From a15854bd92db69fcd0b4444fe1b8fe3610a7acf6 Mon Sep 17 00:00:00 2001 From: Martin Lucina Date: Mon, 23 Jan 2012 08:53:19 +0100 Subject: Imported Upstream version 2.0.7.dfsg --- src/decoder.hpp | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 src/decoder.hpp (limited to 'src/decoder.hpp') diff --git a/src/decoder.hpp b/src/decoder.hpp new file mode 100644 index 0000000..1662bda --- /dev/null +++ b/src/decoder.hpp @@ -0,0 +1,156 @@ +/* + Copyright (c) 2007-2010 iMatix Corporation + + This file is part of 0MQ. + + 0MQ is free software; you can redistribute it and/or modify it under + the terms of the Lesser GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + 0MQ is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + Lesser GNU General Public License for more details. + + You should have received a copy of the Lesser GNU General Public License + along with this program. If not, see . +*/ + +#ifndef __ZMQ_DECODER_HPP_INCLUDED__ +#define __ZMQ_DECODER_HPP_INCLUDED__ + +#include +#include +#include +#include + +#include "err.hpp" + +namespace zmq +{ + + // Helper base class for decoders that know the amount of data to read + // in advance at any moment. Knowing the amount in advance is a property + // of the protocol used. Both AMQP and backend protocol are based on + // size-prefixed paradigm, therefore they are using decoder_t to parse + // the messages. On the other hand, XML-based transports (like XMPP or + // SOAP) don't allow for knowing the size of data to read in advance and + // should use different decoding algorithms. + // + // Decoder implements the state machine that parses the incoming buffer. + // Derived class should implement individual state machine actions. + + template class decoder_t + { + public: + + inline decoder_t (size_t bufsize_) : + read_pos (NULL), + to_read (0), + next (NULL), + bufsize (bufsize_) + { + buf = (unsigned char*) malloc (bufsize_); + zmq_assert (buf); + } + + inline ~decoder_t () + { + free (buf); + } + + // Returns a buffer to be filled with binary data. + inline void get_buffer (unsigned char **data_, size_t *size_) + { + // If we are expected to read large message, we'll opt for zero- + // copy, i.e. we'll ask caller to fill the data directly to the + // message. Note that subsequent read(s) are non-blocking, thus + // each single read reads at most SO_RCVBUF bytes at once not + // depending on how large is the chunk returned from here. + // As a consequence, large messages being received won't block + // other engines running in the same I/O thread for excessive + // amounts of time. + if (to_read >= bufsize) { + *data_ = read_pos; + *size_ = to_read; + return; + } + + *data_ = buf; + *size_ = bufsize; + } + + // Processes the data in the buffer previously allocated using + // get_buffer function. size_ argument specifies nemuber of bytes + // actually filled into the buffer. Function returns number of + // bytes actually processed. + inline size_t process_buffer (unsigned char *data_, size_t size_) + { + // In case of zero-copy simply adjust the pointers, no copying + // is required. Also, run the state machine in case all the data + // were processed. + if (data_ == read_pos) { + read_pos += size_; + to_read -= size_; + + while (!to_read) + if (!(static_cast (this)->*next) ()) + return size_; + return size_; + } + + size_t pos = 0; + while (true) { + + // Try to get more space in the message to fill in. + // If none is available, return. + while (!to_read) + if (!(static_cast (this)->*next) ()) + return pos; + + // If there are no more data in the buffer, return. + if (pos == size_) + return pos; + + // Copy the data from buffer to the message. + size_t to_copy = std::min (to_read, size_ - pos); + memcpy (read_pos, data_ + pos, to_copy); + read_pos += to_copy; + pos += to_copy; + to_read -= to_copy; + } + } + + protected: + + // Prototype of state machine action. Action should return false if + // it is unable to push the data to the system. + typedef bool (T::*step_t) (); + + // This function should be called from derived class to read data + // from the buffer and schedule next state machine action. + inline void next_step (void *read_pos_, size_t to_read_, + step_t next_) + { + read_pos = (unsigned char*) read_pos_; + to_read = to_read_; + next = next_; + } + + private: + + unsigned char *read_pos; + size_t to_read; + step_t next; + + size_t bufsize; + unsigned char *buf; + + decoder_t (const decoder_t&); + void operator = (const decoder_t&); + }; + +} + +#endif -- cgit v1.2.3