feat(profiling) visualise opcache restarts in the timeline

profiling/build.rs

@@ -357,6 +357,7 @@ fn cfg_php_feature_flags(vernum: u64) {
     }
     if vernum >= 80400 {
         println!("cargo:rustc-cfg=php_frameless");
+        println!("cargo:rustc-cfg=php_opcache_restart_hook");
     }
 }
 

profiling/src/bindings/mod.rs

@@ -20,6 +20,8 @@ pub type VmGcCollectCyclesFn = unsafe extern "C" fn() -> i32;
 #[cfg(feature = "timeline")]
 pub type VmZendCompileFile =
     unsafe extern "C" fn(*mut zend_file_handle, i32) -> *mut _zend_op_array;
+#[cfg(all(feature = "timeline", php_opcache_restart_hook))]
+pub type VmZendAccelScheduleRestartHook = unsafe extern "C" fn(i32);
 #[cfg(all(feature = "timeline", php_zend_compile_string_has_position))]
 pub type VmZendCompileString = unsafe extern "C" fn(
     *mut zend_string,

profiling/src/profiling/mod.rs

@@ -1051,6 +1051,50 @@ impl Profiler {
         }
     }
 
+    /// This function can be called to collect an opcache restart
+    #[cfg(all(feature = "timeline", php_opcache_restart_hook))]
+    pub(crate) fn collect_opcache_restart(
+        &self,
+        now: i64,
+        file: String,
+        line: u32,
+        reason: &'static str,
+    ) {
+        let mut labels = Profiler::common_labels(2);
+
+        labels.push(Label {
+            key: "event",
+            value: LabelValue::Str("opcache_restart".into()),
+        });
+        labels.push(Label {
+            key: "reason",
+            value: LabelValue::Str(reason.into()),
+        });
+
+        let n_labels = labels.len();
+
+        match self.prepare_and_send_message(
+            vec![ZendFrame {
+                function: "[opcache restart]".into(),
+                file: Some(file),
+                line,
+            }],
+            SampleValues {
+                timeline: 1,
+                ..Default::default()
+            },
+            labels,
+            now,
+        ) {
+            Ok(_) => {
+                trace!("Sent event 'opcache_restart' with {n_labels} labels to profiler.")
+            }
+            Err(err) => {
+                warn!("Failed to send event 'opcache_restart' with {n_labels} labels to profiler: {err}")
+            }
+        }
+    }
+
     /// This function can be called to collect any kind of inactivity that is happening
     #[cfg(feature = "timeline")]
     pub fn collect_idle(&self, now: i64, duration: i64, reason: &'static str) {

profiling/src/profiling/thread_utils.rs

@@ -119,7 +119,8 @@ pub fn get_current_thread_name() -> String {
             }
 
             thread_name
-        }).clone()
+        })
+        .clone()
     })
 }
 

profiling/src/timeline.rs

@@ -24,6 +24,12 @@ static mut PREV_ZEND_COMPILE_STRING: Option<zend::VmZendCompileString> = None;
 /// The engine's original (or neighbouring extensions) `zend_compile_file()` function
 static mut PREV_ZEND_COMPILE_FILE: Option<zend::VmZendCompileFile> = None;
 
+/// The engine's original (or neighbouring extensions) `zend_accel_schedule_restart_hook()`
+/// function
+#[cfg(php_opcache_restart_hook)]
+static mut PREV_ZEND_ACCEL_SCHEDULE_RESTART_HOOK: Option<zend::VmZendAccelScheduleRestartHook> =
+    None;
+
 thread_local! {
     static IDLE_SINCE: RefCell<Instant> = RefCell::new(Instant::now());
     #[cfg(php_zts)]
@@ -178,12 +184,63 @@ unsafe extern "C" fn ddog_php_prof_zend_error_observer(
     }
 }
 
+/// Will be called by the opcache extension when a restart is scheduled. The `reason` is this enum:
+/// ```C
+/// typedef enum _zend_accel_restart_reason {
+///     ACCEL_RESTART_OOM,    /* restart because of out of memory */
+///     ACCEL_RESTART_HASH,   /* restart because of hash overflow */
+///     ACCEL_RESTART_USER    /* restart scheduled by opcache_reset() */
+/// } zend_accel_restart_reason;
+/// ```
+#[no_mangle]
+#[cfg(php_opcache_restart_hook)]
+unsafe extern "C" fn ddog_php_prof_zend_accel_schedule_restart_hook(reason: i32) {
+    let timeline_enabled = REQUEST_LOCALS.with(|cell| {
+        cell.try_borrow()
+            .map(|locals| locals.system_settings().profiling_timeline_enabled)
+            .unwrap_or(false)
+    });
+
+    if timeline_enabled {
+        let now = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
+        if let Some(profiler) = Profiler::get() {
+            let now = now.as_nanos() as i64;
+            let file = unsafe {
+                zend::zai_str_from_zstr(zend::zend_get_executed_filename_ex().as_mut())
+                    .into_string()
+            };
+            profiler.collect_opcache_restart(
+                now,
+                file,
+                zend::zend_get_executed_lineno(),
+                match reason {
+                    0 => "out of memory",
+                    1 => "hash overflow",
+                    2 => "`opcache_restart()` called",
+                    _ => "unknown",
+                },
+            );
+        }
+    }
+
+    if let Some(prev) = PREV_ZEND_ACCEL_SCHEDULE_RESTART_HOOK {
+        prev(reason);
+    }
+}
+
 /// This functions needs to be called in MINIT of the module
 pub fn timeline_minit() {
     unsafe {
         #[cfg(zend_error_observer)]
         zend::zend_observer_error_register(Some(ddog_php_prof_zend_error_observer));
 
+        #[cfg(php_opcache_restart_hook)]
+        {
+            PREV_ZEND_ACCEL_SCHEDULE_RESTART_HOOK = zend::zend_accel_schedule_restart_hook;
+            zend::zend_accel_schedule_restart_hook =
+                Some(ddog_php_prof_zend_accel_schedule_restart_hook);
+        }
+
         // register our function in the `gc_collect_cycles` pointer
         PREV_GC_COLLECT_CYCLES = zend::gc_collect_cycles;
         zend::gc_collect_cycles = Some(ddog_php_prof_gc_collect_cycles);