Add dynamic_service DBM propagation mode

ext/configuration.c

@@ -76,6 +76,8 @@ static bool dd_parse_dbm_mode(zai_str value, zval *decoded_value, bool persisten
         ZVAL_LONG(decoded_value, DD_TRACE_DBM_PROPAGATION_SERVICE);
     } else if (zai_str_eq_ci_cstr(value, "full")) {
         ZVAL_LONG(decoded_value, DD_TRACE_DBM_PROPAGATION_FULL);
+    } else if (zai_str_eq_ci_cstr(value, "dynamic_service")) {
+        ZVAL_LONG(decoded_value, DD_TRACE_DBM_PROPAGATION_DYNAMIC_SERVICE);
     } else {
         return false;
     }

ext/configuration.h

@@ -22,6 +22,7 @@ enum ddtrace_dbm_propagation_mode {
     DD_TRACE_DBM_PROPAGATION_DISABLED,
     DD_TRACE_DBM_PROPAGATION_SERVICE,
     DD_TRACE_DBM_PROPAGATION_FULL,
+    DD_TRACE_DBM_PROPAGATION_DYNAMIC_SERVICE,
 };
 
 // To remove in 1.0

ext/ddtrace.stub.php

@@ -23,6 +23,12 @@
      */
     const DBM_PROPAGATION_FULL = UNKNOWN;
 
+    /**
+     * @var int
+     * @cvalue DD_TRACE_DBM_PROPAGATION_DYNAMIC_SERVICE
+     */
+    const DBM_PROPAGATION_DYNAMIC_SERVICE = UNKNOWN;
+
     /**
      * @var int
      * @cvalue DDTRACE_FFE_TYPE_STRING

ext/ddtrace_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit ddtrace.stub.php instead.
- * Stub hash: 8d552cbb5a25472ccb510275ab86276a29e85d7a */
+ * Stub hash: b3087c1f239d5aa8ea38f875b7236f47e56a1ca7 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_DDTrace_trace_method, 0, 3, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, className, IS_STRING, 0)
@@ -593,6 +593,7 @@ static void register_ddtrace_symbols(int module_number)
 	REGISTER_LONG_CONSTANT("DDTrace\\DBM_PROPAGATION_DISABLED", DD_TRACE_DBM_PROPAGATION_DISABLED, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\DBM_PROPAGATION_SERVICE", DD_TRACE_DBM_PROPAGATION_SERVICE, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\DBM_PROPAGATION_FULL", DD_TRACE_DBM_PROPAGATION_FULL, CONST_PERSISTENT);
+	REGISTER_LONG_CONSTANT("DDTrace\\DBM_PROPAGATION_DYNAMIC_SERVICE", DD_TRACE_DBM_PROPAGATION_DYNAMIC_SERVICE, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\FFE_STRING", DDTRACE_FFE_TYPE_STRING, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\FFE_INT", DDTRACE_FFE_TYPE_INT, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\FFE_FLOAT", DDTRACE_FFE_TYPE_FLOAT, CONST_PERSISTENT);

src/DDTrace/Integrations/DatabaseIntegrationHelper.php

@@ -49,7 +49,8 @@ public static function injectDatabaseIntegrationData(HookData $hook, $backend, $
             $peerService = $span->meta['peer.service'] ?? '';
 
             // Inject base hash into span tags if enabled
-            if (dd_trace_env_config("DD_DBM_INJECT_SQL_BASEHASH")) {
+            if (dd_trace_env_config("DD_DBM_INJECT_SQL_BASEHASH")
+                || $propagationMode == \DDTrace\DBM_PROPAGATION_DYNAMIC_SERVICE) {
                 $baseHash = \DDTrace\System\process_tags_base_hash();
                 if ($baseHash !== null) {
                     $span->meta[Tag::PROPAGATED_HASH] = $baseHash;
@@ -136,7 +137,8 @@ public static function propagateViaSqlComments(
         }
 
         // Inject base hash into SQL comment if enabled
-        if (dd_trace_env_config("DD_DBM_INJECT_SQL_BASEHASH")) {
+        if (dd_trace_env_config("DD_DBM_INJECT_SQL_BASEHASH")
+            || $mode == \DDTrace\DBM_PROPAGATION_DYNAMIC_SERVICE) {
             $baseHash = \DDTrace\System\process_tags_base_hash();
             if ($baseHash !== null) {
                 $tags["ddsh"] = $baseHash;

tests/Integration/DatabaseMonitoringTest.php

@@ -407,4 +407,49 @@ public function testBaseHashNotInjectedWhenDisabled()
             ])
         ]);
     }
+
+    public function testDynamicServiceMode()
+    {
+        // dynamic_service is equivalent to service + DD_DBM_INJECT_SQL_BASEHASH=true:
+        // service-style comment (no traceparent) plus the base hash, even though
+        // DD_DBM_INJECT_SQL_BASEHASH is left unset.
+        self::putEnv('DD_EXPERIMENTAL_PROPAGATE_PROCESS_TAGS_ENABLED=true');
+        self::putEnv('DD_DBM_PROPAGATION_MODE=dynamic_service');
+        self::putEnv('DD_TRACE_DEBUG_PRNG_SEED=42');
+
+        \dd_trace_internal_fn('reload_process_tags');
+        \dd_trace_internal_fn('set_container_tags_hash', 'abc123');
+
+        try {
+            $hook = \DDTrace\install_hook(self::class . "::instrumented", function (HookData $hook) {
+                $hook->span()->service = "testdb";
+                $hook->span()->name = "instrumented";
+                DatabaseIntegrationHelper::injectDatabaseIntegrationData($hook, 'mysql', 1);
+            });
+
+            $this->assertNotNull(\DDTrace\System\process_tags_base_hash(), 'process_tags_base_hash() is null');
+
+            $traces = $this->isolateTracer(function () use (&$commentedQuery) {
+                \DDTrace\start_trace_span();
+                $commentedQuery = $this->instrumented(0, "SELECT 1");
+                \DDTrace\close_span();
+            });
+        } finally {
+            \DDTrace\remove_hook($hook);
+        }
+
+        // service-style: a ddsh base hash is injected, but no traceparent
+        $this->assertRegularExpression(
+            '/^\/\*dddbs=\'testdb\',ddps=\'phpunit\',ddsh=\'[0-9a-f]+\'\*\/ SELECT 1$/',
+            $commentedQuery
+        );
+
+        $ddshValue = preg_replace('/^.*ddsh=\'([^\']+)\'.*$/', '$1', $commentedQuery);
+        $propagatedHash = $traces[0][1]['meta']['_dd.propagated_hash'] ?? null;
+        $this->assertNotNull($propagatedHash, '_dd.propagated_hash not found in span');
+        $this->assertSame($ddshValue, $propagatedHash, 'ddsh in SQL comment does not match _dd.propagated_hash in span');
+
+        // dynamic_service is not full mode, so the trace-injected marker must be absent
+        $this->assertArrayNotHasKey('_dd.dbm_trace_injected', $traces[0][1]['meta']);
+    }
 }