readmarkers: drop a conditional

readmarkers: add some whitespace

readmarkers: combine parent conditionals

readmarkers: drop temporary substring assignments Assignments are expensive in inner loops

util: introduce unpacker This allows taking advantage of Python 2.5+'s struct.Struct, which provides a slightly faster unpack due to reusing formats. Sadly, .unpack_from is significantly slower.

perf: add a configurable sleep on startup This is intended to counteract power management by giving a consistent idle period before test runs.

revset: use localrepo revbranchcache for branch name filtering Branch name filtering in revsets was expensive. For every rev it created a changectx and called .branch() which retrieved the branch name from the changelog. Instead, use the revbranchcache. The revbranchcache is used read-only. The revset implementation with generators and callbacks makes it hard to figure out when we are done using/updating the cache and could write it back. It would also be 'tricky' to lock the repo for writing from within a revset execution. Finally, the branchmap update will usually make sure that the cache is updated before any revset can be run. The revbranchcache is used without any locking but is short-lived and used in a tight loop where we can assume that the changelog doesn't change ... or where it not is relevant to us if it does. perfrevset 'branch(mobile)' on mozilla-central. Before: ! wall 10.989637 comb 10.970000 user 10.940000 sys 0.030000 (best of 3) After, no cache: ! wall 7.368656 comb 7.370000 user 7.360000 sys 0.010000 (best of 3) After, with cache: ! wall 0.528098 comb 0.530000 user 0.530000 sys 0.000000 (best of 18) The performance improvement even without cache come from being based on branchinfo on the changelog instead of using ctx.branch(). Some tests are added to verify that the revbranchcache works and keep an eye on when the cache files actually are updated.

branchmap: use revbranchcache when updating branch map The revbranchcache is read on demand before it will be used for updating the branch map. It is written back when the branchmap is written and it will thus use the same locking as branchmap. The revbranchcache instance is short-lived; it is only stored in the branchmap from .update() is invoked and until .write() is invoked. Branchmap already assume that the repo is locked in that case. The use of revbranchcache for branch map updates will make sure that the revbranchcache "always" is kept up-to-date. The perfbranchmap benchmark is somewhat bogus, especially when we can see that the caching makes a significant difference between the realistic case of a first run and the rare case of rerunning it with a full cache. Here are some 'base' numbers on mozilla-central: Before: ! wall 6.912745 comb 6.910000 user 6.840000 sys 0.070000 (best of 3) After - initial, cache is empty: ! wall 7.792569 comb 7.790000 user 7.720000 sys 0.070000 (best of 3) After - cache is full: ! wall 0.879688 comb 0.880000 user 0.870000 sys 0.010000 (best of 4) The overhead when running with empty cache comes from checking, missing and updating it every time. Most of the performance improvement comes from not having to extract the branch info from the changelog. The last doubling of performance comes from no longer having to convert all branch names to local encoding but reuse the few already converted branch names. On the hg repo: Before: ! wall 0.715703 comb 0.710000 user 0.710000 sys 0.000000 (best of 14) After: ! wall 0.105489 comb 0.110000 user 0.110000 sys 0.000000 (best of 87)