nodemap: introduce append-only incremental update of the persistent data
Rewriting the full nodemap for each transaction has a cost we would like to
avoid. We introduce a new way to write persistent nodemap data by adding new
information at the end for file. Any new and updated block as added at the end
of the file. The last block is the new root node.
With this method, some of the block already on disk get "dereferenced" and
become dead data. In later changesets, We'll start tracking the amount of dead
data to eventually re-generate a full nodemap.
Differential Revision: https://phab.mercurial-scm.org/D7886
$ . $TESTDIR/wireprotohelpers.sh
$ hg init server
$ enablehttpv2 server
$ cd server
$ cat >> .hg/hgrc << EOF
> [web]
> push_ssl = false
> allow-push = *
> EOF
$ hg debugdrawdag << EOF
> C D
> |/
> B
> |
> A
> EOF
$ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
$ cat hg.pid > $DAEMON_PIDS
pushkey for a bookmark works
$ sendhttpv2peer << EOF
> command pushkey
> namespace bookmarks
> key @
> old
> new 426bada5c67598ca65036d57d9e4b64b0c1ce7a0
> EOF
creating http peer for wire protocol version 2
sending pushkey command
response: True
$ sendhttpv2peer << EOF
> command listkeys
> namespace bookmarks
> EOF
creating http peer for wire protocol version 2
sending listkeys command
response: {
b'@': b'426bada5c67598ca65036d57d9e4b64b0c1ce7a0'
}
$ cat error.log