Use a ReaderAt instead of an in-memory cache to resolve deltas #160
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This retrieves objects from a pack file by using an io.ReaderAt of the packfile rather an in-memory cache of objects that have been found so far. The result is that the amount of memory required to do a fetch or clone is proportional to the number of objects, rather than proportional to the total fully resolved object size of everything in the pack. With this change, I was able to dgit clone https://github.com/golang/go using 311Mb of RAM (according to top) in 12 minutes. (The clone then paniced while trying to reset the index, but I was able to manually do a "dgit reset --hard" and get a fully checked out copy of the Go repo.) Partially resolves #147.
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This retrieves objects from a pack file by using an io.ReaderAt
of the packfile rather an in-memory cache of objects that have
been found so far. The result is that the amount of memory required
to do a fetch or clone is proportional to the number of objects,
rather than proportional to the total fully resolved object size of
everything in the pack.
With this change, I was able to dgit clone https://github.com/golang/go
using 311Mb of RAM (according to top) in 12 minutes. (The clone then
paniced while trying to reset the index, but I was able to manually do
a "dgit reset --hard" and get a fully checked out copy of the Go repo.)
Partially resolves #147.