[PATCHv6 5/8] gitweb: gravatar url cache

[Giuseppe Bilotta <giuseppe.bilotta@gmail.com>]

Views which contain many occurrences of the same email address (e.g.
shortlog view) benefit from not having to recalculate the MD5 of the
email address every time.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
---
 gitweb/gitweb.perl |   24 ++++++++++++++++++++++--
 1 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index f2e0cfe..d3bc849 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -3257,6 +3257,27 @@ sub git_print_header_div {
 	      "\n</div>\n";
 }
 
+# Rather than recomputing the url for an email multiple times, we cache it
+# after the first hit. This gives a visible benefit in views where the avatar
+# for the same email is used repeatedly (e.g. shortlog).
+# The cache is shared by all avatar engines (currently gravatar only), which
+# are free to use it as preferred. Since only one avatar engine is used for any
+# given page, there's no risk for cache conflicts.
+our %avatar_cache = ();
+
+# Compute the gravatar url for a given email, if it's not in the cache already.
+# Gravatar stores only the part of the URL before the size, since that's the
+# one computationally more expensive. This also allows reuse of the cache for
+# different sizes (for this particular engine).
+sub gravatar_url {
+	my $email = lc shift;
+	my $size = shift;
+	$avatar_cache{$email} ||=
+		"http://www.gravatar.com/avatar.php?gravatar_id=" .
+			Digest::MD5::md5_hex($email) . "&amp;size=";
+	return $avatar_cache{$email} . $size;
+}
+
 # Insert an avatar for the given $email at the given $size if the feature
 # is enabled.
 sub git_get_avatar {
@@ -3266,8 +3287,7 @@ sub git_get_avatar {
 	my $size = $avatar_size{$params{'size'}} || $avatar_size{'default'};
 	my $url = "";
 	if ($git_avatar eq 'gravatar') {
-		$url = "http://www.gravatar.com/avatar.php?gravatar_id=" .
-			Digest::MD5::md5_hex(lc $email) . "&amp;size=$size";
+		$url = gravatar_url($email, $size);
 	}
 	# Currently only gravatars are supported, but other forms such as
 	# picons can be added by putting an else up here and defining $url
-- 
1.6.3.rc1.192.gdbfcb