Start an asynchronous operation to read a certain amount of data at the specified offset. More...

Functions
template<typename AsyncRandomAccessReadDevice , typename MutableBufferSequence , typename ReadHandler >
void	asio::async_read_at (AsyncRandomAccessReadDevice &d, boost::uint64_t offset, const MutableBufferSequence &buffers, ReadHandler handler)
template<typename AsyncRandomAccessReadDevice , typename MutableBufferSequence , typename CompletionCondition , typename ReadHandler >
void	asio::async_read_at (AsyncRandomAccessReadDevice &d, boost::uint64_t offset, const MutableBufferSequence &buffers, CompletionCondition completion_condition, ReadHandler handler)
template<typename AsyncRandomAccessReadDevice , typename Allocator , typename ReadHandler >
void	asio::async_read_at (AsyncRandomAccessReadDevice &d, boost::uint64_t offset, basic_streambuf< Allocator > &b, ReadHandler handler)
template<typename AsyncRandomAccessReadDevice , typename Allocator , typename CompletionCondition , typename ReadHandler >
void	asio::async_read_at (AsyncRandomAccessReadDevice &d, boost::uint64_t offset, basic_streambuf< Allocator > &b, CompletionCondition completion_condition, ReadHandler handler)

Detailed Description

Start an asynchronous operation to read a certain amount of data at the specified offset.

Function Documentation

template<typename AsyncRandomAccessReadDevice , typename MutableBufferSequence , typename ReadHandler >

void asio::async_read_at	(	AsyncRandomAccessReadDevice &	d,
		boost::uint64_t	offset,
		const MutableBufferSequence &	buffers,
		ReadHandler	handler
	)

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:

The supplied buffers are full. That is, the bytes transferred is equal to the sum of the buffer sizes.

An error occurred.

This operation is implemented in terms of one or more calls to the device's async_read_some_at function.

Parameters:

d	The device from which the data is to be read. The type must support the AsyncRandomAccessReadDevice concept.
offset	The offset at which the data will be read.
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.
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: 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 ); Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using asio::io_service::post().

Example

To read into a single data buffer use the asio::buffer function as follows:

 asio::async_read_at(d, 42, asio::buffer(data, size), handler);

See the asio::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:

 asio::async_read_at(
     d, 42, buffers,
     asio::transfer_all(),
     handler);

template<typename AsyncRandomAccessReadDevice , typename MutableBufferSequence , typename CompletionCondition , typename ReadHandler >

void asio::async_read_at	(	AsyncRandomAccessReadDevice &	d,
		boost::uint64_t	offset,
		const MutableBufferSequence &	buffers,
		CompletionCondition	completion_condition,
		ReadHandler	handler
	)

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:

The supplied buffers are full. That is, the bytes transferred is equal to the sum of the buffer sizes.

The completion_condition function object returns true.

Parameters:

d	The device from which the data is to be read. The type must support the AsyncRandomAccessReadDevice concept.
offset	The offset at which the data will be read.
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.
completion_condition	The function object to be called to determine whether the read operation is complete. The signature of the function object must be: bool 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 ); A return value of true indicates that the read operation is complete. False indicates that further calls to the device's async_read_some_at function are required.
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: 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 ); Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using asio::io_service::post().

Example

To read into a single data buffer use the asio::buffer function as follows:

 asio::async_read_at(d, 42,
     asio::buffer(data, size),
     asio::transfer_at_least(32),
     handler);

See the asio::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 Allocator , typename ReadHandler >

void asio::async_read_at	(	AsyncRandomAccessReadDevice &	d,
		boost::uint64_t	offset,
		basic_streambuf< Allocator > &	b,
		ReadHandler	handler
	)

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:

An error occurred.

This operation is implemented in terms of one or more calls to the device's async_read_some_at function.

Parameters:

d	The device from which the data is to be read. The type must support the AsyncRandomAccessReadDevice concept.
offset	The offset at which the data will be read.
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.
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: 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 ); Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using asio::io_service::post().

Note:

This overload is equivalent to calling:

 asio::async_read_at(
     d, 42, b,
     asio::transfer_all(),
     handler);

template<typename AsyncRandomAccessReadDevice , typename Allocator , typename CompletionCondition , typename ReadHandler >

void asio::async_read_at	(	AsyncRandomAccessReadDevice &	d,
		boost::uint64_t	offset,
		basic_streambuf< Allocator > &	b,
		CompletionCondition	completion_condition,
		ReadHandler	handler
	)

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:

The completion_condition function object returns true.

This operation is implemented in terms of one or more calls to the device's async_read_some_at function.

Parameters:

d	The device from which the data is to be read. The type must support the AsyncRandomAccessReadDevice concept.
offset	The offset at which the data will be read.
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.
completion_condition	The function object to be called to determine whether the read operation is complete. The signature of the function object must be: bool 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 ); A return value of true indicates that the read operation is complete. False indicates that further calls to the device's async_read_some_at function are required.
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: 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 ); Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using asio::io_service::post().

Functions

Detailed Description

Function Documentation