tests/test-convert-cvsnt-mergepoints.t

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...

#require cvs

  $ filterpath()
  > {
  >     eval "$@" | sed "s:$CVSROOT:*REPO*:g"
  > }
  $ cvscall()
  > {
  >     cvs -f "$@"
  > }

output of 'cvs ci' varies unpredictably, so discard most of it
-- just keep the part that matters

  $ cvsci()
  > {
  >     cvs -f ci -f "$@" > /dev/null
  > }
  $ hgcat()
  > {
  >     hg --cwd src-hg cat -r tip "$1"
  > }
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert = " >> $HGRCPATH

create cvs repository

  $ mkdir cvsmaster
  $ cd cvsmaster
  $ CVSROOT=`pwd`
  $ export CVSROOT
  $ CVS_OPTIONS=-f
  $ export CVS_OPTIONS
  $ cd ..
  $ rmdir cvsmaster
  $ filterpath cvscall -Q -d "$CVSROOT" init

checkout #1: add foo.txt

  $ cvscall -Q checkout -d cvsworktmp .
  $ cd cvsworktmp
  $ mkdir foo
  $ cvscall -Q add foo
  $ cd foo
  $ echo foo > foo.txt
  $ cvscall -Q add foo.txt
  $ cvsci -m "add foo.txt" foo.txt
  $ cd ../..
  $ rm -rf cvsworktmp

checkout #2: create MYBRANCH1 and modify foo.txt on it

  $ cvscall -Q checkout -d cvswork foo
  $ cd cvswork
  $ cvscall -q rtag -b -R MYBRANCH1 foo
  $ cvscall -Q update -P -r MYBRANCH1
  $ echo bar > foo.txt
  $ cvsci -m "bar" foo.txt
  $ echo baz > foo.txt
  $ cvsci -m "baz" foo.txt

create MYBRANCH1_2 and modify foo.txt some more

  $ cvscall -q rtag -b -R -r MYBRANCH1 MYBRANCH1_2 foo
  $ cvscall -Q update -P -r MYBRANCH1_2
  $ echo bazzie > foo.txt
  $ cvsci -m "bazzie" foo.txt

create MYBRANCH1_1 and modify foo.txt yet again

  $ cvscall -q rtag -b -R MYBRANCH1_1 foo
  $ cvscall -Q update -P -r MYBRANCH1_1
  $ echo quux > foo.txt
  $ cvsci -m "quux" foo.txt

merge MYBRANCH1 to MYBRANCH1_1

  $ filterpath cvscall -Q update -P -jMYBRANCH1
  rcsmerge: warning: conflicts during merge
  RCS file: *REPO*/foo/foo.txt,v
  retrieving revision 1.1
  retrieving revision 1.1.2.2
  Merging differences between 1.1 and 1.1.2.2 into foo.txt

carefully placed sleep to dodge cvs bug (optimization?) where it
sometimes ignores a "commit" command if it comes too fast (the -f
option in cvsci seems to work for all the other commits in this
script)

  $ sleep 1
  $ echo xyzzy > foo.txt
  $ cvsci -m "merge1+clobber" foo.txt

#if unix-permissions

return to trunk and merge MYBRANCH1_2

  $ cvscall -Q update -P -A
  $ filterpath cvscall -Q update -P -jMYBRANCH1_2
  RCS file: *REPO*/foo/foo.txt,v
  retrieving revision 1.1
  retrieving revision 1.1.2.2.2.1
  Merging differences between 1.1 and 1.1.2.2.2.1 into foo.txt
  $ cvsci -m "merge2" foo.txt
  $ REALCVS=`which cvs`
  $ echo "for x in \$*; do if [ \"\$x\" = \"rlog\" ]; then echo \"RCS file: $CVSROOT/foo/foo.txt,v\"; cat \"$TESTDIR/test-convert-cvsnt-mergepoints.rlog\"; exit 0; fi; done; $REALCVS \$*" > ../cvs
  $ chmod +x ../cvs
  $ PATH=..:${PATH} hg debugcvsps --parents foo
  collecting CVS rlog
  7 log entries
  creating changesets
  7 changeset entries
  ---------------------
  PatchSet 1 
  Date: * (glob)
  Author: user
  Branch: HEAD
  Tag: (none) 
  Branchpoints: MYBRANCH1, MYBRANCH1_1 
  Log:
  foo.txt
  
  Members: 
  	foo.txt:INITIAL->1.1 
  
  ---------------------
  PatchSet 2 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1
  Tag: (none) 
  Parent: 1
  Log:
  bar
  
  Members: 
  	foo.txt:1.1->1.1.2.1 
  
  ---------------------
  PatchSet 3 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1
  Tag: (none) 
  Branchpoints: MYBRANCH1_2 
  Parent: 2
  Log:
  baz
  
  Members: 
  	foo.txt:1.1.2.1->1.1.2.2 
  
  ---------------------
  PatchSet 4 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_1
  Tag: (none) 
  Parent: 1
  Log:
  quux
  
  Members: 
  	foo.txt:1.1->1.1.4.1 
  
  ---------------------
  PatchSet 5 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_2
  Tag: (none) 
  Parent: 3
  Log:
  bazzie
  
  Members: 
  	foo.txt:1.1.2.2->1.1.2.2.2.1 
  
  ---------------------
  PatchSet 6 
  Date: * (glob)
  Author: user
  Branch: HEAD
  Tag: (none) 
  Parents: 1,5
  Log:
  merge
  
  Members: 
  	foo.txt:1.1->1.2 
  
  ---------------------
  PatchSet 7 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_1
  Tag: (none) 
  Parents: 4,3
  Log:
  merge
  
  Members: 
  	foo.txt:1.1.4.1->1.1.4.2 
  
#endif

  $ cd ..