revlog._chunks: inline getchunk We do this in a somewhat hacky way, relying on the fact that our sole caller preloads the cache right before calling us. An upcoming patch will make this more sensible. For a 20 MB manifest with a delta chain of > 40k, perfmanifest goes from 0.49 seconds to 0.46.

revlog.revision: fix cache preload for inline revlogs Previously the length of data preloaded did not account for the interleaved io contents. This meant that we'd sometimes have cache misses in _chunks despite the preloading. Having a correctly filled out cache will become essential in an upcoming patch.

revlog: add a fast method for getting a list of chunks This moves _chunkraw into the loop. Doing that improves revlog decompression -- in particular, manifest decompression -- significantly. For a 20 MB manifest which is the result of a > 40k delta chain, hg perfmanifest improves from 0.55 seconds to 0.49 seconds.

perfmanifest: allow and require passing in a rev Previously perfmanifest would only test tip.