fix: handle Apache graceful restarts more accurately (#2483)

* fix(profiling): handle Apache graceful restarts more accurately

* fix(tracing): reset pthread_once controls

Author: morrisonlevi

ext/ddtrace.c

@@ -981,6 +981,9 @@ static PHP_MINIT_FUNCTION(ddtrace) {
     atexit(dd_clean_main_thread_locals);
 #endif
 
+    // Reset on every minit for `apachectl graceful`.
+    dd_activate_once_control = PTHREAD_ONCE_INIT;
+
     zai_hook_minit();
     zai_uhook_minit(module_number);
 #if PHP_VERSION_ID >= 80000
@@ -1149,7 +1152,7 @@ static void dd_initialize_request(void) {
     zend_hash_init(&DDTRACE_G(propagated_root_span_tags), 8, unused, ZVAL_PTR_DTOR, 0);
     zend_hash_init(&DDTRACE_G(tracestate_unknown_dd_keys), 8, unused, ZVAL_PTR_DTOR, 0);
 
-    // Things that should only run on the first RINIT
+    // Things that should only run on the first RINIT after each minit.
     pthread_once(&dd_rinit_once_control, dd_rinit_once);
 
     if (!DDTRACE_G(remote_config_reader)) {

ext/handlers_curl.c

@@ -176,7 +176,7 @@ static HashTable *ddtrace_curl_multi_get_gc(zend_object *object, zval **table, i
 }
 
 static pthread_once_t dd_replace_curl_get_gc_once = PTHREAD_ONCE_INIT;
-static zend_object_handlers *dd_curl_object_handlers;
+ZEND_TLS zend_object_handlers *dd_curl_object_handlers = NULL;
 static void dd_replace_curl_get_gc(void) {
     dd_curl_multi_get_gc = dd_curl_object_handlers->get_gc;
     dd_curl_object_handlers->get_gc = ddtrace_curl_multi_get_gc;
@@ -406,6 +406,10 @@ void ddtrace_curl_handlers_startup(void) {
     for (size_t i = 0; i < handlers_len; ++i) {
         datadog_php_install_handler(handlers[i]);
     }
+
+    // Reset object state each MINIT/startup cycle for `apachectl graceful`.
+    dd_curl_object_handlers = NULL;
+    dd_replace_curl_get_gc_once = PTHREAD_ONCE_INIT;
 }
 
 void ddtrace_curl_handlers_rinit(void) {

profiling/src/lib.rs

@@ -290,6 +290,17 @@ extern "C" fn minit(_type: c_int, module_number: c_int) -> ZendResult {
     #[cfg(feature = "exception_profiling")]
     exception::exception_profiling_minit();
 
+    // There are a few things which need to do something on the first rinit of
+    // each minit/mshutdown cycle. In Apache, when doing `apachectl graceful`,
+    // there can be more than one of these cycles per process.
+    // Re-initializing these on each minit allows us to do it once per cycle.
+    // This is unsafe generally, but all SAPIs are supposed to only have one
+    // thread alive during minit, so it should be safe here specifically.
+    unsafe {
+        ZAI_CONFIG_ONCE = Once::new();
+        RINIT_ONCE = Once::new();
+    }
+
     ZendResult::Success
 }
 
@@ -374,15 +385,20 @@ extern "C" fn activate() {
     unsafe { profiling::activate_run_time_cache() };
 }
 
+/// The mut here is *only* for resetting this back to uninitialized each minit.
+static mut ZAI_CONFIG_ONCE: Once = Once::new();
+/// The mut here is *only* for resetting this back to uninitialized each minit.
+static mut RINIT_ONCE: Once = Once::new();
+
 /* If Failure is returned the VM will do a C exit; try hard to avoid that,
  * using it for catastrophic errors only.
  */
 extern "C" fn rinit(_type: c_int, _module_number: c_int) -> ZendResult {
     #[cfg(debug_assertions)]
     trace!("RINIT({_type}, {_module_number})");
 
-    static ONCE: Once = Once::new();
-    ONCE.call_once(|| unsafe {
+    // SAFETY: not being mutated during rinit.
+    unsafe { &ZAI_CONFIG_ONCE }.call_once(|| unsafe {
         bindings::zai_config_first_time_rinit();
         config::first_rinit();
     });
@@ -420,8 +436,7 @@ extern "C" fn rinit(_type: c_int, _module_number: c_int) -> ZendResult {
     // SAFETY: still safe to access in rinit after first_rinit.
     let system_settings = unsafe { system_settings.as_ref() };
 
-    static ONCE2: Once = Once::new();
-    ONCE2.call_once(|| {
+    unsafe { &RINIT_ONCE }.call_once(|| {
         if system_settings.profiling_enabled {
             /* Safety: sapi_module is initialized by rinit and shouldn't be
              * modified at this point (safe to read values).

profiling/src/logging.rs

@@ -17,11 +17,18 @@ pub fn log_init(level_filter: LevelFilter) {
     if fd != -1 {
         // Safety: the fd is a valid and open file descriptor, and the File has sole ownership.
         let target = Box::new(unsafe { File::from_raw_fd(fd) });
-        env_logger::builder()
+        let result = env_logger::builder()
             .filter_level(LevelFilter::Off)
             .filter_module("datadog_php_profiling", level_filter)
             .target(Target::Pipe(target))
             .format_timestamp_micros()
-            .init();
+            .try_init();
+
+        // Due to `apachectl graceful` doing multiple minit/mshutdowns in one
+        // process, this may get called more than once. That's okay, set the
+        // new log level.
+        if result.is_err() {
+            log::set_max_level(level_filter);
+        }
     }
 }