1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_RUNTIME_THREAD_LIST_H_ 18 #define ART_RUNTIME_THREAD_LIST_H_ 19 20 #include "barrier.h" 21 #include "base/histogram.h" 22 #include "base/mutex.h" 23 #include "base/time_utils.h" 24 #include "base/value_object.h" 25 #include "gc_root.h" 26 #include "jni.h" 27 #include "object_callbacks.h" 28 29 #include <bitset> 30 #include <list> 31 #include <vector> 32 33 namespace art { 34 namespace gc { 35 namespace collector { 36 class GarbageCollector; 37 } // namespac collector 38 } // namespace gc 39 class Closure; 40 class Thread; 41 class TimingLogger; 42 43 class ThreadList { 44 public: 45 static constexpr uint32_t kMaxThreadId = 0xFFFF; 46 static constexpr uint32_t kInvalidThreadId = 0; 47 static constexpr uint32_t kMainThreadId = 1; 48 static constexpr uint64_t kDefaultThreadSuspendTimeout = MsToNs(kIsDebugBuild ? 50000 : 10000); 49 50 explicit ThreadList(uint64_t thread_suspend_timeout_ns); 51 ~ThreadList(); 52 53 void DumpForSigQuit(std::ostream& os) 54 REQUIRES(!Locks::thread_list_lock_, !Locks::mutator_lock_); 55 // For thread suspend timeout dumps. 56 void Dump(std::ostream& os, bool dump_native_stack = true) 57 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 58 pid_t GetLockOwner(); // For SignalCatcher. 59 60 // Thread suspension support. 61 void ResumeAll() 62 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 63 UNLOCK_FUNCTION(Locks::mutator_lock_); 64 void Resume(Thread* thread, bool for_debugger = false) 65 REQUIRES(!Locks::thread_suspend_count_lock_); 66 67 // Suspends all threads and gets exclusive access to the mutator_lock_. 68 // If long_suspend is true, then other threads who try to suspend will never timeout. 69 // long_suspend is currenly used for hprof since large heaps take a long time. 70 void SuspendAll(const char* cause, bool long_suspend = false) 71 EXCLUSIVE_LOCK_FUNCTION(Locks::mutator_lock_) 72 REQUIRES(!Locks::thread_list_lock_, 73 !Locks::thread_suspend_count_lock_, 74 !Locks::mutator_lock_); 75 76 // Suspend a thread using a peer, typically used by the debugger. Returns the thread on success, 77 // else null. The peer is used to identify the thread to avoid races with the thread terminating. 78 // If the thread should be suspended then value of request_suspension should be true otherwise 79 // the routine will wait for a previous suspend request. If the suspension times out then *timeout 80 // is set to true. 81 Thread* SuspendThreadByPeer(jobject peer, bool request_suspension, bool debug_suspension, 82 bool* timed_out) 83 REQUIRES(!Locks::mutator_lock_, 84 !Locks::thread_list_lock_, 85 !Locks::thread_suspend_count_lock_); 86 87 // Suspend a thread using its thread id, typically used by lock/monitor inflation. Returns the 88 // thread on success else null. The thread id is used to identify the thread to avoid races with 89 // the thread terminating. Note that as thread ids are recycled this may not suspend the expected 90 // thread, that may be terminating. If the suspension times out then *timeout is set to true. 91 Thread* SuspendThreadByThreadId(uint32_t thread_id, bool debug_suspension, bool* timed_out) 92 REQUIRES(!Locks::mutator_lock_, 93 !Locks::thread_list_lock_, 94 !Locks::thread_suspend_count_lock_); 95 96 // Find an existing thread (or self) by its thread id (not tid). 97 Thread* FindThreadByThreadId(uint32_t thread_id) REQUIRES(Locks::thread_list_lock_); 98 99 // Run a checkpoint on threads, running threads are not suspended but run the checkpoint inside 100 // of the suspend check. Returns how many checkpoints that are expected to run, including for 101 // already suspended threads for b/24191051. Run the callback, if non-null, inside the 102 // thread_list_lock critical section after determining the runnable/suspended states of the 103 // threads. 104 size_t RunCheckpoint(Closure* checkpoint_function, Closure* callback = nullptr) 105 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 106 107 // Run an empty checkpoint on threads. Wait until threads pass the next suspend point or are 108 // suspended. This is used to ensure that the threads finish or aren't in the middle of an 109 // in-flight mutator heap access (eg. a read barrier.) Runnable threads will respond by 110 // decrementing the empty checkpoint barrier count. This works even when the weak ref access is 111 // disabled. Only one concurrent use is currently supported. 112 void RunEmptyCheckpoint() 113 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 114 115 size_t RunCheckpointOnRunnableThreads(Closure* checkpoint_function) 116 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 117 118 // Flip thread roots from from-space refs to to-space refs. Used by 119 // the concurrent copying collector. 120 size_t FlipThreadRoots(Closure* thread_flip_visitor, 121 Closure* flip_callback, 122 gc::collector::GarbageCollector* collector) 123 REQUIRES(!Locks::mutator_lock_, 124 !Locks::thread_list_lock_, 125 !Locks::thread_suspend_count_lock_); 126 127 // Suspends all threads 128 void SuspendAllForDebugger() 129 REQUIRES(!Locks::mutator_lock_, 130 !Locks::thread_list_lock_, 131 !Locks::thread_suspend_count_lock_); 132 133 void SuspendSelfForDebugger() 134 REQUIRES(!Locks::thread_suspend_count_lock_); 135 136 // Resume all threads 137 void ResumeAllForDebugger() 138 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 139 140 void UndoDebuggerSuspensions() 141 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 142 143 // Iterates over all the threads. 144 void ForEach(void (*callback)(Thread*, void*), void* context) 145 REQUIRES(Locks::thread_list_lock_); 146 147 // Add/remove current thread from list. 148 void Register(Thread* self) 149 REQUIRES(Locks::runtime_shutdown_lock_) 150 REQUIRES(!Locks::mutator_lock_, 151 !Locks::thread_list_lock_, 152 !Locks::thread_suspend_count_lock_); 153 void Unregister(Thread* self) 154 REQUIRES(!Locks::mutator_lock_, 155 !Locks::thread_list_lock_, 156 !Locks::thread_suspend_count_lock_); 157 158 void VisitRoots(RootVisitor* visitor, VisitRootFlags flags) const 159 REQUIRES_SHARED(Locks::mutator_lock_); 160 161 void VisitRootsForSuspendedThreads(RootVisitor* visitor) 162 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 163 REQUIRES_SHARED(Locks::mutator_lock_); 164 165 // Return a copy of the thread list. GetList()166 std::list<Thread*> GetList() REQUIRES(Locks::thread_list_lock_) { 167 return list_; 168 } 169 170 void DumpNativeStacks(std::ostream& os) 171 REQUIRES(!Locks::thread_list_lock_); 172 EmptyCheckpointBarrier()173 Barrier* EmptyCheckpointBarrier() { 174 return empty_checkpoint_barrier_.get(); 175 } 176 177 private: 178 uint32_t AllocThreadId(Thread* self); 179 void ReleaseThreadId(Thread* self, uint32_t id) REQUIRES(!Locks::allocated_thread_ids_lock_); 180 181 bool Contains(Thread* thread) REQUIRES(Locks::thread_list_lock_); 182 bool Contains(pid_t tid) REQUIRES(Locks::thread_list_lock_); 183 size_t RunCheckpoint(Closure* checkpoint_function, bool includeSuspended) 184 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 185 186 void DumpUnattachedThreads(std::ostream& os, bool dump_native_stack) 187 REQUIRES(!Locks::thread_list_lock_); 188 189 void SuspendAllDaemonThreadsForShutdown() 190 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 191 void WaitForOtherNonDaemonThreadsToExit() 192 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 193 194 void SuspendAllInternal(Thread* self, 195 Thread* ignore1, 196 Thread* ignore2 = nullptr, 197 bool debug_suspend = false) 198 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 199 200 void AssertThreadsAreSuspended(Thread* self, Thread* ignore1, Thread* ignore2 = nullptr) 201 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 202 203 std::bitset<kMaxThreadId> allocated_ids_ GUARDED_BY(Locks::allocated_thread_ids_lock_); 204 205 // The actual list of all threads. 206 std::list<Thread*> list_ GUARDED_BY(Locks::thread_list_lock_); 207 208 // Ongoing suspend all requests, used to ensure threads added to list_ respect SuspendAll. 209 int suspend_all_count_ GUARDED_BY(Locks::thread_suspend_count_lock_); 210 int debug_suspend_all_count_ GUARDED_BY(Locks::thread_suspend_count_lock_); 211 212 // Number of threads unregistering, ~ThreadList blocks until this hits 0. 213 int unregistering_count_ GUARDED_BY(Locks::thread_list_lock_); 214 215 // Thread suspend time histogram. Only modified when all the threads are suspended, so guarding 216 // by mutator lock ensures no thread can read when another thread is modifying it. 217 Histogram<uint64_t> suspend_all_historam_ GUARDED_BY(Locks::mutator_lock_); 218 219 // Whether or not the current thread suspension is long. 220 bool long_suspend_; 221 222 // Thread suspension timeout in nanoseconds. 223 const uint64_t thread_suspend_timeout_ns_; 224 225 std::unique_ptr<Barrier> empty_checkpoint_barrier_; 226 227 friend class Thread; 228 229 DISALLOW_COPY_AND_ASSIGN(ThreadList); 230 }; 231 232 // Helper for suspending all threads and 233 class ScopedSuspendAll : public ValueObject { 234 public: 235 explicit ScopedSuspendAll(const char* cause, bool long_suspend = false) 236 EXCLUSIVE_LOCK_FUNCTION(Locks::mutator_lock_) 237 REQUIRES(!Locks::thread_list_lock_, 238 !Locks::thread_suspend_count_lock_, 239 !Locks::mutator_lock_); 240 // No REQUIRES(mutator_lock_) since the unlock function already asserts this. 241 ~ScopedSuspendAll() 242 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 243 UNLOCK_FUNCTION(Locks::mutator_lock_); 244 }; 245 246 } // namespace art 247 248 #endif // ART_RUNTIME_THREAD_LIST_H_ 249