sparse-revlog: new requirement enabled with format.sparse-revlog
The meaning of the new 'sparse-revlog' requirement is that the revlogs are
allowed to contain wider delta chains with larger holes between the interesting
chunks. These sparse delta chains should be read in several chunks to avoid a
potential explosion of memory usage.
Former version won't know how to read a delta chain in several chunks. They
would keep reading them in a single read, and therefore would be subject to the
potential memory explosion. Hence this new requirement: only versions having
support of sparse-revlog reading should be allowed to read such a revlog.
Implementation of this new algorithm and tools to enable or disable the
requirement will follow in the next changesets.
#require unix-permissions no-root
$ hg init a
$ cd a
$ echo foo > b
$ hg add b
$ hg ci -m "b"
$ chmod -w .hg/store
$ cd ..
$ hg clone a b
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets 97310831fa1a
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ chmod +w a/.hg/store # let test clean up
$ cd b
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ cd ..