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