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// $Id$
#include "Compressor.h"
#include "ace/SOCK_Stream.h"
Compressor::Compressor( void )
: Protocol_Task()
{
;
}
Compressor::~Compressor(void)
{
;
}
/* This is where you insert your compression code. Most compressors
want to work on a block of data instead of a byte-stream.
Fortunately the message block has a block that can be compressed.
Take a look at libz for a quick way to add compression to your
apps
*/
int Compressor::send(ACE_Message_Block *message, ACE_Time_Value *timeout)
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Compressor::send() compressing (%s)\n", message->rd_ptr() ));
// Create a block to hold the compressed data. I belive libz
// recommends a buffer about 10-20% larger than the source.
// Other libraries/algorithms may have their own quirks.
ACE_Message_Block * compressed = new ACE_Message_Block( message->size() );
// Perform a bogus compression algorithm. 'CD' just tells me
// that this is compressed data and when we "decompress" we'll
// look for this signature to validate the data received.
ACE_OS::sprintf( compressed->wr_ptr(), "CD:%s", message->rd_ptr() );
compressed->wr_ptr( strlen(compressed->wr_ptr())+1 );
// Send the compressed data down the stream to the next module
this->put_next( compressed );
// We're done here.
message->release();
return( 0 );
}
/* And here's the decompression side. We've written Xmit/Recv so that
we're guaranteed to get an entire block of compressed data. If
we'd used recv() in the Recv object then we might have gotten a
partial block and that may not decompress very nicely.
*/
int Compressor::recv(ACE_Message_Block *message, ACE_Time_Value *timeout)
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Compress::recv() decompressing (%s)\n", message->rd_ptr() ));
// Room for the decompressed data. In the real world you
// would probably want to send the original (uncompressed)
// data size in the message. You can predict the maximum
// possible decompression size but it's cheap and easy just to
// send that along. Look again at how I do exacly that
// between Xmit and Recv.
ACE_Message_Block * decompressed = new ACE_Message_Block( message->size() );
// Check for our signature. Even when you use a real
// compression algorithm you may want to include your own
// signature so that you can verify the block. It pays to be
// paranoid!
if( ACE_OS::strncmp( message->rd_ptr(), "CD:", 3 ) )
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Improperly encompressed data.\n" ));
message->release();
return(-1);
}
// Skip past the signature before going any further.
message->rd_ptr( 3 );
// Perform a bogus decompression algorithm. This is where you
// would feed to libz or your favorite decompressor. (It's
// costly but you could invoke popen() on gzip!)
ACE_OS::sprintf( decompressed->wr_ptr(), "%s", message->rd_ptr() );
decompressed->wr_ptr( strlen(decompressed->wr_ptr())+1 );
// Recv the decompressed data down the stream to the next module
this->put_next( decompressed );
// We're done here.
message->release();
return( 0 );
}
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