log discarded span attributes, events, links

.phan/config.php

@@ -375,7 +375,6 @@
         'vendor/guzzlehttp',
         'vendor/psr',
         'vendor/php-http',
-        'vendor/phan/phan/src/Phan',
         'vendor/phpunit/phpunit/src',
         'vendor/google/protobuf/src',
     ],

src/SDK/Trace/Span.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\SDK\Trace;
 
+use OpenTelemetry\API\Behavior\LogsMessagesTrait;
 use OpenTelemetry\API\Common\Time\Clock;
 use OpenTelemetry\API\Trace as API;
 use OpenTelemetry\API\Trace\SpanContextInterface;
@@ -17,6 +18,7 @@
 
 final class Span extends API\Span implements ReadWriteSpanInterface
 {
+    use LogsMessagesTrait;
 
     /** @var list<EventInterface> */
     private array $events = [];
@@ -249,6 +251,15 @@ public function end(int $endEpochNanos = null): void
             return;
         }
 
+        $spanData = $this->toSpanData();
+        if ($spanData->getTotalDroppedLinks() || $spanData->getTotalDroppedEvents() || $spanData->getAttributes()->getDroppedAttributesCount()) {
+            self::logWarning('Dropped span attributes, links or events', [
+                'attributes' => $spanData->getAttributes()->getDroppedAttributesCount(),
+                'links' => $spanData->getTotalDroppedLinks(),
+                'events' => $spanData->getTotalDroppedEvents(),
+            ]);
+        }
+
         $this->endEpochNanos = $endEpochNanos ?? Clock::getDefault()->now();
         $this->hasEnded = true;
 

tests/Integration/SDK/SpanBuilderTest.php

@@ -7,6 +7,7 @@
 use Mockery;
 use Mockery\Adapter\Phpunit\MockeryTestCase;
 use Mockery\MockInterface;
+use OpenTelemetry\API\Behavior\Internal\Logging;
 use OpenTelemetry\API\Trace as API;
 use OpenTelemetry\API\Trace\SpanContext;
 use OpenTelemetry\API\Trace\SpanContextValidator;
@@ -96,6 +97,7 @@ public function test_add_link_invalid(): void
 
     public function test_add_link_dropping_links(): void
     {
+        Logging::disable();
         $maxNumberOfLinks = 8;
         $tracerProvider = new TracerProvider([], null, null, (new SpanLimitsBuilder())->setLinkCountLimit($maxNumberOfLinks)->build());
         $spanBuilder = $tracerProvider

tests/Integration/SDK/TracerTest.php

@@ -4,6 +4,7 @@
 
 namespace OpenTelemetry\Tests\Integration\SDK;
 
+use OpenTelemetry\API\Behavior\Internal\Logging;
 use OpenTelemetry\API\Trace as API;
 use OpenTelemetry\API\Trace\NonRecordingSpan;
 use OpenTelemetry\API\Trace\SpanContext;
@@ -113,6 +114,7 @@ public function test_factory_returns_noop_tracer_when_sdk_disabled(): void
 
     public function test_general_identity_attributes_are_dropped_by_default(): void
     {
+        Logging::disable();
         $exporter = new InMemoryExporter();
         $tracerProvider = new TracerProvider(new SimpleSpanProcessor($exporter));
         $tracer = $tracerProvider->getTracer('test');

tests/Unit/SDK/Trace/SpanTest.php

@@ -48,6 +48,8 @@
 #[CoversClass(Span::class)]
 class SpanTest extends MockeryTestCase
 {
+    private const TRACE_ID = 'e4a8d4e0d75c0702200af2882cb16c6b';
+    private const SPAN_ID = '46701247e52c2d1b';
     private const SPAN_NAME = 'test_span';
     private const NEW_SPAN_NAME = 'new_test_span';
     private const START_EPOCH = 1000123789654;
@@ -655,6 +657,7 @@ public function test_attribute_length(): void
     public function test_dropping_attributes(): void
     {
         $maxNumberOfAttributes = 8;
+        $this->expectDropped(8, 0, 0);
         $span = $this->createTestSpan(API\SpanKind::KIND_INTERNAL, (new SpanLimitsBuilder())->setAttributeCountLimit($maxNumberOfAttributes)->build());
 
         foreach (range(1, $maxNumberOfAttributes * 2) as $idx) {
@@ -676,6 +679,7 @@ public function test_dropping_attributes(): void
     public function test_dropping_attributes_provided_via_span_builder(): void
     {
         $maxNumberOfAttributes = 8;
+        $this->expectDropped(8, 0, 0);
 
         $attributesBuilder = Attributes::factory()->builder();
 
@@ -704,6 +708,7 @@ public function test_dropping_attributes_provided_via_span_builder(): void
 
     public function test_dropping_events(): void
     {
+        $this->expectDropped(0, 8, 0);
         $maxNumberOfEvents = 8;
         $span = $this->createTestSpan(API\SpanKind::KIND_INTERNAL, (new SpanLimitsBuilder())->setEventCountLimit($maxNumberOfEvents)->build());
 
@@ -719,6 +724,26 @@ public function test_dropping_events(): void
         $span->end();
     }
 
+    public function test_dropping_links(): void
+    {
+        $maxNumberOfLinks = 8;
+        $expectedDroppedLinks = 9; //test span contains one link by default
+        $this->expectDropped(0, 0, $expectedDroppedLinks);
+        $span = $this->createTestSpan(API\SpanKind::KIND_INTERNAL, (new SpanLimitsBuilder())->setLinkCountLimit($maxNumberOfLinks)->build());
+        $ctx = SpanContext::create(self::TRACE_ID, self::SPAN_ID);
+
+        foreach (range(1, $maxNumberOfLinks * 2) as $_idx) {
+            $span->addLink($ctx);
+            $this->testClock->advanceSeconds();
+        }
+
+        $spanData = $span->toSpanData();
+        $this->assertCount($maxNumberOfLinks, $spanData->getLinks());
+        $this->assertSame($expectedDroppedLinks, $spanData->getTotalDroppedLinks());
+
+        $span->end();
+    }
+
     // endregion SDK
     #[Group('trace-compliance')]
     public function test_set_attributes_merges_attributes(): void
@@ -915,4 +940,18 @@ private function assertSpanData(
         $this->assertSame($hasEnded, $spanData->hasEnded());
         $this->assertEquals($attributes, $spanData->getAttributes());
     }
+
+    private function expectDropped(int $attributes, int $events, int $links): void
+    {
+        $this->logWriter->expects($this->once())->method('write')->with(
+            $this->anything(),
+            $this->stringContains('Dropped span attributes'),
+            $this->equalTo([
+                'attributes' => $attributes,
+                'links' => $links,
+                'events' => $events,
+                'source' => 'OpenTelemetry\\SDK\\Trace\\Span',
+            ])
+        );
+    }
 }