refactor(prof): tag handling (#3423)

morrisonlevi · web-flow · commit b8bf258521bc · 2025-09-19T17:05:51.000-06:00
Tags are now divided into three groups:

1. Globals which are language, profiler version, process ID, etc.
2. Unified service tags which are service, env, and version.
3. Locals, which are request-local tags where DD_TAGS are stored.
Unified service tag are also request-local but stored separately.

Globals are initialized lazily. This moves more tags into global.

The warning for an invalid tag now includes the key name. All our tag
keys are static, so there's not privacy concern to include it.

The `Vec&lt;Tag&gt;` now reserves exactly how much memory it needs. I don't
expect this to be a meaningful performance change, just doing it while
I'm here.
diff --git a/profiling/src/lib.rs b/profiling/src/lib.rs
@@ -76,15 +76,35 @@ static mut RUNTIME_PHP_VERSION: &str = {
 };
 
 lazy_static! {
-    static ref LAZY_STATICS_TAGS: Vec<Tag> = {
-        vec![
+    /// # Safety
+    /// The first time this is accessed must be after config is initialized in
+    /// the first RINIT and before mshutdown!
+    static ref GLOBAL_TAGS: Vec<Tag> = {
+        let mut tags = vec![
             tag!("language", "php"),
             tag!("profiler_version", env!("PROFILER_VERSION")),
             // SAFETY: calling getpid() is safe.
             Tag::new("process_id", unsafe { libc::getpid() }.to_string())
                 .expect("process_id tag to be valid"),
             Tag::new("runtime-id", runtime_id().to_string()).expect("runtime-id tag to be valid"),
-        ]
+        ];
+
+        // This should probably be "language_version", but this is the
+        // standardized tag name.
+        // SAFETY: PHP_VERSION is safe to access in rinit (only
+        // mutated during minit).
+        add_tag(&mut tags, "runtime_version", unsafe { RUNTIME_PHP_VERSION });
+        add_tag(&mut tags, "php.sapi", SAPI.as_ref());
+        // In case we ever add PHP debug build support, we should add `zend-zts-debug` and
+        // `zend-nts-debug`. For the time being we only support `zend-zts-ndebug` and
+        // `zend-nts-ndebug`
+        let runtime_engine = if cfg!(php_zts) {
+            "zend-zts-ndebug"
+        } else {
+            "zend-nts-ndebug"
+        };
+        add_tag(&mut tags, "runtime_engine", runtime_engine);
+        tags
     };
 
     /// The Server API the profiler is running under.
@@ -660,26 +680,19 @@ extern "C" fn rinit(_type: c_int, _module_number: c_int) -> ZendResult {
             CLOCKS.with_borrow_mut(|clocks| clocks.initialize(cpu_time_enabled));
 
             TAGS.set({
-                let mut tags = LAZY_STATICS_TAGS.clone();
+                // SAFETY: accessing in RINIT after config is initialized.
+                let globals = GLOBAL_TAGS.deref();
+                let unified_service_tags_len = locals.service.is_some() as usize
+                    + locals.env.is_some() as usize
+                    + locals.version.is_some() as usize;
+
+                let mut tags = Vec::new();
+                tags.reserve_exact(globals.len() + unified_service_tags_len + locals.tags.len());
+                tags.extend_from_slice(globals.as_slice());
                 add_optional_tag(&mut tags, "service", &locals.service);
                 add_optional_tag(&mut tags, "env", &locals.env);
                 add_optional_tag(&mut tags, "version", &locals.version);
-                // This should probably be "language_version", but this is the
-                // standardized tag name.
-                // SAFETY: PHP_VERSION is safe to access in rinit (only
-                // mutated during minit).
-                add_tag(&mut tags, "runtime_version", unsafe { RUNTIME_PHP_VERSION });
-                add_tag(&mut tags, "php.sapi", SAPI.as_ref());
-                // In case we ever add PHP debug build support, we should add `zend-zts-debug` and
-                // `zend-nts-debug`. For the time being we only support `zend-zts-ndebug` and
-                // `zend-nts-ndebug`
-                let runtime_engine = if cfg!(php_zts) {
-                    "zend-zts-ndebug"
-                } else {
-                    "zend-nts-ndebug"
-                };
-                add_tag(&mut tags, "runtime_engine", runtime_engine);
-                tags.extend_from_slice(&locals.tags);
+                tags.extend_from_slice(locals.tags.as_slice());
                 Arc::new(tags)
             });
 
@@ -721,12 +734,8 @@ fn add_optional_tag<T: AsRef<str>>(tags: &mut Vec<Tag>, key: &str, value: &Optio
 fn add_tag(tags: &mut Vec<Tag>, key: &str, value: &str) {
     assert!(!value.is_empty());
     match Tag::new(key, value) {
-        Ok(tag) => {
-            tags.push(tag);
-        }
-        Err(err) => {
-            warn!("invalid tag: {err}");
-        }
+        Ok(tag) => tags.push(tag),
+        Err(err) => warn!("invalid {key} tag: {err}"),
     }
 }
 
