function TraceContextPropagator::extractImpl

1 call to TraceContextPropagator::extractImpl()

TraceContextPropagator::extract in vendor/open-telemetry/api/Trace/Propagation/TraceContextPropagator.php

Extracts specific values from the provided carrier into the provided {via an {

File

vendor/open-telemetry/api/Trace/Propagation/TraceContextPropagator.php, line 97

Class

TraceContextPropagator

TraceContext is a propagator that supports the W3C Trace Context format (https://www.w3.org/TR/trace-context/)

Namespace

OpenTelemetry\API\Trace\Propagation

Code

private static function extractImpl($carrier, PropagationGetterInterface $getter) : SpanContextInterface {
    $traceparent = $getter->get($carrier, self::TRACEPARENT);
    if ($traceparent === null) {
        return SpanContext::getInvalid();
    }
    // traceParent = {version}-{trace-id}-{parent-id}-{trace-flags}
    $pieces = explode('-', $traceparent);
    // If the header does not have at least 4 pieces, it is invalid -- restart the trace.
    if (count($pieces) < 4) {
        return SpanContext::getInvalid();
    }
    [
        $version,
        $traceId,
        $spanId,
        $traceFlags,
    ] = $pieces;
    
    /**
     * Return invalid if:
     * - Version is invalid (not 2 char hex or 'ff')
     * - Trace version, trace ID, span ID or trace flag are invalid
     */
    if (!TraceContextValidator::isValidTraceVersion($version) || !SpanContextValidator::isValidTraceId($traceId) || !SpanContextValidator::isValidSpanId($spanId) || !TraceContextValidator::isValidTraceFlag($traceFlags)) {
        return SpanContext::getInvalid();
    }
    // Return invalid if the trace version is not a future version but still has > 4 pieces.
    $versionIsFuture = hexdec($version) > hexdec(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;
    // 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, $tracestate);
    }
    // Only traceparent header is extracted. No tracestate.
    return SpanContext::createFromRemoteParent($traceId, $spanId, $isSampled ? TraceFlags::SAMPLED : TraceFlags::DEFAULT);
}