test: reduce sidecar testing flakes

tests/Common/TracerTestTrait.php

@@ -178,9 +178,9 @@ public function isolateLimitedTracer($fn, $tracer = null)
      * This method executes a request into an ad-hoc web server configured with the provided envs and inis that is
      * created and destroyed with the scope of this test.
      */
-    public function inWebServer($fn, $rootPath, $envs = [], $inis = [], &$curlInfo = null)
+    public function inWebServer($fn, $rootPath, $envs = [], $inis = [], $retryOnEmptyTraces = true, &$curlInfo = null)
     {
-        $retries = 1;
+        $retries = $retryOnEmptyTraces ? 1 : 0;
         do {
             self::putEnv('DD_TRACE_SHUTDOWN_TIMEOUT=666666'); // Arbitrarily high value to avoid flakiness
             self::putEnv('DD_TRACE_AGENT_RETRIES=3');

tests/Composer/ComposerInteroperabilityTest.php

@@ -30,6 +30,8 @@ protected function ddSetUp()
 
     public function testComposerInteroperabilityWhenNoInitHook()
     {
+        // Empty traces are the expected result, so they must not trigger the retry
+        // used by tests which expect the agent to receive a trace.
         $traces = $this->inWebServer(
             function ($execute) {
                 $output = $execute(GetSpec::create('default', '/'));
@@ -43,7 +45,8 @@ function ($execute) {
             ],
             [
                 'datadog.trace.sources_path' => 'do_not_exists',
-            ]
+            ],
+            false
         );
 
         // Will fallback to installed sources, which does not include DDTrace, only api/, thus doing a Noop

tests/DistributedTracing/GH1070OriginHeaderSegfault/GH1070OriginHeaderSegfaultTest.php

@@ -31,6 +31,7 @@ function ($execute) use (&$response) {
                 'DD_TRACE_DEBUG' => 1,
             ],
             [],
+            true,
             $curlInfo
         );
 

tests/ext/background-sender/agent_sampling_sidecar.phpt

@@ -21,7 +21,9 @@ include __DIR__ . '/../includes/request_replayer.inc';
 $contents = [];
 $filename = null;
 
-// Race conditions are annoying, especially with parallel test runs
+// Wait until the sidecar has published this test invocation's response. Each
+// invocation uses random markers so a repeated or parallel run cannot match a
+// stale shared-memory file left by an earlier process.
 function checkUpdated($marker) {
     if (PHP_OS === "Linux") {
         $retries = 100;
@@ -43,6 +45,7 @@ function checkUpdated($marker) {
         foreach (glob("/dev/shm/*") as $f) {
             var_dump($f, bin2hex(file_get_contents($f)));
         }
+        throw new RuntimeException("Timed out waiting for sidecar sampling configuration marker: {$marker}");
     }
 }
 
@@ -56,37 +59,40 @@ function recordContents() {
 $rr = new RequestReplayer();
 $rr->replayRequest(); // cleanup possible leftover
 
-$expected = [1,0,1];
-$error = false;
-$get_sampling = function() use ($rr, &$expected, &$error) {
+$errors = [];
+$get_sampling = function($label, $expected) use ($rr, &$errors) {
     $root = json_decode($rr->waitForDataAndReplay()["body"], true);
     $spans = $root["chunks"][0]["spans"] ?? $root[0];
     $priority = $spans[0]["metrics"]["_sampling_priority_v1"];
-    if ($priority != array_shift($expected)) {
-        $error = true;
+    if ($priority != $expected) {
+        $errors[] = "{$label} sampling priority: expected {$expected}, got {$priority}";
     }
     return $priority;
 };
 
-$rr->setResponse(["rate_by_service" => ["service:,env:" => 0, "service:agent_sampling_sidecar_test,env:first" => 1]]);
+$nonce = getmypid() . "-" . bin2hex(random_bytes(8));
+$firstMarker = "service:agent-sampling-sidecar-sync-{$nonce},env:first";
+$secondMarker = "service:agent-sampling-sidecar-sync-{$nonce},env:second";
+
+$rr->setResponse(["rate_by_service" => ["service:,env:" => 0, $firstMarker => 1]]);
 
 \DDTrace\start_span();
 \DDTrace\close_span();
 
-echo "Initial sampling: {$get_sampling()}\n";
+echo "Initial sampling: {$get_sampling('Initial', 1)}\n";
 
-checkUpdated("service:agent_sampling_sidecar_test,env:first");
+checkUpdated($firstMarker);
 
-$rr->setResponse(["rate_by_service" => ["service:,env:" => 0, "service:foo,env:none" => 1, "service:agent_sampling_sidecar_test,env:second" => 0]]);
+$rr->setResponse(["rate_by_service" => ["service:,env:" => 0, "service:foo,env:none" => 1, $secondMarker => 0]]);
 
 recordContents();
 \DDTrace\start_span();
 \DDTrace\close_span();
 recordContents();
 
-checkUpdated("service:agent_sampling_sidecar_test,env:second");
+checkUpdated($secondMarker);
 
-echo "Generic sampling: {$get_sampling()}\n";
+echo "Generic sampling: {$get_sampling('Generic', 0)}\n";
 
 // reset it for other tests
 $rr->setResponse(["rate_by_service" => []]);
@@ -98,10 +104,15 @@ $s->env = "none";
 \DDTrace\close_span();
 recordContents();
 
-echo "Specific sampling: {$get_sampling()}\n";
+echo "Specific sampling: {$get_sampling('Specific', 1)}\n";
 
-if ($error && PHP_OS === "Linux") {
-    var_dump($contents);
+if ($errors) {
+    foreach ($errors as $error) {
+        echo "{$error}\n";
+    }
+    if (PHP_OS === "Linux") {
+        var_dump($contents);
+    }
 }
 
 ?>