task.cxx

由GOOGLE的JINGLE项目中移植的网络库

/*
 * libjingle
 * Copyright 2004--2006, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice, 
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products 
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if defined(_MSC_VER) && _MSC_VER < 1300
#pragma warning(disable:4786 4530)
#endif

#include <algorithm>

#include "task.h"
#include "common.h"
#include "taskrunner.h"

namespace buzz {

int32 Task::unique_id_seed_ = 0;

const int64 kSecToMsec = 1000;
const int64 kMsecTo100ns = 10000;

Task::Task(Task *parent)
    : state_(STATE_INIT),
      parent_(parent),
      blocked_(false),
      done_(false),
      aborted_(false),
      busy_(false),
      error_(false),
      child_error_(false),
      start_time_(0),
      timeout_seconds_(0),
      timeout_time_(0),
      timeout_suspended_(false)  {
  children_.reset(new ChildSet());
  runner_ = ((parent == NULL) ?
             reinterpret_cast<TaskRunner *>(this) :
             parent->GetRunner());
  if (parent_ != NULL) {
    parent_->AddChild(this);
  }

  unique_id_ = unique_id_seed_++;

  // sanity check that we didn't roll-over our id seed
  ASSERT(unique_id_ < unique_id_seed_);
}

int64 Task::CurrentTime() {
  return runner_->CurrentTime();
}

int64 Task::ElapsedTime() {
  return CurrentTime() - start_time_;
}

void Task::Start() {
  if (state_ != STATE_INIT)
    return;
  GetRunner()->StartTask(this);
  start_time_ = CurrentTime();
}

void Task::Step() {
  if (done_) {
#ifdef DEBUG
    // we do not know how !blocked_ happens when done_ - should be impossible.
    // But it causes problems, so in retail build, we force blocked_, and
    // under debug we assert.
    assert(blocked_);
#else
    blocked_ = true;
#endif
    return;
  }

  // Async Error() was called
  if (error_) {
    done_ = true;
    state_ = STATE_ERROR;
    blocked_ = true;
//   obsolete - an errored task is not considered done now
//   SignalDone();
    Stop();
    return;
  }

  busy_ = true;
  int new_state = Process(state_);
  busy_ = false;

  if (aborted_) {
    Abort(true);  // no need to wake because we're awake
    return;
  }

  if (new_state == STATE_BLOCKED) {
    blocked_ = true;
  } else {
    state_ = new_state;
    blocked_ = false;
  }

  if (new_state == STATE_DONE) {
    done_ = true;
  } else if (new_state == STATE_ERROR) {
    done_ = true;
    error_ = true;
  }

  if (done_) {
//  obsolete - call this yourself
//    SignalDone();
    Stop();
    blocked_ = true;
  }
}

void Task::Abort(bool nowake) {
  if (aborted_ || done_)
    return;
  aborted_ = true;
  if (!busy_) {
    done_ = true;
    blocked_ = true;
    error_ = true;
    Stop();
    if (!nowake)
      Wake();  // to self-delete
  }
}

void Task::Wake() {
  if (done_)
    return;
  if (blocked_) {
    blocked_ = false;
    GetRunner()->WakeTasks();
  }
}

void Task::Error() {
  if (error_ || done_)
    return;
  error_ = true;
  Wake();
}

std::string Task::GetStateName(int state) const {
  static const std::string STR_BLOCKED("BLOCKED");
  static const std::string STR_INIT("INIT");
  static const std::string STR_START("START");
  static const std::string STR_DONE("DONE");
  static const std::string STR_ERROR("ERROR");
  static const std::string STR_RESPONSE("RESPONSE");
  static const std::string STR_HUH("??");
  switch (state) {
    case STATE_BLOCKED: return STR_BLOCKED;
    case STATE_INIT: return STR_INIT;
    case STATE_START: return STR_START;
    case STATE_DONE: return STR_DONE;
    case STATE_ERROR: return STR_ERROR;
    case STATE_RESPONSE: return STR_RESPONSE;
  }
  return STR_HUH;
}

int Task::Process(int state) {
  int newstate = STATE_ERROR;

  if (TimedOut()) {
    ClearTimeout();
    newstate = OnTimeout();
    SignalTimeout();
  } else {
    switch (state) {
      case STATE_INIT:
        newstate = STATE_START;
        break;
      case STATE_START:
        newstate = ProcessStart();
        break;
      case STATE_RESPONSE:
        newstate = ProcessResponse();
        break;
      case STATE_DONE:
      case STATE_ERROR:
        newstate = STATE_BLOCKED;
        break;
    }
  }

  switch (newstate) {
    case STATE_BLOCKED:
      // do nothing -- let our timeout continue
      break;

    case STATE_DONE:
    case STATE_ERROR:
      ClearTimeout();
      break;

    default:
      ResetTimeout();
      break;
  }

  return newstate;
}

void Task::AddChild(Task *child) {
  children_->insert(child);
}

bool Task::AllChildrenDone() {
  for (ChildSet::iterator it = children_->begin();
       it != children_->end();
       ++it) {
    if (!(*it)->IsDone())
      return false;
  }
  return true;
}

bool Task::AnyChildError() {
  return child_error_;
}

void Task::AbortAllChildren() {
  if (children_->size() > 0) {
    ChildSet copy = *children_;
    for (ChildSet::iterator it = copy.begin(); it != copy.end(); ++it) {
      (*it)->Abort(true);  // Note we do not wake
    }
  }
}

void Task::Stop() {
  // No need to wake because we're either awake or in abort
  AbortAllChildren();
  parent_->OnChildStopped(this);
}

void Task::OnChildStopped(Task *child) {
  if (child->HasError())
    child_error_ = true;
  children_->erase(child);
}

void Task::set_timeout_seconds(const int timeout_seconds) {
  timeout_seconds_ = timeout_seconds;
  ResetTimeout();
}

bool Task::TimedOut() {
  return timeout_seconds_ &&
    timeout_time_ &&
    CurrentTime() > timeout_time_;
}

void Task::ResetTimeout() {
  if (timeout_seconds_ && !timeout_suspended_)
    timeout_time_ = CurrentTime() +
                    (timeout_seconds_ * kSecToMsec ); //  * kMsecTo100ns);
  else
    timeout_time_ = 0;

  GetRunner()->UpdateTaskTimeout(this);
}

void Task::ClearTimeout() {
  timeout_time_ = 0;
  GetRunner()->UpdateTaskTimeout(this);
}

void Task::SuspendTimeout() {
  ClearTimeout();
  timeout_suspended_ = true;
}

void Task::ResumeTimeout() {
  ResetTimeout();
  timeout_suspended_ = false;
}
}