1 /* 2 * Copyright (c) 1998, 2021, 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 "utilities/growableArray.hpp" 33 #include "utilities/linkedlist.hpp" 34 #include "utilities/resourceHash.hpp" 35 36 class LogStream; 37 class ObjectMonitor; 38 class ThreadsList; 39 40 // Hash table of void* to a list of ObjectMonitor* owned by the JavaThread. 41 // The JavaThread's owner key is either a JavaThread* or a stack lock 42 // address in the JavaThread so we use "void*". 43 // 44 class ObjectMonitorsHashtable { 45 private: 46 static unsigned int ptr_hash(void* const& s1) { 47 // 2654435761 = 2^32 * Phi (golden ratio) 48 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u); 49 } 50 51 public: 52 typedef LinkedListImpl<ObjectMonitor*, 53 ResourceObj::C_HEAP, mtThread, 54 AllocFailStrategy::RETURN_NULL> PtrList; 55 56 // ResourceHashtable SIZE is specified at compile time so we 57 // use 1031 which is the first prime after 1024. 58 typedef ResourceHashtable<void*, PtrList*, 1031, ResourceObj::C_HEAP, mtThread, 59 &ObjectMonitorsHashtable::ptr_hash> PtrTable; 60 private: 61 PtrTable* _ptrs; 62 size_t _key_count; 63 size_t _om_count; 64 65 public: 66 // ResourceHashtable is passed to various functions and populated in 67 // different places so we allocate it using C_HEAP to make it immune 68 // from any ResourceMarks that happen to be in the code paths. 69 ObjectMonitorsHashtable() : _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()), _key_count(0), _om_count(0) {} 70 71 ~ObjectMonitorsHashtable(); 72 73 void add_entry(void* key, ObjectMonitor* om); 74 75 void add_entry(void* key, PtrList* list) { 76 _ptrs->put(key, list); 77 _key_count++; 78 } 79 80 PtrList* get_entry(void* key) { 81 PtrList** listpp = _ptrs->get(key); 82 return (listpp == nullptr) ? nullptr : *listpp; 83 } 84 85 bool has_entry(void* key) { 86 PtrList** listpp = _ptrs->get(key); 87 return listpp != nullptr && *listpp != nullptr; 88 } 89 90 bool has_entry(void* key, ObjectMonitor* om); 91 92 size_t key_count() { return _key_count; } 93 size_t om_count() { return _om_count; } 94 }; 95 96 class MonitorList { 97 friend class VMStructs; 98 99 private: 100 ObjectMonitor* volatile _head; 101 volatile size_t _count; 102 volatile size_t _max; 103 104 public: 105 void add(ObjectMonitor* monitor); 106 size_t unlink_deflated(Thread* current, LogStream* ls, elapsedTimer* timer_p, 107 GrowableArray<ObjectMonitor*>* unlinked_list); 108 size_t count() const; 109 size_t max() const; 110 111 class Iterator; 112 Iterator iterator() const; 113 }; 114 115 class MonitorList::Iterator { 116 ObjectMonitor* _current; 117 118 public: 119 Iterator(ObjectMonitor* head) : _current(head) {} 120 bool has_next() const { return _current != NULL; } 121 ObjectMonitor* next(); 122 }; 123 124 class ObjectSynchronizer : AllStatic { 125 friend class VMStructs; 126 127 public: 128 typedef enum { 129 inflate_cause_vm_internal = 0, 130 inflate_cause_monitor_enter = 1, 131 inflate_cause_wait = 2, 132 inflate_cause_notify = 3, 133 inflate_cause_hash_code = 4, 134 inflate_cause_jni_enter = 5, 135 inflate_cause_jni_exit = 6, 136 inflate_cause_nof = 7 // Number of causes 137 } InflateCause; 138 139 typedef enum { 140 NOT_ENABLED = 0, 141 FATAL_EXIT = 1, 142 LOG_WARNING = 2 143 } SyncDiagnosticOption; 144 145 // exit must be implemented non-blocking, since the compiler cannot easily handle 146 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 147 148 // This is the "slow path" version of monitor enter and exit. 149 static void enter(Handle obj, BasicLock* lock, JavaThread* current); 150 static void exit(oop obj, BasicLock* lock, JavaThread* current); 151 152 // Used only to handle jni locks or other unmatched monitor enter/exit 153 // Internally they will use heavy weight monitor. 154 static void jni_enter(Handle obj, JavaThread* current); 155 static void jni_exit(oop obj, TRAPS); 156 157 // Handle all interpreter, compiler and jni cases 158 static int wait(Handle obj, jlong millis, TRAPS); 159 static void notify(Handle obj, TRAPS); 160 static void notifyall(Handle obj, TRAPS); 161 162 static bool quick_notify(oopDesc* obj, JavaThread* current, bool All); 163 static bool quick_enter(oop obj, JavaThread* current, BasicLock* Lock); 164 165 // Special internal-use-only method for use by JVM infrastructure 166 // that needs to wait() on a java-level object but must not respond 167 // to interrupt requests and doesn't timeout. 168 static void wait_uninterruptibly(Handle obj, JavaThread* current); 169 170 // used by classloading to free classloader object lock, 171 // wait on an internal lock, and reclaim original lock 172 // with original recursion count 173 static intx complete_exit(Handle obj, JavaThread* current); 174 static void reenter (Handle obj, intx recursions, JavaThread* current); 175 176 // Inflate light weight monitor to heavy weight monitor 177 static ObjectMonitor* inflate(Thread* current, oop obj, const InflateCause cause); 178 // This version is only for internal use 179 static void inflate_helper(oop obj); 180 static const char* inflate_cause_name(const InflateCause cause); 181 182 // Returns the identity hash value for an oop 183 // NOTE: It may cause monitor inflation 184 static intptr_t identity_hash_value_for(Handle obj); 185 static intptr_t FastHashCode(Thread* current, oop obj); 186 187 // Read mark-word and spin-wait as long as INFLATING is observed. 188 static markWord read_stable_mark(oop obj); 189 190 static markWord stable_mark(oop obj); 191 192 // java.lang.Thread support 193 static bool current_thread_holds_lock(JavaThread* current, Handle h_obj); 194 195 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 196 197 // JNI detach support 198 static void release_monitors_owned_by_thread(JavaThread* current); 199 200 // Iterate ObjectMonitors where the owner == thread; this does NOT include 201 // ObjectMonitors where owner is set to a stack lock address in thread: 202 // 203 // This version of monitors_iterate() works with the in-use monitor list. 204 static void monitors_iterate(MonitorClosure* m, JavaThread* thread); 205 // This version of monitors_iterate() works with the specified linked list. 206 static void monitors_iterate(MonitorClosure* closure, 207 ObjectMonitorsHashtable::PtrList* list, 208 JavaThread* thread); 209 210 // Initialize the gInflationLocks 211 static void initialize(); 212 213 // GC: we currently use aggressive monitor deflation policy 214 // Basically we try to deflate all monitors that are not busy. 215 static size_t deflate_idle_monitors(ObjectMonitorsHashtable* table); 216 217 // Deflate idle monitors: 218 static void chk_for_block_req(JavaThread* current, const char* op_name, 219 const char* cnt_name, size_t cnt, LogStream* ls, 220 elapsedTimer* timer_p); 221 static size_t deflate_monitor_list(Thread* current, LogStream* ls, elapsedTimer* timer_p, 222 ObjectMonitorsHashtable* table); 223 static size_t in_use_list_ceiling(); 224 static void dec_in_use_list_ceiling(); 225 static void inc_in_use_list_ceiling(); 226 static void set_in_use_list_ceiling(size_t new_value); 227 static bool is_async_deflation_needed(); 228 static bool is_async_deflation_requested() { return _is_async_deflation_requested; } 229 static bool is_final_audit() { return _is_final_audit; } 230 static void set_is_final_audit() { _is_final_audit = true; } 231 static jlong last_async_deflation_time_ns() { return _last_async_deflation_time_ns; } 232 static bool request_deflate_idle_monitors(); // for whitebox test support 233 static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; } 234 static jlong time_since_last_async_deflation_ms(); 235 236 // debugging 237 static void audit_and_print_stats(bool on_exit); 238 static void chk_in_use_list(outputStream* out, int* error_cnt_p); 239 static void chk_in_use_entry(ObjectMonitor* n, outputStream* out, 240 int* error_cnt_p); 241 static void do_final_audit_and_print_stats(); 242 static void log_in_use_monitor_details(outputStream* out); 243 244 private: 245 friend class SynchronizerTest; 246 247 static MonitorList _in_use_list; 248 static volatile bool _is_async_deflation_requested; 249 static volatile bool _is_final_audit; 250 static jlong _last_async_deflation_time_ns; 251 252 // Support for SynchronizerTest access to GVars fields: 253 static u_char* get_gvars_addr(); 254 static u_char* get_gvars_hc_sequence_addr(); 255 static size_t get_gvars_size(); 256 static u_char* get_gvars_stw_random_addr(); 257 258 static void handle_sync_on_value_based_class(Handle obj, JavaThread* current); 259 }; 260 261 // ObjectLocker enforces balanced locking and can never throw an 262 // IllegalMonitorStateException. However, a pending exception may 263 // have to pass through, and we must also be able to deal with 264 // asynchronous exceptions. The caller is responsible for checking 265 // the thread's pending exception if needed. 266 class ObjectLocker : public StackObj { 267 private: 268 JavaThread* _thread; 269 Handle _obj; 270 BasicLock _lock; 271 public: 272 ObjectLocker(Handle obj, JavaThread* current); 273 ~ObjectLocker(); 274 275 // Monitor behavior 276 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever 277 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 278 void wait_uninterruptibly(JavaThread* current) { ObjectSynchronizer::wait_uninterruptibly(_obj, current); } 279 }; 280 281 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP