadsList; 37 38 typedef PaddedEnd<ObjectMonitor, DEFAULT_CACHE_LINE_SIZE> PaddedObjectMonitor; 39 40 struct DeflateMonitorCounters { 41 int n_in_use; // currently associated with objects 42 int n_in_circulation; // extant 43 int n_scavenged; // reclaimed (global and per-thread) 44 int per_thread_scavenged; // per-thread scavenge total 45 double per_thread_times; // per-thread scavenge times 46 }; 47 48 class ObjectSynchronizer : AllStatic { 49 friend class VMStructs; 50 public: 51 typedef enum { 52 owner_self, 53 owner_none, 54 owner_other 55 } LockOwnership; 56 57 typedef enum { 58 inflate_cause_vm_internal = 0, 59 inflate_cause_monitor_enter = 1, 60 inflate_cause_wait = 2, 61 inflate_cause_notify = 3, 62 inflate_cause_hash_code = 4, 63 inflate_cause_jni_enter = 5, 64 inflate_cause_jni_exit = 6, 65 inflate_cause_nof = 7 // Number of causes 66 } InflateCause; 67 68 // exit must be implemented non-blocking, since the compiler cannot easily handle 69 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 70 71 // This is full version of monitor enter and exit. I choose not 72 // to use enter() and exit() in order to make sure user be ware 73 // of the performance and semantics difference. They are normally 74 // used by ObjectLocker etc. The interpreter and compiler use 75 // assembly copies of these routines. Please keep them synchronized. 76 // 77 // attempt_rebias flag is used by UseBiasedLocking implementation 78 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, 79 TRAPS); 80 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); 81 82 // WARNING: They are ONLY used to handle the slow cases. They should 83 // only be used when the fast cases failed. Use of these functions 84 // without previous fast case check may cause fatal error. 85 static void slow_enter(Handle obj, BasicLock* lock, TRAPS); 86 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); 87 88 // Used only to handle jni locks or other unmatched monitor enter/exit 89 // Internally they will use heavy weight monitor. 90 static void jni_enter(Handle obj, TRAPS); 91 static void jni_exit(oop obj, Thread* THREAD); 92 93 // Handle all interpreter, compiler and jni cases 94 static int wait(Handle obj, jlong millis, TRAPS); 95 static void notify(Handle obj, TRAPS); 96 static void notifyall(Handle obj, TRAPS); 97 98 static bool quick_notify(oopDesc* obj, Thread* self, bool All); 99 static bool quick_enter(oop obj, Thread* self, BasicLock* Lock); 100 101 // Special internal-use-only method for use by JVM infrastructure 102 // that needs to wait() on a java-level object but that can't risk 103 // throwing unexpected InterruptedExecutionExceptions. 104 static void wait_uninterruptibly(Handle obj, jlong Millis, Thread* THREAD); 105 106 // used by classloading to free classloader object lock, 107 // wait on an internal lock, and reclaim original lock 108 // with original recursion count 109 static intptr_t complete_exit(Handle obj, TRAPS); 110 static void reenter (Handle obj, intptr_t recursion, TRAPS); 111 112 // thread-specific and global ObjectMonitor free list accessors 113 static ObjectMonitor* om_alloc(Thread* self, const InflateCause cause); 114 static void om_release(Thread* self, ObjectMonitor* m, 115 bool FromPerThreadAlloc); 116 static void om_flush(Thread* self); 117 118 // Inflate light weight monitor to heavy weight monitor 119 static void inflate(ObjectMonitorHandle* omh_p, Thread* self, oop obj, 120 const InflateCause cause); 121 // This version is only for internal use 122 static void inflate_helper(ObjectMonitorHandle* omh_p, oop obj); 123 static const char* inflate_cause_name(const InflateCause cause); 124 125 // Returns the identity hash value for an oop 126 // NOTE: It may cause monitor inflation 127 static intptr_t identity_hash_value_for(Handle obj); 128 static intptr_t FastHashCode(Thread* self, oop obj); 129 130 // java.lang.Thread support 131 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 132 static LockOwnership query_lock_ownership(JavaThread* self, Handle h_obj); 133 134 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 135 136 // JNI detach support 137 static void release_monitors_owned_by_thread(TRAPS); 138 static void monitors_iterate(MonitorClosure* m); 139 140 // GC: we current use aggressive monitor deflation policy 141 // Basically we deflate all monitors that are not busy. 142 // An adaptive profile-based deflation policy could be used if needed 143 static void deflate_idle_monitors(DeflateMonitorCounters* counters); 144 static void deflate_global_idle_monitors_using_JT(); 145 static void deflate_per_thread_idle_monitors_using_JT(); 146 static void deflate_common_idle_monitors_using_JT(bool is_global, JavaThread* self); 147 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters); 148 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); 149 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); 150 151 // For a given monitor list: global or per-thread, deflate idle monitors 152 static int deflate_monitor_list(ObjectMonitor** list_p, 153 ObjectMonitor** free_head_p, 154 ObjectMonitor** free_tail_p); 155 // For a given in-use monitor list: global or per-thread, deflate idle 156 // monitors using a JavaThread. 157 static int deflate_monitor_list_using_JT(ObjectMonitor** list_p, 158 ObjectMonitor** free_head_p, 159 ObjectMonitor** free_tail_p, 160 ObjectMonitor** saved_mid_in_use_p); 161 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 162 ObjectMonitor** free_head_p, 163 ObjectMonitor** free_tail_p); 164 static bool deflate_monitor_using_JT(ObjectMonitor* mid, 165 ObjectMonitor** free_head_p, 166 ObjectMonitor** free_tail_p); 167 static bool is_async_deflation_needed(); 168 static bool is_safepoint_deflation_needed(); 169 static bool is_async_deflation_requested() { return _is_async_deflation_requested; } 170 static bool is_special_deflation_requested() { return _is_special_deflation_requested; } 171 static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; } 172 static void set_is_special_deflation_requested(bool new_value) { _is_special_deflation_requested = new_value; } 173 static jlong time_since_last_async_deflation_ms(); 174 static void oops_do(OopClosure* f); 175 // Process oops in thread local used monitors 176 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 177 178 // debugging 179 static void audit_and_print_stats(bool on_exit); 180 static void chk_free_entry(JavaThread* jt, ObjectMonitor* n, 181 outputStream * out, int *error_cnt_p); 182 static void chk_global_free_list_and_count(outputStream * out, 183 int *error_cnt_p); 184 static void chk_global_in_use_list_and_count(outputStream * out, 185 int *error_cnt_p); 186 static void chk_in_use_entry(JavaThread* jt, ObjectMonitor* n, 187 outputStream * out, int *error_cnt_p); 188 static void chk_per_thread_in_use_list_and_count(JavaThread *jt, 189 outputStream * out, 190 int *error_cnt_p); 191 static void chk_per_thread_free_list_and_count(JavaThread *jt, 192 outputStream * out, 193 int *error_cnt_p); 194 static void log_in_use_monitor_details(outputStream * out, bool on_exit); 195 static int log_monitor_list_counts(outputStream * out); 196 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 197 198 static void do_safepoint_work(DeflateMonitorCounters* _counters); 199 200 private: 201 friend class SynchronizerTest; 202 203 enum { _BLOCKSIZE = 128 }; 204 // global list of blocks of monitors 205 static PaddedObjectMonitor* volatile g_block_list; 206 // global monitor free list 207 static ObjectMonitor* volatile g_free_list; 208 // global monitor in-use list, for moribund threads, 209 // monitors they inflated need to be scanned for deflation 210 static ObjectMonitor* volatile g_om_in_use_list; 211 // count of entries in g_om_in_use_list 212 static int g_om_in_use_count; 213 static volatile bool _is_async_deflation_requested; 214 static volatile bool _is_special_deflation_requested; 215 static jlong _last_async_deflation_time_ns; 216 217 // Process oops in all global used monitors (i.e. moribund thread's monitors) 218 static void global_used_oops_do(OopClosure* f); 219 // Process oops in monitors on the given list 220 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 221 222 // Support for SynchronizerTest access to GVars fields: 223 static u_char* get_gvars_addr(); 224 static u_char* get_gvars_hc_sequence_addr(); 225 static size_t get_gvars_size(); 226 static u_char* get_gvars_stw_random_addr(); 227 }; 228 229 // ObjectLocker enforces balanced locking and can never throw an 230 // IllegalMonitorStateException. However, a pending exception may 231 // have to pass through, and we must also be able to deal with 232 // asynchronous exceptions. The caller is responsible for checking 233 // the thread's pending exception if needed. 234 class ObjectLocker : public StackObj { 235 private: 236 Thread* _thread; 237 Handle _obj; 238 BasicLock _lock; 239 bool _dolock; // default true 240 public: 241 ObjectLocker(Handle obj, Thread* thread, bool do_lock = true); 242 ~ObjectLocker(); 243 244 // Monitor behavior 245 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 246 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 247 void wait_uninterruptibly(TRAPS) { ObjectSynchronizer::wait_uninterruptibly(_obj, 0, CHECK); } 248 // complete_exit gives up lock completely, returning recursion count 249 // reenter reclaims lock with original recursion count 250 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 251 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 252 }; 253 254 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP