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_(true, false) {} 100 101 void SetUp() override { 102 peer_.set_num_idle_threads_cv(new ConditionVariable(peer_.lock())); 103 } 104 105 void TearDown() override { 106 // Wake up the idle threads so they can terminate. 107 if (pool_.get()) 108 pool_->Terminate(); 109 } 110 111 void WaitForTasksToStart(int num_tasks) { 112 base::AutoLock num_waiting_to_start_locked(num_waiting_to_start_lock_); 113 while (num_waiting_to_start_ < num_tasks) { 114 num_waiting_to_start_cv_.Wait(); 115 } 116 } 117 118 void WaitForIdleThreads(int num_idle_threads) { 119 base::AutoLock pool_locked(*peer_.lock()); 120 while (peer_.num_idle_threads() < num_idle_threads) { 121 peer_.num_idle_threads_cv()->Wait(); 122 } 123 } 124 125 base::Closure CreateNewIncrementingTaskCallback() { 126 return base::Bind(&IncrementingTask, &counter_lock_, &counter_, 127 &unique_threads_lock_, &unique_threads_); 128 } 129 130 base::Closure CreateNewBlockingIncrementingTaskCallback() { 131 BlockingIncrementingTaskArgs args = { 132 &counter_lock_, &counter_, &unique_threads_lock_, &unique_threads_, 133 &num_waiting_to_start_lock_, &num_waiting_to_start_, 134 &num_waiting_to_start_cv_, &start_ 135 }; 136 return base::Bind(&BlockingIncrementingTask, args); 137 } 138 139 scoped_refptr<base::PosixDynamicThreadPool> pool_; 140 base::PosixDynamicThreadPool::PosixDynamicThreadPoolPeer peer_; 141 Lock counter_lock_; 142 int counter_; 143 Lock unique_threads_lock_; 144 std::set<PlatformThreadId> unique_threads_; 145 Lock num_waiting_to_start_lock_; 146 int num_waiting_to_start_; 147 ConditionVariable num_waiting_to_start_cv_; 148 base::WaitableEvent start_; 149 }; 150 151 } // namespace 152 153 TEST_F(PosixDynamicThreadPoolTest, Basic) { 154 EXPECT_EQ(0, peer_.num_idle_threads()); 155 EXPECT_EQ(0U, unique_threads_.size()); 156 EXPECT_EQ(0U, peer_.pending_tasks().size()); 157 158 // Add one task and wait for it to be completed. 159 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 160 161 WaitForIdleThreads(1); 162 163 EXPECT_EQ(1U, unique_threads_.size()) << 164 "There should be only one thread allocated for one task."; 165 EXPECT_EQ(1, counter_); 166 } 167 168 TEST_F(PosixDynamicThreadPoolTest, ReuseIdle) { 169 // Add one task and wait for it to be completed. 170 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 171 172 WaitForIdleThreads(1); 173 174 // Add another 2 tasks. One should reuse the existing worker thread. 175 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 176 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 177 178 WaitForTasksToStart(2); 179 start_.Signal(); 180 WaitForIdleThreads(2); 181 182 EXPECT_EQ(2U, unique_threads_.size()); 183 EXPECT_EQ(2, peer_.num_idle_threads()); 184 EXPECT_EQ(3, counter_); 185 } 186 187 TEST_F(PosixDynamicThreadPoolTest, TwoActiveTasks) { 188 // Add two blocking tasks. 189 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 190 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 191 192 EXPECT_EQ(0, counter_) << "Blocking tasks should not have started yet."; 193 194 WaitForTasksToStart(2); 195 start_.Signal(); 196 WaitForIdleThreads(2); 197 198 EXPECT_EQ(2U, unique_threads_.size()); 199 EXPECT_EQ(2, peer_.num_idle_threads()) << "Existing threads are now idle."; 200 EXPECT_EQ(2, counter_); 201 } 202 203 TEST_F(PosixDynamicThreadPoolTest, Complex) { 204 // Add two non blocking tasks and wait for them to finish. 205 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 206 207 WaitForIdleThreads(1); 208 209 // Add two blocking tasks, start them simultaneously, and wait for them to 210 // finish. 211 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 212 pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback()); 213 214 WaitForTasksToStart(2); 215 start_.Signal(); 216 WaitForIdleThreads(2); 217 218 EXPECT_EQ(3, counter_); 219 EXPECT_EQ(2, peer_.num_idle_threads()); 220 EXPECT_EQ(2U, unique_threads_.size()); 221 222 // Wake up all idle threads so they can exit. 223 { 224 base::AutoLock locked(*peer_.lock()); 225 while (peer_.num_idle_threads() > 0) { 226 peer_.pending_tasks_available_cv()->Signal(); 227 peer_.num_idle_threads_cv()->Wait(); 228 } 229 } 230 231 // Add another non blocking task. There are no threads to reuse. 232 pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback()); 233 WaitForIdleThreads(1); 234 235 // The POSIX implementation of PlatformThread::CurrentId() uses pthread_self() 236 // which is not guaranteed to be unique after a thread joins. The OS X 237 // implemntation of pthread_self() returns the address of the pthread_t, which 238 // is merely a malloc()ed pointer stored in the first TLS slot. When a thread 239 // joins and that structure is freed, the block of memory can be put on the 240 // OS free list, meaning the same address could be reused in a subsequent 241 // allocation. This in fact happens when allocating in a loop as this test 242 // does. 243 // 244 // Because there are two concurrent threads, there's at least the guarantee 245 // of having two unique thread IDs in the set. But after those two threads are 246 // joined, the next-created thread can get a re-used ID if the allocation of 247 // the pthread_t structure is taken from the free list. Therefore, there can 248 // be either 2 or 3 unique thread IDs in the set at this stage in the test. 249 EXPECT_TRUE(unique_threads_.size() >= 2 && unique_threads_.size() <= 3) 250 << "unique_threads_.size() = " << unique_threads_.size(); 251 EXPECT_EQ(1, peer_.num_idle_threads()); 252 EXPECT_EQ(4, counter_); 253 } 254 255 } // namespace base 256
