Support ApmTracingMulticonfig in dynamic config

Signed-off-by: Bob Weinand <bob.weinand@datadoghq.com>

Author: bwoebi

Cargo.lock

@@ -60,13 +60,33 @@ type VecRemoteConfigCapabilities = libdd_common_ffi::Vec<RemoteConfigCapabilitie
 pub static mut DDTRACE_REMOTE_CONFIG_CAPABILITIES: VecRemoteConfigCapabilities =
     libdd_common_ffi::Vec::new();
 
+struct ActiveDynamicConfig {
+    priority: u8,
+    configs: Vec<Configs>,
+}
+
 #[derive(Default)]
 struct DynamicConfig {
-    active_config_path: Option<String>,
-    configs: Vec<Configs>,
+    active_configs: HashMap<String, ActiveDynamicConfig>,
+    merged_configs: Vec<Configs>,
     old_config_values: HashMap<String, Option<OwnedZendString>>,
 }
 
+fn compute_merged_configs(active_configs: &HashMap<String, ActiveDynamicConfig>) -> Vec<Configs> {
+    let mut sorted: Vec<_> = active_configs.values().collect();
+    sorted.sort_by_key(|c| c.priority);
+    let mut seen = HashSet::new();
+    let mut merged = vec![];
+    for entry in sorted {
+        for config in &entry.configs {
+            if seen.insert(mem::discriminant(config)) {
+                merged.push(config.clone());
+            }
+        }
+    }
+    merged
+}
+
 pub struct RemoteConfigState {
     manager: RemoteConfigManager,
     live_debugger: LiveDebuggerState,
@@ -109,6 +129,7 @@ pub unsafe extern "C" fn ddog_init_remote_config(
     DDTRACE_REMOTE_CONFIG_CAPABILITIES.push(RemoteConfigCapabilities::ApmTracingLogsInjection);
     DDTRACE_REMOTE_CONFIG_CAPABILITIES.push(RemoteConfigCapabilities::ApmTracingSampleRate);
     DDTRACE_REMOTE_CONFIG_CAPABILITIES.push(RemoteConfigCapabilities::ApmTracingSampleRules);
+    DDTRACE_REMOTE_CONFIG_CAPABILITIES.push(RemoteConfigCapabilities::ApmTracingMulticonfig);
 
     DDTRACE_REMOTE_CONFIG_PRODUCTS.push(RemoteConfigProduct::AsmFeatures);
     DDTRACE_REMOTE_CONFIG_CAPABILITIES.push(RemoteConfigCapabilities::AsmAutoUserInstrumMode);
@@ -254,8 +275,8 @@ fn remove_old_configs(remote_config: &mut RemoteConfigState) {
     for (name, val) in remote_config.dynamic_config.old_config_values.drain() {
         reset_old_config(name.as_str(), val);
     }
-    remote_config.dynamic_config.old_config_values.clear();
-    remote_config.dynamic_config.active_config_path = None;
+    remote_config.dynamic_config.active_configs.clear();
+    remote_config.dynamic_config.merged_configs.clear();
 }
 
 fn insert_new_configs(
@@ -338,14 +359,17 @@ pub extern "C" fn ddog_process_remote_configs(remote_config: &mut RemoteConfigSt
                     apply_config(rc_ref, debugger, limiter);
                 }
                 RemoteConfigData::DynamicConfig(config_data) => {
+                    let priority = config_data.priority();
                     let configs: Vec<Configs> = config_data.lib_config.into();
                     if !configs.is_empty() {
+                        remote_config.dynamic_config.active_configs
+                            .insert(value.config_id, ActiveDynamicConfig { priority, configs });
+                        let merged = compute_merged_configs(&remote_config.dynamic_config.active_configs);
                         insert_new_configs(
                             &mut remote_config.dynamic_config.old_config_values,
-                            &mut remote_config.dynamic_config.configs,
-                            configs,
+                            &mut remote_config.dynamic_config.merged_configs,
+                            merged,
                         );
-                        remote_config.dynamic_config.active_config_path = Some(value.config_id);
                     }
                 }
                 RemoteConfigData::Ignored(_) => (),
@@ -360,8 +384,17 @@ pub extern "C" fn ddog_process_remote_configs(remote_config: &mut RemoteConfigSt
                     }
                 }
                 RemoteConfigProduct::ApmTracing => {
-                    if Some(path.config_id) == remote_config.dynamic_config.active_config_path {
-                        remove_old_configs(remote_config);
+                    if remote_config.dynamic_config.active_configs.remove(&path.config_id).is_some() {
+                        if remote_config.dynamic_config.active_configs.is_empty() {
+                            remove_old_configs(remote_config);
+                        } else {
+                            let merged = compute_merged_configs(&remote_config.dynamic_config.active_configs);
+                            insert_new_configs(
+                                &mut remote_config.dynamic_config.old_config_values,
+                                &mut remote_config.dynamic_config.merged_configs,
+                                merged,
+                            );
+                        }
                     }
                 }
                 _ => (),
@@ -529,7 +562,7 @@ pub unsafe extern "C" fn ddog_remote_config_alter_dynamic_config(
     {
         let mut ret = false;
         let config_name = config.to_utf8_lossy();
-        for config in remote_config.dynamic_config.configs.iter() {
+        for config in remote_config.dynamic_config.merged_configs.iter() {
             let name = map_config_name(config);
             if name == config_name.as_ref() {
                 let val = map_config_value(config);
@@ -559,6 +592,8 @@ pub unsafe extern "C" fn ddog_setup_remote_config(
 pub extern "C" fn ddog_rshutdown_remote_config(remote_config: &mut RemoteConfigState) {
     remote_config.live_debugger.spans_map.clear();
     remote_config.dynamic_config.old_config_values.clear();
+    remote_config.dynamic_config.active_configs.clear();
+    remote_config.dynamic_config.merged_configs.clear();
     remote_config.manager.unload_configs(&[
         RemoteConfigProduct::ApmTracing,
         RemoteConfigProduct::LiveDebugger,

components-rs/remote_config.rs

@@ -99,7 +99,10 @@ static zend_string *dd_dynamic_configuration_update(ddog_CharSlice config, zend_
         }
     } else {
         ZEND_ASSERT(mode == DDOG_DYNAMIC_CONFIG_UPDATE_MODE_WRITE);
+        ddog_RemoteConfigState *saved = DDTRACE_G(remote_config_state);
+        DDTRACE_G(remote_config_state) = NULL;
         zend_alter_ini_entry(name, value, ZEND_INI_USER, ZEND_INI_STAGE_RUNTIME);
+        DDTRACE_G(remote_config_state) = saved;
         zend_string_release(value);
     }
     zend_string_release(name);

ext/remote_config.c

@@ -0,0 +1,62 @@
+--TEST--
+Test dynamic config multiconfig priority merging
+--SKIPIF--
+<?php include __DIR__ . '/../includes/skipif_no_dev_env.inc'; ?>
+--ENV--
+DD_AGENT_HOST=request-replayer
+DD_TRACE_AGENT_PORT=80
+DD_TRACE_GENERATE_ROOT_SPAN=0
+DD_REMOTE_CONFIG_POLL_INTERVAL_SECONDS=0.01
+--INI--
+datadog.trace.agent_test_session_token=remote-config/dynamic_config_multiconfig
+--FILE--
+<?php
+
+require __DIR__ . "/remote_config.inc";
+include __DIR__ . '/../includes/request_replayer.inc';
+
+reset_request_replayer();
+$rr = new RequestReplayer();
+
+\DDTrace\start_span();
+
+// Add both configs before sleeping so a single polling cycle sees both.
+// Org-level: sets sample_rate=0.3 and log_injection=true.
+// Specific service+env: overrides sample_rate=0.7, does not set log_injection.
+$org_path = put_wildcard_dynamic_config_file([
+    "tracing_sample_rate" => 0.3,
+    "log_injection_enabled" => true,
+]);
+$specific_path = put_dynamic_config_file([
+    "tracing_sample_rate" => 0.7,
+]);
+
+sleep(20); // signal interrupts interrupt the sleep().
+
+// Specific config wins for sample_rate; org-level provides log_injection.
+print "After both configs:\n";
+var_dump(ini_get("datadog.trace.sample_rate"));
+var_dump(ini_get("datadog.logs_injection"));
+
+del_rc_file($specific_path);
+
+sleep(20); // signal interrupts interrupt the sleep().
+
+// Only org-level remains: sample_rate falls back to 0.3.
+print "After removing specific config:\n";
+var_dump(ini_get("datadog.trace.sample_rate"));
+var_dump(ini_get("datadog.logs_injection"));
+
+?>
+--CLEAN--
+<?php
+require __DIR__ . "/remote_config.inc";
+reset_request_replayer();
+?>
+--EXPECT--
+After both configs:
+string(3) "0.7"
+string(1) "1"
+After removing specific config:
+string(3) "0.3"
+string(1) "1"

libdatadog

@@ -56,3 +56,18 @@ function put_dynamic_config_file($configs, $service = null, $env = null) {
     put_rc_file($path, $data, $service);
     return $path;
 }
+
+function put_wildcard_dynamic_config_file($configs, $service = "*", $env = "*") {
+    $json = [
+        "action" => "enable",
+        "service_target" => [
+            "service" => $service,
+            "env" => $env,
+        ],
+        "lib_config" => $configs,
+    ];
+    $data = json_encode($json);
+    $path = "datadog/2/APM_TRACING/" . sha1($data) . "/config";
+    put_rc_file($path, $data);
+    return $path;
+}