Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/task.cc

@@ -0,0 +1,272 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/task.h"
+#include "webrtc/base/common.h"
+#include "webrtc/base/taskrunner.h"
+
+namespace rtc {
+
+int32 Task::unique_id_seed_ = 0;
+
+Task::Task(TaskParent *parent)
+    : TaskParent(this, parent),
+      state_(STATE_INIT),
+      blocked_(false),
+      done_(false),
+      aborted_(false),
+      busy_(false),
+      error_(false),
+      start_time_(0),
+      timeout_time_(0),
+      timeout_seconds_(0),
+      timeout_suspended_(false)  {
+  unique_id_ = unique_id_seed_++;
+
+  // sanity check that we didn't roll-over our id seed
+  ASSERT(unique_id_ < unique_id_seed_);
+}
+
+Task::~Task() {
+  // Is this task being deleted in the correct manner?
+  ASSERT(!done_ || GetRunner()->is_ok_to_delete(this));
+  ASSERT(state_ == STATE_INIT || done_);
+  ASSERT(state_ == STATE_INIT || blocked_);
+
+  // If the task is being deleted without being done, it
+  // means that it hasn't been removed from its parent.
+  // This happens if a task is deleted outside of TaskRunner.
+  if (!done_) {
+    Stop();
+  }
+}
+
+int64 Task::CurrentTime() {
+  return GetRunner()->CurrentTime();
+}
+
+int64 Task::ElapsedTime() {
+  return CurrentTime() - start_time_;
+}
+
+void Task::Start() {
+  if (state_ != STATE_INIT)
+    return;
+  // Set the start time before starting the task.  Otherwise if the task
+  // finishes quickly and deletes the Task object, setting start_time_
+  // will crash.
+  start_time_ = CurrentTime();
+  GetRunner()->StartTask(this);
+}
+
+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();
+#ifdef _DEBUG
+    // verify that stop removed this from its parent
+    ASSERT(!parent()->IsChildTask(this));
+#endif
+    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;
+    // Let the timeout continue
+  } else {
+    state_ = new_state;
+    blocked_ = false;
+    ResetTimeout();
+  }
+
+  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();
+#if _DEBUG
+    // verify that stop removed this from its parent
+    ASSERT(!parent()->IsChildTask(this));
+#endif
+    blocked_ = true;
+  }
+}
+
+void Task::Abort(bool nowake) {
+  // Why only check for done_ (instead of "aborted_ || done_")?
+  //
+  // If aborted_ && !done_, it means the logic for aborting still
+  // needs to be executed (because busy_ must have been true when
+  // Abort() was previously called).
+  if (done_)
+    return;
+  aborted_ = true;
+  if (!busy_) {
+    done_ = true;
+    blocked_ = true;
+    error_ = true;
+
+    // "done_" is set before calling "Stop()" to ensure that this code 
+    // doesn't execute more than once (recursively) for the same task.
+    Stop();
+#ifdef _DEBUG
+    // verify that stop removed this from its parent
+    ASSERT(!parent()->IsChildTask(this));
+#endif
+    if (!nowake) {
+      // WakeTasks to self-delete.
+      // Don't call Wake() because it is a no-op after "done_" is set.
+      // Even if Wake() did run, it clears "blocked_" which isn't desireable.
+      GetRunner()->WakeTasks();
+    }
+  }
+}
+
+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 {
+  switch (state) {
+    case STATE_BLOCKED: return "BLOCKED";
+    case STATE_INIT: return "INIT";
+    case STATE_START: return "START";
+    case STATE_DONE: return "DONE";
+    case STATE_ERROR: return "ERROR";
+    case STATE_RESPONSE: return "RESPONSE";
+  }
+  return "??";
+}
+
+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;
+    }
+  }
+
+  return newstate;
+}
+
+void Task::Stop() {
+  // No need to wake because we're either awake or in abort
+  TaskParent::OnStopped(this);
+}
+
+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() {
+  int64 previous_timeout_time = timeout_time_;
+  bool timeout_allowed = (state_ != STATE_INIT)
+                      && (state_ != STATE_DONE)
+                      && (state_ != STATE_ERROR);
+  if (timeout_seconds_ && timeout_allowed && !timeout_suspended_)
+    timeout_time_ = CurrentTime() +
+                    (timeout_seconds_ * kSecToMsec * kMsecTo100ns);
+  else
+    timeout_time_ = 0;
+
+  GetRunner()->UpdateTaskTimeout(this, previous_timeout_time);
+}
+
+void Task::ClearTimeout() {
+  int64 previous_timeout_time = timeout_time_;
+  timeout_time_ = 0;
+  GetRunner()->UpdateTaskTimeout(this, previous_timeout_time);
+}
+
+void Task::SuspendTimeout() {
+  if (!timeout_suspended_) {
+    timeout_suspended_ = true;
+    ResetTimeout();
+  }
+}
+
+void Task::ResumeTimeout() {
+  if (timeout_suspended_) {
+    timeout_suspended_ = false;
+    ResetTimeout();
+  }
+}
+
+} // namespace rtc