1 files changed, 56 insertions, 0 deletions
diff --git a/vendor/open-telemetry/api/Metrics/ObservableCallbackInterface.php b/vendor/open-telemetry/api/Metrics/ObservableCallbackInterface.php
new file mode 100644
index 000000000..a20e59666
--- /dev/null
+++ b/vendor/open-telemetry/api/Metrics/ObservableCallbackInterface.php
@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\API\Metrics;
+
+/**
+ * An observed callback.
+ *
+ * Callbacks that are bound to an object are automatically detached when the
+ * `ObservableCallbackInterface` and the bound object are out of scope.
+ * This means that the `ObservableCallbackInterface` can be ignored if the
+ * observed callback should be bound to the lifetime of the object.
+ * ```php
+ * class Example {
+ *     function __construct(MeterProviderInterface $meterProvider) {
+ *         $meterProvider->getMeter('example')
+ *             ->createObservableGauge('random')
+ *             ->observe(fn(ObserverInterface $observer)
+ *                     => $observer->observe(rand(0, 10)));
+ *     }
+ * }
+ * ```
+ * Keeping a reference to the `ObservableCallbackInterface` within the bound
+ * object to gain a more fine-grained control over the life-time of the callback
+ * does not prevent garbage collection (but might require cycle collection).
+ *
+ * Unbound (static) callbacks must be detached manually using
+ * {@link ObservableCallbackInterface::detach()}.
+ * ```php
+ * class Example {
+ *     private ObservableCallbackInterface $gauge;
+ *     function __construct(MeterProviderInterface $meterProvider) {
+ *         $this->gauge = $meterProvider->getMeter('example')
+ *             ->createObservableGauge('random')
+ *             ->observe(static fn(ObserverInterface $observer)
+ *                     => $observer->observe(rand(0, 10)));
+ *     }
+ *     function __destruct() {
+ *         $this->gauge->detach();
+ *     }
+ * }
+ * ```
+ *
+ * @see ObservableCounterInterface::observe()
+ * @see ObservableGaugeInterface::observe()
+ * @see ObservableUpDownCounterInterface::observe()
+ */
+interface ObservableCallbackInterface
+{
+
+    /**
+     * Detaches the associated callback from the instrument.
+     */
+    public function detach(): void;
+}