test-bundle2: dump bundle content using f --hexdump Thanks to Greg Szorc for pointing this out.

treemanifest: rework lazy-copying code (issue4840) The old lazy-copy code formed a chain of copied manifests with each copy. Under typical operation, the stack never got more than a couple of manifests deep and was fine. Under conditions like hgsubversion or convert, the stack could get hundreds of manifests deep, and eventually overflow the recursion limit for Python. I was able to consistently reproduce this by converting an hgsubversion clone of svn's history to treemanifests. This may result in fewer manifests staying in memory during operations like convert when treemanifests are in use, and should make those operations faster since there will be significantly fewer noop function calls going on. A previous attempt (never mailed) of mine to fix this problem tried to simply have all treemanifests only have a loadfunc - that caused somewhat weird problems because the gettext() callable passed into read() wasn't idempotent, so the easy solution is to have a loadfunc and a copyfunc.

manifest: rename treemanifest load functions to ease debugging I'm hunting an infinite recursion bug at the moment, and having both of these methods named just _load is muddying the waters slightly.

manifest: add id(self) to treemanifest __repr__ Also rename __str__ to __repr__ since that's what we really want for pdb.

bundlerepo: let bundle repo look in the _mancache When looking up a base revision, we were ignoring the contents that were already available in the manifest's _mancache. This patch allows us to use that data instead of reading from the revlog. This is useful in our pushrebase extension (which allows rebasing on the server side during a push) because it allows us to prefetch the bundle base manifest before aquiring the repo lock (1 second saving), which means doing less work inside the lock, which means a 20% higher commit rate.

check-seclevel: wrap entry point by function This is intended to narrow scope of local variables. The global _verbose flag will be replaced later by ui.verbose.

check-seclevel: set executable bit as it has shebang

bundle20: extract core payload generation in its own function We are about to allow compressing the core of the bundle2. So we extract the generation of this bits in its own parts to make this compression phases easier in a later changesets.

unbundle20: allow registering handlers for stream level parameters As a comment in the code have been asking for, it is now possible to register piece of code that handle parameters for the stream. I've been wondering is such function should be class methods or not. I eventually went for externally decorated methods to stick with the culture of extensibility from an extensions that apply to bundle2.

bundle2: allow to specify unsupported value on error A client may support an argument but not some of its values (eg: coming "compression" parameters). We allow this case to be carried in the exception.

bundle2: rename error exception class for unsupported feature The original name explicitly mention "Part", however it is also used outside of parts related feature. We rename from 'UnsupportedPartError' to 'BundleUnknownFeatureError' to fix this.

changegroup: use a different compression key for BZ in HG10 For "space saving", bundle1 "strip" the first two bytes of the BZ stream since they always are 'BZ'. So the current code boostrap the uncompressor with 'BZ'. This hack is impractical in more generic case so we move it in a dedicated "decompression".

monoblue: provide links to branches, tags and bookmarks by name This is adapted from cd842821db2c, that was added to paper for 3.5 release. It adds another way to refer to branches, tags and bookmarks in urls: by name. It's still possible to navigate to a specific changeset hash, but now you can get more descriptive urls straight from /summary page, for example. branchentry template (and so the whole branches table on /summary and /branches) lost the column that had a plain changeset hash, because tags and bookmarks don't have this column and also because there is already a way to address branch by its changeset hash (changeset link just next to it). Maybe we can instead bring this column with a plain changeset hash to tags and bookmarks, but this, more terse, new look feels fine.

gitweb: provide links to branches, tags and bookmarks by name This is adapted from cd842821db2c, that was added to paper for 3.5 release. It adds another way to refer to branches, tags and bookmarks in urls: by name. It's still possible to navigate to a specific changeset hash, but now you can get more descriptive urls straight from /summary page, for example. branchentry template (and so the whole branches table on /summary and /branches) lost the column that had a plain changeset hash, because tags and bookmarks don't have this column and also because there is already a way to address branch by its changeset hash (changeset link just next to it). Maybe we can instead bring this column with a plain changeset hash to tags and bookmarks, but this, more terse, new look feels fine.

cmdutil: remove HG: prefix from translation strings

i18n-zh_CN: annotate broken HG: translations

lock: recognize parent locks while acquiring This is part of a series that will allow locks to be inherited by subprocesses in limited circumstances. This patch enables the logic introduced in previous patches.

test-lock.py: fix testing for forks The earlier test worked only because the held count went up to 2, so the first release brought it down to 1. Making a copy of the lock fixes that issue.

test-lock.py: allow PID to be changed in test state This will be used in upcoming patches to create locks that appear as if they're being created by child processes.

test-lock.py: add a lock wrapper that allows faking the PID This will be used in upcoming patches to create locks that appear as if they're being created by child processes.

lock: add a wrapper to os.getpid() to make testing easier This will allow us to fake locks across processes more easily.

test-lock.py: move temp dir generation to testcase In upcoming patches we'll want to create multiple test state objects with a common test directory.

test-lock.py: copy-edit assertions about file existing Before: expected lock to exists but actually did not exists After: expected lock to exist but actually did not exist

revlog: don't flush data file after every added revision The current behavior of revlogs is to flush the data file when writing data to it. Tracing system calls revealed that changegroup processing incurred numerous write(2) calls for values much smaller than the default buffer size (Python defaults to 4096, but it can be adjusted based on detected block size at run time by CPython). The reason we flush revlogs is so readers have all data available. For example, the current code in revlog.py will re-open the revlog file (instead of seeking an existing file handle) to read the text of a revision. This happens when starting a new delta chain when adding several revisions from changegroups, for example. Yes, this is likely sub-optimal (we should probably be sharing file descriptors between readers and writers to avoid the flushing and associated overhead of re-opening files). While flushing revlogs is necessary, it appears all callers are diligent about flushing files before a read is performed (see buildtext() in _addrevision()), making the flush in _writeentry() redundant and unncessary. So, we remove it. In practice, this means we incur a write(2) a) when the buffer is full (typically 4096 bytes) b) when a new delta chain is created rather than after every added revision. This applies to every revlog, but by volume it mostly impacts filelogs. Removing the redundant flush from _writeentry() significantly reduces the number of write(2) calls during changegroup processing on my Linux machine. When applying a changegroup of the hg repo based on my local repo, the total number of write(2) calls during application of the mercurial/localrepo.py revlogs dropped from 1,320 to 217 with this patch applied. Total I/O related system calls dropped from 1,577 to 474. When unbundling a mozilla-central gzipped bundle (264,403 changesets with 1,492,215 changes to 222,507 files), total write(2) calls dropped from 1,252,881 to 827,106 and total system calls dropped from 3,601,259 to 3,178,636 - a reduction of 425,775! While the system call reduction is significant, it appears to have no impact on wall time on my Linux and Windows machines. Still, fewer syscalls is fewer syscalls. Surely this can't hurt. If nothing else, it makes examining remaining system call usage simpler and opens the door to experimenting with the performance impact of different buffer sizes.

revlog: use existing file handle when reading during _addrevision _addrevision() may need to read from revlogs as part of computing deltas. Previously, we would flush existing file handles and open a new, short-lived file handle to perform the reading. If we have an existing file handle, it seems logical to reuse it for reading instead of opening a new file handle. This patch makes that the new behavior. After this patch, revlog files are only reopened when adding revisions if the revlog is switched from inline to non-inline. On Linux when unbundling a bundle of the mozilla-central repo, this patch has the following impact on system call counts: Call Before After Delta write 827,639 673,390 -154,249 open 700,103 684,089 -16,014 read 74,489 74,489 0 fstat 493,924 461,896 -32,028 close 249,131 233,117 -16,014 stat 242,001 242,001 0 lstat 18,676 18,676 0 lseek 20,268 20,268 0 ioctl 14,652 13,173 -1,479 TOTAL 3,180,758 2,930,679 -250,079 It's worth noting that many of the open() calls fail due to missing files. That's why there are many more open() calls than close(). Despite the significant system call reduction, this change does not seem to have a significant performance impact on Linux. On Windows 10 (not a VM, on a SSD), this patch appears to reduce unbundle time for mozilla-central from ~960s to ~920s. This isn't as significant as I was hoping. But a decrease it is nonetheless. Still, Windows unbundle performance is still >2x slower than Linux. Despite the lack of significant gains, fewer system calls is fewer system calls. If nothing else, this will narrow the focus of potential areas to optimize in the future.

revlog: always open revlogs for reading and appending An upcoming patch will teach revlogs to use the existing file handle to read revision data instead of opening a new file handle just for quick reads. For this to work, files must be opened for reading as well. This patch is merely cosmetic: there are no behavior changes.

revlog: support using an existing file handle when reading revlogs Currently, the low-level revlog reading code always opens a new file handle. In some key scenarios, the revlog is already opened and an existing file handle could be used to read. This patch paves the road to that by teaching various revlog reading functions to accept an optional existing file handle to read from.

revlog: add docstring for checkinlinesize() The name is deceptive: it does more than just "check." Add a docstring to clarify what's going on.

windows: insert file positioning call between reads and writes fopen() and fdopen() have a unique-to-Windows requirement that transitions between read and write operations in files opened in modes r+, w+, and a+ perform a file positioning call (fsetpos, fseek, or rewind) in between. While the MSDN docs don't say what will happen if this is not done, observations reveal that Python raises an IOError with errno 0. Furthermore, I /think/ this behavior isn't deterministic. But I can reproduce it reliably with subsequent patches applied that open revlogs in a+ mode and perform both reads and writes. This patch introduces a proxy class for file handles opened in r+, w+, and a+ mode on Windows. The class intercepts calls and audits whether a file positioning function has been called between read and write operations. If not, a dummy, no-op seek to the current file position is performed. This appears to be sufficient to "trick" Windows into allowing transitions between read and writes without raising errors.

tests: suppress verbose output of svn transaction Subversion 1.9 shows more verbose messages than 1.8 and the tests fail because of them. These outputs are not important in our tests, so let's suppress them by -q or grep -v.