// // buffered_read_stream.hpp // ~~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2008 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_BUFFERED_READ_STREAM_HPP #define ASIO_BUFFERED_READ_STREAM_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include "asio/detail/push_options.hpp" #include "asio/detail/push_options.hpp" #include #include #include #include #include "asio/detail/pop_options.hpp" #include "asio/buffered_read_stream_fwd.hpp" #include "asio/buffer.hpp" #include "asio/error.hpp" #include "asio/io_service.hpp" #include "asio/detail/bind_handler.hpp" #include "asio/detail/buffer_resize_guard.hpp" #include "asio/detail/buffered_stream_storage.hpp" #include "asio/detail/noncopyable.hpp" namespace asio { /// Adds buffering to the read-related operations of a stream. /** * The buffered_read_stream class template can be used to add buffering to the * synchronous and asynchronous read operations of a stream. * * @par Thread Safety * @e Distinct @e objects: Safe.@n * @e Shared @e objects: Unsafe. * * @par Concepts: * AsyncReadStream, AsyncWriteStream, Stream, Sync_Read_Stream, SyncWriteStream. */ template class buffered_read_stream : private noncopyable { public: /// The type of the next layer. typedef typename boost::remove_reference::type next_layer_type; /// The type of the lowest layer. typedef typename next_layer_type::lowest_layer_type lowest_layer_type; #if defined(GENERATING_DOCUMENTATION) /// The default buffer size. static const std::size_t default_buffer_size = implementation_defined; #else BOOST_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024); #endif /// Construct, passing the specified argument to initialise the next layer. template explicit buffered_read_stream(Arg& a) : next_layer_(a), storage_(default_buffer_size) { } /// Construct, passing the specified argument to initialise the next layer. template buffered_read_stream(Arg& a, std::size_t buffer_size) : next_layer_(a), storage_(buffer_size) { } /// Get a reference to the next layer. next_layer_type& next_layer() { return next_layer_; } /// Get a reference to the lowest layer. lowest_layer_type& lowest_layer() { return next_layer_.lowest_layer(); } /// (Deprecated: use get_io_service().) Get the io_service associated with /// the object. asio::io_service& io_service() { return next_layer_.get_io_service(); } /// Get the io_service associated with the object. asio::io_service& get_io_service() { return next_layer_.get_io_service(); } /// Close the stream. void close() { next_layer_.close(); } /// Close the stream. asio::error_code close(asio::error_code& ec) { return next_layer_.close(ec); } /// Write the given data to the stream. Returns the number of bytes written. /// Throws an exception on failure. template std::size_t write_some(const ConstBufferSequence& buffers) { return next_layer_.write_some(buffers); } /// Write the given data to the stream. Returns the number of bytes written, /// or 0 if an error occurred. template std::size_t write_some(const ConstBufferSequence& buffers, asio::error_code& ec) { return next_layer_.write_some(buffers, ec); } /// Start an asynchronous write. The data being written must be valid for the /// lifetime of the asynchronous operation. template void async_write_some(const ConstBufferSequence& buffers, WriteHandler handler) { next_layer_.async_write_some(buffers, handler); } /// Fill the buffer with some data. Returns the number of bytes placed in the /// buffer as a result of the operation. Throws an exception on failure. std::size_t fill() { detail::buffer_resize_guard resize_guard(storage_); std::size_t previous_size = storage_.size(); storage_.resize(storage_.capacity()); storage_.resize(previous_size + next_layer_.read_some(buffer( storage_.data() + previous_size, storage_.size() - previous_size))); resize_guard.commit(); return storage_.size() - previous_size; } /// Fill the buffer with some data. Returns the number of bytes placed in the /// buffer as a result of the operation, or 0 if an error occurred. std::size_t fill(asio::error_code& ec) { detail::buffer_resize_guard resize_guard(storage_); std::size_t previous_size = storage_.size(); storage_.resize(storage_.capacity()); storage_.resize(previous_size + next_layer_.read_some(buffer( storage_.data() + previous_size, storage_.size() - previous_size), ec)); resize_guard.commit(); return storage_.size() - previous_size; } template class fill_handler { public: fill_handler(asio::io_service& io_service, detail::buffered_stream_storage& storage, std::size_t previous_size, ReadHandler handler) : io_service_(io_service), storage_(storage), previous_size_(previous_size), handler_(handler) { } void operator()(const asio::error_code& ec, std::size_t bytes_transferred) { storage_.resize(previous_size_ + bytes_transferred); io_service_.dispatch(detail::bind_handler( handler_, ec, bytes_transferred)); } private: asio::io_service& io_service_; detail::buffered_stream_storage& storage_; std::size_t previous_size_; ReadHandler handler_; }; /// Start an asynchronous fill. template void async_fill(ReadHandler handler) { std::size_t previous_size = storage_.size(); storage_.resize(storage_.capacity()); next_layer_.async_read_some( buffer( storage_.data() + previous_size, storage_.size() - previous_size), fill_handler(get_io_service(), storage_, previous_size, handler)); } /// Read some data from the stream. Returns the number of bytes read. Throws /// an exception on failure. template std::size_t read_some(const MutableBufferSequence& buffers) { if (storage_.empty()) fill(); return copy(buffers); } /// Read some data from the stream. Returns the number of bytes read or 0 if /// an error occurred. template std::size_t read_some(const MutableBufferSequence& buffers, asio::error_code& ec) { ec = asio::error_code(); if (storage_.empty() && !fill(ec)) return 0; return copy(buffers); } template class read_some_handler { public: read_some_handler(asio::io_service& io_service, detail::buffered_stream_storage& storage, const MutableBufferSequence& buffers, ReadHandler handler) : io_service_(io_service), storage_(storage), buffers_(buffers), handler_(handler) { } void operator()(const asio::error_code& ec, std::size_t) { if (ec || storage_.empty()) { std::size_t length = 0; io_service_.dispatch(detail::bind_handler(handler_, ec, length)); } else { using namespace std; // For memcpy. std::size_t bytes_avail = storage_.size(); std::size_t bytes_copied = 0; typename MutableBufferSequence::const_iterator iter = buffers_.begin(); typename MutableBufferSequence::const_iterator end = buffers_.end(); for (; iter != end && bytes_avail > 0; ++iter) { std::size_t max_length = buffer_size(*iter); std::size_t length = (max_length < bytes_avail) ? max_length : bytes_avail; memcpy(buffer_cast(*iter), storage_.data() + bytes_copied, length); bytes_copied += length; bytes_avail -= length; } storage_.consume(bytes_copied); io_service_.dispatch(detail::bind_handler(handler_, ec, bytes_copied)); } } private: asio::io_service& io_service_; detail::buffered_stream_storage& storage_; MutableBufferSequence buffers_; ReadHandler handler_; }; /// Start an asynchronous read. The buffer into which the data will be read /// must be valid for the lifetime of the asynchronous operation. template void async_read_some(const MutableBufferSequence& buffers, ReadHandler handler) { if (storage_.empty()) { async_fill(read_some_handler( get_io_service(), storage_, buffers, handler)); } else { std::size_t length = copy(buffers); get_io_service().post(detail::bind_handler( handler, asio::error_code(), length)); } } /// Peek at the incoming data on the stream. Returns the number of bytes read. /// Throws an exception on failure. template std::size_t peek(const MutableBufferSequence& buffers) { if (storage_.empty()) fill(); return peek_copy(buffers); } /// Peek at the incoming data on the stream. Returns the number of bytes read, /// or 0 if an error occurred. template std::size_t peek(const MutableBufferSequence& buffers, asio::error_code& ec) { ec = asio::error_code(); if (storage_.empty() && !fill(ec)) return 0; return peek_copy(buffers); } /// Determine the amount of data that may be read without blocking. std::size_t in_avail() { return storage_.size(); } /// Determine the amount of data that may be read without blocking. std::size_t in_avail(asio::error_code& ec) { ec = asio::error_code(); return storage_.size(); } private: /// Copy data out of the internal buffer to the specified target buffer. /// Returns the number of bytes copied. template std::size_t copy(const MutableBufferSequence& buffers) { using namespace std; // For memcpy. std::size_t bytes_avail = storage_.size(); std::size_t bytes_copied = 0; typename MutableBufferSequence::const_iterator iter = buffers.begin(); typename MutableBufferSequence::const_iterator end = buffers.end(); for (; iter != end && bytes_avail > 0; ++iter) { std::size_t max_length = buffer_size(*iter); std::size_t length = (max_length < bytes_avail) ? max_length : bytes_avail; memcpy(buffer_cast(*iter), storage_.data() + bytes_copied, length); bytes_copied += length; bytes_avail -= length; } storage_.consume(bytes_copied); return bytes_copied; } /// Copy data from the internal buffer to the specified target buffer, without /// removing the data from the internal buffer. Returns the number of bytes /// copied. template std::size_t peek_copy(const MutableBufferSequence& buffers) { using namespace std; // For memcpy. std::size_t bytes_avail = storage_.size(); std::size_t bytes_copied = 0; typename MutableBufferSequence::const_iterator iter = buffers.begin(); typename MutableBufferSequence::const_iterator end = buffers.end(); for (; iter != end && bytes_avail > 0; ++iter) { std::size_t max_length = buffer_size(*iter); std::size_t length = (max_length < bytes_avail) ? max_length : bytes_avail; memcpy(buffer_cast(*iter), storage_.data() + bytes_copied, length); bytes_copied += length; bytes_avail -= length; } return bytes_copied; } /// The next layer. Stream next_layer_; // The data in the buffer. detail::buffered_stream_storage storage_; }; } // namespace asio #include "asio/detail/pop_options.hpp" #endif // ASIO_BUFFERED_READ_STREAM_HPP