1 /* 2 * Copyright (c) 1998, 2020, 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 #ifndef OM_CACHE_LINE_SIZE 38 // Use DEFAULT_CACHE_LINE_SIZE if not already specified for 39 // the current build platform. 40 #define OM_CACHE_LINE_SIZE DEFAULT_CACHE_LINE_SIZE 41 #endif 42 43 typedef PaddedEnd<ObjectMonitor, OM_CACHE_LINE_SIZE> PaddedObjectMonitor; 44 45 struct DeflateMonitorCounters { 46 volatile int n_in_use; // currently associated with objects 47 volatile int n_in_circulation; // extant 48 volatile int n_scavenged; // reclaimed (global and per-thread) 49 volatile int per_thread_scavenged; // per-thread scavenge total 50 double per_thread_times; // per-thread scavenge times 51 }; 52 53 class ObjectSynchronizer : AllStatic { 54 friend class VMStructs; 55 public: 56 typedef enum { 57 owner_self, 58 owner_none, 59 owner_other 60 } LockOwnership; 61 62 typedef enum { 63 inflate_cause_vm_internal = 0, 64 inflate_cause_monitor_enter = 1, 65 inflate_cause_wait = 2, 66 inflate_cause_notify = 3, 67 inflate_cause_hash_code = 4, 68 inflate_cause_jni_enter = 5, 69 inflate_cause_jni_exit = 6, 70 inflate_cause_nof = 7 // Number of causes 71 } InflateCause; 72 73 // exit must be implemented non-blocking, since the compiler cannot easily handle 74 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 75 76 // This is the "slow path" version of monitor enter and exit. 77 static void enter(Handle obj, BasicLock* lock, TRAPS); 78 static void exit(oop obj, BasicLock* lock, Thread* THREAD); 79 80 // Used only to handle jni locks or other unmatched monitor enter/exit 81 // Internally they will use heavy weight monitor. 82 static void jni_enter(Handle obj, TRAPS); 83 static void jni_exit(oop obj, Thread* THREAD); 84 85 // Handle all interpreter, compiler and jni cases 86 static int wait(Handle obj, jlong millis, TRAPS); 87 static void notify(Handle obj, TRAPS); 88 static void notifyall(Handle obj, TRAPS); 89 90 static bool quick_notify(oopDesc* obj, Thread* self, bool All); 91 static bool quick_enter(oop obj, Thread* self, BasicLock* Lock); 92 93 // Special internal-use-only method for use by JVM infrastructure 94 // that needs to wait() on a java-level object but that can't risk 95 // throwing unexpected InterruptedExecutionExceptions. 96 static void wait_uninterruptibly(Handle obj, jlong Millis, Thread* THREAD); 97 98 // used by classloading to free classloader object lock, 99 // wait on an internal lock, and reclaim original lock 100 // with original recursion count 101 static intx complete_exit(Handle obj, TRAPS); 102 static void reenter (Handle obj, intx recursions, TRAPS); 103 104 // thread-specific and global ObjectMonitor free list accessors 105 static ObjectMonitor* om_alloc(Thread* self); 106 static void om_release(Thread* self, ObjectMonitor* m, 107 bool FromPerThreadAlloc); 108 static void om_flush(Thread* self); 109 110 // Inflate light weight monitor to heavy weight monitor 111 static ObjectMonitor* inflate(Thread* self, oop obj, const InflateCause cause); 112 // This version is only for internal use 113 static void inflate_helper(oop obj); 114 static const char* inflate_cause_name(const InflateCause cause); 115 116 // Returns the identity hash value for an oop 117 // NOTE: It may cause monitor inflation 118 static intptr_t identity_hash_value_for(Handle obj); 119 static intptr_t FastHashCode(Thread* self, oop obj); 120 121 // java.lang.Thread support 122 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 123 static LockOwnership query_lock_ownership(JavaThread* self, Handle h_obj); 124 125 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); 126 127 // JNI detach support 128 static void release_monitors_owned_by_thread(TRAPS); 129 static void monitors_iterate(MonitorClosure* m); 130 131 // GC: we current use aggressive monitor deflation policy 132 // Basically we deflate all monitors that are not busy. 133 // An adaptive profile-based deflation policy could be used if needed 134 static void deflate_idle_monitors(DeflateMonitorCounters* counters); 135 static void deflate_idle_monitors_using_JT(); 136 static void deflate_global_idle_monitors_using_JT(); 137 static void deflate_per_thread_idle_monitors_using_JT(JavaThread* target); 138 static void deflate_common_idle_monitors_using_JT(bool is_global, JavaThread* target); 139 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters); 140 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); 141 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); 142 143 // For a given monitor list: global or per-thread, deflate idle monitors 144 static int deflate_monitor_list(ObjectMonitor** list_p, 145 int* count_p, 146 ObjectMonitor** free_head_p, 147 ObjectMonitor** free_tail_p); 148 // For a given in-use monitor list: global or per-thread, deflate idle 149 // monitors using a JavaThread. 150 static int deflate_monitor_list_using_JT(ObjectMonitor** list_p, 151 int* count_p, 152 ObjectMonitor** free_head_p, 153 ObjectMonitor** free_tail_p, 154 ObjectMonitor** saved_mid_in_use_p); 155 static bool deflate_monitor(ObjectMonitor* mid, oop obj, 156 ObjectMonitor** free_head_p, 157 ObjectMonitor** free_tail_p); 158 static bool deflate_monitor_using_JT(ObjectMonitor* mid, 159 ObjectMonitor** free_head_p, 160 ObjectMonitor** free_tail_p); 161 static bool is_async_deflation_needed(); 162 static bool is_safepoint_deflation_needed(); is_async_deflation_requested()163 static bool is_async_deflation_requested() { return _is_async_deflation_requested; } is_special_deflation_requested()164 static bool is_special_deflation_requested() { return _is_special_deflation_requested; } set_is_async_deflation_requested(bool new_value)165 static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; } set_is_special_deflation_requested(bool new_value)166 static void set_is_special_deflation_requested(bool new_value) { _is_special_deflation_requested = new_value; } 167 static jlong time_since_last_async_deflation_ms(); 168 static void oops_do(OopClosure* f); 169 // Process oops in thread local used monitors 170 static void thread_local_used_oops_do(Thread* thread, OopClosure* f); 171 172 // debugging 173 static void audit_and_print_stats(bool on_exit); 174 static void chk_free_entry(JavaThread* jt, ObjectMonitor* n, 175 outputStream * out, int *error_cnt_p); 176 static void chk_global_free_list_and_count(outputStream * out, 177 int *error_cnt_p); 178 static void chk_global_wait_list_and_count(outputStream * out, 179 int *error_cnt_p); 180 static void chk_global_in_use_list_and_count(outputStream * out, 181 int *error_cnt_p); 182 static void chk_in_use_entry(JavaThread* jt, ObjectMonitor* n, 183 outputStream * out, int *error_cnt_p); 184 static void chk_per_thread_in_use_list_and_count(JavaThread *jt, 185 outputStream * out, 186 int *error_cnt_p); 187 static void chk_per_thread_free_list_and_count(JavaThread *jt, 188 outputStream * out, 189 int *error_cnt_p); 190 static void log_in_use_monitor_details(outputStream * out); 191 static int log_monitor_list_counts(outputStream * out); 192 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 193 194 static void do_safepoint_work(DeflateMonitorCounters* counters); 195 196 private: 197 friend class SynchronizerTest; 198 199 enum { _BLOCKSIZE = 128 }; 200 // global list of blocks of monitors 201 static PaddedObjectMonitor* g_block_list; 202 static volatile bool _is_async_deflation_requested; 203 static volatile bool _is_special_deflation_requested; 204 static jlong _last_async_deflation_time_ns; 205 206 // Function to prepend new blocks to the appropriate lists: 207 static void prepend_block_to_lists(PaddedObjectMonitor* new_blk); 208 209 // Process oops in all global used monitors (i.e. moribund thread's monitors) 210 static void global_used_oops_do(OopClosure* f); 211 // Process oops in monitors on the given list 212 static void list_oops_do(ObjectMonitor* list, OopClosure* f); 213 214 // Support for SynchronizerTest access to GVars fields: 215 static u_char* get_gvars_addr(); 216 static u_char* get_gvars_hc_sequence_addr(); 217 static size_t get_gvars_size(); 218 static u_char* get_gvars_stw_random_addr(); 219 }; 220 221 // ObjectLocker enforces balanced locking and can never throw an 222 // IllegalMonitorStateException. However, a pending exception may 223 // have to pass through, and we must also be able to deal with 224 // asynchronous exceptions. The caller is responsible for checking 225 // the thread's pending exception if needed. 226 class ObjectLocker : public StackObj { 227 private: 228 Thread* _thread; 229 Handle _obj; 230 BasicLock _lock; 231 bool _dolock; // default true 232 public: 233 ObjectLocker(Handle obj, Thread* thread, bool do_lock = true); 234 ~ObjectLocker(); 235 236 // Monitor behavior wait(TRAPS)237 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever notify_all(TRAPS)238 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } wait_uninterruptibly(TRAPS)239 void wait_uninterruptibly(TRAPS) { ObjectSynchronizer::wait_uninterruptibly(_obj, 0, CHECK); } 240 // complete_exit gives up lock completely, returning recursion count 241 // reenter reclaims lock with original recursion count complete_exit(TRAPS)242 intx complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } reenter(intx recursions,TRAPS)243 void reenter(intx recursions, TRAPS) { ObjectSynchronizer::reenter(_obj, recursions, CHECK); } 244 }; 245 246 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP 247