Added adaptive sampling

Author: allflame

src/Sampler/AdaptiveSampler.php

@@ -0,0 +1,48 @@
+<?php
+declare(strict_types=1);
+
+namespace Jaeger\Sampler;
+
+class AdaptiveSampler implements SamplerInterface
+{
+    private $rateLimit;
+
+    private $probabilistic;
+
+    public function __construct(SamplerInterface $rateLimit, SamplerInterface $probabilistic)
+    {
+        $this->rateLimit = $rateLimit;
+        $this->probabilistic = $probabilistic;
+    }
+
+    public function decide(int $tracerId, string $operationName, string $debugId): SamplerResult
+    {
+        $rateLimitResult = $this->rateLimit->decide($tracerId, $operationName, $debugId);
+        if ($rateLimitResult->isSampled()) {
+            return new SamplerResult(
+                true,
+                $rateLimitResult->getFlags(),
+                array_merge([new SamplerTypeTag('adaptive'),], $rateLimitResult->getTags())
+            );
+        }
+
+        $probabilisticResult = $this->probabilistic->decide($tracerId, $operationName, $debugId);
+        if ($probabilisticResult->isSampled()) {
+            return new SamplerResult(
+                true,
+                $rateLimitResult->getFlags(),
+                array_merge([new SamplerTypeTag('adaptive'),], $rateLimitResult->getTags())
+            );
+        }
+
+        return new SamplerResult(
+            false,
+            0,
+            [
+                new SamplerTypeTag('adaptive'),
+                new SamplerDecisionTag(false),
+                new SamplerFlagsTag(0x00),
+            ]
+        );
+    }
+}

src/Sampler/ConstSampler.php

@@ -7,12 +7,12 @@ class ConstSampler extends AbstractSampler
 {
     private $debugEnabled;
 
-    public function __construct(bool $debugEnabled)
+    public function __construct($debugEnabled)
     {
-        $this->debugEnabled = $debugEnabled;
+        $this->debugEnabled = (bool)$debugEnabled;
     }
 
-    public function doDecide(int $traceId, string $operationName): SamplerResult
+    public function doDecide(int $tracerId, string $operationName): SamplerResult
     {
         if (false === $this->debugEnabled) {
             return new SamplerResult(

src/Sampler/ProbabilisticSampler.php

@@ -15,9 +15,9 @@ public function __construct(float $rate)
         $this->threshold = 0.5 * $rate * PHP_INT_MAX;
     }
 
-    public function doDecide(int $traceId, string $operationName): SamplerResult
+    public function doDecide(int $tracerId, string $operationName): SamplerResult
     {
-        if (abs($traceId) > $this->threshold) {
+        if (abs($tracerId) > $this->threshold) {
             return new SamplerResult(
                 false,
                 0x00,

src/Sampler/RateLimitingSampler.php

@@ -15,9 +15,9 @@ public function __construct(float $rate, GeneratorInterface $generator)
         $this->generator = $generator;
     }
 
-    public function doDecide(int $traceId, string $operationName): SamplerResult
+    public function doDecide(int $tracerId, string $operationName): SamplerResult
     {
-        $key = $this->generator->generate($traceId, $operationName);
+        $key = $this->generator->generate($tracerId, $operationName);
         if (false !== ($current = apcu_add($key, sprintf('%s:%d', time(), 1), 1 / $this->rate))) {
             return new SamplerResult(
                 true, 0x01, [
@@ -31,7 +31,7 @@ public function doDecide(int $traceId, string $operationName): SamplerResult
 
         while (true) {
             if (false === ($current = apcu_fetch($key))) {
-                return $this->doDecide($traceId, $operationName);
+                return $this->doDecide($tracerId, $operationName);
             }
             list ($timestamp, $count) = explode(':', $current);
             if ($count / (time() - $timestamp) > $this->rate) {