private function canCompressFirstPair()

in agent/php/ElasticApm/Impl/Span.php [354:407]
43 lines of code
11 McCabe index (conditional complexity)

    private function canCompressFirstPair(Span $sibling): ?string
    {
        if (($loggerProxyTrace = $this->logger->ifTraceLevelEnabledNoLine(__FUNCTION__)) !== null) {
            $localLogger = $this->logger->inherit()->addAllContext(
                [
                    'this'    => ['name' => $this->name, 'type' => $this->type, 'duration' => $this->duration],
                    'sibling' => ['name' => $sibling->name, 'type' => $sibling->type, 'duration' => $sibling->duration],
                ]
            );
            $loggerProxyTrace = $localLogger->ifTraceLevelEnabledNoLine(__FUNCTION__);
        }

        if (!$this->isSameKind($sibling)) {
            $loggerProxyTrace && $loggerProxyTrace->log(__LINE__, 'Cannot compress because not even same kind');
            return null;
        }

        $config = $this->containingTransaction->tracer()->getConfig();
        $exactMatchMaxDuration = $config->spanCompressionExactMatchMaxDuration();
        if ($this->name === $sibling->name) {
            if ($this->duration <= $exactMatchMaxDuration && $sibling->duration <= $exactMatchMaxDuration) {
                $loggerProxyTrace && $loggerProxyTrace->log(__LINE__, 'Can compress as ' . Constants::COMPRESSION_STRATEGY_EXACT_MATCH);
                return Constants::COMPRESSION_STRATEGY_EXACT_MATCH;
            } else {
                /**
                 * Note that if the spans are exact match but duration threshold requirement is not satisfied we just stop compression sequence.
                 * In particular it means that the implementation should not proceed to try same kind strategy.
                 * Otherwise user would have to lower both span_compression_exact_match_max_duration and span_compression_same_kind_max_duration
                 * to prevent longer exact match spans from being compressed.
                 *
                 * @link https://github.com/elastic/apm/blob/e528576a5b0f3e95fe3c1da493466882fa7d8329/specs/agents/handling-huge-traces/tracing-spans-compress.md?plain=1#L200
                 */
                $loggerProxyTrace && $loggerProxyTrace->log(
                    __LINE__,
                    'Cannot compress as ' . Constants::COMPRESSION_STRATEGY_EXACT_MATCH . ' because one of the durations is above configured threshold',
                    ['exactMatchMaxDuration (ms)' => $exactMatchMaxDuration]
                );
                return null;
            }
        }

        $sameKindMaxDuration = $config->spanCompressionSameKindMaxDuration();
        if ($this->duration <= $sameKindMaxDuration && $sibling->duration <= $sameKindMaxDuration) {
            $loggerProxyTrace && $loggerProxyTrace->log(__LINE__, 'Can compress as ' . Constants::COMPRESSION_STRATEGY_SAME_KIND);
            return Constants::COMPRESSION_STRATEGY_SAME_KIND;
        } else {
            $loggerProxyTrace && $loggerProxyTrace->log(
                __LINE__,
                'Cannot compress as ' . Constants::COMPRESSION_STRATEGY_SAME_KIND . ' because one of the durations is above configured threshold',
                ['sameKindMaxDuration (ms)' => $sameKindMaxDuration]
            );
            return null;
        }
    }