85bab67083
My concept with `class CancellableOperation` doesn't work properly, because the kernel may continue to write to the given buffer as soon as the read finishes. To fix this, this commit adds `class ReadOperation` which owns the buffer and the `struct iovec`. Instances of this class persist until the read really finishes, even if the operation is canceled.
89 lines
2.5 KiB
C++
89 lines
2.5 KiB
C++
/*
|
|
* Copyright 2020 Max Kellermann <max.kellermann@gmail.com>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* - Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* - 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* ``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
|
|
* FOUNDATION OR CONTRIBUTORS 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.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "Operation.hxx"
|
|
|
|
#include <cstddef>
|
|
#include <memory>
|
|
|
|
#include <sys/uio.h> // for struct iovec
|
|
|
|
class FileDescriptor;
|
|
|
|
namespace Uring {
|
|
|
|
class Queue;
|
|
|
|
class ReadHandler {
|
|
public:
|
|
virtual void OnRead(std::unique_ptr<std::byte[]> buffer,
|
|
std::size_t size) noexcept = 0;
|
|
|
|
/**
|
|
* @param error an errno value
|
|
*/
|
|
virtual void OnReadError(int error) noexcept = 0;
|
|
};
|
|
|
|
/**
|
|
* Read into a newly allocated buffer.
|
|
*
|
|
* Instances of this class must be allocated with `new`, because
|
|
* cancellation will require this object (and the allocated buffer) to
|
|
* persist until the kernel completes the operation.
|
|
*/
|
|
class ReadOperation final : Operation {
|
|
ReadHandler *handler;
|
|
|
|
struct iovec iov;
|
|
|
|
std::unique_ptr<std::byte[]> buffer;
|
|
|
|
public:
|
|
void Start(Queue &queue, FileDescriptor fd, off_t offset,
|
|
std::size_t size, ReadHandler &_handler) noexcept;
|
|
|
|
/**
|
|
* Cancel this operation. This instance will be freed using
|
|
* `delete` after the kernel has finished cancellation,
|
|
* i.e. the caller resigns ownership.
|
|
*/
|
|
void Cancel() noexcept {
|
|
handler = nullptr;
|
|
}
|
|
|
|
private:
|
|
/* virtual methods from class Operation */
|
|
void OnUringCompletion(int res) noexcept override;
|
|
};
|
|
|
|
} // namespace Uring
|