Propagate W3C spec level 2 random-trace-id flag

https://www.w3.org/TR/trace-context-2/#random-trace-id-flag
Nevay · Apr 1, 2024 · fdc1c6a · fdc1c6a
1 parent 7ec0e90
commit fdc1c6a
Show file tree

Hide file tree

Showing 2 changed files with 39 additions and 20 deletions.
diff --git a/src/API/Trace/Propagation/TraceContextPropagator.php b/src/API/Trace/Propagation/TraceContextPropagator.php
@@ -11,14 +11,14 @@
 use OpenTelemetry\API\Trace\SpanContext;
 use OpenTelemetry\API\Trace\SpanContextInterface;
 use OpenTelemetry\API\Trace\SpanContextValidator;
-use OpenTelemetry\API\Trace\TraceFlags;
 use OpenTelemetry\API\Trace\TraceState;
 use OpenTelemetry\Context\Context;
 use OpenTelemetry\Context\ContextInterface;
 use OpenTelemetry\Context\Propagation\ArrayAccessGetterSetter;
 use OpenTelemetry\Context\Propagation\PropagationGetterInterface;
 use OpenTelemetry\Context\Propagation\PropagationSetterInterface;
 use OpenTelemetry\Context\Propagation\TextMapPropagatorInterface;
+use function sprintf;
 
 /**
  * TraceContext is a propagator that supports the W3C Trace Context format
@@ -34,7 +34,8 @@ final class TraceContextPropagator implements TextMapPropagatorInterface
 {
     public const TRACEPARENT = 'traceparent';
     public const TRACESTATE = 'tracestate';
-    private const VERSION = '00'; // Currently, only '00' is supported
+    private const VERSION = 0x00; // Currently, only '00' is supported
+    private const SUPPORTED_FLAGS = 0x03;
 
     public const FIELDS = [
         self::TRACEPARENT,
@@ -70,7 +71,13 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
         }
 
         // Build and inject the traceparent header
-        $traceparent = self::VERSION . '-' . $spanContext->getTraceId() . '-' . $spanContext->getSpanId() . '-' . ($spanContext->isSampled() ? '01' : '00');
+        $traceparent = sprintf(
+            '%02x-%s-%s-%02x',
+            self::VERSION,
+            $spanContext->getTraceId(),
+            $spanContext->getSpanId(),
+            $spanContext->getTraceFlags() & self::SUPPORTED_FLAGS,
+        );
         $setter->set($carrier, self::TRACEPARENT, $traceparent);
 
         // Build and inject the tracestate header
@@ -102,7 +109,7 @@ private static function extractImpl($carrier, PropagationGetterInterface $getter
         }
 
         // traceParent = {version}-{trace-id}-{parent-id}-{trace-flags}
-        $pieces = explode('-', $traceparent);
+        $pieces = explode('-', $traceparent, 5);
 
         // If the header does not have at least 4 pieces, it is invalid -- restart the trace.
         if (count($pieces) < 4) {
@@ -125,33 +132,22 @@ private static function extractImpl($carrier, PropagationGetterInterface $getter
         }
 
         // Return invalid if the trace version is not a future version but still has > 4 pieces.
-        $versionIsFuture = hexdec($version) > hexdec(self::VERSION);
+        $versionIsFuture = hexdec($version) > self::VERSION;
         if (count($pieces) > 4 && !$versionIsFuture) {
             return SpanContext::getInvalid();
         }
 
-        // Only the sampled flag is extracted from the traceFlags (00000001)
-        $convertedTraceFlags = hexdec($traceFlags);
-        $isSampled = ($convertedTraceFlags & TraceFlags::SAMPLED) === TraceFlags::SAMPLED;
+        $traceFlags = hexdec($traceFlags) & self::SUPPORTED_FLAGS;
 
         // Tracestate = 'Vendor1=Value1,...,VendorN=ValueN'
         $rawTracestate = $getter->get($carrier, self::TRACESTATE);
-        if ($rawTracestate !== null) {
-            $tracestate = new TraceState($rawTracestate);
-
-            return SpanContext::createFromRemoteParent(
-                $traceId,
-                $spanId,
-                $isSampled ? TraceFlags::SAMPLED : TraceFlags::DEFAULT,
-                $tracestate
-            );
-        }
+        $tracestate = $rawTracestate !== null ? new TraceState($rawTracestate) : null;
 
-        // Only traceparent header is extracted. No tracestate.
         return SpanContext::createFromRemoteParent(
             $traceId,
             $spanId,
-            $isSampled ? TraceFlags::SAMPLED : TraceFlags::DEFAULT
+            $traceFlags,
+            $tracestate,
         );
     }
 }
diff --git a/tests/Unit/API/Trace/Propagation/TraceContextPropagatorTest.php b/tests/Unit/API/Trace/Propagation/TraceContextPropagatorTest.php
@@ -219,6 +219,29 @@ public function test_extract_non_sampled_context_with_trace_state(): void
         );
     }
 
+    public function test_extract_random_flag(): void
+    {
+        $carrier = [
+            TraceContextPropagator::TRACEPARENT => '00-12345678901234567890123456789012-1234567890123456-02',
+        ];
+
+        $spanContext = $this->getSpanContext($this->traceContextPropagator->extract($carrier));
+        $this->assertSame('12345678901234567890123456789012', $spanContext->getTraceId());
+        $this->assertSame('1234567890123456', $spanContext->getSpanId());
+        $this->assertSame(0x2, $spanContext->getTraceFlags() & 0x2);
+    }
+
+    public function test_inject_random_flag(): void
+    {
+        $context = $this->withSpanContext(SpanContext::create('12345678901234567890123456789012', '1234567890123456', 0x2), Context::getCurrent());
+
+        $carrier = [];
+        $this->traceContextPropagator->inject($carrier, context: $context);
+
+        $this->assertArrayHasKey(TraceContextPropagator::TRACEPARENT, $carrier);
+        $this->assertSame('00-12345678901234567890123456789012-1234567890123456-02', $carrier[TraceContextPropagator::TRACEPARENT]);
+    }
+
     public function test_extract_and_inject(): void
     {
         $traceParent = '00-' . self::TRACE_ID_BASE16 . '-' . self::SPAN_ID_BASE16 . '-01';