Add OPcache restart hook, fired when a restart is carried out

UPGRADING.INTERNALS

@@ -60,6 +60,9 @@ PHP 8.7 INTERNALS UPGRADE NOTES
 - The ZTS symbols compiler_globals_offset and executor_globals_offset have been
   removed: CG()/EG() now reach the globals through a __thread struct.
 - Removed zend_error_noreturn_unchecked().
+- Added the zend_accel_restart_hook callback, which OPcache calls once a
+  scheduled restart has been carried out, on the thread that carried it out,
+  with the same reason as the zend_accel_schedule_restart_hook callback.
 
 ========================
 2. Build system changes

Zend/zend.c

@@ -98,6 +98,7 @@ ZEND_API zend_string *(*zend_resolve_path)(zend_string *filename);
 ZEND_API zend_result (*zend_post_startup_cb)(void) = NULL;
 ZEND_API void (*zend_post_shutdown_cb)(void) = NULL;
 ZEND_API void (*zend_accel_schedule_restart_hook)(int reason) = NULL;
+ZEND_API void (*zend_accel_restart_hook)(int reason) = NULL;
 ZEND_ATTRIBUTE_NONNULL ZEND_API zend_result (*zend_random_bytes)(void *bytes, size_t size, char *errstr, size_t errstr_size) = NULL;
 ZEND_ATTRIBUTE_NONNULL ZEND_API void (*zend_random_bytes_insecure)(zend_random_bytes_insecure_state *state, void *bytes, size_t size) = NULL;
 

Zend/zend.h

@@ -384,7 +384,10 @@ extern ZEND_ATTRIBUTE_NONNULL ZEND_API void (*zend_random_bytes_insecure)(
 extern ZEND_API zend_result (*zend_post_startup_cb)(void);
 extern ZEND_API void (*zend_post_shutdown_cb)(void);
 
+/* Called by opcache when a restart is scheduled, with a zend_accel_restart_reason */
 extern ZEND_API void (*zend_accel_schedule_restart_hook)(int reason);
+/* Called by opcache once a scheduled restart has been carried out and the SHM lock is released, with the same reason */
+extern ZEND_API void (*zend_accel_restart_hook)(int reason);
 
 ZEND_API ZEND_COLD void zend_error(int type, const char *format, ...) ZEND_ATTRIBUTE_FORMAT(printf, 2, 3);
 ZEND_NORETURN ZEND_API ZEND_COLD void zend_error_noreturn(int type, const char *format, ...) ZEND_ATTRIBUTE_FORMAT(printf, 2, 3);

ext/opcache/ZendAccelerator.c

@@ -2974,6 +2974,9 @@ ZEND_RINIT_FUNCTION(zend_accelerator)
 		ZCG(counted) = false;
 	}
 
+	bool restarted = false;
+	zend_accel_restart_reason restart_reason = ACCEL_RESTART_OOM;
+
 	if (ZCSG(restart_pending)) {
 		zend_shared_alloc_lock();
 		if (ZCSG(restart_pending)) { /* check again, to ensure that the cache wasn't already cleaned by another process */
@@ -3019,6 +3022,9 @@ ZEND_RINIT_FUNCTION(zend_accelerator)
 					ZCSG(last_restart_time)++;
 				}
 				accel_restart_leave();
+
+				restarted = true;
+				restart_reason = ZCSG(restart_reason);
 			}
 		}
 		zend_shared_alloc_unlock();
@@ -3029,6 +3035,11 @@ ZEND_RINIT_FUNCTION(zend_accelerator)
 	SHM_PROTECT();
 	HANDLE_UNBLOCK_INTERRUPTIONS();
 
+	/* Called once the SHM lock is released and the memory is protected again */
+	if (UNEXPECTED(restarted) && zend_accel_restart_hook) {
+		zend_accel_restart_hook(restart_reason);
+	}
+
 	if (ZCG(accelerator_enabled) && ZCSG(last_restart_time) != ZCG(last_restart_time)) {
 		/* SHM was reinitialized. */
 		ZCG(last_restart_time) = ZCSG(last_restart_time);