team-10/venv/Lib/site-packages/pyarrow/include/arrow/acero/task_util.h
2025-08-02 02:00:33 +02:00

102 lines
3.6 KiB
C++

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
#pragma once
#include <atomic>
#include <cstdint>
#include <functional>
#include <vector>
#include "arrow/acero/visibility.h"
#include "arrow/status.h"
#include "arrow/util/config.h"
#include "arrow/util/logging.h"
namespace arrow {
namespace acero {
// Atomic value surrounded by padding bytes to avoid cache line invalidation
// whenever it is modified by a concurrent thread on a different CPU core.
//
template <typename T>
class AtomicWithPadding {
private:
static constexpr int kCacheLineSize = 64;
uint8_t padding_before[kCacheLineSize];
public:
std::atomic<T> value;
private:
uint8_t padding_after[kCacheLineSize];
};
// Used for asynchronous execution of operations that can be broken into
// a fixed number of symmetric tasks that can be executed concurrently.
//
// Implements priorities between multiple such operations, called task groups.
//
// Allows to specify the maximum number of in-flight tasks at any moment.
//
// Also allows for executing next pending tasks immediately using a caller thread.
//
class ARROW_ACERO_EXPORT TaskScheduler {
public:
using TaskImpl = std::function<Status(size_t, int64_t)>;
using TaskGroupContinuationImpl = std::function<Status(size_t)>;
using ScheduleImpl = std::function<Status(TaskGroupContinuationImpl)>;
using AbortContinuationImpl = std::function<void()>;
virtual ~TaskScheduler() = default;
// Order in which task groups are registered represents priorities of their tasks
// (the first group has the highest priority).
//
// Returns task group identifier that is used to request operations on the task group.
virtual int RegisterTaskGroup(TaskImpl task_impl,
TaskGroupContinuationImpl cont_impl) = 0;
virtual void RegisterEnd() = 0;
// total_num_tasks may be zero, in which case task group continuation will be executed
// immediately
virtual Status StartTaskGroup(size_t thread_id, int group_id,
int64_t total_num_tasks) = 0;
// Execute given number of tasks immediately using caller thread
virtual Status ExecuteMore(size_t thread_id, int num_tasks_to_execute,
bool execute_all) = 0;
// Begin scheduling tasks using provided callback and
// the limit on the number of in-flight tasks at any moment.
//
// Scheduling will continue as long as there are waiting tasks.
//
// It will automatically resume whenever new task group gets started.
virtual Status StartScheduling(size_t thread_id, ScheduleImpl schedule_impl,
int num_concurrent_tasks, bool use_sync_execution) = 0;
// Abort scheduling and execution.
// Used in case of being notified about unrecoverable error for the entire query.
virtual void Abort(AbortContinuationImpl impl) = 0;
static std::unique_ptr<TaskScheduler> Make();
};
} // namespace acero
} // namespace arrow