It doesn't look like it has an existing interface for setting zlib
options. Reading through the source[1], it looks like it chooses
Z_BEST_COMPRESSION (-9 to the gzip command line program) whereas gzip
defaults to -6. I'll work up a patch to pass the compression value
through as another option to the constructor.
--Pete
On Jul 15, 4:09 pm, Kenton Varda <ken...@google.com> wrote:
> Hmm, probably GzipOutputStream is not setting the same compression
> parameters as gzip itself uses by default. I'm happy to accept a patch
> fixing this. Does the interface (to GzipOutputStream) currently have a way
> to control compression parameters? If not, it probably should.
>
>
>
> On Wed, Jul 15, 2009 at 3:50 PM, Peter Keen <peter.k...@gmail.com> wrote:
>
> > Hi guys,
>
> > I'm playing around with protocol buffers for a project at work and I'm
> > coming across a possibly weird problem. I have the following setup in
> > my main():
>
> > std::cerr << "creating file" << std::endl;
> > int fd = open("blah.repo", O_WRONLY, O_CREAT);
> > if ( fd == -1 ) {
> > std::cerr << "ERROR: " << errno << " " << strerror(errno) <<
> > std::endl;
> > return 1;
> > }
>
> > ZeroCopyOutputStream* raw_output = new FileOutputStream(fd);
> > GzipOutputStream* gzip_output = new GzipOutputStream(raw_output,
> > GzipOutputStream::ZLIB);
> > CodedOutputStream* coded_output = new CodedOutputStream
> > (gzip_output);
> > // CodedOutputStream* coded_output = new CodedOutputStream
> > (raw_output);
>
> > This version takes, say, 8 seconds to create and serialize 100k simple
> > messages. If I flip it to not use the GzipOutputStream, it takes
> > roughly 1 second. Using gzip(1) to compress the resulting file takes
> > less than half a second.
>
> > Is there an option I need to be setting to bring it up to parity with
> > the command-line program or could there be a bug in GzipOutputStream?
> > For what it's worth, GzipInputStream is roughly on parity with a raw
> > CodedOutputStream.
>
> > Thanks,
> > Pete
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