Merge commit 'e988fee1679536137b87d10e939eff5c1f27c8ab' as 'libs/libzmq'

libs/libzmq/src/encoder.hpp

@@ -0,0 +1,178 @@
+/*
+    Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq 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 GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_ENCODER_HPP_INCLUDED__
+#define __ZMQ_ENCODER_HPP_INCLUDED__
+
+#if defined(_MSC_VER)
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+#endif
+
+#include <stddef.h>
+#include <string.h>
+#include <stdlib.h>
+#include <algorithm>
+
+#include "err.hpp"
+#include "i_encoder.hpp"
+#include "msg.hpp"
+
+namespace zmq
+{
+//  Helper base class for encoders. It implements the state machine that
+//  fills the outgoing buffer. Derived classes should implement individual
+//  state machine actions.
+
+template <typename T> class encoder_base_t : public i_encoder
+{
+  public:
+    explicit encoder_base_t (size_t bufsize_) :
+        _write_pos (0),
+        _to_write (0),
+        _next (NULL),
+        _new_msg_flag (false),
+        _buf_size (bufsize_),
+        _buf (static_cast<unsigned char *> (malloc (bufsize_))),
+        _in_progress (NULL)
+    {
+        alloc_assert (_buf);
+    }
+
+    ~encoder_base_t () ZMQ_OVERRIDE { free (_buf); }
+
+    //  The function returns a batch of binary data. The data
+    //  are filled to a supplied buffer. If no buffer is supplied (data_
+    //  points to NULL) decoder object will provide buffer of its own.
+    size_t encode (unsigned char **data_, size_t size_) ZMQ_FINAL
+    {
+        unsigned char *buffer = !*data_ ? _buf : *data_;
+        const size_t buffersize = !*data_ ? _buf_size : size_;
+
+        if (in_progress () == NULL)
+            return 0;
+
+        size_t pos = 0;
+        while (pos < buffersize) {
+            //  If there are no more data to return, run the state machine.
+            //  If there are still no data, return what we already have
+            //  in the buffer.
+            if (!_to_write) {
+                if (_new_msg_flag) {
+                    int rc = _in_progress->close ();
+                    errno_assert (rc == 0);
+                    rc = _in_progress->init ();
+                    errno_assert (rc == 0);
+                    _in_progress = NULL;
+                    break;
+                }
+                (static_cast<T *> (this)->*_next) ();
+            }
+
+            //  If there are no data in the buffer yet and we are able to
+            //  fill whole buffer in a single go, let's use zero-copy.
+            //  There's no disadvantage to it as we cannot stuck multiple
+            //  messages into the buffer anyway. Note that subsequent
+            //  write(s) are non-blocking, thus each single write writes
+            //  at most SO_SNDBUF bytes at once not depending on how large
+            //  is the chunk returned from here.
+            //  As a consequence, large messages being sent won't block
+            //  other engines running in the same I/O thread for excessive
+            //  amounts of time.
+            if (!pos && !*data_ && _to_write >= buffersize) {
+                *data_ = _write_pos;
+                pos = _to_write;
+                _write_pos = NULL;
+                _to_write = 0;
+                return pos;
+            }
+
+            //  Copy data to the buffer. If the buffer is full, return.
+            const size_t to_copy = std::min (_to_write, buffersize - pos);
+            memcpy (buffer + pos, _write_pos, to_copy);
+            pos += to_copy;
+            _write_pos += to_copy;
+            _to_write -= to_copy;
+        }
+
+        *data_ = buffer;
+        return pos;
+    }
+
+    void load_msg (msg_t *msg_) ZMQ_FINAL
+    {
+        zmq_assert (in_progress () == NULL);
+        _in_progress = msg_;
+        (static_cast<T *> (this)->*_next) ();
+    }
+
+  protected:
+    //  Prototype of state machine action.
+    typedef void (T::*step_t) ();
+
+    //  This function should be called from derived class to write the data
+    //  to the buffer and schedule next state machine action.
+    void next_step (void *write_pos_,
+                    size_t to_write_,
+                    step_t next_,
+                    bool new_msg_flag_)
+    {
+        _write_pos = static_cast<unsigned char *> (write_pos_);
+        _to_write = to_write_;
+        _next = next_;
+        _new_msg_flag = new_msg_flag_;
+    }
+
+    msg_t *in_progress () { return _in_progress; }
+
+  private:
+    //  Where to get the data to write from.
+    unsigned char *_write_pos;
+
+    //  How much data to write before next step should be executed.
+    size_t _to_write;
+
+    //  Next step. If set to NULL, it means that associated data stream
+    //  is dead.
+    step_t _next;
+
+    bool _new_msg_flag;
+
+    //  The buffer for encoded data.
+    const size_t _buf_size;
+    unsigned char *const _buf;
+
+    msg_t *_in_progress;
+
+    ZMQ_NON_COPYABLE_NOR_MOVABLE (encoder_base_t)
+};
+}
+
+#endif