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.
#!/bin/sh
hg init test
cd test
cat >>afile <<EOF
0
EOF
hg add afile
hg commit -m "0.0"
cat >>afile <<EOF
1
EOF
hg commit -m "0.1"
cat >>afile <<EOF
2
EOF
hg commit -m "0.2"
cat >>afile <<EOF
3
EOF
hg commit -m "0.3"
hg update -C 0
cat >>afile <<EOF
1
EOF
hg commit -m "1.1"
cat >>afile <<EOF
2
EOF
hg commit -m "1.2"
cat >fred <<EOF
a line
EOF
cat >>afile <<EOF
3
EOF
hg add fred
hg commit -m "1.3"
hg mv afile adifferentfile
hg commit -m "1.3m"
hg update -C 3
hg mv afile anotherfile
hg commit -m "0.3m"
hg debugindex .hg/store/data/afile.i
hg debugindex .hg/store/data/adifferentfile.i
hg debugindex .hg/store/data/anotherfile.i
hg debugindex .hg/store/data/fred.i
hg debugindex .hg/store/00manifest.i
hg verify
cd ..
for i in 0 1 2 3 4 5 6 7 8; do
mkdir test-"$i"
hg --cwd test-"$i" init
hg -R test push -r "$i" test-"$i"
cd test-"$i"
hg verify
cd ..
done
cd test-8
hg pull ../test-7
hg verify