view tests/test-narrow-widen.t @ 48068:bf8837e3d7ce

dirstate: Remove the flat Rust DirstateMap implementation

Before this changeset we had two Rust implementations of `DirstateMap`.
This removes the "flat" DirstateMap so that the "tree" DirstateMap is always
used when Rust enabled. This simplifies the code a lot, and will enable
(in the next changeset) further removal of a trait abstraction.

This is a performance regression when:

* Rust is enabled, and
* The repository uses the legacy dirstate-v1 file format, and
* For `hg status`, unknown files are not listed (such as with `-mard`)

The regression is about 100 milliseconds for `hg status -mard` on a
semi-large repository (mozilla-central), from ~320ms to ~420ms.
We deem this to be small enough to be worth it.

The new dirstate-v2 is still experimental at this point, but we aim to
stabilize it (though not yet enable it by default for new repositories)
in Mercurial 6.0. Eventually, upgrating repositories to dirsate-v2 will
eliminate this regression (and enable other performance improvements).


# Background

The flat DirstateMap was introduced with the first Rust implementation of the
status algorithm. It works similarly to the previous Python + C one, with a
single `HashMap` that associates file paths to a `DirstateEntry` (where Python
has a dict).

We later added the tree DirstateMap where the root of the tree contains nodes
for files and directories that are directly at the root of the repository,
and nodes for directories can contain child nodes representing the files and
directly that *they* contain directly. The shape of this tree mirrors that of
the working directory in the filesystem. This enables the status algorithm to
traverse this tree in tandem with traversing the filesystem tree, which in
turns enables a more efficient algorithm.

Furthermore, the new dirstate-v2 file format is also based on a tree of the
same shape. The tree DirstateMap can access a dirstate-v2 file without parsing
it: binary data in a single large (possibly memory-mapped) bytes buffer is
traversed on demand. This allows `DirstateMap` creation to take `O(1)` time.
(Mutation works by creating new in-memory nodes with copy-on-write semantics,
and serialization is append-mostly.)

The tradeoff is that for "legacy" repositories that use the dirstate-v1 file
format, parsing that file into a tree DirstateMap takes more time. Profiling
shows that this time is dominated by `HashMap`. For a dirstate containing `F`
files with an average `D` directory depth, the flat DirstateMap does parsing
in `O(F)` number of HashMap operations but the tree DirstateMap in `O(F × D)`
operations, since each node has its own HashMap containing its child nodes.
This slower costs ~140ms on an old snapshot of mozilla-central, and ~80ms
on an old snapshot of the Netbeans repository.

The status algorithm is faster, but with `-mard` (when not listing unknown
files) it is typically not faster *enough* to compensate the slower parsing.

Both Rust implementations are always faster than the Python + C implementation


# Benchmark results

All benchmarks are run on changeset 98c0408324e6, with repositories that use
the dirstate-v1 file format, on a server with 4 CPU cores and 4 CPU threads
(no HyperThreading).

`hg status` benchmarks show wall clock times of the entire command as the
average and standard deviation of serveral runs, collected by
https://github.com/sharkdp/hyperfine and reformated.

Parsing benchmarks are wall clock time of the Rust function that converts a
bytes buffer of the dirstate file into the `DirstateMap` data structure as
used by the status algorithm. A single run each, collected by running
`hg status` this environment variable:

    RUST_LOG=hg::dirstate::dirstate_map=trace,hg::dirstate_tree::dirstate_map=trace


Benchmark 1: Rust flat DirstateMap → Rust tree DirstateMap

    hg status

    mozilla-clean    	562.3 ms ± 2.0 ms	→	462.5 ms ± 0.6 ms	 1.22 ± 0.00 times faster
    mozilla-dirty    	859.6 ms ± 2.2 ms	→	719.5 ms ± 3.2 ms	 1.19 ± 0.01 times faster
    mozilla-ignored  	558.2 ms ± 3.0 ms	→	457.9 ms ± 2.9 ms	 1.22 ± 0.01 times faster
    mozilla-unknowns 	859.4 ms ± 5.7 ms	→	716.0 ms ± 4.7 ms	 1.20 ± 0.01 times faster
    netbeans-clean   	336.5 ms ± 0.9 ms	→	339.5 ms ± 0.4 ms	 0.99 ± 0.00 times faster
    netbeans-dirty   	491.4 ms ± 1.6 ms	→	475.1 ms ± 1.2 ms	 1.03 ± 0.00 times faster
    netbeans-ignored 	343.7 ms ± 1.0 ms	→	347.8 ms ± 0.4 ms	 0.99 ± 0.00 times faster
    netbeans-unknowns	484.3 ms ± 1.0 ms	→	466.0 ms ± 1.2 ms	 1.04 ± 0.00 times faster

    hg status -mard

    mozilla-clean    	317.3 ms ± 0.6 ms	→	422.5 ms ± 1.2 ms	 0.75 ± 0.00 times faster
    mozilla-dirty    	315.4 ms ± 0.6 ms	→	417.7 ms ± 1.1 ms	 0.76 ± 0.00 times faster
    mozilla-ignored  	314.6 ms ± 0.6 ms	→	417.4 ms ± 1.0 ms	 0.75 ± 0.00 times faster
    mozilla-unknowns 	312.9 ms ± 0.9 ms	→	417.3 ms ± 1.6 ms	 0.75 ± 0.00 times faster
    netbeans-clean   	212.0 ms ± 0.6 ms	→	283.6 ms ± 0.8 ms	 0.75 ± 0.00 times faster
    netbeans-dirty   	211.4 ms ± 1.0 ms	→	283.4 ms ± 1.6 ms	 0.75 ± 0.01 times faster
    netbeans-ignored 	211.4 ms ± 0.9 ms	→	283.9 ms ± 0.8 ms	 0.74 ± 0.01 times faster
    netbeans-unknowns	211.1 ms ± 0.6 ms	→	283.4 ms ± 1.0 ms	 0.74 ± 0.00 times faster

    Parsing

    mozilla-clean       38.4ms → 177.6ms
    mozilla-dirty       38.8ms → 177.0ms
    mozilla-ignored     38.8ms → 178.0ms
    mozilla-unknowns    38.7ms → 176.9ms
    netbeans-clean      16.5ms → 97.3ms
    netbeans-dirty      16.5ms → 98.4ms
    netbeans-ignored    16.9ms → 97.4ms
    netbeans-unknowns   16.9ms → 96.3ms


Benchmark 2: Python + C dirstatemap → Rust tree DirstateMap

    hg status

    mozilla-clean    	1261.0 ms ± 3.6 ms	→	461.1 ms ± 0.5 ms	 2.73 ± 0.00 times faster
    mozilla-dirty    	2293.4 ms ± 9.1 ms	→	719.6 ms ± 3.6 ms	 3.19 ± 0.01 times faster
    mozilla-ignored  	1240.4 ms ± 2.3 ms	→	457.7 ms ± 1.9 ms	 2.71 ± 0.00 times faster
    mozilla-unknowns 	2283.3 ms ± 9.0 ms	→	719.7 ms ± 3.8 ms	 3.17 ± 0.01 times faster
    netbeans-clean   	879.7 ms ± 3.5 ms	→	339.9 ms ± 0.5 ms	 2.59 ± 0.00 times faster
    netbeans-dirty   	1257.3 ms ± 4.7 ms	→	474.6 ms ± 1.6 ms	 2.65 ± 0.01 times faster
    netbeans-ignored 	943.9 ms ± 1.9 ms	→	347.3 ms ± 1.1 ms	 2.72 ± 0.00 times faster
    netbeans-unknowns	1188.1 ms ± 5.0 ms	→	465.2 ms ± 2.3 ms	 2.55 ± 0.01 times faster

    hg status -mard

    mozilla-clean    	903.2 ms ± 3.6 ms	→	423.4 ms ± 2.2 ms	 2.13 ± 0.01 times faster
    mozilla-dirty    	884.6 ms ± 4.5 ms	→	417.3 ms ± 1.4 ms	 2.12 ± 0.01 times faster
    mozilla-ignored  	881.9 ms ± 1.3 ms	→	417.3 ms ± 0.8 ms	 2.11 ± 0.00 times faster
    mozilla-unknowns 	878.5 ms ± 1.9 ms	→	416.4 ms ± 0.9 ms	 2.11 ± 0.00 times faster
    netbeans-clean   	434.9 ms ± 1.8 ms	→	284.0 ms ± 0.8 ms	 1.53 ± 0.01 times faster
    netbeans-dirty   	434.1 ms ± 0.8 ms	→	283.1 ms ± 0.8 ms	 1.53 ± 0.00 times faster
    netbeans-ignored 	431.7 ms ± 1.1 ms	→	283.6 ms ± 1.8 ms	 1.52 ± 0.01 times faster
    netbeans-unknowns	433.0 ms ± 1.3 ms	→	283.5 ms ± 0.7 ms	 1.53 ± 0.00 times faster

Differential Revision: https://phab.mercurial-scm.org/D11516

#testcases flat tree
  $ . "$TESTDIR/narrow-library.sh"

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > l = log -G -T "{if(ellipsis, '...')}{rev}: {desc}\n"
  > EOF

#if tree
  $ cat << EOF >> $HGRCPATH
  > [experimental]
  > treemanifest = 1
  > EOF
#endif

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [narrow]
  > serveellipses=True
  > EOF

  $ mkdir inside
  $ echo 'inside' > inside/f
  $ hg add inside/f
  $ hg commit -m 'add inside'

  $ mkdir widest
  $ echo 'widest' > widest/f
  $ hg add widest/f
  $ hg commit -m 'add widest'

  $ mkdir outside
  $ echo 'outside' > outside/f
  $ hg add outside/f
  $ hg commit -m 'add outside'

  $ cd ..

narrow clone the inside file

  $ hg clone --narrow ssh://user@dummy/master narrow --include inside
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files
  new changesets *:* (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow
  $ hg tracked
  I path:inside
  $ ls -A
  .hg
  inside
  $ cat inside/f
  inside
  $ cd ..

add more upstream files which we will include in a wider narrow spec

  $ cd master

  $ mkdir wider
  $ echo 'wider' > wider/f
  $ hg add wider/f
  $ echo 'widest v2' > widest/f
  $ hg commit -m 'add wider, update widest'

  $ echo 'widest v3' > widest/f
  $ hg commit -m 'update widest v3'

  $ echo 'inside v2' > inside/f
  $ hg commit -m 'update inside'

  $ mkdir outside2
  $ echo 'outside2' > outside2/f
  $ hg add outside2/f
  $ hg commit -m 'add outside2'

  $ echo 'widest v4' > widest/f
  $ hg commit -m 'update widest v4'

  $ hg l
  @  7: update widest v4
  |
  o  6: add outside2
  |
  o  5: update inside
  |
  o  4: update widest v3
  |
  o  3: add wider, update widest
  |
  o  2: add outside
  |
  o  1: add widest
  |
  o  0: add inside
  

  $ cd ..

Widen the narrow spec to see the widest file. This should not get the newly
added upstream revisions.

  $ cd narrow
  $ hg l
  @  ...1: add outside
  |
  o  0: add inside
  
  $ hg tracked --addinclude widest/f
  comparing with ssh://user@dummy/master
  searching for changes
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 3 files
  $ hg l
  @  ...2: add outside
  |
  o  1: add widest
  |
  o  0: add inside
  
  $ hg tracked
  I path:inside
  I path:widest/f

  $ cat widest/f
  widest

Pull down the newly added upstream revision.

  $ hg pull
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 4 changes to 2 files
  new changesets *:* (glob)
  (run 'hg update' to get a working copy)
  $ hg update -r 'desc("add wider")'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat widest/f
  widest v2

  $ hg update -r 'desc("update inside")'
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat widest/f
  widest v3
  $ cat inside/f
  inside v2

  $ hg l
  o  7: update widest v4
  |
  o  ...6: add outside2
  |
  @  5: update inside
  |
  o  4: update widest v3
  |
  o  3: add wider, update widest
  |
  o  ...2: add outside
  |
  o  1: add widest
  |
  o  0: add inside
  

Check that widening with a newline fails

  $ hg tracked --addinclude 'widest
  > '
  abort: newlines are not allowed in narrowspec paths
  [255]

widen the narrow spec to include the wider file

  $ hg tracked --addinclude wider
  comparing with ssh://user@dummy/master
  searching for changes
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 5 files
  $ hg tracked
  I path:inside
  I path:wider
  I path:widest/f
  $ hg update 'desc("add widest")'
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cat widest/f
  widest
  $ hg update 'desc("add wider, update widest")'
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat wider/f
  wider
  $ cat widest/f
  widest v2
  $ hg update 'desc("update widest v3")'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat widest/f
  widest v3
  $ hg update 'desc("update widest v4")'
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat widest/f
  widest v4

  $ hg l
  @  7: update widest v4
  |
  o  ...6: add outside2
  |
  o  5: update inside
  |
  o  4: update widest v3
  |
  o  3: add wider, update widest
  |
  o  ...2: add outside
  |
  o  1: add widest
  |
  o  0: add inside
  

separate suite of tests: files from 0-10 modified in changes 0-10. This allows
more obvious precise tests tickling particular corner cases.

  $ cd ..
  $ hg init upstream
  $ cd upstream
  $ cat >> .hg/hgrc <<EOF
  > [narrow]
  > serveellipses=True
  > EOF
  $ for x in `$TESTDIR/seq.py 0 10`
  > do
  >   mkdir d$x
  >   echo $x > d$x/f
  >   hg add d$x/f
  >   hg commit -m "add d$x/f"
  > done
  $ hg log -T "{rev}: {desc}\n"
  10: add d10/f
  9: add d9/f
  8: add d8/f
  7: add d7/f
  6: add d6/f
  5: add d5/f
  4: add d4/f
  3: add d3/f
  2: add d2/f
  1: add d1/f
  0: add d0/f

make narrow clone with every third node.

  $ cd ..
  $ hg clone --narrow ssh://user@dummy/upstream narrow2 --include d0 --include d3 --include d6 --include d9
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 4 changes to 4 files
  new changesets *:* (glob)
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow2
  $ hg tracked
  I path:d0
  I path:d3
  I path:d6
  I path:d9
  $ hg verify
  checking changesets
  checking manifests
  checking directory manifests (tree !)
  crosschecking files in changesets and manifests
  checking files
  checked 8 changesets with 4 changes to 4 files
  $ hg l
  @  ...7: add d10/f
  |
  o  6: add d9/f
  |
  o  ...5: add d8/f
  |
  o  4: add d6/f
  |
  o  ...3: add d5/f
  |
  o  2: add d3/f
  |
  o  ...1: add d2/f
  |
  o  0: add d0/f
  
  $ hg tracked --addinclude d1
  comparing with ssh://user@dummy/upstream
  searching for changes
  saved backup bundle to $TESTTMP/narrow2/.hg/strip-backup/*-widen.hg (glob)
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 5 changes to 9 files
  $ hg tracked
  I path:d0
  I path:d1
  I path:d3
  I path:d6
  I path:d9
  $ hg l
  @  ...8: add d10/f
  |
  o  7: add d9/f
  |
  o  ...6: add d8/f
  |
  o  5: add d6/f
  |
  o  ...4: add d5/f
  |
  o  3: add d3/f
  |
  o  ...2: add d2/f
  |
  o  1: add d1/f
  |
  o  0: add d0/f
  

Verify shouldn't claim the repo is corrupt after a widen.

  $ hg verify
  checking changesets
  checking manifests
  checking directory manifests (tree !)
  crosschecking files in changesets and manifests
  checking files
  checked 9 changesets with 5 changes to 5 files

Widening preserves parent of local commit

  $ cd ..
  $ hg clone -q --narrow ssh://user@dummy/upstream narrow3 --include d2 -r 2
  $ cd narrow3
  $ hg l
  @  1: add d2/f
  |
  o  ...0: add d1/f
  
  $ hg pull -q -r 3
  $ hg co -q tip
  $ hg pull -q -r 4
  $ echo local > d2/f
  $ hg ci -m local
  created new head
  $ hg l
  @  4: local
  |
  | o  ...3: add d4/f
  |/
  o  ...2: add d3/f
  |
  o  1: add d2/f
  |
  o  ...0: add d1/f
  
  $ hg tracked -q --addinclude d0 --addinclude d9
  $ hg l
  @  5: local
  |
  | o  ...4: add d4/f
  |/
  o  ...3: add d3/f
  |
  o  2: add d2/f
  |
  o  ...1: add d1/f
  |
  o  0: add d0/f
  

Widening preserves bookmarks

  $ cd ..
  $ hg clone -q --narrow ssh://user@dummy/upstream narrow-bookmarks --include d4
  $ cd narrow-bookmarks
  $ echo local > d4/f
  $ hg ci -m local
  $ hg bookmarks bookmark
  $ hg bookmarks
   * bookmark                  3:* (glob)
  $ hg -q tracked --addinclude d2
  $ hg bookmarks
   * bookmark                  5:* (glob)
  $ hg log -r bookmark -T '{desc}\n'
  local

Widening that fails can be recovered from

  $ cd ..
  $ hg clone -q --narrow ssh://user@dummy/upstream interrupted --include d0
  $ cd interrupted
  $ echo local > d0/f
  $ hg ci -m local
  $ hg l
  @  2: local
  |
  o  ...1: add d10/f
  |
  o  0: add d0/f
  
  $ hg bookmarks bookmark
  $ hg --config hooks.pretxnchangegroup.bad=false tracked --addinclude d1
  comparing with ssh://user@dummy/upstream
  searching for changes
  saved backup bundle to $TESTTMP/interrupted/.hg/strip-backup/*-widen.hg (glob)
  adding changesets
  adding manifests
  adding file changes
  transaction abort!
  rollback completed
  abort: pretxnchangegroup.bad hook exited with status 1
  [40]
  $ hg l
  $ hg bookmarks
  no bookmarks set
  $ hg unbundle .hg/strip-backup/*-widen.hg
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 1 files
  new changesets *:* (glob)
  (run 'hg update' to get a working copy)
  $ hg l
  o  2: local
  |
  o  ...1: add d10/f
  |
  o  0: add d0/f
  
  $ hg bookmarks
   * bookmark                  2:* (glob)