NAME
    Vcdiff::OpenVcdiff - open-vcdiff backend for Vcdiff

SYNOPSIS
        use Vcdiff::OpenVcdiff;

        my $delta = Vcdiff::OpenVcdiff::diff($source, $target);

        my $target2 = Vcdiff::OpenVcdiff::patch($source, $delta);

        ## $target2 eq $target

    This module is a backend to the Vcdiff module and isn't usually used
    directly.

DESCRIPTION
    This module uses Alien::OpenVcdiff which is a module that configures,
    builds, and installs Google's <open-vcdiff> library.

    The alien package installs the "vcdiff" binary for your convenience but
    this module uses the "libvcdenc.so" and "libvcddec.so" shared libraries
    so that the diffing computation is done in-process instead of forking
    processes.

PROS
    *   Apache licensed

    *   open-vcdiff has a really cool feature that lets you re-use "hashed
        dictionaries" for multiple diff operations (but this module doesn't
        expose that yet).

CONS
    *   Even with the streaming API "open-vcdiff" has a hard upper-limit of
        2G file sizes and the default (which this module hasn't changed) is
        64M so be warned.

    *   If the source argument is a file handle, Vcdiff::OpenVcdiff will try
        to mmap(2) the entire file into memory with Sys::Mmap. As well as
        adding a dependency, this means that source files must be able to
        fit in your address space. Because of the file size limitation
        described above, this shouldn't be an issue. See the "STREAMING API"
        section of Vcdiff for more details.

    *   The Alien::OpenVcdiff dependency takes a long time to compile
        compared to Vcdiff::Xdelta3 although it's not a completely fair
        comparison because the alien module also runs open-vcdiff's
        test-suite (which is good).

    *   The library writes to standard error in the event of errors and I
        don't believe there is any way to silence these messages.

SEE ALSO
    <Vcdiff-OpenVcdiff github repo>

    Vcdiff

    Alien::OpenVcdiff

    <Official open-vcdiff website>

AUTHOR
    Doug Hoyte, "<doug@hcsw.org>"

COPYRIGHT & LICENSE
    Copyright 2013 Doug Hoyte.

    This module is licensed under the same terms as perl itself.

