refactor lastrecords method and enable caching

app/Sensor/DiskEvolution.php

@@ -45,7 +45,7 @@ class DiskEvolution extends \App\AbstractSensor
      */
     public function get2Partitions(int $timeInterval) : ?array
     {
-        $records = $this->getServer()->lastRecords("disks", $timeInterval * 12);
+        $records = $this->getServer()->lastRecords1Day();
 
         if (count($records) < 2) {
             return null;

app/Sensor/Ifconfig.php

@@ -29,7 +29,7 @@ class Ifconfig extends AbstractSensor
     public function points()
     {
         // Get records in time ascending order
-        $records = $this->getServer()->lastRecords("ifconfig", 289);
+        $records = $this->getServer()->lastRecords1Day();
 
         // Compute the time ordered list of arrays of interfaces
         $interfaces = [];

app/Sensor/LoadAvg.php

@@ -21,7 +21,7 @@ class LoadAvg extends AbstractSensor
 
     public function loadPoints()
     {
-        $records = $this->getServer()->lastRecords("loadavg", 288);
+        $records = $this->getServer()->lastRecords1Day();
 
         $points = [];
         foreach ($records as $record) {

app/Sensor/MemInfo.php

@@ -20,7 +20,7 @@ class MemInfo extends AbstractSensor
 
     public function usedMemoryPoints()
     {
-        $records = $this->getServer()->lastRecords("memory", 288);
+        $records = $this->getServer()->lastRecords1Day();
 
         $used = [];
         foreach ($records as $record) {
@@ -36,7 +36,7 @@ class MemInfo extends AbstractSensor
 
     public function cachedMemoryPoints()
     {
-        $records = $this->getServer()->lastRecords("memory", 288);
+        $records = $this->getServer()->lastRecords1Day();
 
         $points = [];
         foreach ($records as $record) {

app/Sensor/Netstat.php

@@ -20,7 +20,7 @@ class Netstat extends AbstractSensor
 
     public function points() : array
     {
-        $records = $this->getServer()->lastRecords("netstat-statistics", 289);
+        $records = $this->getServer()->lastRecords1Day();
 
         if (count($records) == 0) {
             return [];

app/Server.php

@@ -16,6 +16,8 @@ class Server extends Model
      */
     private $last_record = null;
 
+    private $records_1day = null;
+
     private static $sensors = [
         \App\Sensor\LoadAvg::class,
         \App\Sensor\MemInfo::class,
@@ -61,34 +63,27 @@ class Server extends Model
     }
 
     /**
-     * Get the last $count records containing $field.
-     * !! $count is the MAXIMUM number of returned records.
-     * To optimize mongo's usage of index, we get the last $count records
-     * then filter locally for records containing this record
-     * Records are returned in chronological order
-     * @param type $field
-     * @param type $count
+     * Get the last day of data.
      * @return type
      */
-    public function lastRecords(string $field, int $count)
+    public function lastRecords1Day()
     {
+        if ($this->records_1day !== null) {
+            return $this->records_1day;
+        }
+
         $records = \Mongo::get()->monitoring->records->find(
             ["server_id" => $this->id],
-            ["limit" => $count, "sort" => ["_id" => -1]]
-        );
+            ["limit" => 288, "sort" => ["_id" => -1]]
+        )->toArray();
 
-        $results = [];
-        foreach ($records as $record) {
-            if (isset($record->$field)) {
-                $results[] = $record;
-            }
-        }
-
-        usort($results, function ($r1, $r2) {
+        usort($records, function ($r1, $r2) {
             return $r1->time  > $r2->time ? 1 : -1;
         });
 
-        return $results;
+        $this->records_1day = $records;
+
+        return $records;
     }
 
     public function hasData() : bool