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      1 /*
      2  * Copyright (C) 2014 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 #include "task_processor.h"
     18 
     19 #include "base/time_utils.h"
     20 #include "scoped_thread_state_change-inl.h"
     21 
     22 namespace art {
     23 namespace gc {
     24 
     25 TaskProcessor::TaskProcessor()
     26     : lock_("Task processor lock", kReferenceProcessorLock),
     27       cond_("Task processor condition", lock_),
     28       is_running_(false),
     29       running_thread_(nullptr) {
     30 }
     31 
     32 TaskProcessor::~TaskProcessor() {
     33   if (!tasks_.empty()) {
     34     LOG(WARNING) << "TaskProcessor: Finalizing " << tasks_.size() << " unprocessed tasks.";
     35     for (HeapTask* task : tasks_) {
     36       task->Finalize();
     37     }
     38   }
     39 }
     40 
     41 void TaskProcessor::AddTask(Thread* self, HeapTask* task) {
     42   ScopedThreadStateChange tsc(self, kWaitingForTaskProcessor);
     43   MutexLock mu(self, lock_);
     44   tasks_.insert(task);
     45   cond_.Signal(self);
     46 }
     47 
     48 HeapTask* TaskProcessor::GetTask(Thread* self) {
     49   ScopedThreadStateChange tsc(self, kWaitingForTaskProcessor);
     50   MutexLock mu(self, lock_);
     51   while (true) {
     52     if (tasks_.empty()) {
     53       if (!is_running_) {
     54         return nullptr;
     55       }
     56       cond_.Wait(self);  // Empty queue, wait until we are signalled.
     57     } else {
     58       // Non empty queue, look at the top element and see if we are ready to run it.
     59       const uint64_t current_time = NanoTime();
     60       HeapTask* task = *tasks_.begin();
     61       // If we are shutting down, return the task right away without waiting. Otherwise return the
     62       // task if it is late enough.
     63       uint64_t target_time = task->GetTargetRunTime();
     64       if (!is_running_ || target_time <= current_time) {
     65         tasks_.erase(tasks_.begin());
     66         return task;
     67       }
     68       DCHECK_GT(target_time, current_time);
     69       // Wait until we hit the target run time.
     70       const uint64_t delta_time = target_time - current_time;
     71       const uint64_t ms_delta = NsToMs(delta_time);
     72       const uint64_t ns_delta = delta_time - MsToNs(ms_delta);
     73       cond_.TimedWait(self, static_cast<int64_t>(ms_delta), static_cast<int32_t>(ns_delta));
     74     }
     75   }
     76   UNREACHABLE();
     77 }
     78 
     79 void TaskProcessor::UpdateTargetRunTime(Thread* self, HeapTask* task, uint64_t new_target_time) {
     80   MutexLock mu(self, lock_);
     81   // Find the task.
     82   auto range = tasks_.equal_range(task);
     83   for (auto it = range.first; it != range.second; ++it) {
     84     if (*it == task) {
     85       // Check if the target time was updated, if so re-insert then wait.
     86       if (new_target_time != task->GetTargetRunTime()) {
     87         tasks_.erase(it);
     88         task->SetTargetRunTime(new_target_time);
     89         tasks_.insert(task);
     90         // If we became the first task then we may need to signal since we changed the task that we
     91         // are sleeping on.
     92         if (*tasks_.begin() == task) {
     93           cond_.Signal(self);
     94         }
     95         return;
     96       }
     97     }
     98   }
     99 }
    100 
    101 bool TaskProcessor::IsRunning() const {
    102   MutexLock mu(Thread::Current(), lock_);
    103   return is_running_;
    104 }
    105 
    106 Thread* TaskProcessor::GetRunningThread() const {
    107   MutexLock mu(Thread::Current(), lock_);
    108   return running_thread_;
    109 }
    110 
    111 void TaskProcessor::Stop(Thread* self) {
    112   MutexLock mu(self, lock_);
    113   is_running_ = false;
    114   running_thread_ = nullptr;
    115   cond_.Broadcast(self);
    116 }
    117 
    118 void TaskProcessor::Start(Thread* self) {
    119   MutexLock mu(self, lock_);
    120   is_running_ = true;
    121   running_thread_ = self;
    122 }
    123 
    124 void TaskProcessor::RunAllTasks(Thread* self) {
    125   while (true) {
    126     // Wait and get a task, may be interrupted.
    127     HeapTask* task = GetTask(self);
    128     if (task != nullptr) {
    129       task->Run(self);
    130       task->Finalize();
    131     } else if (!IsRunning()) {
    132       break;
    133     }
    134   }
    135 }
    136 
    137 }  // namespace gc
    138 }  // namespace art
    139