C++ Promise类代码示例

 inline void set_result(Promise& p, T&& t)
 {
     p.set_result(std::forward<T>(t));
 }

TEST(Wait, waitWithDuration) {
 {
  Promise<int> p;
  Future<int> f = p.getFuture();
  f.wait(milliseconds(1));
  EXPECT_FALSE(f.isReady());
  p.setValue(1);
  EXPECT_TRUE(f.isReady());
 }
 {
  Promise<int> p;
  Future<int> f = p.getFuture();
  p.setValue(1);
  f.wait(milliseconds(1));
  EXPECT_TRUE(f.isReady());
 }
 {
  vector<Future<bool>> v_fb;
  v_fb.push_back(makeFuture(true));
  v_fb.push_back(makeFuture(false));
  auto f = collectAll(v_fb);
  f.wait(milliseconds(1));
  EXPECT_TRUE(f.isReady());
  EXPECT_EQ(2, f.value().size());
 }
 {
  vector<Future<bool>> v_fb;
  Promise<bool> p1;
  Promise<bool> p2;
  v_fb.push_back(p1.getFuture());
  v_fb.push_back(p2.getFuture());
  auto f = collectAll(v_fb);
  f.wait(milliseconds(1));
  EXPECT_FALSE(f.isReady());
  p1.setValue(true);
  EXPECT_FALSE(f.isReady());
  p2.setValue(true);
  EXPECT_TRUE(f.isReady());
 }
 {
  auto f = makeFuture().wait(milliseconds(1));
  EXPECT_TRUE(f.isReady());
 }

 {
   Promise<Unit> p;
   auto start = std::chrono::steady_clock::now();
   auto f = p.getFuture().wait(milliseconds(100));
   auto elapsed = std::chrono::steady_clock::now() - start;
   EXPECT_GE(elapsed, milliseconds(100));
   EXPECT_FALSE(f.isReady());
   p.setValue();
   EXPECT_TRUE(f.isReady());
 }

 {
   // Try to trigger the race where the resultant Future is not yet complete
   // even if we didn't hit the timeout, and make sure we deal with it properly
   Promise<Unit> p;
   folly::Baton<> b;
   auto t = std::thread([&]{
     b.post();
     /* sleep override */ std::this_thread::sleep_for(milliseconds(100));
     p.setValue();
   });
   b.wait();
   auto f = p.getFuture().wait(std::chrono::seconds(3600));
   EXPECT_TRUE(f.isReady());
   t.join();
 }
}

// This test ensures that reconciliation requests for tasks that are
// pending are exposed in reconciliation.
TEST_F(ReconciliationTest, PendingTask)
{
  MockAuthorizer authorizer;
  Try<PID<Master> > master = StartMaster(&authorizer);
  ASSERT_SOME(master);

  MockExecutor exec(DEFAULT_EXECUTOR_ID);

  Future<SlaveRegisteredMessage> slaveRegisteredMessage =
    FUTURE_PROTOBUF(SlaveRegisteredMessage(), _, _);

  Try<PID<Slave> > slave = StartSlave();
  ASSERT_SOME(slave);

  // Wait for the slave to register and get the slave id.
  AWAIT_READY(slaveRegisteredMessage);
  const SlaveID slaveId = slaveRegisteredMessage.get().slave_id();

  MockScheduler sched;
  MesosSchedulerDriver driver(
      &sched, DEFAULT_FRAMEWORK_INFO, master.get(), DEFAULT_CREDENTIAL);

  EXPECT_CALL(sched, registered(&driver, _, _))
    .Times(1);

  Future<vector<Offer> > offers;
  EXPECT_CALL(sched, resourceOffers(&driver, _))
    .WillOnce(FutureArg<1>(&offers))
    .WillRepeatedly(Return()); // Ignore subsequent offers.

  driver.start();

  AWAIT_READY(offers);
  EXPECT_NE(0u, offers.get().size());

  // Return a pending future from authorizer.
  Future<Nothing> authorize;
  Promise<bool> promise;
  EXPECT_CALL(authorizer, authorize(An<const mesos::ACL::RunTask&>()))
    .WillOnce(DoAll(FutureSatisfy(&authorize),
                    Return(promise.future())));

  TaskInfo task = createTask(offers.get()[0], "", DEFAULT_EXECUTOR_ID);
  vector<TaskInfo> tasks;
  tasks.push_back(task);

  driver.launchTasks(offers.get()[0].id(), tasks);

  // Wait until authorization is in progress.
  AWAIT_READY(authorize);

  // First send an implicit reconciliation request for this task.
  Future<TaskStatus> update;
  EXPECT_CALL(sched, statusUpdate(&driver, _))
    .WillOnce(FutureArg<1>(&update));

  vector<TaskStatus> statuses;
  driver.reconcileTasks(statuses);

  AWAIT_READY(update);
  EXPECT_EQ(TASK_STAGING, update.get().state());
  EXPECT_TRUE(update.get().has_slave_id());

  // Now send an explicit reconciliation request for this task.
  Future<TaskStatus> update2;
  EXPECT_CALL(sched, statusUpdate(&driver, _))
    .WillOnce(FutureArg<1>(&update2));

  TaskStatus status;
  status.mutable_task_id()->CopyFrom(task.task_id());
  status.mutable_slave_id()->CopyFrom(slaveId);
  status.set_state(TASK_STAGING);
  statuses.push_back(status);

  driver.reconcileTasks(statuses);

  AWAIT_READY(update2);
  EXPECT_EQ(TASK_STAGING, update2.get().state());
  EXPECT_TRUE(update2.get().has_slave_id());

  driver.stop();
  driver.join();

  Shutdown(); // Must shutdown before 'containerizer' gets deallocated.
}

// Runs the provided command in a subprocess.
inline Try<Subprocess> subprocess(const std::string& command)
{
  // Create pipes for stdin, stdout, stderr.
  // Index 0 is for reading, and index 1 is for writing.
  int stdinPipe[2];
  int stdoutPipe[2];
  int stderrPipe[2];

  if (pipe(stdinPipe) == -1) {
    return ErrnoError("Failed to create pipe");
  } else if (pipe(stdoutPipe) == -1) {
    os::close(stdinPipe[0]);
    os::close(stdinPipe[1]);
    return ErrnoError("Failed to create pipe");
  } else if (pipe(stderrPipe) == -1) {
    os::close(stdinPipe[0]);
    os::close(stdinPipe[1]);
    os::close(stdoutPipe[0]);
    os::close(stdoutPipe[1]);
    return ErrnoError("Failed to create pipe");
  }

  pid_t pid;
  if ((pid = fork()) == -1) {
    os::close(stdinPipe[0]);
    os::close(stdinPipe[1]);
    os::close(stdoutPipe[0]);
    os::close(stdoutPipe[1]);
    os::close(stderrPipe[0]);
    os::close(stderrPipe[1]);
    return ErrnoError("Failed to fork");
  }

  Subprocess process;
  process.data->pid = pid;

  if (process.data->pid == 0) {
    // Child.
    // Close parent's end of the pipes.
    os::close(stdinPipe[1]);
    os::close(stdoutPipe[0]);
    os::close(stderrPipe[0]);

    // Make our pipes look like stdin, stderr, stdout before we exec.
    while (dup2(stdinPipe[0], STDIN_FILENO)   == -1 && errno == EINTR);
    while (dup2(stdoutPipe[1], STDOUT_FILENO) == -1 && errno == EINTR);
    while (dup2(stderrPipe[1], STDERR_FILENO) == -1 && errno == EINTR);

    // Close the copies.
    os::close(stdinPipe[0]);
    os::close(stdoutPipe[1]);
    os::close(stderrPipe[1]);

    execl("/bin/sh", "sh", "-c", command.c_str(), (char *) NULL);

    ABORT("Failed to execl '/bin sh -c ", command.c_str(), "'\n");
  }

  // Parent.

  // Close the child's end of the pipes.
  os::close(stdinPipe[0]);
  os::close(stdoutPipe[1]);
  os::close(stderrPipe[1]);

  process.data->in = stdinPipe[1];
  process.data->out = stdoutPipe[0];
  process.data->err = stderrPipe[0];

  // Rather than directly exposing the future from process::reap, we
  // must use an explicit promise so that we can ensure we can receive
  // the termination signal. Otherwise, the caller can discard the
  // reap future, and we will not know when it is safe to close the
  // file descriptors.
  Promise<Option<int> >* promise = new Promise<Option<int> >();
  process.data->status = promise->future();

  // We need to bind a copy of this Subprocess into the onAny callback
  // below to ensure that we don't close the file descriptors before
  // the subprocess has terminated (i.e., because the caller doesn't
  // keep a copy of this Subprocess around themselves).
  process::reap(process.data->pid)
    .onAny(lambda::bind(internal::cleanup, lambda::_1, promise, process));

  return process;
}

 void close_and_destroy(Promise<> promise) {
   binlog_->close_and_destroy().ensure();
   promise.set_value(Unit());
   LOG(INFO) << "close_and_destroy: done";
   stop();
 }

TEST(Timekeeper, futureGetTimeout) {
  Promise<int> p;
  EXPECT_THROW(p.getFuture().get(one_ms), folly::TimedOut);
}

TEST(Future, getFutureAfterSetValue) {
  Promise<int> p;
  p.setValue(42);
  EXPECT_EQ(42, p.getFuture().value());
}

 Future<Unit> at(std::chrono::time_point<Clock> when) {
   Promise<Unit> p;
   auto f = p.getFuture();
   promises_.push_back(std::move(p));
   return std::move(f);
 }

 virtual Future<Unit> after(Duration dur) {
   Promise<Unit> p;
   auto f = p.getFuture();
   promises_.push_back(std::move(p));
   return std::move(f);
 }

TEST(Unit, promiseSetValue) {
  Promise<Unit> p;
  p.setValue();
}

// This test verifies that two tasks each launched on a different
// slave with same executor id but different executor info are
// allowed even when the first task is pending due to authorization.
TEST_F(MasterAuthorizationTest, PendingExecutorInfoDiffersOnDifferentSlaves)
{
  MockAuthorizer authorizer;
  Try<PID<Master> > master = StartMaster(&authorizer);
  ASSERT_SOME(master);

  MockScheduler sched;
  MesosSchedulerDriver driver(
      &sched, DEFAULT_FRAMEWORK_INFO, master.get(), DEFAULT_CREDENTIAL);

  Future<Nothing> registered;
  EXPECT_CALL(sched, registered(&driver, _, _))
    .WillOnce(FutureSatisfy(&registered));

  driver.start();

  AWAIT_READY(registered);

  Future<vector<Offer> > offers1;
  EXPECT_CALL(sched, resourceOffers(&driver, _))
    .WillOnce(FutureArg<1>(&offers1));

  // Start the first slave.
  MockExecutor exec1(DEFAULT_EXECUTOR_ID);

  Try<PID<Slave> > slave1 = StartSlave(&exec1);
  ASSERT_SOME(slave1);

  AWAIT_READY(offers1);
  EXPECT_NE(0u, offers1.get().size());

  // Launch the first task with the default executor id.
  ExecutorInfo executor1;
  executor1 = DEFAULT_EXECUTOR_INFO;
  executor1.mutable_command()->set_value("exit 1");

  TaskInfo task1 = createTask(
      offers1.get()[0], executor1.command().value(), executor1.executor_id());

  vector<TaskInfo> tasks1;
  tasks1.push_back(task1);

  // Return a pending future from authorizer.
  Future<Nothing> future;
  Promise<bool> promise;
  EXPECT_CALL(authorizer, authorize(An<const mesos::ACL::RunTask&>()))
    .WillOnce(DoAll(FutureSatisfy(&future),
                    Return(promise.future())));

  driver.launchTasks(offers1.get()[0].id(), tasks1);

  // Wait until authorization is in progress.
  AWAIT_READY(future);

  Future<vector<Offer> > offers2;
  EXPECT_CALL(sched, resourceOffers(&driver, _))
    .WillOnce(FutureArg<1>(&offers2))
    .WillRepeatedly(Return()); // Ignore subsequent offers.

  // Now start the second slave.
  MockExecutor exec2(DEFAULT_EXECUTOR_ID);

  Try<PID<Slave> > slave2 = StartSlave(&exec2);
  ASSERT_SOME(slave2);

  AWAIT_READY(offers2);
  EXPECT_NE(0u, offers2.get().size());

  // Now launch the second task with the same executor id but
  // a different executor command.
  ExecutorInfo executor2;
  executor2 = executor1;
  executor2.mutable_command()->set_value("exit 2");

  TaskInfo task2 = createTask(
      offers2.get()[0], executor2.command().value(), executor2.executor_id());

  vector<TaskInfo> tasks2;
  tasks2.push_back(task2);

  EXPECT_CALL(exec2, registered(_, _, _, _))
    .Times(1);

  EXPECT_CALL(exec2, launchTask(_, _))
    .WillOnce(SendStatusUpdateFromTask(TASK_RUNNING));

  Future<TaskStatus> status2;
  EXPECT_CALL(sched, statusUpdate(&driver, _))
    .WillOnce(FutureArg<1>(&status2));

  EXPECT_CALL(authorizer, authorize(An<const mesos::ACL::RunTask&>()))
    .WillOnce(Return(true));

  driver.launchTasks(offers2.get()[0].id(), tasks2);

  AWAIT_READY(status2);
  ASSERT_EQ(TASK_RUNNING, status2.get().state());
//.........这里部分代码省略.........

void FileStatsWorker::get_stats(bool need_all_files, bool split_by_owner_dialog_id, Promise<FileStats> promise) {
  if (!G()->parameters().use_chat_info_db) {
    split_by_owner_dialog_id = false;
  }
  if (!split_by_owner_dialog_id) {
    FileStats file_stats;
    file_stats.need_all_files = need_all_files;
    auto start = Time::now();
    scan_fs([&](FsFileInfo &fs_info) {
      FullFileInfo info;
      info.file_type = fs_info.file_type;
      info.path = std::move(fs_info.path);
      info.size = fs_info.size;
      info.atime_nsec = fs_info.atime_nsec;
      info.mtime_nsec = fs_info.mtime_nsec;
      file_stats.add(std::move(info));
    });
    auto passed = Time::now() - start;
    LOG_IF(INFO, passed > 0.5) << "Get file stats took: " << format::as_time(passed);
    promise.set_value(std::move(file_stats));
  } else {
    auto start = Time::now();

    std::vector<FullFileInfo> full_infos;
    scan_fs([&](FsFileInfo &fs_info) {
      FullFileInfo info;
      info.file_type = fs_info.file_type;
      info.path = std::move(fs_info.path);
      info.size = fs_info.size;
      info.atime_nsec = fs_info.atime_nsec;
      info.mtime_nsec = fs_info.mtime_nsec;

      // LOG(INFO) << "Found file of size " << info.size << " at " << info.path;

      full_infos.push_back(std::move(info));
    });

    std::unordered_map<size_t, size_t> hash_to_pos;
    size_t pos = 0;
    for (auto &full_info : full_infos) {
      hash_to_pos[std::hash<std::string>()(full_info.path)] = pos;
      pos++;
    }
    scan_db([&](DbFileInfo &db_info) {
      auto it = hash_to_pos.find(std::hash<std::string>()(db_info.path));
      if (it == hash_to_pos.end()) {
        return;
      }
      // LOG(INFO) << "Match! " << db_info.path << " from " << db_info.owner_dialog_id;
      full_infos[it->second].owner_dialog_id = db_info.owner_dialog_id;
    });

    FileStats file_stats;
    file_stats.need_all_files = need_all_files;
    file_stats.split_by_owner_dialog_id = split_by_owner_dialog_id;
    for (auto &full_info : full_infos) {
      file_stats.add(std::move(full_info));
    }
    auto passed = Time::now() - start;
    LOG_IF(INFO, passed > 0.5) << "Get file stats took: " << format::as_time(passed);
    promise.set_value(std::move(file_stats));
  }
}

TEST(FutureTest, Stringify)
{
  Future<bool> future;
  EXPECT_EQ("Abandoned", stringify(future));

  {
    Owned<Promise<bool>> promise(new Promise<bool>());
    future = promise->future();
    promise.reset();
    EXPECT_EQ("Abandoned", stringify(future));
  }

  {
    Owned<Promise<bool>> promise(new Promise<bool>());
    future = promise->future();
    promise->future().discard();
    promise.reset();
    EXPECT_EQ("Abandoned (with discard)", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    EXPECT_EQ("Pending", stringify(future));
    promise.future().discard();
    EXPECT_EQ("Pending (with discard)", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.set(true);
    EXPECT_EQ("Ready", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.future().discard();
    promise.set(true);
    EXPECT_EQ("Ready (with discard)", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.fail("Failure");
    EXPECT_EQ("Failed: Failure", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.future().discard();
    promise.fail("Failure");
    EXPECT_EQ("Failed (with discard): Failure", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.discard();
    EXPECT_EQ("Discarded", stringify(future));
  }

  {
    Promise<bool> promise;
    future = promise.future();
    promise.future().discard();
    promise.discard();
    EXPECT_EQ("Discarded (with discard)", stringify(future));
  }
}

TEST(Poll, ready) {
  Promise<int> p;
  auto f = p.getFuture();
  p.setValue(42);
  EXPECT_EQ(42, f.poll().value().value());
}

void SET_PRVALUE(SEXP x, SEXP v)
{
    Promise* prom = SEXP_downcast<Promise*>(x);
    prom->setValue(v);
}