localrepo: use ProgrammingError This is an example usage of ProgrammingError. Let's start migrating RuntimeError to ProgrammingError. The code only runs when devel.all-warnings or devel.check-locks is set, so it does not affect the end-user experience.

error: add ProgrammingError We have requirement to express "this is clearly an error caused by the programmer". The code base uses RuntimeError for that in some places, not ideal. So let's add a formal exception for that.

chgserver: call "load" for new ui objects After d83ca854fa21, we need to call "ui.load" explicitly to load config files.

localrepository: remove None as default value of path argument in __init__() The path variable in localrepository.__init__() has a default value None. So it gives us a option to create an object to localrespository class without path variable. But things break if you try to do so. The second line in the init which will be executed when we try to create a localrepository object will call os.path.expandvars(path) which returns TypeError: argument of type 'NoneType' is not iterable I checked occurrences when it is called and can't find any piece of code which calls it without path variable. Also if something is calling it, its should break.

py3: use pycompat.sysstr() in __import__() __import__() on Python 3 accepts strings which are different from that of Python 2. Used pycompat.sysstr() to get string accordingly.

py3: avoid use of basestring "In this case, result is a source variable of a list to be returned, it shouldn't be unicode. Hence we can use bytes instead of basestring here." -Yuya

py3: use unicodes in __slots__ __slots__ in Python 3 accepts only unicodes and there is no harm using unicodes in __slots__. So just adding u'' is fine. Previous occurences of this problem are treated the same way.

memctx: allow the metadataonlyctx thats reusing the manifest node When we have a lot of files writing a new manifest revision can be expensive. This commit adds a possibility for memctx to reuse a manifest from a different commit. This can be beneficial for commands that are creating metadata changes without any actual files changed like "hg metaedit" in evolve extension. I will send the change for evolve that leverages this once this is accepted.

localrepo: make it possible to reuse manifest when commiting context This makes the commit function understand the context that's reusing manifest.

manifest: expose the parents() method

httppeer: assign Vary request header last In preparation for adding another value to it in a subsequent patch. While I was here, I added some empty lines because walls of text are hard to read.

wireproto: only advertise HTTP-specific capabilities to HTTP peers (BC) Previously, the capabilities list was protocol agnostic and we advertised the same capabilities list to all clients, regardless of transport protocol. A few capabilities are specific to HTTP. I see no good reason why we should advertise them to SSH clients. So this patch limits their advertisement to HTTP clients. This patch is BC, but SSH clients shouldn't be using the removed capabilities so there should be no impact.

protocol: declare transport protocol name We add an attribute to the HTTP and SSH protocol implementations identifying the transport so future patches can conditionally expose capabilities on a per-transport basis.

bdiff: early pruning of common prefix before doing expensive computations It seems quite common that files don't change completely. New lines are often pretty much appended, and modifications will often only change a small section of the file which on average will be in the middle. There can thus be a big win by pruning a common prefix before starting the more expensive search for longest common substrings. Worst case, it will scan through a long sequence of similar bytes without encountering a newline. Splitlines will then have to do the same again ... twice for each side. If similar lines are found, splitlines will save the double iteration and hashing of the lines ... plus there will be less lines to find common substrings in. This change might in some cases make the algorith pick shorter or less optimal common substrings. We can't have the cake and eat it. This make hg --time bundle --base null -r 4.0 go from 14.5 to 15 s - a 3% increase. On mozilla-unified: perfbdiff -m 3041e4d59df2 ! wall 0.053088 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) to ! wall 0.024618 comb 0.020000 user 0.020000 sys 0.000000 (best of 116) perfbdiff 0e9928989e9c --alldata --count 10 ! wall 0.702075 comb 0.700000 user 0.700000 sys 0.000000 (best of 15) to ! wall 0.579235 comb 0.580000 user 0.580000 sys 0.000000 (best of 18)

formatter: add overview of API and example as doctest