revlog: automatically read from opened file handles
The revlog reading code commonly opens a new file handle for
reading on demand. There is support for passing a file handle
to revlog.revision(). But it is marked as an internal argument.
When revlogs are written, we write() data as it is available. But
we don't flush() data until all revisions are written.
Putting these two traits together, it is possible for an in-process
revlog reader during active writes to trigger the opening of a new
file handle on a file with unflushed writes. The reader won't have
access to all "available" revlog data (as it hasn't been flushed).
And with the introduction of the previous patch, this can lead to
the revlog raising an error due to a partial read.
I witnessed this behavior when applying changegroup data (via
`hg pull`) before issue6006 was fixed via different means. Having
this and the previous patch in play would have helped cause errors
earlier rather than manifesting as hash verification failures.
While this has been a long-standing issue, I believe the relatively
new delta computation code has tickled it into being more common.
This is because the new delta computation code will compute deltas
in more scenarios. This can lead to revlog reading. While the delta
computation code is probably supposed to reuse file handles, it
appears it isn't doing so in all circumstances.
But the issue runs deeper than that. Theoretically, any code can
access revision data during revlog writes. It appears we were just
getting lucky that it wasn't. (The "add revision callback" passed to
addgroup() provides an avenue to do this.)
If I changed the revlog's behavior to not cache the full revision
text or to clear caches after revision insertion during addgroup(),
I was able to produce crashes 100% of the time when writing changelog
revisions. This is because changelog's add revision callback attempts
to resolve the revision data to access the changed files list. And
without the revision's fulltext being cached, we performed a revlog
read, which required opening a new file handle. This attempted to read
unflushed data, leading to a partial read and a crash.
This commit teaches the revlog to store the file handles used for
writing multiple revisions during addgroup(). It also teaches the
code for resolving a file handle when reading to use these handles,
if available. This ensures that *any* reads (regardless of their
source) use the active writing file handles, if available. These
file handles have access to the unflushed data because they wrote it.
This allows reads to complete without issue.
Differential Revision: https://phab.mercurial-scm.org/D5267
Test EOL extension
$ cat >> $HGRCPATH <<EOF
> [diff]
> git = True
> EOF
Set up helpers
$ cat > switch-eol.py <<'EOF'
> from __future__ import absolute_import
> import os
> import sys
> try:
> import msvcrt
> msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
> msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
> except ImportError:
> pass
> eolmap = {b'\n': '\\n', b'\r\n': '\\r\\n'}
> (old, new) = sys.argv[1] == 'LF' and (b'\n', b'\r\n') or (b'\r\n', b'\n')
> print("%% switching encoding from '%s' to '%s'"
> % (eolmap[old], eolmap[new]))
> for path in sys.argv[2:]:
> data = open(path, 'rb').read()
> data = data.replace(old, new)
> open(path, 'wb').write(data)
> EOF
$ seteol () {
> if [ $1 = "LF" ]; then
> EOL='\n'
> else
> EOL='\r\n'
> fi
> }
$ makerepo () {
> seteol $1
> echo "% setup $1 repository"
> hg init repo
> cd repo
> cat > .hgeol <<EOF
> [repository]
> native = $1
> [patterns]
> mixed.txt = BIN
> **.txt = native
> EOF
> printf "first${EOL}second${EOL}third${EOL}" > a.txt
> hg commit --addremove -m 'checkin'
> echo
> cd ..
> }
$ dotest () {
> seteol $1
> echo "% hg clone repo repo-$1"
> hg clone --noupdate repo repo-$1
> cd repo-$1
> cat > .hg/hgrc <<EOF
> [extensions]
> eol =
> [eol]
> native = $1
> EOF
> hg update
> echo '% a.txt'
> cat a.txt
> echo '% hg cat a.txt'
> hg cat a.txt
> printf "fourth${EOL}" >> a.txt
> echo '% a.txt'
> cat a.txt
> hg diff
> "$PYTHON" ../switch-eol.py $1 a.txt
> echo '% hg diff only reports a single changed line:'
> hg diff
> echo "% reverting back to $1 format"
> hg revert a.txt
> cat a.txt
> printf "first\r\nsecond\n" > mixed.txt
> hg add mixed.txt
> echo "% hg commit of inconsistent .txt file marked as binary (should work)"
> hg commit -m 'binary file'
> echo "% hg commit of inconsistent .txt file marked as native (should fail)"
> printf "first\nsecond\r\nthird\nfourth\r\n" > a.txt
> hg commit -m 'inconsistent file'
> echo "% hg commit --config eol.only-consistent=False (should work)"
> hg commit --config eol.only-consistent=False -m 'inconsistent file'
> echo "% hg commit of binary .txt file marked as native (binary files always okay)"
> printf "first${EOL}\0${EOL}third${EOL}" > a.txt
> hg commit -m 'binary file'
> cd ..
> rm -r repo-$1
> }
$ makemixedrepo () {
> echo
> echo "# setup $1 repository"
> hg init mixed
> cd mixed
> printf "foo\r\nbar\r\nbaz\r\n" > win.txt
> printf "foo\nbar\nbaz\n" > unix.txt
> #printf "foo\r\nbar\nbaz\r\n" > mixed.txt
> hg commit --addremove -m 'created mixed files'
> echo "# setting repository-native EOLs to $1"
> cat > .hgeol <<EOF
> [repository]
> native = $1
> [patterns]
> **.txt = native
> EOF
> hg commit --addremove -m 'added .hgeol'
> cd ..
> }
$ testmixed () {
> echo
> echo "% hg clone mixed mixed-$1"
> hg clone mixed mixed-$1
> cd mixed-$1
> echo '% hg status (eol extension not yet activated)'
> hg status
> cat > .hg/hgrc <<EOF
> [extensions]
> eol =
> [eol]
> native = $1
> EOF
> echo '% hg status (eol activated)'
> hg status
> echo '% hg commit'
> hg commit -m 'synchronized EOLs'
> echo '% hg status'
> hg status
> cd ..
> rm -r mixed-$1
> }
Basic tests
$ makerepo LF
% setup LF repository
adding .hgeol
adding a.txt
$ dotest LF
% hg clone repo repo-LF
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% a.txt
first
second
third
% hg cat a.txt
first
second
third
% a.txt
first
second
third
fourth
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first
second
third
+fourth
% switching encoding from '\n' to '\r\n'
% hg diff only reports a single changed line:
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first
second
third
+fourth
% reverting back to LF format
first
second
third
% hg commit of inconsistent .txt file marked as binary (should work)
% hg commit of inconsistent .txt file marked as native (should fail)
abort: inconsistent newline style in a.txt
% hg commit --config eol.only-consistent=False (should work)
% hg commit of binary .txt file marked as native (binary files always okay)
$ dotest CRLF
% hg clone repo repo-CRLF
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% a.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg cat a.txt
first
second
third
% a.txt
first\r (esc)
second\r (esc)
third\r (esc)
fourth\r (esc)
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first
second
third
+fourth
% switching encoding from '\r\n' to '\n'
% hg diff only reports a single changed line:
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first
second
third
+fourth
% reverting back to CRLF format
first\r (esc)
second\r (esc)
third\r (esc)
% hg commit of inconsistent .txt file marked as binary (should work)
% hg commit of inconsistent .txt file marked as native (should fail)
abort: inconsistent newline style in a.txt
% hg commit --config eol.only-consistent=False (should work)
% hg commit of binary .txt file marked as native (binary files always okay)
$ rm -r repo
$ makerepo CRLF
% setup CRLF repository
adding .hgeol
adding a.txt
$ dotest LF
% hg clone repo repo-LF
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% a.txt
first
second
third
% hg cat a.txt
first\r (esc)
second\r (esc)
third\r (esc)
% a.txt
first
second
third
fourth
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first\r (esc)
second\r (esc)
third\r (esc)
+fourth\r (esc)
% switching encoding from '\n' to '\r\n'
% hg diff only reports a single changed line:
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first\r (esc)
second\r (esc)
third\r (esc)
+fourth\r (esc)
% reverting back to LF format
first
second
third
% hg commit of inconsistent .txt file marked as binary (should work)
% hg commit of inconsistent .txt file marked as native (should fail)
abort: inconsistent newline style in a.txt
% hg commit --config eol.only-consistent=False (should work)
% hg commit of binary .txt file marked as native (binary files always okay)
$ dotest CRLF
% hg clone repo repo-CRLF
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% a.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg cat a.txt
first\r (esc)
second\r (esc)
third\r (esc)
% a.txt
first\r (esc)
second\r (esc)
third\r (esc)
fourth\r (esc)
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first\r (esc)
second\r (esc)
third\r (esc)
+fourth\r (esc)
% switching encoding from '\r\n' to '\n'
% hg diff only reports a single changed line:
diff --git a/a.txt b/a.txt
--- a/a.txt
+++ b/a.txt
@@ -1,3 +1,4 @@
first\r (esc)
second\r (esc)
third\r (esc)
+fourth\r (esc)
% reverting back to CRLF format
first\r (esc)
second\r (esc)
third\r (esc)
% hg commit of inconsistent .txt file marked as binary (should work)
% hg commit of inconsistent .txt file marked as native (should fail)
abort: inconsistent newline style in a.txt
% hg commit --config eol.only-consistent=False (should work)
% hg commit of binary .txt file marked as native (binary files always okay)
$ rm -r repo
Mixed tests
$ makemixedrepo LF
# setup LF repository
adding unix.txt
adding win.txt
# setting repository-native EOLs to LF
adding .hgeol
$ testmixed LF
% hg clone mixed mixed-LF
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg status (eol extension not yet activated)
% hg status (eol activated)
M win.txt
% hg commit
% hg status
$ testmixed CRLF
% hg clone mixed mixed-CRLF
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg status (eol extension not yet activated)
% hg status (eol activated)
M win.txt
% hg commit
% hg status
$ rm -r mixed
$ makemixedrepo CRLF
# setup CRLF repository
adding unix.txt
adding win.txt
# setting repository-native EOLs to CRLF
adding .hgeol
$ testmixed LF
% hg clone mixed mixed-LF
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg status (eol extension not yet activated)
% hg status (eol activated)
M unix.txt
% hg commit
% hg status
$ testmixed CRLF
% hg clone mixed mixed-CRLF
updating to branch default
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg status (eol extension not yet activated)
% hg status (eol activated)
M unix.txt
% hg commit
% hg status
$ rm -r mixed
$ echo '[extensions]' >> $HGRCPATH
$ echo 'eol =' >> $HGRCPATH
#if unix-permissions
Test issue2569 -- eol extension takes write lock on reading:
$ hg init repo
$ cd repo
$ touch .hgeol
$ hg status
? .hgeol
$ chmod -R -w .hg
$ sleep 1
$ touch .hgeol
$ hg status --traceback
? .hgeol
$ chmod -R u+w .hg
$ cd ..
#endif
Test cleverencode: and cleverdecode: aliases for win32text extension
$ cat <<EOF >> $HGRCPATH
> [encode]
> **.txt = cleverencode:
> [decode]
> **.txt = cleverdecode:
> EOF
$ hg init win32compat
$ cd win32compat
$ printf "foo\r\nbar\r\nbaz\r\n" > win.txt
$ printf "foo\nbar\nbaz\n" > unix.txt
$ hg add
adding unix.txt
adding win.txt
$ hg commit -m checkin
Check that both files have LF line-endings in the repository:
$ hg cat win.txt
foo
bar
baz
$ hg cat unix.txt
foo
bar
baz
Test handling of a broken .hgeol file:
$ touch .hgeol
$ hg add .hgeol
$ hg commit -m 'clean version'
$ echo "bad" > .hgeol
$ hg status
warning: ignoring .hgeol file due to parse error at .hgeol:1: bad
M .hgeol
$ hg revert .hgeol
warning: ignoring .hgeol file due to parse error at .hgeol:1: bad
$ hg status
? .hgeol.orig
Test eol.only-consistent can be specified in .hgeol
$ cd $TESTTMP
$ hg init only-consistent
$ cd only-consistent
$ printf "first\nsecond\r\n" > a.txt
$ hg add a.txt
$ cat > .hgeol << EOF
> [eol]
> only-consistent = True
> EOF
$ hg commit -m 'inconsistent'
abort: inconsistent newline style in a.txt
[255]
$ cat > .hgeol << EOF
> [eol]
> only-consistent = False
> EOF
$ hg commit -m 'consistent'
$ hg init subrepo
$ hg -R subrepo pull -qu .
$ echo "subrepo = subrepo" > .hgsub
$ hg ci -Am "add subrepo"
adding .hgeol
adding .hgsub
$ hg archive -S ../archive
$ find ../archive/* | sort
../archive/a.txt
../archive/subrepo
../archive/subrepo/a.txt
$ cat ../archive/a.txt ../archive/subrepo/a.txt
first\r (esc)
second\r (esc)
first\r (esc)
second\r (esc)
Test trailing newline
$ cat >> $HGRCPATH <<EOF
> [extensions]
> eol=
> EOF
setup repository
$ cd $TESTTMP
$ hg init trailing
$ cd trailing
$ cat > .hgeol <<EOF
> [patterns]
> **.txt = native
> [eol]
> fix-trailing-newline = False
> EOF
add text without trailing newline
$ printf "first\nsecond" > a.txt
$ hg commit --addremove -m 'checking in'
adding .hgeol
adding a.txt
$ rm a.txt
$ hg update -C -q
$ cat a.txt
first
second (no-eol)
$ cat > .hgeol <<EOF
> [patterns]
> **.txt = native
> [eol]
> fix-trailing-newline = True
> EOF
$ printf "third\nfourth" > a.txt
$ hg commit -m 'checking in with newline fix'
$ rm a.txt
$ hg update -C -q
$ cat a.txt
third
fourth
append a line without trailing newline
$ printf "fifth" >> a.txt
$ hg commit -m 'adding another line line'
$ rm a.txt
$ hg update -C -q
$ cat a.txt
third
fourth
fifth
amend of changesets with renamed/deleted files expose new code paths
$ hg mv a.txt b.txt
$ hg ci --amend -q
$ hg diff -c.
diff --git a/a.txt b/b.txt
rename from a.txt
rename to b.txt
--- a/a.txt
+++ b/b.txt
@@ -1,2 +1,3 @@
third
fourth
+fifth
$ cd ..