revlog: break up compression of large deltas
Python's zlib apparently makes an internal copy of strings passed to
compress(). To avoid this, compress strings 1M at a time, then join
them at the end if the result would be smaller than the original.
For initial commits of large but compressible files, this cuts peak
memory usage nearly in half.
changeset: 3:593cbf6fb2b4
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag some-tag for changeset ad681a868e44
changeset: 2:ad681a868e44
tag: some-tag
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add foo/file
changeset: 1:cbba8ecc03b7
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: remove foo
changeset: 0:327daa9251fa
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add foo and bar
initializing destination new repository
scanning source...
sorting...
converting...
3 add foo and bar
2 remove foo
1 add foo/file
0 Added tag some-tag for changeset ad681a868e44
comparing with ../orig
searching for changes
no changes found
% dirstate should be empty:
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% put something in the dirstate:
a 0 -1 unset baz
copy: bar -> baz
% add a new revision in the original repo
destination new is a Mercurial repository
scanning source...
sorting...
converting...
0 add baz
comparing with ../orig
searching for changes
no changes found
% dirstate should be the same (no output below):
% no copies
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
baz not renamed