YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

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// under the License.

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// The following only applies to changes made to this file as part of YugaByte development.

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// Portions Copyright (c) YugaByte, Inc.

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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

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// Unless required by applicable law or agreed to in writing, software distributed under the License

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// or implied.  See the License for the specific language governing permissions and limitations

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#include <mutex>

#include <unordered_set>

#include <glog/logging.h>

#include "yb/gutil/macros.h"

#include "yb/gutil/map-util.h"

#include "yb/gutil/ref_counted.h"

#include "yb/gutil/stl_util.h"

#include "yb/util/countdown_latch.h"

#include "yb/util/env.h"

#include "yb/util/locks.h"

#include "yb/util/status_log.h"

#include "yb/util/test_util.h"

#include "yb/util/thread.h"

#include "yb/util/threadlocal.h"

using std::unordered_set;

using std::vector;

using strings::Substitute;

namespace yb {

namespace threadlocal {

class ThreadLocalTest : public YBTest {};

const int kTargetCounterVal = 1000000;

class Counter;

typedef unordered_set<Counter*> CounterPtrSet;

typedef Mutex RegistryLockType;

typedef simple_spinlock CounterLockType;

// Registry to provide reader access to the thread-local Counters.

// The methods are only thread-safe if the calling thread holds the lock.

class CounterRegistry {

 public:

  CounterRegistry() {

  }

  RegistryLockType* get_lock() const {

    return &lock_;

  }

  bool RegisterUnlocked(Counter* counter) {

    LOG(INFO) << "Called RegisterUnlocked()";

    return InsertIfNotPresent(&counters_, counter);

  }

  bool UnregisterUnlocked(Counter* counter) {

    LOG(INFO) << "Called UnregisterUnlocked()";

    return counters_.erase(counter) > 0;

  }

  CounterPtrSet* GetCountersUnlocked() {

    return &counters_;

  }

 private:

  mutable RegistryLockType lock_;

  CounterPtrSet counters_;

  DISALLOW_COPY_AND_ASSIGN(CounterRegistry);

};

// A simple Counter class that registers itself with a CounterRegistry.

class Counter {

 public:

  Counter(CounterRegistry* registry, int val)

    : tid_(Env::Default()->gettid()),

      registry_(CHECK_NOTNULL(registry)),

      val_(val) {

    LOG(INFO) << "Counter::~Counter(): tid = " << tid_ << ", addr = " << this << ", val = " << val_;

    std::lock_guard<RegistryLockType> reg_lock(*registry_->get_lock());

    CHECK(registry_->RegisterUnlocked(this));

  }

  ~Counter() {

    LOG(INFO) << "Counter::~Counter(): tid = " << tid_ << ", addr = " << this << ", val = " << val_;

    std::lock_guard<RegistryLockType> reg_lock(*registry_->get_lock());

    std::lock_guard<CounterLockType> self_lock(lock_);

    LOG(INFO) << tid_ << ": deleting self from registry...";

    CHECK(registry_->UnregisterUnlocked(this));

  }

  uint64_t tid() {

    return tid_;

  }

  CounterLockType* get_lock() const {

    return &lock_;

  }

  void IncrementUnlocked() {

    val_++;

  }

  int GetValueUnlocked() {

    return val_;

  }

 private:

  // We expect that most of the time this lock will be uncontended.

  mutable CounterLockType lock_;

  // TID of thread that constructed this object.

  const uint64_t tid_;

  // Register / unregister ourselves with this on construction / destruction.

  CounterRegistry* const registry_;

  // Current value of the counter.

  int val_;

  DISALLOW_COPY_AND_ASSIGN(Counter);

};

// Create a new THREAD_LOCAL Counter and loop an increment operation on it.

static void RegisterCounterAndLoopIncr(CounterRegistry* registry,

                                       CountDownLatch* counters_ready,

                                       CountDownLatch* reader_ready,

                                       CountDownLatch* counters_done,

                                       CountDownLatch* reader_done) {

  BLOCK_STATIC_THREAD_LOCAL(Counter, counter, registry, 0);

  // Inform the reader that we are alive.

  counters_ready->CountDown();

  // Let the reader initialize before we start counting.

  reader_ready->Wait();

  // Now rock & roll on the counting loop.

  for (int i = 0; i < kTargetCounterVal; i++) {

    std::lock_guard<CounterLockType> l(*counter->get_lock());

    counter->IncrementUnlocked();

  }

  // Let the reader know we're ready for him to verify our counts.

  counters_done->CountDown();

  // Wait until the reader is done before we exit the thread, which will call

  // delete on the Counter.

  reader_done->Wait();

}

// Iterate over the registered counters and their values.

static uint64_t Iterate(CounterRegistry* registry, int expected_counters) {

  uint64_t sum = 0;

  int seen_counters = 0;

  std::lock_guard<RegistryLockType> l(*registry->get_lock());

  for (Counter* counter : *registry->GetCountersUnlocked()) {

    uint64_t value;

    {

      std::lock_guard<CounterLockType> l(*counter->get_lock());

      value = counter->GetValueUnlocked();

    }

    LOG(INFO) << "tid " << counter->tid() << " (counter " << counter << "): " << value;

    sum += value;

    seen_counters++;

  }

  CHECK_EQ(expected_counters, seen_counters);

  return sum;

}

static void TestThreadLocalCounters(CounterRegistry* registry, const int num_threads) {

  LOG(INFO) << "Starting threads...";

  vector<scoped_refptr<yb::Thread> > threads;

  CountDownLatch counters_ready(num_threads);

  CountDownLatch reader_ready(1);

  CountDownLatch counters_done(num_threads);

  CountDownLatch reader_done(1);

  for (int i = 0; i < num_threads; i++) {

    scoped_refptr<yb::Thread> new_thread;

    CHECK_OK(yb::Thread::Create("test", strings::Substitute("t$0", i),

        &RegisterCounterAndLoopIncr, registry, &counters_ready, &reader_ready,

        &counters_done, &reader_done, &new_thread));

    threads.push_back(new_thread);

  }

  // Wait for all threads to start and register their Counters.

  counters_ready.Wait();

  CHECK_EQ(0, Iterate(registry, num_threads));

  LOG(INFO) << "--";

  // Let the counters start spinning.

  reader_ready.CountDown();

  // Try to catch them in the act, just for kicks.

  for (int i = 0; i < 2; i++) {

    Iterate(registry, num_threads);

    LOG(INFO) << "--";

    SleepFor(MonoDelta::FromMicroseconds(1));

  }

  // Wait until they're done and assure they sum up properly.

  counters_done.Wait();

  LOG(INFO) << "Checking Counter sums...";

  CHECK_EQ(kTargetCounterVal * num_threads, Iterate(registry, num_threads));

  LOG(INFO) << "Counter sums add up!";

  reader_done.CountDown();

  LOG(INFO) << "Joining & deleting threads...";

  for (scoped_refptr<yb::Thread> thread : threads) {

    CHECK_OK(ThreadJoiner(thread.get()).Join());

  }

  LOG(INFO) << "Done.";

}

TEST_F(ThreadLocalTest, TestConcurrentCounters) {

  // Run this multiple times to ensure we don't leave remnants behind in the

  // CounterRegistry.

  CounterRegistry registry;

  for (int i = 0; i < 3; i++) {

    TestThreadLocalCounters(&registry, 8);

  }

}

// Test class that stores a string in a static thread local member.

// This class cannot be instantiated. The methods are all static.

class ThreadLocalString {

 public:

  static void set(std::string value);

  static const std::string& get();

 private:

  ThreadLocalString() {

  }

  DECLARE_STATIC_THREAD_LOCAL(std::string, value_);

  DISALLOW_COPY_AND_ASSIGN(ThreadLocalString);

};

DEFINE_STATIC_THREAD_LOCAL(std::string, ThreadLocalString, value_);

void ThreadLocalString::set(std::string value) {

  INIT_STATIC_THREAD_LOCAL(std::string, value_);

  *value_ = value;

}

const std::string& ThreadLocalString::get() {

  INIT_STATIC_THREAD_LOCAL(std::string, value_);

  return *value_;

}

static void RunAndAssign(CountDownLatch* writers_ready,

                         CountDownLatch *readers_ready,

                         CountDownLatch *all_done,

                         CountDownLatch *threads_exiting,

                         const std::string& in,

                         std::string* out) {

  writers_ready->Wait();

  // Ensure it starts off as an empty string.

  CHECK_EQ("", ThreadLocalString::get());

  ThreadLocalString::set(in);

  readers_ready->Wait();

  out->assign(ThreadLocalString::get());

  all_done->Wait();

  threads_exiting->CountDown();

}

TEST_F(ThreadLocalTest, TestTLSMember) {

  const int num_threads = 8;

  vector<CountDownLatch*> writers_ready;

  vector<CountDownLatch*> readers_ready;

  vector<std::string*> out_strings;

  vector<scoped_refptr<yb::Thread> > threads;

  ElementDeleter writers_deleter(&writers_ready);

  ElementDeleter readers_deleter(&readers_ready);

  ElementDeleter out_strings_deleter(&out_strings);

  CountDownLatch all_done(1);

  CountDownLatch threads_exiting(num_threads);

  LOG(INFO) << "Starting threads...";

  for (int i = 0; i < num_threads; i++) {

    writers_ready.push_back(new CountDownLatch(1));

    readers_ready.push_back(new CountDownLatch(1));

    out_strings.push_back(new std::string());

    scoped_refptr<yb::Thread> new_thread;

    CHECK_OK(yb::Thread::Create("test", strings::Substitute("t$0", i),

        &RunAndAssign, writers_ready[i], readers_ready[i],

        &all_done, &threads_exiting, Substitute("$0", i), out_strings[i], &new_thread));

    threads.push_back(new_thread);

  }

  // Unlatch the threads in order.

  LOG(INFO) << "Writing to thread locals...";

  for (int i = 0; i < num_threads; i++) {

    writers_ready[i]->CountDown();

  }

  LOG(INFO) << "Reading from thread locals...";

  for (int i = 0; i < num_threads; i++) {

    readers_ready[i]->CountDown();

  }

  all_done.CountDown();

  // threads_exiting acts as a memory barrier.

  threads_exiting.Wait();

  for (int i = 0; i < num_threads; i++) {

    ASSERT_EQ(Substitute("$0", i), *out_strings[i]);

    LOG(INFO) << "Read " << *out_strings[i];

  }

  LOG(INFO) << "Joining & deleting threads...";

  for (scoped_refptr<yb::Thread> thread : threads) {

    CHECK_OK(ThreadJoiner(thread.get()).Join());

  }

}

} // namespace threadlocal

} // namespace yb