From 01ff3ba8fbe9e89399a48adeddabd60eebc826d4 Mon Sep 17 00:00:00 2001
From: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Date: Thu, 10 Mar 2016 08:55:27 +0000
Subject: [PATCH] Bug 11998: Add a L1 cache for sysprefs

Accessing to the cache for each call to C4::Context->preference might
have an impact on performances.
To avoid that this patch introduces a L1 cache (simple hashref). It will
be populated by accessing the L2 cache (Koha::Cache).
If a pref is retrieved 10x, the first one will get the value from the L2
cache, then the L1 cache will be check.
To do so we will need to clear the L1 cache every time a page is loaded.

Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>
Signed-off-by: Jacek Ablewicz <abl@biblos.pk.edu.pl>
---
 C4/Context.pm |   33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/C4/Context.pm b/C4/Context.pm
index 6811e32..bae5f12 100644
--- a/C4/Context.pm
+++ b/C4/Context.pm
@@ -505,6 +505,7 @@ with this method.
 =cut
 
 my $syspref_cache = Koha::Cache->get_instance();
+my %syspref_L1_cache;
 my $use_syspref_cache = 1;
 sub preference {
     my $self = shift;
@@ -512,13 +513,16 @@ sub preference {
 
     $var = lc $var;
 
+    # Return the value if the var has already been accessed
+    if ($use_syspref_cache && exists $syspref_L1_cache{$var}) {
+        return $syspref_L1_cache{$var};
+    }
+
     my $cached_var = $use_syspref_cache
         ? $syspref_cache->get_from_cache("syspref_$var")
         : undef;
     return $cached_var if defined $cached_var;
 
-    my $dbh  = C4::Context->dbh or return 0;
-
     my $value;
     if ( defined $ENV{"OVERRIDE_SYSPREF_$var"} ) {
         $value = $ENV{"OVERRIDE_SYSPREF_$var"};
@@ -528,7 +532,10 @@ sub preference {
         $value = $syspref ? $syspref->value() : undef;
     }
 
-    $syspref_cache->set_in_cache("syspref_$var", $value) if $use_syspref_cache;
+    if ( $use_syspref_cache ) {
+        $syspref_cache->set_in_cache("syspref_$var", $value);
+        $syspref_L1_cache{$var} = $value;
+    }
     return $value;
 }
 
@@ -581,7 +588,13 @@ will not be seen by this process.
 =cut
 
 sub clear_syspref_cache {
-    $syspref_cache->flush_all if $use_syspref_cache;
+    return unless $use_syspref_cache;
+    $syspref_cache->flush_all;
+    clear_syspref_L1_cache()
+}
+
+sub clear_syspref_L1_cache {
+    %syspref_L1_cache = ();
 }
 
 =head2 set_preference
@@ -632,8 +645,10 @@ sub set_preference {
         )->store();
     }
 
-    $syspref_cache->set_in_cache( "syspref_$variable", $value )
-      if $use_syspref_cache;
+    if ( $use_syspref_cache ) {
+        $syspref_cache->set_in_cache( "syspref_$variable", $value );
+        $syspref_L1_cache{$variable} = $value;
+    }
 
     return $syspref;
 }
@@ -652,7 +667,11 @@ sub delete_preference {
     my ( $self, $var ) = @_;
 
     if ( Koha::Config::SysPrefs->find( $var )->delete ) {
-        $syspref_cache->clear_from_cache("syspref_$var") if $use_syspref_cache;
+        if ( $use_syspref_cache ) {
+            $syspref_cache->clear_from_cache("syspref_$var");
+            delete $syspref_L1_cache{$var};
+        }
+
         return 1;
     }
     return 0;
-- 
1.7.10.4