revlog: use compression engine APIs for decompression Now that compression engines declare their header in revlog chunks and can decompress revlog chunks, we refactor revlog.decompress() to use them. Making full use of the property that revlog compressor objects are reusable, revlog instances now maintain a dict mapping an engine's revlog header to a compressor object. This is not only a performance optimization for engines where compressor object reuse can result in better performance, but it also serves as a cache of header values so we don't need to perform redundant lookups against the compression engine manager. (Yes, I measured and the overhead of a function call versus a dict lookup was observed.) Replacing the previous inline lookup table with a dict lookup was measured to make chunk reading ~2.5% slower on changelogs and ~4.5% slower on manifests. So, the inline lookup table has been mostly preserved so we don't lose performance. This is unfortunate. But many decompression operations complete in microseconds, so Python attribute lookup, dict lookup, and function calls do matter. The impact of this change on mozilla-unified is as follows: $ hg perfrevlogchunks -c ! chunk ! wall 1.953663 comb 1.950000 user 1.920000 sys 0.030000 (best of 6) ! wall 1.946000 comb 1.940000 user 1.910000 sys 0.030000 (best of 6) ! chunk batch ! wall 1.791075 comb 1.800000 user 1.760000 sys 0.040000 (best of 6) ! wall 1.785690 comb 1.770000 user 1.750000 sys 0.020000 (best of 6) $ hg perfrevlogchunks -m ! chunk ! wall 2.587262 comb 2.580000 user 2.550000 sys 0.030000 (best of 4) ! wall 2.616330 comb 2.610000 user 2.560000 sys 0.050000 (best of 4) ! chunk batch ! wall 2.427092 comb 2.420000 user 2.400000 sys 0.020000 (best of 5) ! wall 2.462061 comb 2.460000 user 2.400000 sys 0.060000 (best of 4) Changelog chunk reading is slightly faster but manifest reading is slower. What gives? On this repo, 99.85% of changelog entries are zlib compressed (the 'x' header). On the manifest, 67.5% are zlib and 32.4% are '\0'. This patch swapped the test order of 'x' and '\0' so now 'x' is tested first. This makes changelogs faster since they almost always hit the first branch. This makes a significant percentage of manifest '\0' chunks slower because that code path now performs an extra test. Yes, I too can't believe we're able to measure the impact of an if..elif with simple string compares. I reckon this code would benefit from being written in C...

hgweb: build the "entries" list directly in filelog command There's no apparent reason to have this "entries" generator function that builds a list and then yields its elements in reverse order and which is only called to build the "entries" list. So just build the list directly, in reverse order. Adjust "parity" generator's offset to keep rendering the same.

convert: remove "replacecommitter" action As pointed out by Yuya, this action doesn't add much (any?) value.

ui: check EOF of getpass() response read from command-server channel readline() returns '' only when EOF is encountered, in which case, Python's getpass() raises EOFError. We should do the same to abort the session as "response expected." This bug was reported to https://bitbucket.org/tortoisehg/thg/issues/4659/

convert: config option to control Git committer actions When converting a Git repository to Mercurial at Mozilla, I encountered a scenario where I didn't want `hg convert` to automatically add the "committer: <committer>" line to commit messages. While I can hack around this by rewriting the Git commit before it is fed into `hg convert`, I figured it would be a useful knob to control. This patch introduces a config option that allows lots of control over the committer value. I initially implemented this as a single boolean flag to control whether to save the committer message. But then there was feedback that it would be useful to save the committer in extra data. While this patch doesn't implement support for saving in extra data, it does add a mechanism for extending which actions to take on the committer field. We should be able to easily add actions to save in extra data. Some of the implemented features weren't asked for. But I figured they could be useful. If nothing else they demonstrate the extensibility of this mechanism.

help: make "mergetool" an alias for "merge-tools" I've probably typed `hg help mergetool` dozens of times. I'm tired of it not working.

templatekw: force noprefix=False to insure diffstat consistency (issue4755) The result of diffstatdata should not depend on having noprefix set or not, as was reported in issue 4755. Forcing noprefix to false on call makes sure the parser receives the diff in the correct format and returns the proper result. Another way to fix this would have been to change the regular expressions in path.diffstatdata(), but that would have introduced many unecessary special cases.

check-code: reject module-level @cachefunc Module-level @cachefunc usage is risky because it can easily create a memory "leak". Let's reject it completely for now. If a valid usage comes up in the future, we can always improve the check or reconsider.

similar: remove caching from the module level To prevent Bad Things™ from happening, let's rework the logic to not use util.cachefunc.

patch: add label for coloring the similarity extended header Just like the summary says, this will colorize the: similarity index 88% line in the diff output.