695 lines
26 KiB
C++
695 lines
26 KiB
C++
|
//
|
||
|
// read_at.hpp
|
||
|
// ~~~~~~~~~~~
|
||
|
//
|
||
|
// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
|
||
|
//
|
||
|
// Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||
|
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
||
|
//
|
||
|
|
||
|
#ifndef ASIO_READ_AT_HPP
|
||
|
#define ASIO_READ_AT_HPP
|
||
|
|
||
|
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
|
||
|
# pragma once
|
||
|
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
|
||
|
|
||
|
#include "asio/detail/config.hpp"
|
||
|
#include <cstddef>
|
||
|
#include "asio/async_result.hpp"
|
||
|
#include "asio/detail/cstdint.hpp"
|
||
|
#include "asio/error.hpp"
|
||
|
|
||
|
#if !defined(ASIO_NO_EXTENSIONS)
|
||
|
# include "asio/basic_streambuf_fwd.hpp"
|
||
|
#endif // !defined(ASIO_NO_EXTENSIONS)
|
||
|
|
||
|
#include "asio/detail/push_options.hpp"
|
||
|
|
||
|
namespace asio {
|
||
|
|
||
|
/**
|
||
|
* @defgroup read_at asio::read_at
|
||
|
*
|
||
|
* @brief The @c read_at function is a composed operation that reads a certain
|
||
|
* amount of data at the specified offset before returning.
|
||
|
*/
|
||
|
/*@{*/
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @throws asio::system_error Thrown on failure.
|
||
|
*
|
||
|
* @par Example
|
||
|
* To read into a single data buffer use the @ref buffer function as follows:
|
||
|
* @code asio::read_at(d, 42, asio::buffer(data, size)); @endcode
|
||
|
* See the @ref buffer documentation for information on reading into multiple
|
||
|
* buffers in one go, and how to use it with arrays, boost::array or
|
||
|
* std::vector.
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::read_at(
|
||
|
* d, 42, buffers,
|
||
|
* asio::transfer_all()); @endcode
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, const MutableBufferSequence& buffers);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device.
|
||
|
*
|
||
|
* @param ec Set to indicate what error occurred, if any.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @par Example
|
||
|
* To read into a single data buffer use the @ref buffer function as follows:
|
||
|
* @code asio::read_at(d, 42,
|
||
|
* asio::buffer(data, size), ec); @endcode
|
||
|
* See the @ref buffer documentation for information on reading into multiple
|
||
|
* buffers in one go, and how to use it with arrays, boost::array or
|
||
|
* std::vector.
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::read_at(
|
||
|
* d, 42, buffers,
|
||
|
* asio::transfer_all(), ec); @endcode
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, const MutableBufferSequence& buffers,
|
||
|
asio::error_code& ec);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's read_some_at function.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @throws asio::system_error Thrown on failure.
|
||
|
*
|
||
|
* @par Example
|
||
|
* To read into a single data buffer use the @ref buffer function as follows:
|
||
|
* @code asio::read_at(d, 42, asio::buffer(data, size),
|
||
|
* asio::transfer_at_least(32)); @endcode
|
||
|
* See the @ref buffer documentation for information on reading into multiple
|
||
|
* buffers in one go, and how to use it with arrays, boost::array or
|
||
|
* std::vector.
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
|
||
|
typename CompletionCondition>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, const MutableBufferSequence& buffers,
|
||
|
CompletionCondition completion_condition);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's read_some_at function.
|
||
|
*
|
||
|
* @param ec Set to indicate what error occurred, if any.
|
||
|
*
|
||
|
* @returns The number of bytes read. If an error occurs, returns the total
|
||
|
* number of bytes successfully transferred prior to the error.
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
|
||
|
typename CompletionCondition>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, const MutableBufferSequence& buffers,
|
||
|
CompletionCondition completion_condition, asio::error_code& ec);
|
||
|
|
||
|
#if !defined(ASIO_NO_EXTENSIONS)
|
||
|
#if !defined(ASIO_NO_IOSTREAM)
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b The basic_streambuf object into which the data will be read.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @throws asio::system_error Thrown on failure.
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::read_at(
|
||
|
* d, 42, b,
|
||
|
* asio::transfer_all()); @endcode
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename Allocator>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b The basic_streambuf object into which the data will be read.
|
||
|
*
|
||
|
* @param ec Set to indicate what error occurred, if any.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::read_at(
|
||
|
* d, 42, b,
|
||
|
* asio::transfer_all(), ec); @endcode
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename Allocator>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b,
|
||
|
asio::error_code& ec);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b The basic_streambuf object into which the data will be read.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's read_some_at function.
|
||
|
*
|
||
|
* @returns The number of bytes transferred.
|
||
|
*
|
||
|
* @throws asio::system_error Thrown on failure.
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename Allocator,
|
||
|
typename CompletionCondition>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b,
|
||
|
CompletionCondition completion_condition);
|
||
|
|
||
|
/// Attempt to read a certain amount of data at the specified offset before
|
||
|
/// returning.
|
||
|
/**
|
||
|
* This function is used to read a certain number of bytes of data from a
|
||
|
* random access device at the specified offset. The call will block until one
|
||
|
* of the following conditions is true:
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the SyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b The basic_streambuf object into which the data will be read.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's read_some_at function.
|
||
|
*
|
||
|
* @param ec Set to indicate what error occurred, if any.
|
||
|
*
|
||
|
* @returns The number of bytes read. If an error occurs, returns the total
|
||
|
* number of bytes successfully transferred prior to the error.
|
||
|
*/
|
||
|
template <typename SyncRandomAccessReadDevice, typename Allocator,
|
||
|
typename CompletionCondition>
|
||
|
std::size_t read_at(SyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b,
|
||
|
CompletionCondition completion_condition, asio::error_code& ec);
|
||
|
|
||
|
#endif // !defined(ASIO_NO_IOSTREAM)
|
||
|
#endif // !defined(ASIO_NO_EXTENSIONS)
|
||
|
|
||
|
/*@}*/
|
||
|
/**
|
||
|
* @defgroup async_read_at asio::async_read_at
|
||
|
*
|
||
|
* @brief The @c async_read_at function is a composed asynchronous operation
|
||
|
* that reads a certain amount of data at the specified offset.
|
||
|
*/
|
||
|
/*@{*/
|
||
|
|
||
|
/// Start an asynchronous operation to read a certain amount of data at the
|
||
|
/// specified offset.
|
||
|
/**
|
||
|
* This function is used to asynchronously read a certain number of bytes of
|
||
|
* data from a random access device at the specified offset. The function call
|
||
|
* always returns immediately. The asynchronous operation will continue until
|
||
|
* one of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* async_read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the AsyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device. Although the buffers object may be copied as necessary, ownership of
|
||
|
* the underlying memory blocks is retained by the caller, which must guarantee
|
||
|
* that they remain valid until the handler is called.
|
||
|
*
|
||
|
* @param handler The handler to be called when the read operation completes.
|
||
|
* Copies will be made of the handler as required. The function signature of the
|
||
|
* handler must be:
|
||
|
* @code void handler(
|
||
|
* // Result of operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes copied into the buffers. If an error
|
||
|
* // occurred, this will be the number of bytes successfully
|
||
|
* // transferred prior to the error.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* Regardless of whether the asynchronous operation completes immediately or
|
||
|
* not, the handler will not be invoked from within this function. On
|
||
|
* immediate completion, invocation of the handler will be performed in a
|
||
|
* manner equivalent to using asio::post().
|
||
|
*
|
||
|
* @par Example
|
||
|
* To read into a single data buffer use the @ref buffer function as follows:
|
||
|
* @code
|
||
|
* asio::async_read_at(d, 42, asio::buffer(data, size), handler);
|
||
|
* @endcode
|
||
|
* See the @ref buffer documentation for information on reading into multiple
|
||
|
* buffers in one go, and how to use it with arrays, boost::array or
|
||
|
* std::vector.
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::async_read_at(
|
||
|
* d, 42, buffers,
|
||
|
* asio::transfer_all(),
|
||
|
* handler); @endcode
|
||
|
*/
|
||
|
template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
|
||
|
ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
|
||
|
std::size_t)) ReadHandler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type)>
|
||
|
ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
|
||
|
void (asio::error_code, std::size_t))
|
||
|
async_read_at(AsyncRandomAccessReadDevice& d, uint64_t offset,
|
||
|
const MutableBufferSequence& buffers,
|
||
|
ASIO_MOVE_ARG(ReadHandler) handler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type));
|
||
|
|
||
|
/// Start an asynchronous operation to read a certain amount of data at the
|
||
|
/// specified offset.
|
||
|
/**
|
||
|
* This function is used to asynchronously read a certain number of bytes of
|
||
|
* data from a random access device at the specified offset. The function call
|
||
|
* always returns immediately. The asynchronous operation will continue until
|
||
|
* one of the following conditions is true:
|
||
|
*
|
||
|
* @li The supplied buffers are full. That is, the bytes transferred is equal to
|
||
|
* the sum of the buffer sizes.
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the AsyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param buffers One or more buffers into which the data will be read. The sum
|
||
|
* of the buffer sizes indicates the maximum number of bytes to read from the
|
||
|
* device. Although the buffers object may be copied as necessary, ownership of
|
||
|
* the underlying memory blocks is retained by the caller, which must guarantee
|
||
|
* that they remain valid until the handler is called.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest async_read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's async_read_some_at function.
|
||
|
*
|
||
|
* @param handler The handler to be called when the read operation completes.
|
||
|
* Copies will be made of the handler as required. The function signature of the
|
||
|
* handler must be:
|
||
|
* @code void handler(
|
||
|
* // Result of operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes copied into the buffers. If an error
|
||
|
* // occurred, this will be the number of bytes successfully
|
||
|
* // transferred prior to the error.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* Regardless of whether the asynchronous operation completes immediately or
|
||
|
* not, the handler will not be invoked from within this function. On
|
||
|
* immediate completion, invocation of the handler will be performed in a
|
||
|
* manner equivalent to using asio::post().
|
||
|
*
|
||
|
* @par Example
|
||
|
* To read into a single data buffer use the @ref buffer function as follows:
|
||
|
* @code asio::async_read_at(d, 42,
|
||
|
* asio::buffer(data, size),
|
||
|
* asio::transfer_at_least(32),
|
||
|
* handler); @endcode
|
||
|
* See the @ref buffer documentation for information on reading into multiple
|
||
|
* buffers in one go, and how to use it with arrays, boost::array or
|
||
|
* std::vector.
|
||
|
*/
|
||
|
template <typename AsyncRandomAccessReadDevice,
|
||
|
typename MutableBufferSequence, typename CompletionCondition,
|
||
|
ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
|
||
|
std::size_t)) ReadHandler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type)>
|
||
|
ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
|
||
|
void (asio::error_code, std::size_t))
|
||
|
async_read_at(AsyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, const MutableBufferSequence& buffers,
|
||
|
CompletionCondition completion_condition,
|
||
|
ASIO_MOVE_ARG(ReadHandler) handler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type));
|
||
|
|
||
|
#if !defined(ASIO_NO_EXTENSIONS)
|
||
|
#if !defined(ASIO_NO_IOSTREAM)
|
||
|
|
||
|
/// Start an asynchronous operation to read a certain amount of data at the
|
||
|
/// specified offset.
|
||
|
/**
|
||
|
* This function is used to asynchronously read a certain number of bytes of
|
||
|
* data from a random access device at the specified offset. The function call
|
||
|
* always returns immediately. The asynchronous operation will continue until
|
||
|
* one of the following conditions is true:
|
||
|
*
|
||
|
* @li An error occurred.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* async_read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the AsyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b A basic_streambuf object into which the data will be read. Ownership
|
||
|
* of the streambuf is retained by the caller, which must guarantee that it
|
||
|
* remains valid until the handler is called.
|
||
|
*
|
||
|
* @param handler The handler to be called when the read operation completes.
|
||
|
* Copies will be made of the handler as required. The function signature of the
|
||
|
* handler must be:
|
||
|
* @code void handler(
|
||
|
* // Result of operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes copied into the buffers. If an error
|
||
|
* // occurred, this will be the number of bytes successfully
|
||
|
* // transferred prior to the error.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* Regardless of whether the asynchronous operation completes immediately or
|
||
|
* not, the handler will not be invoked from within this function. On
|
||
|
* immediate completion, invocation of the handler will be performed in a
|
||
|
* manner equivalent to using asio::post().
|
||
|
*
|
||
|
* @note This overload is equivalent to calling:
|
||
|
* @code asio::async_read_at(
|
||
|
* d, 42, b,
|
||
|
* asio::transfer_all(),
|
||
|
* handler); @endcode
|
||
|
*/
|
||
|
template <typename AsyncRandomAccessReadDevice, typename Allocator,
|
||
|
ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
|
||
|
std::size_t)) ReadHandler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type)>
|
||
|
ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
|
||
|
void (asio::error_code, std::size_t))
|
||
|
async_read_at(AsyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b,
|
||
|
ASIO_MOVE_ARG(ReadHandler) handler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type));
|
||
|
|
||
|
/// Start an asynchronous operation to read a certain amount of data at the
|
||
|
/// specified offset.
|
||
|
/**
|
||
|
* This function is used to asynchronously read a certain number of bytes of
|
||
|
* data from a random access device at the specified offset. The function call
|
||
|
* always returns immediately. The asynchronous operation will continue until
|
||
|
* one of the following conditions is true:
|
||
|
*
|
||
|
* @li The completion_condition function object returns 0.
|
||
|
*
|
||
|
* This operation is implemented in terms of zero or more calls to the device's
|
||
|
* async_read_some_at function.
|
||
|
*
|
||
|
* @param d The device from which the data is to be read. The type must support
|
||
|
* the AsyncRandomAccessReadDevice concept.
|
||
|
*
|
||
|
* @param offset The offset at which the data will be read.
|
||
|
*
|
||
|
* @param b A basic_streambuf object into which the data will be read. Ownership
|
||
|
* of the streambuf is retained by the caller, which must guarantee that it
|
||
|
* remains valid until the handler is called.
|
||
|
*
|
||
|
* @param completion_condition The function object to be called to determine
|
||
|
* whether the read operation is complete. The signature of the function object
|
||
|
* must be:
|
||
|
* @code std::size_t completion_condition(
|
||
|
* // Result of latest async_read_some_at operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes transferred so far.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* A return value of 0 indicates that the read operation is complete. A non-zero
|
||
|
* return value indicates the maximum number of bytes to be read on the next
|
||
|
* call to the device's async_read_some_at function.
|
||
|
*
|
||
|
* @param handler The handler to be called when the read operation completes.
|
||
|
* Copies will be made of the handler as required. The function signature of the
|
||
|
* handler must be:
|
||
|
* @code void handler(
|
||
|
* // Result of operation.
|
||
|
* const asio::error_code& error,
|
||
|
*
|
||
|
* // Number of bytes copied into the buffers. If an error
|
||
|
* // occurred, this will be the number of bytes successfully
|
||
|
* // transferred prior to the error.
|
||
|
* std::size_t bytes_transferred
|
||
|
* ); @endcode
|
||
|
* Regardless of whether the asynchronous operation completes immediately or
|
||
|
* not, the handler will not be invoked from within this function. On
|
||
|
* immediate completion, invocation of the handler will be performed in a
|
||
|
* manner equivalent to using asio::post().
|
||
|
*/
|
||
|
template <typename AsyncRandomAccessReadDevice,
|
||
|
typename Allocator, typename CompletionCondition,
|
||
|
ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
|
||
|
std::size_t)) ReadHandler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type)>
|
||
|
ASIO_INITFN_AUTO_RESULT_TYPE(ReadHandler,
|
||
|
void (asio::error_code, std::size_t))
|
||
|
async_read_at(AsyncRandomAccessReadDevice& d,
|
||
|
uint64_t offset, basic_streambuf<Allocator>& b,
|
||
|
CompletionCondition completion_condition,
|
||
|
ASIO_MOVE_ARG(ReadHandler) handler
|
||
|
ASIO_DEFAULT_COMPLETION_TOKEN(
|
||
|
typename AsyncRandomAccessReadDevice::executor_type));
|
||
|
|
||
|
#endif // !defined(ASIO_NO_IOSTREAM)
|
||
|
#endif // !defined(ASIO_NO_EXTENSIONS)
|
||
|
|
||
|
/*@}*/
|
||
|
|
||
|
} // namespace asio
|
||
|
|
||
|
#include "asio/detail/pop_options.hpp"
|
||
|
|
||
|
#include "asio/impl/read_at.hpp"
|
||
|
|
||
|
#endif // ASIO_READ_AT_HPP
|