/usr/include/ola/io/NonBlockingSender.h is in libola-dev 0.10.3.nojsmin-2+deb9u1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 | /*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* NonBlockingSender.h
* Copyright (C) 2013 Simon Newton
*
* Explaination:
* If we just write IOStacks directly to ConnectedDescriptors, we may not be
* able to write the entire message. This can happen if the remote end is slow
* to ack and data builds up in the kernel socket buffer.
*
* This class abstracts the caller from having to deal with this situation. At
* construction time we specify the maximum number of message bytes we want to
* buffer. Once the buffer reaches this size subsequent calls to SendMessage
* will return false.
*/
#ifndef INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_
#define INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_
#include <ola/io/Descriptor.h>
#include <ola/io/IOQueue.h>
#include <ola/io/MemoryBlockPool.h>
#include <ola/io/OutputBuffer.h>
#include <ola/io/SelectServerInterface.h>
namespace ola {
namespace io {
/**
* @brief Write data to ConnectedDescriptors without blocking or losing data
*
* A NonBlockingSender handles writing data from IOStacks or IOQueues to a
* ConnectedDescriptor. On calling SendMessage() the data from the stack or
* queue is 0-copied to an internal buffer and then as much as possible is
* written to the ConnectedDescriptor using scatter/gather I/O calls (if
* available). If there is more data than fits in the descriptor's socket
* buffer, the remaining data is held in the internal buffer.
*
* The internal buffer has a limit on the size. Once the limit is
* exceeded, calls to SendMessage() will return false. The limit is a soft
* limit however, a call to SendMessage() may cause the buffer to exceed the
* internal limit, provided the limit has not already been reached.
*/
class NonBlockingSender {
public:
/**
* @brief Create a new NonBlockingSender.
* @param descriptor the ConnectedDescriptor to send on, ownership is not
* transferred.
* @param ss the SelectServer to use to register for on-write events.
* @param memory_pool the pool to return MemoryBlocks to
* @param max_buffer_size the maximum amount of data to buffer. Note that
* because the underlying MemoryBlocks may be partially used, this does not
* reflect the actual amount of memory used (in pathological cases we may
* allocate up to max_buffer_size * memory_block_size bytes.
*/
NonBlockingSender(ola::io::ConnectedDescriptor *descriptor,
ola::io::SelectServerInterface *ss,
ola::io::MemoryBlockPool *memory_pool,
unsigned int max_buffer_size = DEFAULT_MAX_BUFFER_SIZE);
/**
* @brief Destructor
*/
~NonBlockingSender();
/**
* @brief Check if the limit for the internal buffer has been reached.
* @return true if the limit has been reached, false otherwise.
*/
bool LimitReached() const;
/**
* @brief Send the contents of an IOStack on the ConnectedDescriptor.
* @param stack the IOStack to send. All data in this stack will be sent and
* the stack will be emptied.
* @returns true if the contents of the stack were buffered for transmit,
* false the limit for this NonBlockingSender had already been reached.
*/
bool SendMessage(class IOStack *stack);
/**
* @brief Send the contents of an IOQueue on the ConnectedDescriptor.
* @param queue the IOQueue to send. All data in this queue will be sent and
* the queue will be emptied.
* @returns true if the contents of the stack were buffered for transmit,
* false the limit for this NonBlockingSender had already been reached.
*/
bool SendMessage(IOQueue *queue);
/**
* @brief The default max internal buffer size.
*
* Once this limit has been reached, calls to SendMessage() will return
* false.
*
* 1k is probably enough for userspace. The Linux kernel default is 4k,
* tunable via /proc/sys/net/core/wmem_{max,default}.
*/
static const unsigned int DEFAULT_MAX_BUFFER_SIZE;
private:
ola::io::ConnectedDescriptor *m_descriptor;
ola::io::SelectServerInterface *m_ss;
ola::io::IOQueue m_output_buffer;
bool m_associated;
unsigned int m_max_buffer_size;
void PerformWrite();
void AssociateIfRequired();
DISALLOW_COPY_AND_ASSIGN(NonBlockingSender);
};
} // namespace io
} // namespace ola
#endif // INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_
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