adding event dispatcher

composer.json

@@ -15,6 +15,7 @@
         "php-http/async-client-implementation": "^1.0",
         "php-http/discovery": "^1.14",
         "promphp/prometheus_client_php": "^2.2.1",
+        "psr/event-dispatcher": "^1",
         "psr/http-factory-implementation": "^1.0",
         "psr/log": "^1.1|^2.0|^3.0",
         "symfony/polyfill-mbstring": "^1.23"

examples/EventsExample.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+require __DIR__ . '/../vendor/autoload.php';
+
+use Monolog\Formatter\JsonFormatter;
+use Monolog\Handler\StreamHandler;
+use Monolog\Logger;
+use OpenTelemetry\Contrib\Zipkin\Exporter as ZipkinExporter;
+use OpenTelemetry\SDK\Common\Event\Dispatcher;
+use OpenTelemetry\SDK\Common\Event\Event\ErrorEvent;
+use OpenTelemetry\SDK\Common\Event\EventType;
+use OpenTelemetry\SDK\Common\Event\SimpleDispatcher;
+use OpenTelemetry\SDK\Common\Event\SimpleListenerProvider;
+use OpenTelemetry\SDK\Common\Log\LoggerHolder;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+use Psr\Log\LogLevel;
+
+/**
+ * This example shows how you can hook in to OpenTelemetry's events, such as when an error or warning is emitted by
+ * the library. OpenTelemetry will always attempt to log and continue on error, and may provide no-op implementations
+ * of classes if it was unable to create them as requested.
+ * The default event handlers will use a PSR-3 logger to log events - verbosity and output format can be controlled
+ * through the usual PSR-3 log levels and formatters (if available).
+ * If you wish to do something different with events, you may provide an alternative PSR-14 implementation, but be
+ * aware that you will need to register handlers for all events that you are interested in.
+ */
+
+//logger used by default event handlers
+LoggerHolder::set(
+    new Logger('otel-php', [(new StreamHandler(STDOUT, LogLevel::DEBUG))->setFormatter(new JsonFormatter())])
+);
+
+/**
+ * Register event listeners - this only works for SimpleEventDispatcher. For other PSR-14 implementations, you will
+/* need to register all events that you are interested in, @see {SDK\Event\EventTypes}
+ */
+$listenerProvider = new SimpleListenerProvider();
+$listenerProvider->listen(EventType::ERROR, function (ErrorEvent $event) {
+    echo 'Custom handling of an error event: ' . $event->getError()->getMessage() . PHP_EOL;
+}, -10); //runs before built-in handler
+$listenerProvider->listen(EventType::ERROR, function (ErrorEvent $event) {
+    echo 'Another custom handling of an error event: ' . $event->getMessage() . PHP_EOL;
+    echo json_encode($event->getError()->getTrace()) . PHP_EOL;
+    echo 'Stopping event propagation...' . PHP_EOL;
+    $event->stopPropagation();
+}, 5); //runs after build-in handler
+$listenerProvider->listen(EventType::ERROR, function (ErrorEvent $event) {
+    echo 'This will not be executed, because a high priority handler stopped event propagation.' . PHP_EOL;
+}, 10);
+
+Dispatcher::setInstance(new SimpleDispatcher($listenerProvider));
+
+//or, provide your own PSR-14 event dispatcher. This must be done before getting a tracer:
+//$listenerProvider = new \Any\Psr14\ListenerProvider();
+//$listenerProvider->listen(EventType::ERROR, function(ErrorEvent $event){...});
+//DispatcherHolder::setInstance(\Any\Psr14\EventDispatcherInterface($listenerProvider));
+
+$tracerProvider =  new TracerProvider(
+    new SimpleSpanProcessor(
+        ZipkinExporter::fromConnectionString('http://invalid-host:9999', 'zipkin-exporter')
+    )
+);
+$tracer = $tracerProvider->getTracer();
+
+$span = $tracer->spanBuilder('root')->startSpan();
+$span->end();

src/Contrib/Jaeger/JaegerTransport.php

@@ -8,14 +8,13 @@
 use Jaeger\Thrift\Batch;
 use Jaeger\Thrift\Process;
 use Jaeger\Thrift\Span;
-use OpenTelemetry\SDK\Behavior\LogsMessagesTrait;
+use OpenTelemetry\SDK\Common\Event\Dispatcher;
+use OpenTelemetry\SDK\Common\Event\Event\ErrorEvent;
 use Thrift\Exception\TTransportException;
 use Thrift\Protocol\TCompactProtocol;
 
 final class JaegerTransport implements TransportInterface
 {
-    use LogsMessagesTrait;
-
     // DEFAULT_BUFFER_SIZE indicates the default maximum buffer size, or the size threshold
     // at which the buffer will be flushed to the agent.
     const DEFAULT_BUFFER_SIZE = 1;
@@ -93,7 +92,7 @@ public function flush($force = false): int
             // reset the process tag
             $this->process = null;
         } catch (TTransportException $e) {
-            self::logError('jaeger: transport failure: ' . $e->getMessage());
+            Dispatcher::getInstance()->dispatch(new ErrorEvent('jaeger transport failure', $e));
 
             return 0;
         }

src/Contrib/OtlpGrpc/Exporter.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\Contrib\OtlpGrpc;
 
+use Exception;
 use grpc;
 use Grpc\ChannelCredentials;
 use OpenTelemetry\Contrib\Otlp\ExporterTrait;
@@ -12,6 +13,9 @@
 use Opentelemetry\Proto\Collector\Trace\V1\TraceServiceClient;
 use OpenTelemetry\SDK\Common\Environment\KnownValues as Values;
 use OpenTelemetry\SDK\Common\Environment\Variables as Env;
+use OpenTelemetry\SDK\Common\Event\Dispatcher;
+use OpenTelemetry\SDK\Common\Event\Event\ErrorEvent;
+use OpenTelemetry\SDK\Common\Event\Event\WarningEvent;
 use OpenTelemetry\SDK\Trace\Behavior\SpanExporterTrait;
 use OpenTelemetry\SDK\Trace\SpanExporterInterface;
 
@@ -140,12 +144,12 @@ protected function doExport(iterable $spans): int
             \Grpc\STATUS_DATA_LOSS,
             \Grpc\STATUS_UNAUTHENTICATED,
         ], true)) {
-            self::logWarning('Retryable error exporting grpc span', ['error' => $error]);
+            Dispatcher::getInstance()->dispatch(new WarningEvent('Retryable error exporting grpc span', new Exception($error['error'], $error['code'])));
 
             return self::STATUS_FAILED_RETRYABLE;
         }
 
-        self::logError('Error exporting grpc span', ['error' => $error]);
+        Dispatcher::getInstance()->dispatch(new ErrorEvent('Error exporting grpc span', new Exception($error['error'])));
 
         return self::STATUS_FAILED_NOT_RETRYABLE;
     }

src/SDK/Common/Event/Dispatcher.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event;
+
+use OpenTelemetry\SDK\Common\Event\Handler\DebugEventHandler;
+use OpenTelemetry\SDK\Common\Event\Handler\ErrorEventHandler;
+use OpenTelemetry\SDK\Common\Event\Handler\WarningEventHandler;
+use Psr\EventDispatcher\EventDispatcherInterface;
+
+class Dispatcher
+{
+    private static ?EventDispatcherInterface $instance = null;
+
+    public static function getInstance(): EventDispatcherInterface
+    {
+        if (self::$instance === null) {
+            $dispatcher = new SimpleDispatcher(new SimpleListenerProvider());
+            $dispatcher->listen(EventType::ERROR, new ErrorEventHandler());
+            $dispatcher->listen(EventType::WARNING, new WarningEventHandler());
+            $dispatcher->listen(EventType::DEBUG, new DebugEventHandler());
+
+            self::$instance = $dispatcher;
+        }
+
+        return self::$instance;
+    }
+
+    public static function setInstance(EventDispatcherInterface $dispatcher): void
+    {
+        self::$instance = $dispatcher;
+    }
+
+    public static function unset(): void
+    {
+        self::$instance = null;
+    }
+}

src/SDK/Common/Event/Event/DebugEvent.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Event;
+
+class DebugEvent
+{
+    private string $message;
+    private array $extra;
+
+    public function __construct(string $message, array $extra = [])
+    {
+        $this->message = $message;
+        $this->extra = $extra;
+    }
+
+    public function getMessage(): string
+    {
+        return $this->message;
+    }
+
+    public function getExtra(): array
+    {
+        return $this->extra;
+    }
+}

src/SDK/Common/Event/Event/ErrorEvent.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Event;
+
+use OpenTelemetry\SDK\Common\Event\StoppableEventTrait;
+use Psr\EventDispatcher\StoppableEventInterface;
+use Throwable;
+
+class ErrorEvent implements StoppableEventInterface
+{
+    use StoppableEventTrait;
+
+    protected string $message;
+    protected Throwable $error;
+
+    public function __construct(string $message, Throwable $error)
+    {
+        $this->message = $message;
+        $this->error = $error;
+    }
+
+    public function getError(): Throwable
+    {
+        return $this->error;
+    }
+
+    public function getMessage(): string
+    {
+        return $this->message;
+    }
+}

src/SDK/Common/Event/Event/WarningEvent.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Event;
+
+use OpenTelemetry\SDK\Common\Event\StoppableEventTrait;
+use Psr\EventDispatcher\StoppableEventInterface;
+use Throwable;
+
+class WarningEvent implements StoppableEventInterface
+{
+    use StoppableEventTrait;
+
+    protected string $message;
+    protected ?Throwable $error = null;
+
+    public function __construct(string $message, ?Throwable $error = null)
+    {
+        $this->message = $message;
+        $this->error = $error;
+    }
+
+    public function getError(): ?Throwable
+    {
+        return $this->error;
+    }
+
+    public function hasError(): bool
+    {
+        return $this->error !== null;
+    }
+
+    public function getMessage(): string
+    {
+        return $this->message;
+    }
+}

src/SDK/Common/Event/EventType.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event;
+
+use OpenTelemetry\SDK\Common\Event\Event\DebugEvent;
+use OpenTelemetry\SDK\Common\Event\Event\ErrorEvent;
+use OpenTelemetry\SDK\Common\Event\Event\WarningEvent;
+
+class EventType
+{
+    public const ERROR = ErrorEvent::class;
+    public const WARNING = WarningEvent::class;
+    public const DEBUG = DebugEvent::class;
+}

src/SDK/Common/Event/Handler/DebugEventHandler.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Handler;
+
+use OpenTelemetry\SDK\Behavior\LogsMessagesTrait;
+use OpenTelemetry\SDK\Common\Event\Event\DebugEvent;
+
+class DebugEventHandler
+{
+    use LogsMessagesTrait;
+
+    public function __invoke(DebugEvent $event): void
+    {
+        self::logDebug($event->getMessage(), $event->getExtra());
+    }
+}

src/SDK/Common/Event/Handler/ErrorEventHandler.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Handler;
+
+use OpenTelemetry\SDK\Behavior\LogsMessagesTrait;
+use OpenTelemetry\SDK\Common\Event\Event\ErrorEvent;
+
+class ErrorEventHandler
+{
+    use LogsMessagesTrait;
+
+    public function __invoke(ErrorEvent $event): void
+    {
+        self::logError($event->getError()->getMessage(), ['error' => $event->getError()]);
+    }
+}

src/SDK/Common/Event/Handler/WarningEventHandler.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\SDK\Common\Event\Handler;
+
+use OpenTelemetry\SDK\Behavior\LogsMessagesTrait;
+use OpenTelemetry\SDK\Common\Event\Event\WarningEvent;
+
+class WarningEventHandler
+{
+    use LogsMessagesTrait;
+
+    public function __invoke(WarningEvent $event): void
+    {
+        self::logWarning($event->getMessage(), ['error' => $event->getError()]);
+    }
+}