Bug 16365: [QA Follow-up] Add some comment lines to Cache.pm

Resolve typo inifinite too.
Adds a few lines in order to stress that the thawed key of the L1
cache SHOULD ONLY be used for unsafe calls, and not be mixed with
regular (safe) calls.

Test plan:
Nothing to test, but verify the quality of the added comments.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

diff --git a/Koha/Cache.pm b/Koha/Cache.pm
index 034d77b..08577bd 100644 (file)
--- a/Koha/Cache.pm
+++ b/Koha/Cache.pm
@@ -268,7 +268,10 @@ sub set_in_cache {
 
     my $flag = '-CF0'; # 0: scalar, 1: frozen data structure
     if (ref($value)) {
-        # Set in L1 cache as a data structure, initially only in frozen form (for performance reasons)
+        # Set in L1 cache as a data structure
+        # We only save the frozen form: we do want to save $value in L1
+        # directly in order to protect it. And thawing now may not be
+        # needed, so improves performance.
         $value = $L1_encoder->encode($value);
         $L1_cache{$self->{namespace}}{$key}->{frozen} = $value;
         $flag = '-CF1';
@@ -279,7 +282,7 @@ sub set_in_cache {
     }
 
     $value .= $flag;
-    # We consider an expiry of 0 to be inifinite
+    # We consider an expiry of 0 to be infinite
     if ( $expiry ) {
         return $set_sub
           ? $set_sub->( $key, $value, $expiry )
@@ -331,6 +334,7 @@ sub get_from_cache {
     if ( exists $L1_cache{$self->{namespace}}{$key} ) {
         if (ref($L1_cache{$self->{namespace}}{$key})) {
             if ($unsafe) {
+                # ONLY use thawed for unsafe calls !!!
                 $L1_cache{$self->{namespace}}{$key}->{thawed} ||= $L1_decoder->decode($L1_cache{$self->{namespace}}{$key}->{frozen});
                 return $L1_cache{$self->{namespace}}{$key}->{thawed};
             } else {
@@ -359,6 +363,7 @@ sub get_from_cache {
         eval { $thawed = $L1_decoder->decode($L2_value); };
         return if $@;
         $L1_cache{$self->{namespace}}{$key}->{frozen} = $L2_value;
+        # ONLY save thawed for unsafe calls !!!
         $L1_cache{$self->{namespace}}{$key}->{thawed} = $thawed if $unsafe;
         return $thawed;
     }