view tests/test-extdiff.t @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "extdiff=" >> $HGRCPATH

  $ hg init a
  $ cd a
  $ echo a > a
  $ echo b > b
  $ hg add
  adding a
  adding b

Should diff cloned directories:

  $ hg extdiff -o -r $opt
  Only in a: a
  Only in a: b
  [1]

  $ cat <<EOF >> $HGRCPATH
  > [extdiff]
  > cmd.falabala = echo
  > opts.falabala = diffing
  > cmd.edspace = echo
  > opts.edspace = "name  <[e-mail]>"
  > EOF

  $ hg falabala
  diffing a.000000000000 a
  [1]

  $ hg help falabala
  hg falabala [OPTION]... [FILE]...
  
  use external program to diff repository (or selected files)
  
      Show differences between revisions for the specified files, using the
      following program:
  
        'echo'
  
      When two revision arguments are given, then changes are shown between
      those revisions. If only one revision is specified then that revision is
      compared to the working directory, and, when no revisions are specified,
      the working directory files are compared to its parent.
  
  options ([+] can be repeated):
  
   -o --option OPT [+]      pass option to comparison program
   -r --rev REV [+]         revision
   -c --change REV          change made by revision
      --patch               compare patches for two revisions
   -I --include PATTERN [+] include names matching the given patterns
   -X --exclude PATTERN [+] exclude names matching the given patterns
   -S --subrepos            recurse into subrepositories
  
  (some details hidden, use --verbose to show complete help)

  $ hg ci -d '0 0' -mtest1

  $ echo b >> a
  $ hg ci -d '1 0' -mtest2

Should diff cloned files directly:

  $ hg falabala -r 0:1
  diffing "*\\extdiff.*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  diffing */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

Specifying an empty revision should abort.

  $ hg extdiff -p diff --patch --rev 'ancestor()' --rev 1
  abort: empty revision on one side of range
  [255]

Test diff during merge:

  $ hg update -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo c >> c
  $ hg add c
  $ hg ci -m "new branch" -d '1 0'
  created new head
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

Should diff cloned file against wc file:

  $ hg falabala
  diffing "*\\extdiff.*\\a.2a13a4d2da36\\a" "*\\a\\a" (glob) (windows !)
  diffing */extdiff.*/a.2a13a4d2da36/a */a/a (glob) (no-windows !)
  [1]


Test --change option:

  $ hg ci -d '2 0' -mtest3

  $ hg falabala -c 1
  diffing "*\\extdiff.*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  diffing */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

Check diff are made from the first parent:

  $ hg falabala -c 3 || echo "diff-like tools yield a non-zero exit code"
  diffing "*\\extdiff.*\\a.2a13a4d2da36\\a" "a.46c0e4daeb72\\a" (glob) (windows !)
  diffing */extdiff.*/a.2a13a4d2da36/a a.46c0e4daeb72/a (glob) (no-windows !)
  diff-like tools yield a non-zero exit code

issue3153: ensure using extdiff with removed subrepos doesn't crash:

  $ hg init suba
  $ cd suba
  $ echo suba > suba
  $ hg add
  adding suba
  $ hg ci -m "adding suba file"
  $ cd ..
  $ echo suba=suba > .hgsub
  $ hg add
  adding .hgsub
  $ hg ci -Sm "adding subrepo"
  $ echo > .hgsub
  $ hg ci -m "removing subrepo"
  $ hg falabala -r 4 -r 5 -S
  diffing a.398e36faf9c6 a.5ab95fb166c4
  [1]

issue4463: usage of command line configuration without additional quoting

  $ cat <<EOF >> $HGRCPATH
  > [extdiff]
  > cmd.4463a = echo
  > opts.4463a = a-naked 'single quoted' "double quoted"
  > 4463b = echo b-naked 'single quoted' "double quoted"
  > echo =
  > EOF
  $ hg update -q -C 0
  $ echo a >> a

  $ hg --debug 4463a | grep '^running'
  running 'echo a-naked \'single quoted\' "double quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running 'echo a-naked \'single quoted\' "double quoted" */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)
  $ hg --debug 4463b | grep '^running'
  running 'echo b-naked \'single quoted\' "double quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running 'echo b-naked \'single quoted\' "double quoted" */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)
  $ hg --debug echo | grep '^running'
  running '*echo* "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running '*echo */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)

(getting options from other than extdiff section)

  $ cat <<EOF >> $HGRCPATH
  > [extdiff]
  > # using diff-tools diffargs
  > 4463b2 = echo
  > # using merge-tools diffargs
  > 4463b3 = echo
  > # no diffargs
  > 4463b4 = echo
  > [diff-tools]
  > 4463b2.diffargs = b2-naked 'single quoted' "double quoted"
  > [merge-tools]
  > 4463b3.diffargs = b3-naked 'single quoted' "double quoted"
  > EOF

  $ hg --debug 4463b2 | grep '^running'
  running 'echo b2-naked \'single quoted\' "double quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running 'echo b2-naked \'single quoted\' "double quoted" */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)
  $ hg --debug 4463b3 | grep '^running'
  running 'echo b3-naked \'single quoted\' "double quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running 'echo b3-naked \'single quoted\' "double quoted" */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)
  $ hg --debug 4463b4 | grep '^running'
  running 'echo "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running 'echo */a $TESTTMP/a/a' in */extdiff.* (glob) (no-windows !)
  $ hg --debug 4463b4 --option b4-naked --option 'being quoted' | grep '^running'
  running 'echo b4-naked "being quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running "echo b4-naked 'being quoted' */a $TESTTMP/a/a" in */extdiff.* (glob) (no-windows !)
  $ hg --debug extdiff -p echo --option echo-naked --option 'being quoted' | grep '^running'
  running 'echo echo-naked "being quoted" "*\\a" "*\\a"' in */extdiff.* (glob) (windows !)
  running "echo echo-naked 'being quoted' */a $TESTTMP/a/a" in */extdiff.* (glob) (no-windows !)

  $ touch 'sp ace'
  $ hg add 'sp ace'
  $ hg ci -m 'sp ace'
  created new head
  $ echo > 'sp ace'

Test pre-72a89cf86fcd backward compatibility with half-baked manual quoting

  $ cat <<EOF >> $HGRCPATH
  > [extdiff]
  > odd =
  > [merge-tools]
  > odd.diffargs = --foo='\$clabel' '\$clabel' "--bar=\$clabel" "\$clabel"
  > odd.executable = echo
  > EOF

  $ hg --debug odd | grep '^running'
  running '"*\\echo.exe" --foo="sp ace" "sp ace" --bar="sp ace" "sp ace"' in * (glob) (windows !)
  running "*/echo --foo='sp ace' 'sp ace' --bar='sp ace' 'sp ace'" in * (glob) (no-windows !)

Empty argument must be quoted

  $ cat <<EOF >> $HGRCPATH
  > [extdiff]
  > kdiff3 = echo
  > [merge-tools]
  > kdiff3.diffargs=--L1 \$plabel1 --L2 \$clabel \$parent \$child
  > EOF

  $ hg --debug kdiff3 -r0 | grep '^running'
  running 'echo --L1 "@0" --L2 "" a.8a5febb7f867 a' in * (glob) (windows !)
  running "echo --L1 '@0' --L2 '' a.8a5febb7f867 a" in * (glob) (no-windows !)


Test extdiff of multiple files in tmp dir:

  $ hg update -C 0 > /dev/null
  $ echo changed > a
  $ echo changed > b
#if execbit
  $ chmod +x b
#endif

Diff in working directory, before:

  $ hg diff --git
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,1 +1,1 @@
  -a
  +changed
  diff --git a/b b/b
  old mode 100644 (execbit !)
  new mode 100755 (execbit !)
  --- a/b
  +++ b/b
  @@ -1,1 +1,1 @@
  -b
  +changed


Edit with extdiff -p:

Prepare custom diff/edit tool:

  $ cat > 'diff tool.py' << EOT
  > #!$PYTHON
  > import time
  > time.sleep(1) # avoid unchanged-timestamp problems
  > open('a/a', 'ab').write(b'edited\n')
  > open('a/b', 'ab').write(b'edited\n')
  > EOT

#if execbit
  $ chmod +x 'diff tool.py'
#endif

will change to /tmp/extdiff.TMP and populate directories a.TMP and a
and start tool

#if windows
  $ cat > 'diff tool.bat' << EOF
  > @"$PYTHON" "`pwd`/diff tool.py"
  > EOF
  $ hg extdiff -p "`pwd`/diff tool.bat"
  [1]
#else
  $ hg extdiff -p "`pwd`/diff tool.py"
  [1]
#endif

Diff in working directory, after:

  $ hg diff --git
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,1 +1,2 @@
  -a
  +changed
  +edited
  diff --git a/b b/b
  old mode 100644 (execbit !)
  new mode 100755 (execbit !)
  --- a/b
  +++ b/b
  @@ -1,1 +1,2 @@
  -b
  +changed
  +edited

Test extdiff with --option:

  $ hg extdiff -p echo -o this -c 1
  this "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  this */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

  $ hg falabala -o this -c 1
  diffing this "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  diffing this */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

Test extdiff's handling of options with spaces in them:

  $ hg edspace -c 1
  "name  <[e-mail]>" "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  name  <[e-mail]> */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

  $ hg extdiff -p echo -o "name  <[e-mail]>" -c 1
  "name  <[e-mail]>" "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  name  <[e-mail]> */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

Test with revsets:

  $ hg extdif -p echo -c "rev(1)"
  "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

  $ hg extdif -p echo -r "0::1"
  "*\\a.8a5febb7f867\\a" "a.34eed99112ab\\a" (glob) (windows !)
  */extdiff.*/a.8a5febb7f867/a a.34eed99112ab/a (glob) (no-windows !)
  [1]

Fallback to merge-tools.tool.executable|regkey
  $ mkdir dir
  $ cat > 'dir/tool.sh' << 'EOF'
  > #!/bin/sh
  > # Mimic a tool that syncs all attrs, including mtime
  > cp $1/a $2/a
  > touch -r $1/a $2/a
  > chmod +x $2/a
  > echo "** custom diff **"
  > EOF
#if execbit
  $ chmod +x dir/tool.sh
#endif

Windows can't run *.sh directly, so create a shim executable that can be.
Without something executable, the next hg command will try to run `tl` instead
of $tool (and fail).
#if windows
  $ cat > dir/tool.bat <<EOF
  > @sh -c "`pwd`/dir/tool.sh %1 %2"
  > EOF
  $ tool=`pwd`/dir/tool.bat
#else
  $ tool=`pwd`/dir/tool.sh
#endif

  $ cat a
  changed
  edited
  $ hg --debug tl --config extdiff.tl= --config merge-tools.tl.executable=$tool
  making snapshot of 2 files from rev * (glob)
    a
    b
  making snapshot of 2 files from working directory
    a
    b
  running '$TESTTMP/a/dir/tool.bat a.* a' in */extdiff.* (glob) (windows !)
  running '$TESTTMP/a/dir/tool.sh a.* a' in */extdiff.* (glob) (no-windows !)
  ** custom diff **
  file changed while diffing. Overwriting: $TESTTMP/a/a (src: */extdiff.*/a/a) (glob)
  cleaning up temp directory
  [1]
  $ cat a
  a

#if execbit
  $ [ -x a ]

  $ cat > 'dir/tool.sh' << 'EOF'
  > #!/bin/sh
  > chmod -x $2/a
  > echo "** custom diff **"
  > EOF

  $ hg --debug tl --config extdiff.tl= --config merge-tools.tl.executable=$tool
  making snapshot of 2 files from rev * (glob)
    a
    b
  making snapshot of 2 files from working directory
    a
    b
  running '$TESTTMP/a/dir/tool.sh a.* a' in */extdiff.* (glob)
  ** custom diff **
  file changed while diffing. Overwriting: $TESTTMP/a/a (src: */extdiff.*/a/a) (glob)
  cleaning up temp directory
  [1]

  $ [ -x a ]
  [1]
#endif

  $ cd ..

#if symlink

Test symlinks handling (issue1909)

  $ hg init testsymlinks
  $ cd testsymlinks
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ ln -s missing linka
  $ hg add linka
  $ hg falabala -r 0 --traceback
  diffing testsymlinks.07f494440405 testsymlinks
  [1]
  $ cd ..

#endif

Test handling of non-ASCII paths in generated docstrings (issue5301)

  >>> with open("u", "wb") as f:
  ...     n = f.write(b"\xa5\xa5")
  $ U=`cat u`

  $ HGPLAIN=1 hg --config hgext.extdiff= --config extdiff.cmd.td=hi help -k xyzzy
  abort: no matches
  (try 'hg help' for a list of topics)
  [255]

  $ HGPLAIN=1 hg --config hgext.extdiff= --config extdiff.cmd.td=hi help td > /dev/null

  $ LC_MESSAGES=ja_JP.UTF-8 hg --config hgext.extdiff= --config extdiff.cmd.td=$U help -k xyzzy
  abort: no matches
  (try 'hg help' for a list of topics)
  [255]

  $ LC_MESSAGES=ja_JP.UTF-8 hg --config hgext.extdiff= --config extdiff.cmd.td=$U help td \
  > | grep "^      '"
        '\xa5\xa5'