feat(tracer): add configuration for connection mode

Signed-off-by: Alexandre Rulleau <alexandre.rulleau@datadoghq.com>

Author: Leiyks

ext/configuration.c

@@ -96,6 +96,21 @@ static bool dd_parse_sampling_rules_format(zai_str value, zval *decoded_value, b
     return true;
 }
 
+static bool dd_parse_sidecar_connection_mode(zai_str value, zval *decoded_value, bool persistent) {
+    UNUSED(persistent);
+    if (zai_str_eq_ci_cstr(value, "auto")) {
+        ZVAL_LONG(decoded_value, DD_TRACE_SIDECAR_CONNECTION_MODE_AUTO);
+    } else if (zai_str_eq_ci_cstr(value, "subprocess")) {
+        ZVAL_LONG(decoded_value, DD_TRACE_SIDECAR_CONNECTION_MODE_SUBPROCESS);
+    } else if (zai_str_eq_ci_cstr(value, "thread")) {
+        ZVAL_LONG(decoded_value, DD_TRACE_SIDECAR_CONNECTION_MODE_THREAD);
+    } else {
+        return false;
+    }
+
+    return true;
+}
+
 static bool dd_parse_tags(zai_str value, zval *decoded_value, bool persistent) {
     ZVAL_ARR(decoded_value, pemalloc(sizeof(HashTable), persistent));
     zend_hash_init(Z_ARR_P(decoded_value), 8, NULL, persistent ? ZVAL_INTERNAL_PTR_DTOR : ZVAL_PTR_DTOR, persistent);

ext/configuration.h

@@ -30,6 +30,12 @@ enum ddtrace_sampling_rules_format {
     DD_TRACE_SAMPLING_RULES_FORMAT_GLOB
 };
 
+enum ddtrace_sidecar_connection_mode {
+    DD_TRACE_SIDECAR_CONNECTION_MODE_AUTO = 0,       // Default: try subprocess, fallback to thread
+    DD_TRACE_SIDECAR_CONNECTION_MODE_SUBPROCESS = 1, // Force subprocess only
+    DD_TRACE_SIDECAR_CONNECTION_MODE_THREAD = 2,     // Force thread only
+};
+
 /* From the curl docs on CONNECT_TIMEOUT_MS:
  *     If libcurl is built to use the standard system name resolver, that
  *     portion of the transfer will still use full-second resolution for
@@ -225,6 +231,7 @@ enum ddtrace_sampling_rules_format {
     CONFIG(STRING, DD_TRACE_AGENT_TEST_SESSION_TOKEN, "", .ini_change = ddtrace_alter_test_session_token)      \
     CONFIG(BOOL, DD_TRACE_PROPAGATE_USER_ID_DEFAULT, "false")                                                  \
     CONFIG(CUSTOM(INT), DD_DBM_PROPAGATION_MODE, "disabled", .parser = dd_parse_dbm_mode)                      \
+    CONFIG(CUSTOM(INT), DD_TRACE_SIDECAR_CONNECTION_MODE, "auto", .parser = dd_parse_sidecar_connection_mode) \
     CONFIG(SET, DD_TRACE_WORDPRESS_ADDITIONAL_ACTIONS, "")                                                     \
     CONFIG(BOOL, DD_TRACE_WORDPRESS_CALLBACKS, "true")                                                         \
     CONFIG(BOOL, DD_INTEGRATION_METRICS_ENABLED, "true",                                                       \

ext/ddtrace_arginfo.h

@@ -541,6 +541,9 @@ 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\\SIDECAR_CONNECTION_MODE_AUTO", DD_TRACE_SIDECAR_CONNECTION_MODE_AUTO, CONST_PERSISTENT);
+	REGISTER_LONG_CONSTANT("DDTrace\\SIDECAR_CONNECTION_MODE_SUBPROCESS", DD_TRACE_SIDECAR_CONNECTION_MODE_SUBPROCESS, CONST_PERSISTENT);
+	REGISTER_LONG_CONSTANT("DDTrace\\SIDECAR_CONNECTION_MODE_THREAD", DD_TRACE_SIDECAR_CONNECTION_MODE_THREAD, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\Internal\\SPAN_FLAG_OPENTELEMETRY", DDTRACE_SPAN_FLAG_OPENTELEMETRY, CONST_PERSISTENT);
 	REGISTER_LONG_CONSTANT("DDTrace\\Internal\\SPAN_FLAG_OPENTRACING", DDTRACE_SPAN_FLAG_OPENTRACING, CONST_PERSISTENT);
 	REGISTER_STRING_CONSTANT("DD_TRACE_VERSION", PHP_DDTRACE_VERSION, CONST_PERSISTENT);