1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/threading/worker_pool_posix.h" 6 7 #include <set> 8 9 #include "base/bind.h" 10 #include "base/callback.h" 11 #include "base/macros.h" 12 #include "base/synchronization/condition_variable.h" 13 #include "base/synchronization/lock.h" 14 #include "base/synchronization/waitable_event.h" 15 #include "base/threading/platform_thread.h" 16 #include "testing/gtest/include/gtest/gtest.h" 17 18 namespace base { 19 20 // Peer class to provide passthrough access to PosixDynamicThreadPool internals. 21 class PosixDynamicThreadPool::PosixDynamicThreadPoolPeer { 22 public: 23 explicit PosixDynamicThreadPoolPeer(PosixDynamicThreadPool* pool) 24 : pool_(pool) {} 25 26 Lock* lock() { return &pool_->lock_; } 27 ConditionVariable* pending_tasks_available_cv() { 28 return &pool_->pending_tasks_available_cv_; 29 } 30 const std::queue<PendingTask>& pending_tasks() const { 31 return pool_->pending_tasks_; 32 } 33 int num_idle_threads() const { return pool_->num_idle_threads_; } 34 ConditionVariable* num_idle_threads_cv() { 35 return pool_->num_idle_threads_cv_.get(); 36 } 37 void set_num_idle_threads_cv(ConditionVariable* cv) { 38 pool_->num_idle_threads_cv_.reset(cv); 39 } 40 41 private: 42 PosixDynamicThreadPool* pool_; 43 44 DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPoolPeer); 45 }; 46 47 namespace { 48 49 // IncrementingTask's main purpose is to increment a counter. It also updates a 50 // set of unique thread ids, and signals a ConditionVariable on completion. 51 // Note that since it does not block, there is no way to control the number of 52 // threads used if more than one IncrementingTask is consecutively posted to the 53 // thread pool, since the first one might finish executing before the subsequent 54 // PostTask() calls get invoked. 55 void IncrementingTask(Lock* counter_lock, 56 int* counter, 57 Lock* unique_threads_lock, 58 std::set<PlatformThreadId>* unique_threads) { 59 { 60 base::AutoLock locked(*unique_threads_lock); 61 unique_threads->insert(PlatformThread::CurrentId()); 62 } 63 base::AutoLock locked(*counter_lock); 64 (*counter)++; 65 } 66 67 // BlockingIncrementingTask is a simple wrapper around IncrementingTask that 68 // allows for waiting at the start of Run() for a WaitableEvent to be signalled. 69 struct BlockingIncrementingTaskArgs { 70 Lock* counter_lock; 71 int* counter; 72 Lock* unique_threads_lock; 73 std::set<PlatformThreadId>* unique_threads; 74 Lock* num_waiting_to_start_lock; 75 int* num_waiting_to_start; 76 ConditionVariable* num_waiting_to_start_cv; 77 base::WaitableEvent* start; 78 }; 79 80 void BlockingIncrementingTask(const BlockingIncrementingTaskArgs& args) { 81 { 82 base::AutoLock num_waiting_to_start_locked(*args.num_waiting_to_start_lock); 83 (*args.num_waiting_to_start)++; 84 } 85 args.num_waiting_to_start_cv->Signal(); 86 args.start->Wait(); 87 IncrementingTask(args.counter_lock, args.counter, args.unique_threads_lock, 88 args.unique_threads); 89 } 90 91 class PosixDynamicThreadPoolTest : public testing::Test { 92 protected: 93 PosixDynamicThreadPoolTest() 94 : pool_(new base::PosixDynamicThreadPool("dynamic_pool", 60 * 60)), 95 peer_(pool_.get()), 96 counter_(0), 97 num_waiting_to_start_(0), 98 num_waiting_to_start_cv_(&num_waiting_to_start_lock_), 99 start_(WaitableEvent::ResetPolicy::MANUAL, 100 WaitableEvent::InitialState::NOT_SIGNALED) {} 101 102 void SetUp() override { 103 peer_.set_num_idle_threads_cv(new ConditionVariable(peer_.lock())); 104 } 105 106 void WaitForTasksToStart(int num_tasks) { 107 base::AutoLock num_waiting_to_start_locked(num_waiting_to_start_lock_); 108 while (num_waiting_to_start_ < num_tasks) { 109 num_waiting_to_start_cv_.Wait(); 110 } 111 } 112 113 void WaitForIdleThreads(int num_idle_threads) { 114 base::AutoLock pool_locked(*peer_.lock()); 115 while (peer_.num_idle_threads() < num_idle_threads) { 116 peer_.num_idle_threads_cv()->Wait(); 117 } 118 } 119 120 base::Closure CreateNewIncrementingTaskCallback() { 121 return base::Bind(&IncrementingTask, &counter_lock_, &counter_, 122 &unique_threads_lock_, &unique_threads_); 123 } 124 125 base::Closure CreateNewBlockingIncrementingTaskCallback() { 126 BlockingIncrementingTaskArgs args = { 127 &counter_lock_, &counter_, &unique_threads_lock_, &unique_threads_, 128 &num_waiting_to_start_lock_, &num_waiting_to_start_, 129 &num_waiting_to_start_cv_, &start_ 130 }; 131 return base::Bind(&BlockingIncrementingTask, args); 132 } 133 134 scoped_refptr<base::PosixDynamicThreadPool> pool_; 135 base::PosixDynamicThreadPool::PosixDynamicThreadPoolPeer peer_; 136 Lock counter_lock_; 137 int counter_; 138 Lock unique_threads_lock_; 139 std::set<PlatformThreadId> unique_threads_; 140 Lock num_waiting_to_start_lock_; 141 int num_waiting_to_start_; 142 ConditionVariable num_waiting_to_start_cv_; 143 base::WaitableEvent start_; 144 }; 145 146 } // namespace 147 148 TEST_F(PosixDynamicThreadPoolTest, Basic) { 149 EXPECT_EQ(0, peer_.num_idle_threads()); 150 EXPECT_EQ(0U, unique_threads_.size()); 151 EXPECT_EQ(0U, peer_.pending_tasks().size()); 152 153 // Add one task and wait for it to be completed. 154 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 155 156 WaitForIdleThreads(1); 157 158 EXPECT_EQ(1U, unique_threads_.size()) << 159 "There should be only one thread allocated for one task."; 160 EXPECT_EQ(1, counter_); 161 } 162 163 TEST_F(PosixDynamicThreadPoolTest, ReuseIdle) { 164 // Add one task and wait for it to be completed. 165 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 166 167 WaitForIdleThreads(1); 168 169 // Add another 2 tasks. One should reuse the existing worker thread. 170 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 171 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 172 173 WaitForTasksToStart(2); 174 start_.Signal(); 175 WaitForIdleThreads(2); 176 177 EXPECT_EQ(2U, unique_threads_.size()); 178 EXPECT_EQ(2, peer_.num_idle_threads()); 179 EXPECT_EQ(3, counter_); 180 } 181 182 TEST_F(PosixDynamicThreadPoolTest, TwoActiveTasks) { 183 // Add two blocking tasks. 184 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 185 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 186 187 EXPECT_EQ(0, counter_) << "Blocking tasks should not have started yet."; 188 189 WaitForTasksToStart(2); 190 start_.Signal(); 191 WaitForIdleThreads(2); 192 193 EXPECT_EQ(2U, unique_threads_.size()); 194 EXPECT_EQ(2, peer_.num_idle_threads()) << "Existing threads are now idle."; 195 EXPECT_EQ(2, counter_); 196 } 197 198 TEST_F(PosixDynamicThreadPoolTest, Complex) { 199 // Add two non blocking tasks and wait for them to finish. 200 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 201 202 WaitForIdleThreads(1); 203 204 // Add two blocking tasks, start them simultaneously, and wait for them to 205 // finish. 206 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 207 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 208 209 WaitForTasksToStart(2); 210 start_.Signal(); 211 WaitForIdleThreads(2); 212 213 EXPECT_EQ(3, counter_); 214 EXPECT_EQ(2, peer_.num_idle_threads()); 215 EXPECT_EQ(2U, unique_threads_.size()); 216 217 // Wake up all idle threads so they can exit. 218 { 219 base::AutoLock locked(*peer_.lock()); 220 while (peer_.num_idle_threads() > 0) { 221 peer_.pending_tasks_available_cv()->Signal(); 222 peer_.num_idle_threads_cv()->Wait(); 223 } 224 } 225 226 // Add another non blocking task. There are no threads to reuse. 227 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 228 WaitForIdleThreads(1); 229 230 // The POSIX implementation of PlatformThread::CurrentId() uses pthread_self() 231 // which is not guaranteed to be unique after a thread joins. The OS X 232 // implemntation of pthread_self() returns the address of the pthread_t, which 233 // is merely a malloc()ed pointer stored in the first TLS slot. When a thread 234 // joins and that structure is freed, the block of memory can be put on the 235 // OS free list, meaning the same address could be reused in a subsequent 236 // allocation. This in fact happens when allocating in a loop as this test 237 // does. 238 // 239 // Because there are two concurrent threads, there's at least the guarantee 240 // of having two unique thread IDs in the set. But after those two threads are 241 // joined, the next-created thread can get a re-used ID if the allocation of 242 // the pthread_t structure is taken from the free list. Therefore, there can 243 // be either 2 or 3 unique thread IDs in the set at this stage in the test. 244 EXPECT_TRUE(unique_threads_.size() >= 2 && unique_threads_.size() <= 3) 245 << "unique_threads_.size() = " << unique_threads_.size(); 246 EXPECT_EQ(1, peer_.num_idle_threads()); 247 EXPECT_EQ(4, counter_); 248 } 249 250 } // namespace base 251
