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authorMatthew Ogilvie <mmogilvi_git@miniinfo.net>2012-10-13 23:42:16 -0600
committerJunio C Hamano <gitster@pobox.com>2012-10-16 16:16:21 -0700
commit196e48f4d0bac31f4a56b7dc4816f813cc17ad13 (patch)
tree3f4d8b010a37ed7da5b64717008cae4e3d5b64f9 /git-cvsserver.perl
parent39b6a4bd25b6e4e54c1d12028ad79e16a2cfc528 (diff)
downloadgit-196e48f4d0bac31f4a56b7dc4816f813cc17ad13.tar.gz
cvsserver: add comments about database schema/usage
No functionality changes, but these comments should make it easier to understand how it works. Signed-off-by: Matthew Ogilvie <mmogilvi_git@miniinfo.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'git-cvsserver.perl')
-rwxr-xr-xgit-cvsserver.perl46
1 files changed, 42 insertions, 4 deletions
diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index f43d287980..595865c18a 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -2129,6 +2129,10 @@ sub statecleanup
$state->{entries} = {};
}
+# Return working directory revision int "X" from CVS revision "1.X" out
+# of the the working directory "entries" state, for the given filename.
+# Return negative "X" to represent the file is scheduled for removal
+# when it is committed.
sub revparse
{
my $filename = shift;
@@ -2901,6 +2905,16 @@ sub new
}
# Construct the revision table if required
+ # The revision table stores an entry for each file, each time that file
+ # changes.
+ # numberOfRecords = O( numCommits * averageNumChangedFilesPerCommit )
+ # This is not sufficient to support "-r {commithash}" for any
+ # files except files that were modified by that commit (also,
+ # some places in the code ignore/effectively strip out -r in
+ # some cases, before it gets passed to getmeta()).
+ # The "filehash" field typically has a git blob hash, but can also
+ # be set to "dead" to indicate that the given version of the file
+ # should not exist in the sandbox.
unless ( $self->{tables}{$self->tablename("revision")} )
{
my $tablename = $self->tablename("revision");
@@ -2928,6 +2942,15 @@ sub new
}
# Construct the head table if required
+ # The head table (along with the "last_commit" entry in the property
+ # table) is the persisted working state of the "sub update" subroutine.
+ # All of it's data is read entirely first, and completely recreated
+ # last, every time "sub update" runs.
+ # This is also used by "sub getmeta" when it is asked for the latest
+ # version of a file (as opposed to some specific version).
+ # Another way of thinking about it is as a single slice out of
+ # "revisions", giving just the most recent revision information for
+ # each file.
unless ( $self->{tables}{$self->tablename("head")} )
{
my $tablename = $self->tablename("head");
@@ -2950,6 +2973,7 @@ sub new
}
# Construct the properties table if required
+ # - "last_commit" - Used by "sub update".
unless ( $self->{tables}{$self->tablename("properties")} )
{
my $tablename = $self->tablename("properties");
@@ -2962,6 +2986,11 @@ sub new
}
# Construct the commitmsgs table if required
+ # The commitmsgs table is only used for merge commits, since
+ # "sub update" will only keep one branch of parents. Shortlogs
+ # for ignored commits (i.e. not on the chosen branch) will be used
+ # to construct a replacement "collapsed" merge commit message,
+ # which will be stored in this table. See also "sub commitmessage".
unless ( $self->{tables}{$self->tablename("commitmsgs")} )
{
my $tablename = $self->tablename("commitmsgs");
@@ -2993,6 +3022,14 @@ sub tablename
=head2 update
+Bring the database up to date with the latest changes from
+the git repository.
+
+Internal working state is read out of the "head" table and the
+"last_commit" property, then it updates "revisions" based on that, and
+finally it writes the new internal state back to the "head" table
+so it can be used as a starting point the next time update is called.
+
=cut
sub update
{
@@ -3106,17 +3143,18 @@ sub update
next;
} elsif (@{$commit->{parents}} > 1) {
# it is a merge commit, for each parent that is
- # not $lastpicked, see if we can get a log
+ # not $lastpicked (not given a CVS revision number),
+ # see if we can get a log
# from the merge-base to that parent to put it
# in the message as a merge summary.
my @parents = @{$commit->{parents}};
foreach my $parent (@parents) {
- # git-merge-base can potentially (but rarely) throw
- # several candidate merge bases. let's assume
- # that the first one is the best one.
if ($parent eq $lastpicked) {
next;
}
+ # git-merge-base can potentially (but rarely) throw
+ # several candidate merge bases. let's assume
+ # that the first one is the best one.
my $base = eval {
safe_pipe_capture('git', 'merge-base',
$lastpicked, $parent);