[PATCH 0/2] imapd: async prefetch + test fix

[PATCH 0/2] imapd: async prefetch + test fix

[Eric Wong]

prefetch has been on the table since the earliest days of
-imapd, but the interaction with periodic cleanup made things
unreliable.  Now it won't start a git process if it's in cleanup
so things should be all good.  Uncached FETCH with mutt is
noticeably faster.

Now, the HTTP bits will be a little trickier, I think...

Eric Wong (2):
  imap: introduce and use Git->async_prefetch
  xt/imapd-mbsync-oimapd: fix noop due to case sensitivity

 lib/PublicInbox/Git.pm  | 16 ++++++++++++++++
 lib/PublicInbox/IMAP.pm |  7 ++++++-
 xt/imapd-mbsync-oimap.t |  2 +-
 3 files changed, 23 insertions(+), 2 deletions(-)

[PATCH 1/2] imap: introduce and use Git->async_prefetch

[Eric Wong]

We can keep the git process more active by sending another
request to it while fetch_run_ops() is running.  This
parallelization speeds up mutt's initial FETCH for headers by
around ~35%(!).
---
 lib/PublicInbox/Git.pm  | 16 ++++++++++++++++
 lib/PublicInbox/IMAP.pm |  7 ++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index ffc464eb3..7b2ada243 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -410,6 +410,22 @@ sub cat_async ($$$;$) {
 	push(@$inflight, $oid, $cb, $arg);
 }
 
+# this is safe to call inside $cb, but not guaranteed to enqueue
+# returns true if successful, undef if not.
+sub async_prefetch {
+	my ($self, $oid, $cb, $arg) = @_;
+	if (defined($self->{async_cat}) && (my $inflight = $self->{inflight})) {
+		# we could use MAX_INFLIGHT here w/o the halving,
+		# but lets not allow one client to monopolize a git process
+		if (scalar(@$inflight) < int(MAX_INFLIGHT/2)) {
+			print { $self->{out} } $oid, "\n" or
+						fail($self, "write error: $!");
+			return push(@$inflight, $oid, $cb, $arg);
+		}
+	}
+	undef;
+}
+
 sub extract_cmt_time {
 	my ($bref, undef, undef, undef, $modified) = @_;
 
diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 8ab4b1e7d..3d66f9306 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -626,8 +626,13 @@ sub fetch_blob_cb { # called by git->cat_async via git_async_cat
 	} else {
 		$smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
 	}
+	my $pre;
+	if (!$self->{wbuf} && (my $nxt = $msgs->[0])) {
+		$pre = $self->{ibx}->git->async_prefetch($nxt->{blob},
+						\&fetch_blob_cb, $fetch_arg);
+	}
 	fetch_run_ops($self, $smsg, $bref, $ops, $partial);
-	requeue_once($self);
+	$pre ? $self->zflush : requeue_once($self);
 }
 
 sub emit_rfc822 {

[PATCH 2/2] xt/imapd-mbsync-oimapd: fix noop due to case sensitivity

[Eric Wong]

mbsync was not retrieving anything since it was looking for
"inbox" when we need to return "INBOX" as a special case
for IMAP.

Fixes: 8af34015e9aa94e5 (imap: LIST shows "INBOX" in all caps)
---
 xt/imapd-mbsync-oimap.t | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xt/imapd-mbsync-oimap.t b/xt/imapd-mbsync-oimap.t
index edf111fde..f8641d06d 100644
--- a/xt/imapd-mbsync-oimap.t
+++ b/xt/imapd-mbsync-oimap.t
@@ -99,7 +99,7 @@ UseNamespace no
 # DisableExtension COMPRESS=DEFLATE
 
 Channel "test"
-Master ":remote:inbox"
+Master ":remote:INBOX"
 Slave ":local:test"
 Expunge None
 Sync PullNew