improve FindBooks for great number by operating in chunk

Lib/Search/BookSearch.php

@@ -78,7 +78,7 @@ class BookSearch
 
         $books = isset($results['response']['docs']) && $results['response']['docs'] ?
             array_map(function($o) { return (array) $o; }, $results['response']['docs']) :
-            false;
+            array();
 
         return array(
             'count' => $results['response']['numFound'],

NetBiblio.php

@@ -212,16 +212,33 @@ class NetBiblio extends WebService
         $this->getUser()->deleteWish($bookNr);
     }
 
+    private function GetBooks(array $codes) {
+        $bs = new BookSearch();
+        $bs->addQuery('code:('.implode(' OR ', $codes).')', null, false);
+        $results = $bs->getResults(0, count($codes));
+        return $results['books'];
+    }
+
     public function FindBooks($codes)
     {
         $this->CheckSession();
 
         $codes = json_decode($codes);
-        $bs = new BookSearch();
-        $bs->addQuery('code:('.implode(' OR ', $codes).')', null, false);
-        $results = $bs->getResults(0, count($codes));
-        return $results['books'] ? $this->AddBookData($results['books']) : array();
 
+        // it is faster to do multiple small request to Solr rather than one big so separate
+        // in chunks if we are above the limit. 15 was found by testing and seems to be a sweet spot
+        $limit = 15;
+        if(count($codes) > $limit) {
+            $parts = array_chunk($codes, $limit);
+            $books = array();
+            foreach($parts as $p) {
+                $books = array_merge($books, $this->GetBooks($p));
+            }
+        } else {
+            $books = $this->GetBooks($codes);
+        }
+
+        return $this->AddBookData($books);
     }
 
     private function GetFiles(array $ids)
@@ -367,11 +384,7 @@ class NetBiblio extends WebService
     public function FindBook($code)
     {
         $this->CheckSession();
-
-        $bs = new BookSearch();
-        $bs->addQuery($code, 'code');
-        $results = $bs->getResults(0, 1);
-        return $results['books'] ? reset($this->AddBookData($results['books'])) : null;
+        return reset($this->AddBookData($this->GetBooks(array($code))));
     }
 
     public function GetRandomBooks($number = 100, $seed = null) {
@@ -381,8 +394,7 @@ class NetBiblio extends WebService
 
         $bs = new BookSearch();
         $bs->addSortField('random_'.$seed);
-        $results = $bs->getResults(0, $number);
-        return $results['books'] ? $this->AddBookData($results['books']) : array();
+        return $this->AddBookData($bs->getResults(0, $number));
     }
 
     public function Search($query, $start, $limit)
@@ -470,11 +482,7 @@ class NetBiblio extends WebService
             'facets' => $results['facets'],
         );
 
-        if($results['books']) {
-            $data = array_merge($data,  $this->AddBookData($results['books']));
-        }
-
-        return $data;
+        return array_merge($data, $this->AddBookData($results['books']));
     }
 
     public function ListOfReaders()