#44 Metrics init draft

src/Prometheus/Collector.php

@@ -99,6 +99,26 @@ protected function assertLabelsAreDefinedCorrectly(array $labels): void
         }
     }
 
+    /**
+     * @param array[] $labelValuesSet
+     */
+    protected function assertValidInitLabelsValuesSet(array $labelValuesSet = []): void
+    {
+        $initLabelsKeys = array_keys($labelValuesSet);
+
+        $forgottenLabels = array_diff($this->getLabelNames(), $initLabelsKeys);
+        if (count($forgottenLabels) > 0) {
+            throw new InvalidArgumentException("Missing label values for: " . implode(',', $forgottenLabels));
+        }
+
+        $unnecessaryLabels = array_diff($initLabelsKeys, $this->getLabelNames());
+        if (count($unnecessaryLabels) > 0) {
+            throw new InvalidArgumentException(
+                "Some labels values are not mentioned on metric creation:" . implode(',', $unnecessaryLabels)
+            );
+        }
+    }
+
     /**
      * @param string $metricName
      */

src/Prometheus/Counter.php

@@ -46,4 +46,22 @@ public function incBy($count, array $labels = []): void
             ]
         );
     }
+
+    /**
+     * @param array[] $labelValuesSet
+     */
+    public function init(array $labelValuesSet = []): void
+    {
+        $this->assertValidInitLabelsValuesSet($labelValuesSet);
+
+        $this->storageAdapter->initCounter(
+            [
+                'name' => $this->getName(),
+                'help' => $this->getHelp(),
+                'type' => $this->getType(),
+                'labelNames' => $this->getLabelNames(),
+                'labelValuesSet' => $labelValuesSet,
+            ]
+        );
+    }
 }

src/Prometheus/Gauge.php

@@ -84,4 +84,22 @@ public function decBy($value, array $labels = []): void
     {
         $this->incBy(-$value, $labels);
     }
+
+    /**
+     * @param array[] $labelValuesSet
+     */
+    public function init(array $labelValuesSet = []): void
+    {
+        $this->assertValidInitLabelsValuesSet($labelValuesSet);
+
+        $this->storageAdapter->initGauge(
+            [
+                'name' => $this->getName(),
+                'help' => $this->getHelp(),
+                'type' => $this->getType(),
+                'labelNames' => $this->getLabelNames(),
+                'labelValuesSet' => $labelValuesSet,
+            ]
+        );
+    }
 }

src/Prometheus/Histogram.php

@@ -133,6 +133,25 @@ public function observe(float $value, array $labels = []): void
         );
     }
 
+    /**
+     * @param array[] $labelValuesSet
+     */
+    public function init(array $labelValuesSet = []): void
+    {
+        $this->assertValidInitLabelsValuesSet($labelValuesSet);
+
+        $this->storageAdapter->initHistogram(
+            [
+                'name'           => $this->getName(),
+                'help'           => $this->getHelp(),
+                'type'           => $this->getType(),
+                'labelNames'     => $this->getLabelNames(),
+                'labelValuesSet' => $labelValuesSet,
+                'buckets'        => $this->buckets,
+            ]
+        );
+    }
+
     /**
      * @return string
      */

src/Prometheus/Storage/APC.php

@@ -155,6 +155,21 @@ public function updateCounter(array $data): void
         }
     }
 
+    public function initHistogram(array $data): void
+    {
+        throw new \RuntimeException('APC driver currently doesn\'t support this feature');
+    }
+
+    public function initGauge(array $data): void
+    {
+        throw new \RuntimeException('APC driver currently doesn\'t support this feature');
+    }
+
+    public function initCounter(array $data): void
+    {
+        throw new \RuntimeException('APC driver currently doesn\'t support this feature');
+    }
+
     /**
      * @deprecated use replacement method wipeStorage from Adapter interface
      *

src/Prometheus/Storage/APCng.php

@@ -203,6 +203,21 @@ public function updateCounter(array $data): void
         }
     }
 
+    public function initHistogram(array $data): void
+    {
+        throw new \RuntimeException('APCng driver currently doesn\'t support this feature');
+    }
+
+    public function initGauge(array $data): void
+    {
+        throw new \RuntimeException('APCng driver currently doesn\'t support this feature');
+    }
+
+    public function initCounter(array $data): void
+    {
+        throw new \RuntimeException('APCng driver currently doesn\'t support this feature');
+    }
+
     /**
      * @param array<string> $metaData
      * @param string $labels

src/Prometheus/Storage/Adapter.php

@@ -13,6 +13,14 @@ interface Adapter
     const COMMAND_INCREMENT_FLOAT = 2;
     const COMMAND_SET = 3;
 
+    /**
+     * Removes all previously stored metrics from underlying storage
+     *
+     * @throws StorageException
+     * @return void
+     */
+    public function wipeStorage(): void;
+
     /**
      * @return MetricFamilySamples[]
      */
@@ -43,10 +51,21 @@ public function updateGauge(array $data): void;
     public function updateCounter(array $data): void;
 
     /**
-     * Removes all previously stored metrics from underlying storage
-     *
-     * @throws StorageException
+     * @param mixed[] $data
      * @return void
      */
-    public function wipeStorage(): void;
+    public function initHistogram(array $data): void;
+
+
+    /**
+     * @param mixed[] $data
+     * @return void
+     */
+    public function initGauge(array $data): void;
+
+    /**
+     * @param mixed[] $data
+     * @return void
+     */
+    public function initCounter(array $data): void;
 }

src/Prometheus/Storage/InMemory.php

@@ -351,6 +351,21 @@ public function updateCounter(array $data): void
         }
     }
 
+    public function initHistogram(array $data): void
+    {
+        throw new \RuntimeException('InMemory driver currently doesn\'t support this feature');
+    }
+
+    public function initGauge(array $data): void
+    {
+        throw new \RuntimeException('InMemory driver currently doesn\'t support this feature');
+    }
+
+    public function initCounter(array $data): void
+    {
+        throw new \RuntimeException('InMemory driver currently doesn\'t support this feature');
+    }
+
     /**
      * @param mixed[]    $data
      * @param string|int $bucket