This adds the basics of progress reporting during push. While progress
for all aspects of a push operation are not reported with this change,
it lays the foundation to add these later. Push progress reporting
can be improved in the future - and consumers of the API should
just get more accurate information at that point.
The main areas where this is lacking are:
1) packbuilding progress: does not report progress during deltafication,
as this involves coordinating progress from multiple threads.
2) network progress: reports progress as objects and bytes are going
to be written to the subtransport (instead of as client gets
confirmation that they have been received by the server) and leaves
out some of the bytes that are transfered as part of the push protocol.
Basically, this reports the pack bytes that are written to the
subtransport. It does not report the bytes sent on the wire that
are received by the server. This should be a good estimate of
progress (and an improvement over no progress).
It is obviously quite a serious problem if this happens, but mutex
initialization can fail and we should detect it. It's a bit like
a memory allocation failure, in that you're probably pretty screwed
if this occurs, but at least we'll catch it.
git_packbuilder_write() used to write a packfile to the passed file
path. Instead, ask for a destination directory and create both the
packfile and an index, as most users probably do expect.
These offsets are needed for REF_DELTA objects, which encode which
object they use as a base, but not where it lies in the packfile, so
we need a list.
These objects are mostly from older packfiles, before OFS_DELTA was
widely spread. The time spent in indexing these packfiles is greatly
reduced, though remains above what git is able to do.
