revlog-compression: use zstd by default (if available)
As see in changeset
bb271ec2fbfb, zstd is 20% to 50% faster for reading and
writing.
Use take advantage of the new config behavior to try zstd by default, falling
back to zlib is zstd is not available on that plateform.
Differential Revision: https://phab.mercurial-scm.org/D10326
#require unix-permissions no-root reporevlogstore
$ hg init t
$ cd t
$ echo foo > a
$ hg add a
$ hg commit -m "1"
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 1 changesets with 1 changes to 1 files
$ chmod -r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
abort: Permission denied: '$TESTTMP/t/.hg/store/data/a.i'
[255]
$ chmod +r .hg/store/data/a.i
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 1 changesets with 1 changes to 1 files
$ chmod -w .hg/store/data/a.i
$ echo barber > a
$ hg commit -m "2"
trouble committing a!
abort: Permission denied: '$TESTTMP/t/.hg/store/data/a.i'
[255]
$ chmod -w .
$ hg diff --nodates
diff -r 2a18120dc1c9 a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-foo
+barber
$ chmod +w .
$ chmod +w .hg/store/data/a.i
$ mkdir dir
$ touch dir/a
$ hg status
M a
? dir/a
$ chmod -rx dir
#if no-fsmonitor
(fsmonitor makes "hg status" avoid accessing to "dir")
$ hg status
dir: Permission denied
M a
#endif
Reenable perm to allow deletion:
$ chmod +rx dir
$ cd ..