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_INL_H_ 18 #define ART_RUNTIME_THREAD_INL_H_ 19 20 #include "thread.h" 21 22 #ifdef __ANDROID__ 23 #include <bionic_tls.h> // Access to our own TLS slot. 24 #endif 25 26 #include <pthread.h> 27 28 #include "base/casts.h" 29 #include "base/mutex-inl.h" 30 #include "gc/heap.h" 31 #include "jni_env_ext.h" 32 #include "thread_pool.h" 33 34 namespace art { 35 36 // Quickly access the current thread from a JNIEnv. 37 static inline Thread* ThreadForEnv(JNIEnv* env) { 38 JNIEnvExt* full_env(down_cast<JNIEnvExt*>(env)); 39 return full_env->self; 40 } 41 42 inline Thread* Thread::Current() { 43 // We rely on Thread::Current returning null for a detached thread, so it's not obvious 44 // that we can replace this with a direct %fs access on x86. 45 if (!is_started_) { 46 return nullptr; 47 } else { 48 #ifdef __ANDROID__ 49 void* thread = __get_tls()[TLS_SLOT_ART_THREAD_SELF]; 50 #else 51 void* thread = pthread_getspecific(Thread::pthread_key_self_); 52 #endif 53 return reinterpret_cast<Thread*>(thread); 54 } 55 } 56 57 inline void Thread::AllowThreadSuspension() { 58 DCHECK_EQ(Thread::Current(), this); 59 if (UNLIKELY(TestAllFlags())) { 60 CheckSuspend(); 61 } 62 } 63 64 inline void Thread::CheckSuspend() { 65 DCHECK_EQ(Thread::Current(), this); 66 for (;;) { 67 if (ReadFlag(kCheckpointRequest)) { 68 RunCheckpointFunction(); 69 } else if (ReadFlag(kSuspendRequest)) { 70 FullSuspendCheck(); 71 } else { 72 break; 73 } 74 } 75 } 76 77 inline ThreadState Thread::SetState(ThreadState new_state) { 78 // Should only be used to change between suspended states. 79 // Cannot use this code to change into or from Runnable as changing to Runnable should 80 // fail if old_state_and_flags.suspend_request is true and changing from Runnable might 81 // miss passing an active suspend barrier. 82 DCHECK_NE(new_state, kRunnable); 83 if (kIsDebugBuild && this != Thread::Current()) { 84 std::string name; 85 GetThreadName(name); 86 LOG(FATAL) << "Thread \"" << name << "\"(" << this << " != Thread::Current()=" 87 << Thread::Current() << ") changing state to " << new_state; 88 } 89 union StateAndFlags old_state_and_flags; 90 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 91 CHECK_NE(old_state_and_flags.as_struct.state, kRunnable); 92 tls32_.state_and_flags.as_struct.state = new_state; 93 return static_cast<ThreadState>(old_state_and_flags.as_struct.state); 94 } 95 96 inline void Thread::AssertThreadSuspensionIsAllowable(bool check_locks) const { 97 if (kIsDebugBuild) { 98 if (gAborting == 0) { 99 CHECK_EQ(0u, tls32_.no_thread_suspension) << tlsPtr_.last_no_thread_suspension_cause; 100 } 101 if (check_locks) { 102 bool bad_mutexes_held = false; 103 for (int i = kLockLevelCount - 1; i >= 0; --i) { 104 // We expect no locks except the mutator_lock_ or thread list suspend thread lock. 105 if (i != kMutatorLock) { 106 BaseMutex* held_mutex = GetHeldMutex(static_cast<LockLevel>(i)); 107 if (held_mutex != nullptr) { 108 LOG(ERROR) << "holding \"" << held_mutex->GetName() 109 << "\" at point where thread suspension is expected"; 110 bad_mutexes_held = true; 111 } 112 } 113 } 114 if (gAborting == 0) { 115 CHECK(!bad_mutexes_held); 116 } 117 } 118 } 119 } 120 121 inline void Thread::TransitionToSuspendedAndRunCheckpoints(ThreadState new_state) { 122 DCHECK_NE(new_state, kRunnable); 123 DCHECK_EQ(GetState(), kRunnable); 124 union StateAndFlags old_state_and_flags; 125 union StateAndFlags new_state_and_flags; 126 while (true) { 127 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 128 if (UNLIKELY((old_state_and_flags.as_struct.flags & kCheckpointRequest) != 0)) { 129 RunCheckpointFunction(); 130 continue; 131 } 132 // Change the state but keep the current flags (kCheckpointRequest is clear). 133 DCHECK_EQ((old_state_and_flags.as_struct.flags & kCheckpointRequest), 0); 134 new_state_and_flags.as_struct.flags = old_state_and_flags.as_struct.flags; 135 new_state_and_flags.as_struct.state = new_state; 136 137 // CAS the value with a memory ordering. 138 bool done = 139 tls32_.state_and_flags.as_atomic_int.CompareExchangeWeakRelease(old_state_and_flags.as_int, 140 new_state_and_flags.as_int); 141 if (LIKELY(done)) { 142 break; 143 } 144 } 145 } 146 147 inline void Thread::PassActiveSuspendBarriers() { 148 while (true) { 149 uint16_t current_flags = tls32_.state_and_flags.as_struct.flags; 150 if (LIKELY((current_flags & (kCheckpointRequest | kActiveSuspendBarrier)) == 0)) { 151 break; 152 } else if ((current_flags & kActiveSuspendBarrier) != 0) { 153 PassActiveSuspendBarriers(this); 154 } else { 155 // Impossible 156 LOG(FATAL) << "Fatal, thread transitioned into suspended without running the checkpoint"; 157 } 158 } 159 } 160 161 inline void Thread::TransitionFromRunnableToSuspended(ThreadState new_state) { 162 AssertThreadSuspensionIsAllowable(); 163 DCHECK_EQ(this, Thread::Current()); 164 // Change to non-runnable state, thereby appearing suspended to the system. 165 TransitionToSuspendedAndRunCheckpoints(new_state); 166 // Mark the release of the share of the mutator_lock_. 167 Locks::mutator_lock_->TransitionFromRunnableToSuspended(this); 168 // Once suspended - check the active suspend barrier flag 169 PassActiveSuspendBarriers(); 170 } 171 172 inline ThreadState Thread::TransitionFromSuspendedToRunnable() { 173 union StateAndFlags old_state_and_flags; 174 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 175 int16_t old_state = old_state_and_flags.as_struct.state; 176 DCHECK_NE(static_cast<ThreadState>(old_state), kRunnable); 177 do { 178 Locks::mutator_lock_->AssertNotHeld(this); // Otherwise we starve GC.. 179 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 180 DCHECK_EQ(old_state_and_flags.as_struct.state, old_state); 181 if (LIKELY(old_state_and_flags.as_struct.flags == 0)) { 182 // Optimize for the return from native code case - this is the fast path. 183 // Atomically change from suspended to runnable if no suspend request pending. 184 union StateAndFlags new_state_and_flags; 185 new_state_and_flags.as_int = old_state_and_flags.as_int; 186 new_state_and_flags.as_struct.state = kRunnable; 187 // CAS the value with a memory barrier. 188 if (LIKELY(tls32_.state_and_flags.as_atomic_int.CompareExchangeWeakAcquire( 189 old_state_and_flags.as_int, 190 new_state_and_flags.as_int))) { 191 // Mark the acquisition of a share of the mutator_lock_. 192 Locks::mutator_lock_->TransitionFromSuspendedToRunnable(this); 193 break; 194 } 195 } else if ((old_state_and_flags.as_struct.flags & kActiveSuspendBarrier) != 0) { 196 PassActiveSuspendBarriers(this); 197 } else if ((old_state_and_flags.as_struct.flags & kCheckpointRequest) != 0) { 198 // Impossible 199 LOG(FATAL) << "Transitioning to runnable with checkpoint flag, " 200 << " flags=" << old_state_and_flags.as_struct.flags 201 << " state=" << old_state_and_flags.as_struct.state; 202 } else if ((old_state_and_flags.as_struct.flags & kSuspendRequest) != 0) { 203 // Wait while our suspend count is non-zero. 204 MutexLock mu(this, *Locks::thread_suspend_count_lock_); 205 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 206 DCHECK_EQ(old_state_and_flags.as_struct.state, old_state); 207 while ((old_state_and_flags.as_struct.flags & kSuspendRequest) != 0) { 208 // Re-check when Thread::resume_cond_ is notified. 209 Thread::resume_cond_->Wait(this); 210 old_state_and_flags.as_int = tls32_.state_and_flags.as_int; 211 DCHECK_EQ(old_state_and_flags.as_struct.state, old_state); 212 } 213 DCHECK_EQ(GetSuspendCount(), 0); 214 } 215 } while (true); 216 // Run the flip function, if set. 217 Closure* flip_func = GetFlipFunction(); 218 if (flip_func != nullptr) { 219 flip_func->Run(this); 220 } 221 return static_cast<ThreadState>(old_state); 222 } 223 224 inline void Thread::VerifyStack() { 225 if (kVerifyStack) { 226 if (Runtime::Current()->GetHeap()->IsObjectValidationEnabled()) { 227 VerifyStackImpl(); 228 } 229 } 230 } 231 232 inline size_t Thread::TlabSize() const { 233 return tlsPtr_.thread_local_end - tlsPtr_.thread_local_pos; 234 } 235 236 inline mirror::Object* Thread::AllocTlab(size_t bytes) { 237 DCHECK_GE(TlabSize(), bytes); 238 ++tlsPtr_.thread_local_objects; 239 mirror::Object* ret = reinterpret_cast<mirror::Object*>(tlsPtr_.thread_local_pos); 240 tlsPtr_.thread_local_pos += bytes; 241 return ret; 242 } 243 244 inline bool Thread::PushOnThreadLocalAllocationStack(mirror::Object* obj) { 245 DCHECK_LE(tlsPtr_.thread_local_alloc_stack_top, tlsPtr_.thread_local_alloc_stack_end); 246 if (tlsPtr_.thread_local_alloc_stack_top < tlsPtr_.thread_local_alloc_stack_end) { 247 // There's room. 248 DCHECK_LE(reinterpret_cast<uint8_t*>(tlsPtr_.thread_local_alloc_stack_top) + 249 sizeof(StackReference<mirror::Object>), 250 reinterpret_cast<uint8_t*>(tlsPtr_.thread_local_alloc_stack_end)); 251 DCHECK(tlsPtr_.thread_local_alloc_stack_top->AsMirrorPtr() == nullptr); 252 tlsPtr_.thread_local_alloc_stack_top->Assign(obj); 253 ++tlsPtr_.thread_local_alloc_stack_top; 254 return true; 255 } 256 return false; 257 } 258 259 inline void Thread::SetThreadLocalAllocationStack(StackReference<mirror::Object>* start, 260 StackReference<mirror::Object>* end) { 261 DCHECK(Thread::Current() == this) << "Should be called by self"; 262 DCHECK(start != nullptr); 263 DCHECK(end != nullptr); 264 DCHECK_ALIGNED(start, sizeof(StackReference<mirror::Object>)); 265 DCHECK_ALIGNED(end, sizeof(StackReference<mirror::Object>)); 266 DCHECK_LT(start, end); 267 tlsPtr_.thread_local_alloc_stack_end = end; 268 tlsPtr_.thread_local_alloc_stack_top = start; 269 } 270 271 inline void Thread::RevokeThreadLocalAllocationStack() { 272 if (kIsDebugBuild) { 273 // Note: self is not necessarily equal to this thread since thread may be suspended. 274 Thread* self = Thread::Current(); 275 DCHECK(this == self || IsSuspended() || GetState() == kWaitingPerformingGc) 276 << GetState() << " thread " << this << " self " << self; 277 } 278 tlsPtr_.thread_local_alloc_stack_end = nullptr; 279 tlsPtr_.thread_local_alloc_stack_top = nullptr; 280 } 281 282 } // namespace art 283 284 #endif // ART_RUNTIME_THREAD_INL_H_ 285
