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/*
* 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.
*/
#include <algorithm>
#include "talk/base/taskrunner.h"
#include "talk/base/common.h"
#include "talk/base/scoped_ptr.h"
#include "talk/base/task.h"
#include "talk/base/logging.h"
namespace talk_base {
TaskRunner::TaskRunner()
: Task(NULL),
tasks_running_(false),
next_timeout_task_(NULL) {
}
TaskRunner::~TaskRunner() {
// this kills and deletes children silently!
AbortAllChildren();
RunTasks();
}
void TaskRunner::StartTask(Task * task) {
tasks_.push_back(task);
// the task we just started could be about to timeout --
// make sure our "next timeout task" is correct
UpdateTaskTimeout(task);
WakeTasks();
}
void TaskRunner::RunTasks() {
// Running continues until all tasks are Blocked (ok for a small # of tasks)
if (tasks_running_) {
return; // don't reenter
}
tasks_running_ = true;
int did_run = true;
while (did_run) {
did_run = false;
// use indexing instead of iterators because tasks_ may grow
for (size_t i = 0; i < tasks_.size(); ++i) {
while (!tasks_[i]->Blocked()) {
tasks_[i]->Step();
did_run = true;
}
}
}
// Tasks are deleted when running has paused
bool need_timeout_recalc = false;
for (size_t i = 0; i < tasks_.size(); ++i) {
if (tasks_[i]->IsDone()) {
Task* task = tasks_[i];
if (next_timeout_task_ &&
task->get_unique_id() == next_timeout_task_->get_unique_id()) {
next_timeout_task_ = NULL;
need_timeout_recalc = true;
}
delete task;
tasks_[i] = NULL;
}
}
// Finally, remove nulls
std::vector<Task *>::iterator it;
it = std::remove(tasks_.begin(),
tasks_.end(),
reinterpret_cast<Task *>(NULL));
tasks_.erase(it, tasks_.end());
if (need_timeout_recalc)
RecalcNextTimeout(NULL);
tasks_running_ = false;
}
void TaskRunner::PollTasks() {
// see if our "next potentially timed-out task" has indeed timed out.
// If it has, wake it up, then queue up the next task in line
if (next_timeout_task_ &&
next_timeout_task_->TimedOut()) {
next_timeout_task_->Wake();
WakeTasks();
}
}
// this function gets called frequently -- when each task changes
// state to something other than DONE, ERROR or BLOCKED, it calls
// ResetTimeout(), which will call this function to make sure that
// the next timeout-able task hasn't changed. The logic in this function
// prevents RecalcNextTimeout() from getting called in most cases,
// effectively making the task scheduler O-1 instead of O-N
void TaskRunner::UpdateTaskTimeout(Task *task) {
ASSERT(task != NULL);
// if the relevant task has a timeout, then
// check to see if it's closer than the current
// "about to timeout" task
if (task->get_timeout_time()) {
if (next_timeout_task_ == NULL ||
(task->get_timeout_time() <=
next_timeout_task_->get_timeout_time())) {
next_timeout_task_ = task;
}
} else if (next_timeout_task_ != NULL &&
task->get_unique_id() == next_timeout_task_->get_unique_id()) {
// otherwise, if the task doesn't have a timeout,
// and it used to be our "about to timeout" task,
// walk through all the tasks looking for the real
// "about to timeout" task
RecalcNextTimeout(task);
}
}
void TaskRunner::RecalcNextTimeout(Task *exclude_task) {
// walk through all the tasks looking for the one
// which satisfies the following:
// it's not finished already
// we're not excluding it
// it has the closest timeout time
int64 next_timeout_time = 0;
next_timeout_task_ = NULL;
for (size_t i = 0; i < tasks_.size(); ++i) {
Task *task = tasks_[i];
// if the task isn't complete, and it actually has a timeout time
if (!task->IsDone() &&
(task->get_timeout_time() > 0))
// if it doesn't match our "exclude" task
if (exclude_task == NULL ||
exclude_task->get_unique_id() != task->get_unique_id())
// if its timeout time is sooner than our current timeout time
if (next_timeout_time == 0 ||
task->get_timeout_time() <= next_timeout_time) {
// set this task as our next-to-timeout
next_timeout_time = task->get_timeout_time();
next_timeout_task_ = task;
}
}
}
} // namespace talk_base
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