[fsp] Simplify aborting logic.

chrome/browser/chromeos/file_system_provider/queue.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "chrome/browser/chromeos/file_system_provider/queue.h"
 
 namespace chromeos {
 namespace file_system_provider {
 
-Queue::Task::Task() : token(0), completed(false) {
+Queue::Task::Task() : token(0) {
 }
 
 Queue::Task::Task(size_t token, const AbortableCallback& callback)
-    : token(token), completed(false), callback(callback) {
+    : token(token), callback(callback) {
 }
 
 Queue::Task::~Task() {
 }
 
 Queue::Queue(size_t max_in_parallel)
     : max_in_parallel_(max_in_parallel),
       next_token_(1),
       weak_ptr_factory_(this) {
   DCHECK_LT(0u, max_in_parallel);
 }
 
 Queue::~Queue() {
 }
 
 size_t Queue::NewToken() {
   return next_token_++;
 }
 
-AbortCallback Queue::Enqueue(size_t token, const AbortableCallback& callback) {
+void Queue::Enqueue(size_t token, const AbortableCallback& callback) {
 #if !NDEBUG
-  const auto it = executed_.find(token);
-  DCHECK(it == executed_.end());
+  DCHECK(executed_.find(token) == executed_.end());
   for (auto& task : pending_) {
     DCHECK(token != task.token);
   }
 #endif
   pending_.push_back(Task(token, callback));
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
-  return base::Bind(&Queue::Abort, weak_ptr_factory_.GetWeakPtr(), token);
 }
 
 void Queue::Complete(size_t token) {
   const auto it = executed_.find(token);
-  DCHECK(it != executed_.end() && !it->second.completed);
-  it->second.completed = true;
+  DCHECK(it != executed_.end());
+  completed_[token] = it->second;
+  executed_.erase(it);
 }
 
 void Queue::Remove(size_t token) {
-  const auto it = executed_.find(token);
-  DCHECK(it != executed_.end() && it->second.completed);
+  const auto it = completed_.find(token);
+  if (it != completed_.end()) {
+    completed_.erase(it);
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE,
+        base::Bind(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
+    return;
+  }
 
-  executed_.erase(it);
+  // If not completed, then it must be aborted.

[hirono, 2015/01/14 09:27:04]

nit: it must be aborted -> It sounds the task is aborted here. Maybe the task
must have been aborted, or the task must be in the aborted set?

[mtomasz, 2015/01/14 09:31:13]

Good point. Done.

+  const auto aborted_it = aborted_.find(token);
+  DCHECK(aborted_it != aborted_.end());
+  aborted_.erase(aborted_it);
+
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
 }
 
 void Queue::MaybeRun() {
   if (executed_.size() == max_in_parallel_ || !pending_.size()) {
     return;
   }
 
   DCHECK_GT(max_in_parallel_, executed_.size());
   Task task = pending_.front();
   pending_.pop_front();
 
   executed_[task.token] = task;
   executed_[task.token].abort_callback = task.callback.Run();
 }
 
-void Queue::Abort(size_t token,
-                  const storage::AsyncFileUtil::StatusCallback& callback) {
+void Queue::Abort(size_t token) {
   // Check if it's running.
   const auto it = executed_.find(token);
   if (it != executed_.end()) {
-    const Task& task = it->second;
-    // If the task is marked as completed, then it's impossible to abort it.
-    if (task.completed) {
-      callback.Run(base::File::FILE_ERROR_INVALID_OPERATION);
-      return;
-    }
+    Task task = it->second;
+    aborted_[token] = task;
+    executed_.erase(it);
     DCHECK(!task.abort_callback.is_null());
-    it->second.abort_callback.Run(callback);
-    executed_.erase(it);
+    task.abort_callback.Run();
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
     return;
   }
 
   // Aborting not running tasks is linear. TODO(mtomasz): Optimize if feasible.
   for (auto it = pending_.begin(); it != pending_.end(); ++it) {
     if (token == it->token) {
+      aborted_[token] = *it;
       pending_.erase(it);
-      callback.Run(base::File::FILE_OK);
       base::ThreadTaskRunnerHandle::Get()->PostTask(
           FROM_HERE,
           base::Bind(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
       return;
     }
   }
 
-  // The task is already removed.
-  callback.Run(base::File::FILE_ERROR_INVALID_OPERATION);
+  // The task is already removed, marked as completed or aborted.
+  NOTREACHED();
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos