dirstate: change added/modified placeholder hash length to 20 bytes Previously the added/modified placeholder hash for manifests generated from the dirstate was a 21byte long string consisting of the p1 file hash plus a single character to indicate an add or a modify. Normal hashes are only 20 bytes long. This makes it complicated to implement more efficient manifest implementations which rely on the hashes being fixed length. Let's change this hash to just be 20 bytes long, and rely on the astronomical improbability of an actual hash being these 20 bytes (just like we rely on no hash every being the nullid). This changes the possible behavior slightly in that the hash for all added/modified entries in the dirstate manifest will now be the same (so simple node comparisons would say they are equal), but we should never be doing simple node comparisons on these nodes even with the old hashes, because they did not accurately represent the content (i.e. two files based off the same p1 file node, with different working copy contents would have the same hash (even with the appended character) in the old scheme too, so we couldn't depend on the hashes period).

dirstate: change placeholder hash length to 20 bytes Previously the new-node placeholder hash for manifests generated from the dirstate was a 21byte long string of "!" characters. Normal hashes are only 20 bytes long. This makes it complicated to implement more efficient manifest implementations which rely on the hashes being fixed length. Let's change this hash to just be 20 bytes long, and rely on the astronomical improbability of an actual hash being 20 "!" bytes in a row (just like we rely on no hash ever being the nullid). A future diff will do this for added and modified dirstate markers as well, so we're putting the new newnodeid in node.py so there's a common place for these placeholders.

util: remove compressorobj API from compression engines All callers have been replaced with "compressstream." It is quite low-level and redundant with "compressstream." So eliminate it.

hgweb: use compression engine API for zlib compression More low-level compression code elimination because we now have nice APIs. This patch also demonstrates why we needed and implemented the "level" option on the "compressstream" API.

bundle2: use compressstream compression engine API Compression engines now have an API for compressing a stream of chunks. Switch to it and make low-level compression code disappear.

util: add a stream compression API to compression engines It is a common pattern throughout the code to perform compression on an iterator of chunks, yielding an iterator of compressed chunks. Let's formalize that as part of the compression engine API. The zlib and bzip2 implementations allow an optional "level" option to control the compression level. The default values are the same as what the Python modules use. This option will be used in subsequent patches.

util: remove decompressors dict (API) All in-tree consumers are now using the compengines registrar. Extensions should switch to it as well.

changegroup: use compression engines API The new API doesn't have the equivalence for None and 'UN' so we introduce code to use 'UN' explicitly.

bundle2: use compression engines API to obtain decompressor Like the recent change for the compressor side, this too is relatively straightforward. We now store a compression engine on the instance instead of a low-level decompressor. Again, this will allow us to easily transition to different compression engine APIs when they are implemented.

util: remove compressors dict (API) We no longer have any in-tree consumers of this object. Use util.compengines instead.

bundle2: use new compression engine API for compression Now that we have a new API to define compression engines, let's put it to use! The new code stores a reference to the compression engine instead of a low-level compressor object. This will allow us to more easily transition to different APIs on the compression engine interface once we implement them. As part of this, we change the registration in bundletypes to use 'UN' instead of None. Previously, util.compressors had the no-op compressor registered under both the 'UN' and None keys. Since we're switching to a new API, I don't see the point in carrying this dual registration forward.

util: create new abstraction for compression engines Currently, util.py has "compressors" and "decompressors" dicts mapping compression algorithms to callables returning objects that perform well-defined operations. In addition, revlog.py has code for calling into a compressor or decompressor explicitly. And, there is code in the wire protocol for performing zlib compression. The 3rd party lz4revlog extension has demonstrated the utility of supporting alternative compression formats for revlog storage. But it stops short of supporting lz4 for bundles and the wire protocol. There are also plans to support zstd as a general compression replacement. So, there appears to be a market for a unified API for registering compression engines. This commit starts the process of establishing one. This commit establishes a base class/interface for defining compression engines and how they will be used. A collection class to hold references to registered compression engines has also been introduced. The built-in zlib, bz2, truncated bz2, and no-op compression engines are registered with a singleton instance of the collection class. The compression engine API will change once consumers are ported to the new API and some common patterns can be simplified at the engine API level. So don't get too attached to the API...

config: mark parser regexes as bytes explicitly r-strings are not transformed into bytes by our source transformer magic.

ui: explicitly open config files in binary mode This has been working mostly accidentally, but now it works explicitly.

help: fix double word usage "most" was used twice. (I fixed a grammar error before timeless spotted it!)

setup: move cffi stuff to mercurial/cffi This patch moves all setup*cffi stuff to mercurial/cffi to make the root directory cleaner. The idea was from mpm [1]: > It seems like we could have a fair amount of cffi definitions, and > cluttering the root directory (or mercurial/) with them is probably not > a great long-term solution. We could probably add a cffi/ directory > under mercurial/ to parallel pure/. [1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-July/086442.html

manifest: remove manifest.add and add memmfctx.write This removes one more dependency on the manifest class by moving the write functionality onto the memmanifestctx classes and changing the one consumer to use the new API. By moving the write path to a manifestctx, we now give the individual manifests control over how they're read and serialized. This will be useful in developing new manifest formats and storage systems.

context: add manifestctx property on changectx This allows us to access the manifestctx for a given commit. This will be used in a later patch to be able to copy the manifestctx when we want to make a new commit.

manifest: add copy to mfctx classes This adds copy functionality to the manifestctx classes. This will be used in an upcoming diff to copy a manifestctx during commit so we can modify the manifest before committing.

manifest: introduce memmanifestctx and memtreemanifestctx This introduces two new classes to represent in-memory manifest instances. Similar to memchangectx, this lets us prepare a manifest in memory, then in a future patch we will add the apis that can commit this in memory structure.

manifestctx: add _revlog() function The `self._repo.manifestlog._revlog` code is getting copy and pasted a lot in manifestctx. Let's make it a function so it can be reused. This will make future patches cleaner too.

manifest: remove manifest.find As part of removing dependencies on manifest, this drops the find function and fixes up the two existing callers to use the equivalent apis on manifestctx.

changegroup: remove remaining uses of repo.manifest The remaining uses of repo.manifest in the changegroup module are treating the manifest exclusively as a revlog, so let's replace them with instances of the revlog directly. This is part of dropping all dependencies on repo.manifest in favor of repo.manifestlog.

treemanifest: fix a "treeinmem" case f2c5b9d48b29 (manifest: make treemanifestctx store the repo, 2016-10-18) broke most tests when run with treeinmem=True. The treeinmem mode can not be enabled by the user, so this did not break anything in practice, but it's useful to have it working for testing the treemanifest code.

perf: support measuring bdiff for all changeset related data The --all argument changes the behavior of `perfbdiff` to pull in fulltext revision pairs for all changes related to a changeset. The p1 and p2 manifests will be bdiffed against current. Every file that changed between p1 and current will have its file revisions loaded and bdiffed. This mode of operation effectively measured the bdiff time required for `hg commit`.

perf: support bdiffing multiple revisions in a single revlog This is useful for testing bdiff performance on several revision pairs at a time.

perf: prepare to handle multiple pairs in perfbdiff Before, we only supported benchmarking a single pair of texts with bdiff. We want to enable feeding larger corpora into this benchmark. So rewrite the code to support that.

py3: document why os.fsencode() can be used to get back bytes argv And a possible Windows issue. I'm sad we have to do such ugly hack, but that's the unicode on Python 3.

py3: update test-check-py3-compat.t output 4b1af1c867fa (scmutil: move util.termwidth()) changed where the import fails.

spelling: fixes of non-dictionary words

manifest: add __nonzero__ method This adds a __nonzero__ method to manifestdict. This isn't strictly necessary in the vanilla Mercurial implementation, since Python will handle nonzero checks by using __len__, but having it implemented here makes it easier for alternative implementations to implement __nonzero__ and have them be plug-n-play with the normal implementation.

py3: have bytes version of sys.argv sys.argv returns unicodes on Python 3. We need a bytes version for us. There was also a python bug/feature request which wanted then to implement one. They rejected and it is quoted in one of the comments that we can use fsencode() to get a bytes version of sys.argv. Though not sure about its correctness. Link to the comment: http://bugs.python.org/issue8776#msg217416 After this patch we will have pycompat.sysargv which will return us bytes version of sys.argv. If this patch goes in, i will like to make transformer rewrite sys.argv with pycompat.argv because there are lot of occurences.

util: use '\\' rather than using r'\' We need bytes, and I find this just a little more immediately obvious than doing rb'\'.

util: use pycompat urlunquote function

pycompat: introduce an alias for urllib.unquote We have to use unquote_to_bytes on Python 3, so we need an abstraction for this.

keyword: handle filectx _customcmp Suggested by Yuya Nishihara: https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-October/089461.html Related to issue5364.

mail: do not print(), use ui.debug() instead Since print() can't take a bytes output, it's pretty useless in Mercurial on Python 3. As this is a debug message, switching to ui.debug() seems fine.

progress: obtain stderr from ui This will help Python 3 porting.

simplemerge: obtain stdout from ui This will help Python 3 porting.

profiling: obtain stderr from ui This will help Python 3 porting.

bdiff: replace hash algorithm This patch replaces lyhash with the hash algorithm used by diffutils. The algorithm has its origins in Git commit 2e9d1410, which is all the way back from 1992. The license header in the code at that revision in GPL v2. I have not performed an extensive analysis of the distribution (and therefore buckets) of hash output. However, `hg perfbdiff` gives some clear wins. I'd like to think that if it is good enough for diffutils it is good enough for us? From the mozilla-unified repository: $ perfbdiff -m 3041e4d59df2 ! wall 0.053271 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) ! wall 0.035827 comb 0.040000 user 0.040000 sys 0.000000 (best of 100) $ perfbdiff 0e9928989e9c --alldata --count 100 ! wall 6.204277 comb 6.200000 user 6.200000 sys 0.000000 (best of 3) ! wall 4.309710 comb 4.300000 user 4.300000 sys 0.000000 (best of 3) From the hg repo: $ perfbdiff 35000 --alldata --count 1000 ! wall 0.660358 comb 0.660000 user 0.660000 sys 0.000000 (best of 15) ! wall 0.534092 comb 0.530000 user 0.530000 sys 0.000000 (best of 19) Looking at the generated assembly and statistical profiler output from the kernel level, I believe there is room to make this function even faster. Namely, we're still consuming data character by character instead of at the word level. This translates to more loop iterations and more instructions. At this juncture though, the real performance killer is that we're hashing every line. We should get a significant speedup if we change the algorithm to find the longest prefix, longest suffix, treat those as single "lines" and then only do the line splitting and hashing on the parts that are different. That will require a lot of C code, however. I'm optimistic this approach could result in a ~2x speedup.

profiling: make statprof the default profiler (BC) The statprof sampling profiler runs with significantly less overhead. Its data is therefore more useful. Furthermore, its default output shows the hotpath by default, which I've found to be way more useful than the default profiler's function time table. There is one behavioral regression with this change worth noting: the statprof profiler currently doesn't profile individual hgweb requests like lsprof does. This is because the current implementation of statprof only profiles the thread that started profiling. The ability for lsprof to profile individual hgweb requests is relatively new and likely not widely used. Furthermore, I have plans to modify statprof to support profiling multiple threads. I expect that change to go through several iterations. I'm submitting this patch first so there is more time to test statprof. Perfect is the enemy of good.

profiling: use vendored statprof and upstream enhancements (BC) Now that the statprof module is vendored and suitable for use, we switch our statprof profiler to use it. This required some minor changes because of drift between the official statprof profiler and the vendored copy. We also incorporate Facebook's improvements from the "statprofext" extension at https://bitbucket.org/facebook/hg-experimental, notably support for different display formats. Because statprof output is different, this is marked as BC. Although most users likely won't notice since most users don't profile.

crecord: use scmutil.termsize()

scmutil: extend termwidth() to return terminal height, renamed to termsize() It appears crecord.py has its own termsize() function. I want to get rid of it. The fallback height is chosen from the default of cmd.exe on Windows, and VT100 on Unix.

scmutil: clarify that we explicitly do termwidth - 1 on Windows I was a bit confused since we didn't add 1 to the width, which is different from the example shown in StackOverflow. http://stackoverflow.com/a/12642749

scmutil: remove superfluous indent from termwidth()

scmutil: narrow ImportError handling in termwidth() The array module must exist. It's sufficient to suppress the ImportError of termios. Also salvaged the comment why we have to handle AttributeError, from 7002bb17cc5e.

scmutil: make termwidth() obtain stdio from ui I'm getting rid of direct sys.stderr|out|in references so Py3 porting will be slightly easier.

scmutil: move util.termwidth() I'm going to get rid of sys.stderr|out|in references from posix.termwidth(). In order to do that, termwidth() needs to take a ui, but functions in util.py shouldn't depend on a ui object. So moves termwidth() to scmutil.py.

bdiff: don't check border condition in loop `plast = a + len - 1`. So, this "for" loop iterates from "a" to "plast", inclusive. So, `p == plast` can only be true on the final iteration of the loop. So checking for it on every loop iteration is wasteful. This patch simply decreases the upper bound of the loop by 1 and adds an explicit check after iteration for the `p == plast` case. We can't simply add 1 to the initial value for "i" because that doesn't do the correct thing on empty input strings. `perfbdiff -m 3041e4d59df2` on the Firefox repo becomes significantly faster: ! wall 0.072763 comb 0.070000 user 0.070000 sys 0.000000 (best of 100) ! wall 0.053221 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) For the curious, this code has its origins in 8b067bde6679, which is the changeset that introduced bdiff.c in 2005. Also, GNU diffutils is able to perform a similar line-based diff in under 20ms. So there's likely more perf wins to be found in this code. One of them is the hashing algorithm. But it looks like mpm spent some time testing hash collisions in d0c48891dd4a. I'd like to do the same before switching away from lyhash, just to be on the safe side.

perf: add perfbdiff bdiff shows up a lot in profiling. I think it would be useful to have a perf command that runs bdiff over and over so we can find hot spots.

help: show help for disabled extensions (issue5228) This patch does not exactly solve issue5228 but it results in a better condition on this issue. For disabled extensions, we used to parse the module and get the first occurrences of docstring and then return the first line of that as an introductory heading of extension. This is what we get today. This patch returns the whole docstring of the module as a help for extension, which is more informative. There are some modules which don't have much docstring at top level except the heading so those are unaffected by this change. To follow the existing trend of showing commands either we have to load the extension or have a very ugly parsing method which don't even assure correctness.

py3: make scmutil.rcpath() return bytes This patch make sure scmutil.rcpath() returns bytes independent of which platform is used on Python 3. If we want to change type for windows we can just conditionalize the return variable.

py3: use pycompat.ossep at certain places Certain instances of os.sep has been converted to pycompat.ossep where it was sure to use bytes only. There are more such instances which needs some more attention and will get surely.

py3: have pycompat.ospathsep and pycompat.ossep We needed bytes version of os.sep and os.pathsep in py3 as they return unicodes.

py3: add a bytes version of os.name os.name returns unicodes on py3. Most of our checks are like os.name == 'nt' Because of the transformer, on the right hand side we have b'nt'. The condition will never satisfy even if os.name returns 'nt' as that will be an unicode. We either need to encode every occurence of os.name or have a new variable which is much cleaner. Now we have pycompat.osname. There are around 53 occurences of os.name in the codebase which needs to be replaced by pycompat.osname to support Python 3.

py3: make util.datapath a bytes variable In this patch we make util.datapath a bytes variable, but we have to pass a unicode to gettext.translation otherwise it will cry. Used pycompat.fsdecode() to decode it back to unicode as it was converted to bytes using pycompat.fsencode().

py3: add os.fsdecode() as pycompat.fsdecode() We need to use os.fsdecode() but this was not present in Python 2. So added the function in pycompat.py

statprof: return state from stop() I don't like global variables. Have stop() return the captured state so callers can pass data to the display function.