Merge pull request #17244 from guantaol/ev_epollbg

Preparation for the new background poller 'epollbg'

15 files changed, 77 insertions, 8 deletions

diff --git a/src/core/lib/iomgr/ev_epoll1_linux.cc b/src/core/lib/iomgr/ev_epoll1_linux.cc
index 38571b1957..4b8c891e9b 100644
--- a/src/core/lib/iomgr/ev_epoll1_linux.cc
+++ b/src/core/lib/iomgr/ev_epoll1_linux.cc
@@ -1242,6 +1242,8 @@ static void pollset_set_del_pollset_set(grpc_pollset_set* bag,
  * Event engine binding
  */
 
+static void shutdown_background_closure(void) {}
+
 static void shutdown_engine(void) {
   fd_global_shutdown();
   pollset_global_shutdown();
@@ -1255,6 +1257,7 @@ static void shutdown_engine(void) {
 static const grpc_event_engine_vtable vtable = {
     sizeof(grpc_pollset),
     true,
+    false,
 
     fd_create,
     fd_wrapped_fd,
@@ -1284,6 +1287,7 @@ static const grpc_event_engine_vtable vtable = {
     pollset_set_add_fd,
     pollset_set_del_fd,
 
+    shutdown_background_closure,
     shutdown_engine,
 };
 
diff --git a/src/core/lib/iomgr/ev_epollex_linux.cc b/src/core/lib/iomgr/ev_epollex_linux.cc
index 06a382c556..7a4870db78 100644
--- a/src/core/lib/iomgr/ev_epollex_linux.cc
+++ b/src/core/lib/iomgr/ev_epollex_linux.cc
@@ -1604,6 +1604,8 @@ static void pollset_set_del_pollset_set(grpc_pollset_set* bag,
  * Event engine binding
  */
 
+static void shutdown_background_closure(void) {}
+
 static void shutdown_engine(void) {
   fd_global_shutdown();
   pollset_global_shutdown();
@@ -1612,6 +1614,7 @@ static void shutdown_engine(void) {
 static const grpc_event_engine_vtable vtable = {
     sizeof(grpc_pollset),
     true,
+    false,
 
     fd_create,
     fd_wrapped_fd,
@@ -1641,6 +1644,7 @@ static const grpc_event_engine_vtable vtable = {
     pollset_set_add_fd,
     pollset_set_del_fd,
 
+    shutdown_background_closure,
     shutdown_engine,
 };
 
diff --git a/src/core/lib/iomgr/ev_poll_posix.cc b/src/core/lib/iomgr/ev_poll_posix.cc
index 16562538a6..67cbfbbd02 100644
--- a/src/core/lib/iomgr/ev_poll_posix.cc
+++ b/src/core/lib/iomgr/ev_poll_posix.cc
@@ -1782,6 +1782,8 @@ static void global_cv_fd_table_shutdown() {
  * event engine binding
  */
 
+static void shutdown_background_closure(void) {}
+
 static void shutdown_engine(void) {
   pollset_global_shutdown();
   if (grpc_cv_wakeup_fds_enabled()) {
@@ -1796,6 +1798,7 @@ static void shutdown_engine(void) {
 static const grpc_event_engine_vtable vtable = {
     sizeof(grpc_pollset),
     false,
+    false,
 
     fd_create,
     fd_wrapped_fd,
@@ -1825,6 +1828,7 @@ static const grpc_event_engine_vtable vtable = {
     pollset_set_add_fd,
     pollset_set_del_fd,
 
+    shutdown_background_closure,
     shutdown_engine,
 };
 
diff --git a/src/core/lib/iomgr/ev_posix.cc b/src/core/lib/iomgr/ev_posix.cc
index 6f6d134ced..32d1b6c43e 100644
--- a/src/core/lib/iomgr/ev_posix.cc
+++ b/src/core/lib/iomgr/ev_posix.cc
@@ -244,6 +244,10 @@ bool grpc_event_engine_can_track_errors(void) {
   return false;
 }
 
+bool grpc_event_engine_run_in_background(void) {
+  return g_event_engine->run_in_background;
+}
+
 grpc_fd* grpc_fd_create(int fd, const char* name, bool track_err) {
   GRPC_POLLING_API_TRACE("fd_create(%d, %s, %d)", fd, name, track_err);
   GRPC_FD_TRACE("fd_create(%d, %s, %d)", fd, name, track_err);
@@ -395,4 +399,8 @@ void grpc_pollset_set_del_fd(grpc_pollset_set* pollset_set, grpc_fd* fd) {
   g_event_engine->pollset_set_del_fd(pollset_set, fd);
 }
 
+void grpc_shutdown_background_closure(void) {
+  g_event_engine->shutdown_background_closure();
+}
+
 #endif  // GRPC_POSIX_SOCKET_EV
diff --git a/src/core/lib/iomgr/ev_posix.h b/src/core/lib/iomgr/ev_posix.h
index b8fb8f534b..812c7a0f0f 100644
--- a/src/core/lib/iomgr/ev_posix.h
+++ b/src/core/lib/iomgr/ev_posix.h
@@ -42,6 +42,7 @@ typedef struct grpc_fd grpc_fd;
 typedef struct grpc_event_engine_vtable {
   size_t pollset_size;
   bool can_track_err;
+  bool run_in_background;
 
   grpc_fd* (*fd_create)(int fd, const char* name, bool track_err);
   int (*fd_wrapped_fd)(grpc_fd* fd);
@@ -79,6 +80,7 @@ typedef struct grpc_event_engine_vtable {
   void (*pollset_set_add_fd)(grpc_pollset_set* pollset_set, grpc_fd* fd);
   void (*pollset_set_del_fd)(grpc_pollset_set* pollset_set, grpc_fd* fd);
 
+  void (*shutdown_background_closure)(void);
   void (*shutdown_engine)(void);
 } grpc_event_engine_vtable;
 
@@ -101,6 +103,11 @@ const char* grpc_get_poll_strategy_name();
  */
 bool grpc_event_engine_can_track_errors();
 
+/* Returns true if polling engine runs in the background, false otherwise.
+ * Currently only 'epollbg' runs in the background.
+ */
+bool grpc_event_engine_run_in_background();
+
 /* Create a wrapped file descriptor.
    Requires fd is a non-blocking file descriptor.
    \a track_err if true means that error events would be tracked separately
@@ -174,6 +181,9 @@ void grpc_pollset_add_fd(grpc_pollset* pollset, struct grpc_fd* fd);
 void grpc_pollset_set_add_fd(grpc_pollset_set* pollset_set, grpc_fd* fd);
 void grpc_pollset_set_del_fd(grpc_pollset_set* pollset_set, grpc_fd* fd);
 
+/* Shut down all the closures registered in the background poller. */
+void grpc_shutdown_background_closure();
+
 /* override to allow tests to hook poll() usage */
 typedef int (*grpc_poll_function_type)(struct pollfd*, nfds_t, int);
 extern grpc_poll_function_type grpc_poll_function;
diff --git a/src/core/lib/iomgr/iomgr.cc b/src/core/lib/iomgr/iomgr.cc
index fd09a6863b..eb29973514 100644
--- a/src/core/lib/iomgr/iomgr.cc
+++ b/src/core/lib/iomgr/iomgr.cc
@@ -157,6 +157,10 @@ void grpc_iomgr_shutdown() {
   gpr_cv_destroy(&g_rcv);
 }
 
+void grpc_iomgr_shutdown_background_closure() {
+  grpc_iomgr_platform_shutdown_background_closure();
+}
+
 void grpc_iomgr_register_object(grpc_iomgr_object* obj, const char* name) {
   obj->name = gpr_strdup(name);
   gpr_mu_lock(&g_mu);
diff --git a/src/core/lib/iomgr/iomgr.h b/src/core/lib/iomgr/iomgr.h
index 537ef8a6ff..8ea9289e06 100644
--- a/src/core/lib/iomgr/iomgr.h
+++ b/src/core/lib/iomgr/iomgr.h
@@ -35,6 +35,10 @@ void grpc_iomgr_start();
  * exec_ctx. */
 void grpc_iomgr_shutdown();
 
+/** Signals the intention to shutdown all the closures registered in the
+ * background poller. */
+void grpc_iomgr_shutdown_background_closure();
+
 /* Exposed only for testing */
 size_t grpc_iomgr_count_objects_for_testing();
 
diff --git a/src/core/lib/iomgr/iomgr_custom.cc b/src/core/lib/iomgr/iomgr_custom.cc
index d34c8e7cd1..4b112c9097 100644
--- a/src/core/lib/iomgr/iomgr_custom.cc
+++ b/src/core/lib/iomgr/iomgr_custom.cc
@@ -40,9 +40,11 @@ static void iomgr_platform_init(void) {
 }
 static void iomgr_platform_flush(void) {}
 static void iomgr_platform_shutdown(void) { grpc_pollset_global_shutdown(); }
+static void iomgr_platform_shutdown_background_closure(void) {}
 
 static grpc_iomgr_platform_vtable vtable = {
-    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown};
+    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown,
+    iomgr_platform_shutdown_background_closure};
 
 void grpc_custom_iomgr_init(grpc_socket_vtable* socket,
                             grpc_custom_resolver_vtable* resolver,
diff --git a/src/core/lib/iomgr/iomgr_internal.cc b/src/core/lib/iomgr/iomgr_internal.cc
index 32dbabb79d..b6c9211865 100644
--- a/src/core/lib/iomgr/iomgr_internal.cc
+++ b/src/core/lib/iomgr/iomgr_internal.cc
@@ -41,3 +41,7 @@ void grpc_iomgr_platform_init() { iomgr_platform_vtable->init(); }
 void grpc_iomgr_platform_flush() { iomgr_platform_vtable->flush(); }
 
 void grpc_iomgr_platform_shutdown() { iomgr_platform_vtable->shutdown(); }
+
+void grpc_iomgr_platform_shutdown_background_closure() {
+  iomgr_platform_vtable->shutdown_background_closure();
+}
diff --git a/src/core/lib/iomgr/iomgr_internal.h b/src/core/lib/iomgr/iomgr_internal.h
index b011d9c7b1..bca7409907 100644
--- a/src/core/lib/iomgr/iomgr_internal.h
+++ b/src/core/lib/iomgr/iomgr_internal.h
@@ -35,6 +35,7 @@ typedef struct grpc_iomgr_platform_vtable {
   void (*init)(void);
   void (*flush)(void);
   void (*shutdown)(void);
+  void (*shutdown_background_closure)(void);
 } grpc_iomgr_platform_vtable;
 
 void grpc_iomgr_register_object(grpc_iomgr_object* obj, const char* name);
@@ -52,6 +53,9 @@ void grpc_iomgr_platform_flush(void);
 /** tear down all platform specific global iomgr structures */
 void grpc_iomgr_platform_shutdown(void);
 
+/** shut down all the closures registered in the background poller */
+void grpc_iomgr_platform_shutdown_background_closure(void);
+
 bool grpc_iomgr_abort_on_leaks(void);
 
 #endif /* GRPC_CORE_LIB_IOMGR_IOMGR_INTERNAL_H */
diff --git a/src/core/lib/iomgr/iomgr_posix.cc b/src/core/lib/iomgr/iomgr_posix.cc
index ca7334c9a4..9386adf060 100644
--- a/src/core/lib/iomgr/iomgr_posix.cc
+++ b/src/core/lib/iomgr/iomgr_posix.cc
@@ -51,8 +51,13 @@ static void iomgr_platform_shutdown(void) {
   grpc_wakeup_fd_global_destroy();
 }
 
+static void iomgr_platform_shutdown_background_closure(void) {
+  grpc_shutdown_background_closure();
+}
+
 static grpc_iomgr_platform_vtable vtable = {
-    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown};
+    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown,
+    iomgr_platform_shutdown_background_closure};
 
 void grpc_set_default_iomgr_platform() {
   grpc_set_tcp_client_impl(&grpc_posix_tcp_client_vtable);
diff --git a/src/core/lib/iomgr/iomgr_posix_cfstream.cc b/src/core/lib/iomgr/iomgr_posix_cfstream.cc
index 235a9e0712..552ef4309c 100644
--- a/src/core/lib/iomgr/iomgr_posix_cfstream.cc
+++ b/src/core/lib/iomgr/iomgr_posix_cfstream.cc
@@ -54,8 +54,13 @@ static void iomgr_platform_shutdown(void) {
   grpc_wakeup_fd_global_destroy();
 }
 
+static void iomgr_platform_shutdown_background_closure(void) {
+  grpc_shutdown_background_closure();
+}
+
 static grpc_iomgr_platform_vtable vtable = {
-    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown};
+    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown,
+    iomgr_platform_shutdown_background_closure};
 
 void grpc_set_default_iomgr_platform() {
   char* enable_cfstream = getenv(grpc_cfstream_env_var);
diff --git a/src/core/lib/iomgr/iomgr_windows.cc b/src/core/lib/iomgr/iomgr_windows.cc
index cdef89cbf0..24ef0dba7b 100644
--- a/src/core/lib/iomgr/iomgr_windows.cc
+++ b/src/core/lib/iomgr/iomgr_windows.cc
@@ -71,8 +71,11 @@ static void iomgr_platform_shutdown(void) {
   winsock_shutdown();
 }
 
+static void iomgr_platform_shutdown_background_closure(void) {}
+
 static grpc_iomgr_platform_vtable vtable = {
-    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown};
+    iomgr_platform_init, iomgr_platform_flush, iomgr_platform_shutdown,
+    iomgr_platform_shutdown_background_closure};
 
 void grpc_set_default_iomgr_platform() {
   grpc_set_tcp_client_impl(&grpc_windows_tcp_client_vtable);
diff --git a/src/core/lib/iomgr/tcp_posix.cc b/src/core/lib/iomgr/tcp_posix.cc
index 4a5ca615e5..606bfce6e7 100644
--- a/src/core/lib/iomgr/tcp_posix.cc
+++ b/src/core/lib/iomgr/tcp_posix.cc
@@ -260,10 +260,17 @@ static void notify_on_write(grpc_tcp* tcp) {
   if (grpc_tcp_trace.enabled()) {
     gpr_log(GPR_INFO, "TCP:%p notify_on_write", tcp);
   }
-  cover_self(tcp);
-  GRPC_CLOSURE_INIT(&tcp->write_done_closure,
-                    tcp_drop_uncovered_then_handle_write, tcp,
-                    grpc_schedule_on_exec_ctx);
+  if (grpc_event_engine_run_in_background()) {
+    // If there is a polling engine always running in the background, there is
+    // no need to run the backup poller.
+    GRPC_CLOSURE_INIT(&tcp->write_done_closure, tcp_handle_write, tcp,
+                      grpc_schedule_on_exec_ctx);
+  } else {
+    cover_self(tcp);
+    GRPC_CLOSURE_INIT(&tcp->write_done_closure,
+                      tcp_drop_uncovered_then_handle_write, tcp,
+                      grpc_schedule_on_exec_ctx);
+  }
   grpc_fd_notify_on_write(tcp->em_fd, &tcp->write_done_closure);
 }
 
diff --git a/src/core/lib/surface/init.cc b/src/core/lib/surface/init.cc
index c6198b8ae7..67cf5d89bf 100644
--- a/src/core/lib/surface/init.cc
+++ b/src/core/lib/surface/init.cc
@@ -161,6 +161,7 @@ void grpc_shutdown(void) {
   if (--g_initializations == 0) {
     {
       grpc_core::ExecCtx exec_ctx(0);
+      grpc_iomgr_shutdown_background_closure();
       {
         grpc_timer_manager_set_threading(
             false);  // shutdown timer_manager thread