perf: add asv benchmarks Airspeed velocity (ASV) is a python framework for benchmarking Python packages over their lifetime. The results are displayed in an interactive web frontend. Add ASV benchmarks for mercurial that use contrib/perf.py extension that could be run against multiple reference repositories. The benchmark suite now includes revsets from contrib/base-revsets.txt with variants, perftags, perfstatus, perfmanifest and perfheads. Installation requires asv>=0.2, python-hglib and virtualenv This is part of PerformanceTrackingSuitePlan https://www.mercurial-scm.org/wiki/PerformanceTrackingSuitePlan

perf: omit copying ui and redirect to ferr if buffer API is in use This allow to get the output of contrib/perf.py commands using the ui.pushbuffer() API.

manifest: change treemanifestctx to construct subtrees from the manifestlog Previously, treemanifestctx would directly construct its subtrees. By making it get the subtrees through manifestlog.get() we consolidate all treemanifestctx creation into manifestlog.get() and therefore extensions that need to wrap manifestctx creation (like narrow-hg) can intercept manifestctxs at that single place. This also means fetching subtrees will take advantage of the manifestlog ctx cache now, which it did not before.

manifest: make revlog verification optional This patches adds an parameter to manifestlog.get() to disable hash checking. This will be used in an upcoming patch to support treemanifestctx reading sub-trees without loading them from the revlog. (This is already supported but does not go through the manifestlog.get() code path)

debugcommands: move debugbuilddag And we drop some now unused imports from commands.py.

debugcommands: introduce standalone module for debug commands commands.py is our largest .py file by nearly 2x. Debug commands live in a world of their own. So let's extract them to their own module. We start with "debugancestor." We currently reuse the commands table with commands.py and have a hack in dispatch.py for loading debugcommands.py. In the future, we could potentially use a separate commands table and avoid the import of debugcommands.py.

convert: migrate to util.iterfile

match: migrate to util.iterfile

store: migrate to util.iterfile

patch: migrate to util.iterfile

worker: migrate to util.iterfile

util: add iterfile to workaround a fileobj.__iter__ issue with EINTR The fileobj.__iter__ implementation in Python 2.7.12 (hg changeset 45d4cea97b04) is buggy: it cannot handle EINTR correctly. In Objects/fileobject.c: size_t Py_UniversalNewlineFread(....) { .... if (!f->f_univ_newline) return fread(buf, 1, n, stream); .... } According to the "fread" man page: If an error occurs, or the end of the file is reached, the return value is a short item count (or zero). Therefore it's possible for "fread" (and "Py_UniversalNewlineFread") to return a positive value while errno is set to EINTR and ferror(stream) changes from zero to non-zero. There are multiple "Py_UniversalNewlineFread": "file_read", "file_readinto", "file_readlines", "readahead". While the first 3 have code to handle the EINTR case, the last one "readahead" doesn't: static int readahead(PyFileObject *f, Py_ssize_t bufsize) { .... chunksize = Py_UniversalNewlineFread( f->f_buf, bufsize, f->f_fp, (PyObject *)f); .... if (chunksize == 0) { if (ferror(f->f_fp)) { PyErr_SetFromErrno(PyExc_IOError); .... } } .... } It means "readahead" could ignore EINTR, if "Py_UniversalNewlineFread" returns a non-zero value. And at the next time "readahead" got executed, if "Py_UniversalNewlineFread" returns 0, "readahead" would raise a Python error without a incorrect errno - could be 0 - thus "IOError: [Errno 0] Error". The only user of "readahead" is "readahead_get_line_skip". The only user of "readahead_get_line_skip" is "file_iternext", aka. "fileobj.__iter__", which should be avoided. There are multiple places where the pattern "for x in fp" is used. This patch adds a "iterfile" method in "util.py" so we can migrate our code from "for x in fp" to "fox x in util.iterfile(fp)".

filterpyflakes: whitelist listcomp aliasing checking The test change is because of how filterpyflakes is organized - a line number changed.

verify: avoid shadowing two variables with a list comprehension The variable names are clearly worse now, but since we're really just transposing key and value I'm not too worried about the clarity loss.

revset: avoid shadowing a variable with a list comprehension

revlog: avoid shadowing several variables using list comprehensions

minirst: avoid shadowing a variable in a list comprehension

hbisect: avoid shadowing a variable in a list comprehension

filemerge: avoid shadowing a variable in a list comprehension

color: avoid shadowing a variable inside a list comprehension

memory: avoid shadowing variables inside a list comprehension

shelve: move shelve-finishing logic to a separate function With future obs-based shelve, finishing shelve will be different from just aborting a transaction and I would like to keep both variants of this functionality in a separate function.

shelve: move unknown files handling to a separate function This change has nothing to do with future obsshelve introduction, it is done just for readability purposes.

shelve: move actual created commit shelving to a separate function Currently, this code does not have any branching, it just bundles a commit and saves a patch file. Later, obsolescence-based shelve will be added, so this code will also create some obsmarkers and will be one of the few places where obsshelve will be different from traditional shelve.

shelve: move 'nothing changed' messaging to a separate function This has nothing to do with the future obsshelve implementation, I just thought that moving this messaging to a separate function will improve shelve code readability.

shelve: move commitfunc creation to a separate function Special commitfuncs are created as closures at least twice in shelve's code and one time special commitfunc is used within another closure. They all serve very specific purposes like temporarily tweak some configuration or enable editor, etc. This is not immediately important to someone reading shelve code, so I think moving this logic to a separate function is a good idea.

shelve: move mutableancestors to not be a closure There's no value in it being a closure and everyone who tries to read the outer function code will be distracted by it. IMO moving it out significantly improves readability, especially given how clear it is what mutableancestors function does from its name.

shelve: move shelve name generation to a separate function This has nothing to do with future obsshelve introduction, done just for readability purposes.

shelve: move possible shelve file extensions to a single place This and a couple of following patches are a preparation to implementing obsolescense-enabled shelve which was discussed on a Sprint. If this refactoring is not done, shelve is going to look even more hackish than now. This particular commit introduces a slight behavior change. Previously, if only .hg/shelve/name.patch file exists, but .hg/name.hg does not, 'hg shelve -d name' would fail saying "shelve not found". Now deletion will only fail if .patch file does not exist (since .patch is used as an indicator of an existing shelve). Other shelve files being absent are skipped silently to accommodate for future introduction of obs-based shelve, which will mean that for some shelves .hg and .patch files exist, while for others .hg and .oshelve.

manifest: delete manifest.manifest class Now that nothing uses the primary manifest class, we can delete it.

localrepo: delete localrepo.manifest Now that nothing uses normal manifests, we can delete localrepo.manifest.

manifest: remove last uses of repo.manifest Now that all the functionality has been moved to manifestlog/manifestrevlog/etc, we can finally change all the uses of repo.manifest to use the new versions. A future diff will then delete repo.manifest. One additional change in this commit is to change repo.manifestlog to be a @storecache property instead of @property. This is required by some uses of repo.manifest require that it be settable (contrib/perf.py and the static http server). We can't do this in a prior change because we can't use @storecache on this until repo.manifest is no longer used anywhere.

manifest: add unionmanifestlog support As part of deprecating manifest, we need to make the union repo support manifestlog.

manifest: add bundlemanifestlog support As part of deprecating manifest.manifest we need to make bundlerepo support manifestlog.

manifest: make manifestlog use it's own cache As we start to make manifestlog the primary manifest source, the dependency on manifest.manifest will cause circular dependency problems. Let's break this dependency by making manifestlog use it's own cache. In a near future patch we will remove the previous manifest cache so we're not duplicating it.

manifest: delete unused dirlog and _newmanifest functions As part of migrating all manifest functionality out of manifest.manifest, let's migrate a couple spots off of manifest.dirlog() to use the revlog specific accessor. Then we can delete manifest.dirlog() and other unused functions.

manifest: move clearcaches to manifestlog This is part of removing all functionality from manifest.manifest so we can delete the class entirely.

manifest: remove usages of manifest.read Now that the two manifestctx implementations have working read() functions, let's remove the existing uses of manifest.read and drop the function.

manifest: remove dependency on manifestrevlog being able to create trees A future patch will be removing the read() function from the manifest class. Since manifestrevlog currently depends on the read function that manifest implements (as a derived class), we need to break the dependency from manifestrevlog to read(). We do this by adding an argument to manifestrevlog.write() which provides it with the ability to read a manifest. This is good in general because it further separates revlog as the storage format from the actual inmemory data structure implementation.

color: show mode warning based on ui.formatted ui.interactive is only for input and ui.formatted is for output.

protocol: drop unused import of zlib Something weird is happening that breaks pyflakes installed via 'pip install --user'. I haven't had a chance to finish debugging this, but this at least fixes the build.

hook: lower inflated use of sys.__stdout__ and __stderr__ They were introduced at 9f76df0edb7d, where sys.stdout could be replaced by sys.stderr. After that, we've changed the way of stdout redirection by afccc64eea73, so we no longer need to reference the original __stdout__ and __stderr__ objects. Let's move away from using __std*__ objects so we can simply wrap sys.std* objects for Python 3 porting.

hook: flush stdout before restoring stderr redirection There was a similar issue to 8b011ededfb2. If an in-process hook writes to stdout, the data may be buffered. In which case, stdout must be flushed before restoring its file descriptor. Otherwise, remaining data would be sent over the ssh wire and corrupts the protocol. Note that this is a different redirection from the one I've just removed.

hook: do not redirect stdout/err/in to ui while running in-process hooks (BC) It was introduced by a59058fd074a to address command-server issues. After that, I've made a complete fix by 69f86b937035, so we don't need to replace sys.stdio objects to protect the IPC channels. This change means we no longer see data written to sys.stdout/err by an in-process hook on command server. I think that's okay because the canonical way is to use ui functions and in-process hooks should respect the Mercurial API. This will help Python 3 porting, where sys.stdout is TextIO but ui.fout is BytesIO.

merge: change modified indicator to be 20 bytes Previously we indicated that the .hgsubstate file was dirty by adding a '+' to the end of its hash in the wctx manifest. This made is complicated to have new manifest implementations that rely on the node length being fixed. In previous patches we added added and modified node placeholders, so let's use those to indicate dirty here as well. It doesn't look like anything ever depended on this '+' (aside from it being different to the parent), so nothing else needed to change here.

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.

scmutil: ignore EPERM at os.utime, which avoids ambiguity at closing According to POSIX specification, just having group write access to a file causes EPERM at invocation of os.utime() with an explicit time information (e.g. working on the repository shared by group access permission). To ignore EPERM at closing file object in such case, this patch makes checkambigatclosing._checkambig() use filestat.avoidambig() introduced by previous patch. Some functions below imply this code path at truncation of an existing (= might be owned by another user) file. - strip() in repair.py, introduced by e38d85be978f - _playback() in transaction.py, introduced by 599912a62ff6 This is a variant of issue5418.

vfs: ignore EPERM at os.utime, which avoids ambiguity at renaming (issue5418) According to POSIX specification, just having group write access to a file causes EPERM at invocation of os.utime() with an explicit time information (e.g. working on the repository shared by group access permission). To ignore EPERM at renaming in such case, this patch makes vfs.rename() use filestat.avoidambig() introduced by previous patch.

util: add utility function to skip avoiding file stat ambiguity if EPERM Now, advancing stat.st_mtime by os.utime() is used to avoid file stat ambiguity. But according to POSIX specification, utime(2) with an explicit time information is permitted only for a process with: - the effective user ID equal to the user ID of the file, or - appropriate privileges http://pubs.opengroup.org/onlinepubs/9699919799/functions/utime.html Therefore, just having group write access to a file causes EPERM at applying os.utime() on it (e.g. working on the repository shared by group access permission). This patch adds class filestat utility function avoidamgig() to avoid file stat ambiguity but skip it if EPERM. It is reasonable to always ignore EPERM, because utime(2) causes EPERM only in the case described above (EACCES is used only for utime(2) with NULL).

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.

hgweb: cache fctx.parents() in annotate command (issue5414) 9c37df347485 introduced a call to fctx.parents() for each line in annotate output. This function call isn't cheap, as it requires linkrev adjustment. Since multiple lines in annotate output tend to belong to the same file revision, a cache of fctx.parents() lookups for each input should be effective in the common case. So we implement one. Since the cache has to precompute parents so an aborted generator doesn't leave an incomplete cache, we could just return a list. However, we preserve the generator for backwards compatibility. The effect of this change when requesting /annotate/96ca0ecdcfa/ browser/locales/en-US/chrome/browser/downloads/downloads.dtd on the mozilla-aurora repo is significant: p1(9c37df347485) 5.5s 9c37df347485: 66.3s this patch: 10.8s We're still slower than before. But only by ~2x instead of ~12x. On the tip revisions of layout/base/nsCSSFrameConstructor.cpp file in the mozilla-unified repo, time went from 12.5s to 14.5s and back to 12.5s. I'm not sure why the mozilla-aurora repo is so slow. Looking at the code of basefilectx.parents(), there is room for further improvements. Notably, we still perform redundant calls to filelog.renamed() and basefilectx._parentfilectx(). And basefilectx.annotate() also makes similar calls, so there is potential for object reuse. However, introducing caches here are not appropriate for the stable branch.

hghave: check darcs version more strictly test-convert-darcs.t suddenly started failing on my Debian sid machine. The reason was Darcs was upgraded from 2.12.0 to 2.12.4 so the original pattern got to match the last two digits. Fix the pattern to match 2.2+.

tests: silence output of darcs command It appears darcs is more verbose by default these days. I got test failure with Darcs 2.12.4.

manifest: remove manifest.readshallowdelta This removes manifest.readshallowdelta and converts its one consumer to use manifestlog instead.

manifest: get rid of manifest.readshallowfast This removes manifest.readshallowfast and converts it's one user to use manifestlog instead.

manifest: add shallow option to treemanifestctx.readdelta and readfast The old manifest had different functions for performing shallow reads, shallow readdeltas, and shallow readfasts. Since a lot of the code is duplicate (and since those functions don't make sense on a normal manifestctx), let's unify them into flags on the existing readdelta and readfast functions. A future diff will change consumers of these functions to use the manifestctx versions and will delete the old apis.

manifest: change manifestlog mancache to be directory based In the last patch we added a get() function that allows fetching directory level treemanifestctxs. It didn't handle caching at directory level though, so we need to change our mancache to support multiple directories.

manifest: add manifestlog.get to obtain subdirectory instances Previously manifestlog only allowed obtaining root level manifests. Future patches will need direct access to subdirectory manifests as part of changegroup creation, so let's add a get() function that knows how to deal with subdirectories.

manifest: throw LookupError if node not in revlog When accessing a manifest via manifestlog[node], let's verify that the node actually exists and throw a LookupError if it doesn't. This matches the old read behavior, so we don't accidentally return invalid manifestctxs. We do this in manifestlog instead of in the manifestctx/treemanifestctx constructors because the treemanifest code currently relies on the fact that certain code paths can produce treemanifests without touching the revlogs (and it has tests that verify things work if certain revlogs are missing entirely, so they break if we add validation that tries to read them).

revlog: optimize _chunkraw when startrev==endrev In many cases, _chunkraw() is called with startrev==endrev. When this is true, we can avoid an extra index lookup and some other minor operations. On the mozilla-unified repo, `hg perfrevlogchunks -c` says this has the following impact: ! read w/ reused fd ! wall 0.371846 comb 0.370000 user 0.350000 sys 0.020000 (best of 27) ! wall 0.337930 comb 0.330000 user 0.300000 sys 0.030000 (best of 30) ! read batch w/ reused fd ! wall 0.014952 comb 0.020000 user 0.000000 sys 0.020000 (best of 197) ! wall 0.014866 comb 0.010000 user 0.000000 sys 0.010000 (best of 196) So, we've gone from ~25x slower than batch to ~22.5x slower. At this point, there's probably not much else we can do except implement an optimized function in the index itself, including in C.

revlog: inline start() and end() for perf reasons When I implemented `hg perfrevlogchunks`, one of the things that stood out was N * _chunk() calls was ~38x slower than 1 _chunks() call. Specifically, on the mozilla-unified repo: N*_chunk: 0.528997s 1*_chunks: 0.013735s This repo has 352,097 changesets. So the average time per changeset comes out to: N*_chunk: 1.502us 1*_chunks: 0.039us If you extrapolate these numbers to a repository with 1M changesets, that comes out to 1.502s versus 0.039s, which is significant. At these latencies, Python attribute lookups and function calls matter. So, this patch inlines some code to cut down on that overhead. The impact of this patch on N*_chunk() calls is clear: ! wall 0.528997 comb 0.520000 user 0.500000 sys 0.020000 (best of 19) ! wall 0.367723 comb 0.370000 user 0.350000 sys 0.020000 (best of 27) So, we go from ~38x slower to ~27x. A nice improvement. But there's still a long way to go. It's worth noting that functionality like revsets perform changelog lookups one revision at a time. So this code path is worth optimizing.

revlog: reorder index accessors to match data structure order Index entries are ordered tuples. We have accessors in the revlog class to map tuple offsets to names. To help reinforce the order, reorder the methods so they match the order of elements in the tuple. While I'm here, also sneak in some minimal documentation.