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/value_object.h" 24 #include "jni.h" 25 #include "reflective_handle_scope.h" 26 #include "suspend_reason.h" 27 28 #include <bitset> 29 #include <list> 30 #include <vector> 31 32 namespace art { 33 namespace gc { 34 namespace collector { 35 class GarbageCollector; 36 } // namespace collector 37 class GcPauseListener; 38 } // namespace gc 39 class Closure; 40 class IsMarkedVisitor; 41 class RootVisitor; 42 class Thread; 43 class TimingLogger; 44 enum VisitRootFlags : uint8_t; 45 46 class ThreadList { 47 public: 48 static constexpr uint32_t kMaxThreadId = 0xFFFF; 49 static constexpr uint32_t kInvalidThreadId = 0; 50 static constexpr uint32_t kMainThreadId = 1; 51 static constexpr uint64_t kDefaultThreadSuspendTimeout = 52 kIsDebugBuild ? 50'000'000'000ull : 10'000'000'000ull; 53 54 explicit ThreadList(uint64_t thread_suspend_timeout_ns); 55 ~ThreadList(); 56 57 void ShutDown(); 58 59 void DumpForSigQuit(std::ostream& os) 60 REQUIRES(!Locks::thread_list_lock_, !Locks::mutator_lock_); 61 // For thread suspend timeout dumps. 62 void Dump(std::ostream& os, bool dump_native_stack = true) 63 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 64 pid_t GetLockOwner(); // For SignalCatcher. 65 66 // Thread suspension support. 67 void ResumeAll() 68 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 69 UNLOCK_FUNCTION(Locks::mutator_lock_); 70 bool Resume(Thread* thread, SuspendReason reason = SuspendReason::kInternal) 71 REQUIRES(!Locks::thread_suspend_count_lock_) WARN_UNUSED; 72 73 // Suspends all threads and gets exclusive access to the mutator lock. 74 // If long_suspend is true, then other threads who try to suspend will never timeout. 75 // long_suspend is currenly used for hprof since large heaps take a long time. 76 void SuspendAll(const char* cause, bool long_suspend = false) 77 EXCLUSIVE_LOCK_FUNCTION(Locks::mutator_lock_) 78 REQUIRES(!Locks::thread_list_lock_, 79 !Locks::thread_suspend_count_lock_, 80 !Locks::mutator_lock_); 81 82 // Suspend a thread using a peer, typically used by the debugger. Returns the thread on success, 83 // else null. The peer is used to identify the thread to avoid races with the thread terminating. 84 // If the suspension times out then *timeout is set to true. 85 Thread* SuspendThreadByPeer(jobject peer, 86 SuspendReason reason, 87 bool* timed_out) 88 REQUIRES(!Locks::mutator_lock_, 89 !Locks::thread_list_lock_, 90 !Locks::thread_suspend_count_lock_); 91 92 // Suspend a thread using its thread id, typically used by lock/monitor inflation. Returns the 93 // thread on success else null. The thread id is used to identify the thread to avoid races with 94 // the thread terminating. Note that as thread ids are recycled this may not suspend the expected 95 // thread, that may be terminating. If the suspension times out then *timeout is set to true. 96 Thread* SuspendThreadByThreadId(uint32_t thread_id, SuspendReason reason, bool* timed_out) 97 REQUIRES(!Locks::mutator_lock_, 98 !Locks::thread_list_lock_, 99 !Locks::thread_suspend_count_lock_); 100 101 // Find an existing thread (or self) by its thread id (not tid). 102 Thread* FindThreadByThreadId(uint32_t thread_id) REQUIRES(Locks::thread_list_lock_); 103 104 // Find an existing thread (or self) by its tid (not thread id). 105 Thread* FindThreadByTid(int tid) REQUIRES(Locks::thread_list_lock_); 106 107 // Does the thread list still contain the given thread, or one at the same address? 108 // Used by Monitor to provide (mostly accurate) debugging information. 109 bool Contains(Thread* thread) REQUIRES(Locks::thread_list_lock_); 110 111 // Run a checkpoint on all threads. Return the total number of threads for which the checkpoint 112 // function has been or will be called. 113 // Running threads are not suspended but run the checkpoint inside of the suspend check. The 114 // return value includes already suspended threads for b/24191051. Runs or requests the 115 // callback, if non-null, inside the thread_list_lock critical section after determining the 116 // runnable/suspended states of the threads. Does not wait for completion of the callbacks in 117 // running threads. 118 size_t RunCheckpoint(Closure* checkpoint_function, Closure* callback = nullptr) 119 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 120 121 // Run an empty checkpoint on threads. Wait until threads pass the next suspend point or are 122 // suspended. This is used to ensure that the threads finish or aren't in the middle of an 123 // in-flight mutator heap access (eg. a read barrier.) Runnable threads will respond by 124 // decrementing the empty checkpoint barrier count. This works even when the weak ref access is 125 // disabled. Only one concurrent use is currently supported. 126 void RunEmptyCheckpoint() 127 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 128 129 // Flip thread roots from from-space refs to to-space refs. Used by 130 // the concurrent copying collector. 131 size_t FlipThreadRoots(Closure* thread_flip_visitor, 132 Closure* flip_callback, 133 gc::collector::GarbageCollector* collector, 134 gc::GcPauseListener* pause_listener) 135 REQUIRES(!Locks::mutator_lock_, 136 !Locks::thread_list_lock_, 137 !Locks::thread_suspend_count_lock_); 138 139 // Iterates over all the threads. 140 void ForEach(void (*callback)(Thread*, void*), void* context) 141 REQUIRES(Locks::thread_list_lock_); 142 143 template<typename CallBack> ForEach(CallBack cb)144 void ForEach(CallBack cb) REQUIRES(Locks::thread_list_lock_) { 145 ForEach([](Thread* t, void* ctx) REQUIRES(Locks::thread_list_lock_) { 146 (*reinterpret_cast<CallBack*>(ctx))(t); 147 }, &cb); 148 } 149 150 // Add/remove current thread from list. 151 void Register(Thread* self) 152 REQUIRES(Locks::runtime_shutdown_lock_) 153 REQUIRES(!Locks::mutator_lock_, 154 !Locks::thread_list_lock_, 155 !Locks::thread_suspend_count_lock_); 156 void Unregister(Thread* self) 157 REQUIRES(!Locks::mutator_lock_, 158 !Locks::thread_list_lock_, 159 !Locks::thread_suspend_count_lock_); 160 161 void VisitRoots(RootVisitor* visitor, VisitRootFlags flags) const 162 REQUIRES_SHARED(Locks::mutator_lock_); 163 164 void VisitRootsForSuspendedThreads(RootVisitor* visitor) 165 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 166 REQUIRES_SHARED(Locks::mutator_lock_); 167 168 void VisitReflectiveTargets(ReflectiveValueVisitor* visitor) const REQUIRES(Locks::mutator_lock_); 169 170 // Return a copy of the thread list. GetList()171 std::list<Thread*> GetList() REQUIRES(Locks::thread_list_lock_) { 172 return list_; 173 } 174 175 void DumpNativeStacks(std::ostream& os) 176 REQUIRES(!Locks::thread_list_lock_); 177 EmptyCheckpointBarrier()178 Barrier* EmptyCheckpointBarrier() { 179 return empty_checkpoint_barrier_.get(); 180 } 181 182 void SweepInterpreterCaches(IsMarkedVisitor* visitor) const 183 REQUIRES(!Locks::thread_list_lock_) 184 REQUIRES_SHARED(Locks::mutator_lock_); 185 186 void WaitForOtherNonDaemonThreadsToExit(bool check_no_birth = true) 187 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_, 188 !Locks::mutator_lock_); 189 190 private: 191 uint32_t AllocThreadId(Thread* self); 192 void ReleaseThreadId(Thread* self, uint32_t id) REQUIRES(!Locks::allocated_thread_ids_lock_); 193 194 size_t RunCheckpoint(Closure* checkpoint_function, bool includeSuspended) 195 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 196 197 void DumpUnattachedThreads(std::ostream& os, bool dump_native_stack) 198 REQUIRES(!Locks::thread_list_lock_); 199 200 void SuspendAllDaemonThreadsForShutdown() 201 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 202 203 void SuspendAllInternal(Thread* self, 204 Thread* ignore1, 205 Thread* ignore2 = nullptr, 206 SuspendReason reason = SuspendReason::kInternal) 207 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 208 209 void AssertThreadsAreSuspended(Thread* self, Thread* ignore1, Thread* ignore2 = nullptr) 210 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_); 211 212 std::bitset<kMaxThreadId> allocated_ids_ GUARDED_BY(Locks::allocated_thread_ids_lock_); 213 214 // The actual list of all threads. 215 std::list<Thread*> list_ GUARDED_BY(Locks::thread_list_lock_); 216 217 // Ongoing suspend all requests, used to ensure threads added to list_ respect SuspendAll. 218 int suspend_all_count_ GUARDED_BY(Locks::thread_suspend_count_lock_); 219 220 // Number of threads unregistering, ~ThreadList blocks until this hits 0. 221 int unregistering_count_ GUARDED_BY(Locks::thread_list_lock_); 222 223 // Thread suspend time histogram. Only modified when all the threads are suspended, so guarding 224 // by mutator lock ensures no thread can read when another thread is modifying it. 225 Histogram<uint64_t> suspend_all_historam_ GUARDED_BY(Locks::mutator_lock_); 226 227 // Whether or not the current thread suspension is long. 228 bool long_suspend_; 229 230 // Whether the shutdown function has been called. This is checked in the destructor. It is an 231 // error to destroy a ThreadList instance without first calling ShutDown(). 232 bool shut_down_; 233 234 // Thread suspension timeout in nanoseconds. 235 const uint64_t thread_suspend_timeout_ns_; 236 237 std::unique_ptr<Barrier> empty_checkpoint_barrier_; 238 239 friend class Thread; 240 241 DISALLOW_COPY_AND_ASSIGN(ThreadList); 242 }; 243 244 // Helper for suspending all threads and getting exclusive access to the mutator lock. 245 class ScopedSuspendAll : public ValueObject { 246 public: 247 explicit ScopedSuspendAll(const char* cause, bool long_suspend = false) 248 EXCLUSIVE_LOCK_FUNCTION(Locks::mutator_lock_) 249 REQUIRES(!Locks::thread_list_lock_, 250 !Locks::thread_suspend_count_lock_, 251 !Locks::mutator_lock_); 252 // No REQUIRES(mutator_lock_) since the unlock function already asserts this. 253 ~ScopedSuspendAll() 254 REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_) 255 UNLOCK_FUNCTION(Locks::mutator_lock_); 256 }; 257 258 } // namespace art 259 260 #endif // ART_RUNTIME_THREAD_LIST_H_ 261