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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ash/file_system_provider/queue.h"
#include "base/check_op.h"
#include "base/functional/bind.h"
#include "base/location.h"
#include "base/notreached.h"
#include "base/task/single_thread_task_runner.h"
namespace ash::file_system_provider {
Queue::Task::Task() : token(0) {
}
Queue::Task::Task(size_t token, AbortableCallback callback)
: token(token), callback(std::move(callback)) {}
Queue::Task::Task(Task&& other) = default;
Queue::Task& Queue::Task::operator=(Task&& other) = default;
Queue::Task::~Task() = default;
Queue::Queue(size_t max_in_parallel)
: max_in_parallel_(max_in_parallel), next_token_(1) {
CHECK_LT(0u, max_in_parallel);
}
Queue::~Queue() = default;
size_t Queue::NewToken() {
return next_token_++;
}
void Queue::Enqueue(size_t token, AbortableCallback callback) {
#if !NDEBUG
CHECK(executed_.find(token) == executed_.end());
for (auto& task : pending_) {
CHECK(token != task.token);
}
#endif
pending_.push_back(Task(token, std::move(callback)));
base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
FROM_HERE,
base::BindOnce(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
}
void Queue::Complete(size_t token) {
const auto it = executed_.find(token);
DCHECK(it != executed_.end());
executed_.erase(it);
base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
FROM_HERE,
base::BindOnce(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
}
void Queue::MaybeRun() {
if (executed_.size() == max_in_parallel_ || pending_.empty())
return;
CHECK_GT(max_in_parallel_, executed_.size());
Task task = std::move(pending_.front());
const size_t token = task.token;
pending_.pop_front();
auto callback = std::move(task.callback);
executed_[token] = std::move(task);
AbortCallback abort_callback = std::move(callback).Run();
// It may happen that the task is completed and removed synchronously. Hence,
// we need to check if the task is still in the executed collection.
const auto executed_task_it = executed_.find(token);
if (executed_task_it != executed_.end())
executed_task_it->second.abort_callback = std::move(abort_callback);
}
void Queue::Abort(size_t token) {
// Check if it's running. If so, then abort and expect a Complete() call soon.
if (const auto it = executed_.find(token); it != executed_.end()) {
Task& task = it->second;
AbortCallback abort_callback = std::move(task.abort_callback);
DCHECK(!abort_callback.is_null());
std::move(abort_callback).Run();
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) {
pending_.erase(it);
base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
FROM_HERE,
base::BindOnce(&Queue::MaybeRun, weak_ptr_factory_.GetWeakPtr()));
return;
}
}
// The task is already removed, marked as completed or aborted.
NOTREACHED();
}
} // namespace ash::file_system_provider
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