Fix global priority sampling

The global priority sampling was not recognized as explicit sampling and thus ignored. Signed-off-by: Bob Weinand <bob.weinand@datadoghq.com>
DataDog · Jun 21, 2024 · 646eeec · 646eeec
1 parent 59d1238
commit 646eeec
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Showing 2 changed files with 21 additions and 1 deletion.
diff --git a/ext/serializer.c b/ext/serializer.c
@@ -958,7 +958,9 @@ void ddtrace_set_root_span_properties(ddtrace_root_span_data *span) {
         if (DDTRACE_G(propagated_priority_sampling) != DDTRACE_PRIORITY_SAMPLING_UNSET) {
             ZVAL_LONG(&span->property_propagated_sampling_priority, DDTRACE_G(propagated_priority_sampling));
         }
-        ZVAL_LONG(&span->property_sampling_priority, DDTRACE_G(default_priority_sampling));
+        if (DDTRACE_G(default_priority_sampling) != DDTRACE_PRIORITY_SAMPLING_UNKNOWN) {
+            ddtrace_set_priority_sampling_on_span(span, DDTRACE_G(default_priority_sampling), DD_MECHANISM_MANUAL);
+        }
 
         ddtrace_integration *web_integration = &ddtrace_integrations[DDTRACE_INTEGRATION_WEB];
         if (get_DD_TRACE_ANALYTICS_ENABLED() || web_integration->is_analytics_enabled()) {

diff --git a/tests/ext/priority_sampling/manual_global_override.phpt b/tests/ext/priority_sampling/manual_global_override.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Global explicitly set priority sampling must be respected
+--ENV--
+DD_TRACE_SAMPLE_RATE=0
+DD_TRACE_GENERATE_ROOT_SPAN=0
+--FILE--
+<?php
+
+\DDTrace\set_priority_sampling(1);
+
+$root = \DDTrace\start_span();
+
+echo "Sampling: ", \DDTrace\get_priority_sampling(), "\n";
+echo "_dd.p.dm = {$root->meta["_dd.p.dm"]}\n";
+?>
+--EXPECT--
+Sampling: 1
+_dd.p.dm = -4