stream_op cleanup: iomgr closure, executor changes

src/core/iomgr/closure.c

@@ -39,18 +39,17 @@ void grpc_closure_init(grpc_closure *closure, grpc_iomgr_cb_func cb,
                        void *cb_arg) {
   closure->cb = cb;
   closure->cb_arg = cb_arg;
-  closure->next = NULL;
+  closure->final_data = 0;
 }
 
 void grpc_closure_list_add(grpc_closure_list *closure_list,
                            grpc_closure *closure, int success) {
   if (closure == NULL) return;
-  closure->next = NULL;
-  closure->success = success;
+  closure->final_data = (success != 0);
   if (closure_list->head == NULL) {
     closure_list->head = closure;
   } else {
-    closure_list->tail->next = closure;
+    closure_list->tail->final_data |= (gpr_uintptr)closure;
   }
   closure_list->tail = closure;
 }
@@ -66,22 +65,12 @@ void grpc_closure_list_move(grpc_closure_list *src, grpc_closure_list *dst) {
   if (dst->head == NULL) {
     *dst = *src;
   } else {
-    dst->tail->next = src->head;
+    dst->tail->final_data |= (gpr_uintptr)src->head;
     dst->tail = src->tail;
   }
   src->head = src->tail = NULL;
 }
 
-grpc_closure *grpc_closure_list_pop(grpc_closure_list *list) {
-  grpc_closure *head;
-  if (list->head == NULL) {
-    return NULL;
-  }
-  head = list->head;
-  list->head = list->head->next;
-  return head;
-}
-
 typedef struct {
   grpc_iomgr_cb_func cb;
   void *cb_arg;
@@ -103,3 +92,7 @@ grpc_closure *grpc_closure_create(grpc_iomgr_cb_func cb, void *cb_arg) {
   grpc_closure_init(&wc->wrapper, closure_wrapper, wc);
   return &wc->wrapper;
 }
+
+grpc_closure *grpc_closure_next(grpc_closure *closure) {
+  return (grpc_closure *)(closure->final_data & ~(gpr_uintptr)1);
+}

src/core/iomgr/closure.h

@@ -34,7 +34,7 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H
 #define GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H
 
-#include <stddef.h>
+#include <grpc/support/port_platform.h>
 
 struct grpc_closure;
 typedef struct grpc_closure grpc_closure;
@@ -64,13 +64,10 @@ struct grpc_closure {
   /** Arguments to be passed to "cb". */
   void *cb_arg;
 
-  /** Internal. A boolean indication to "cb" on the state of the iomgr.
-   * For instance, closures created during a shutdown would have this field set
-   * to false. */
-  int success;
-
-  /**< Internal. Do not touch */
-  struct grpc_closure *next;
+  /** Once enqueued, contains in the lower bit the success of the closure,
+      and in the upper bits the pointer to the next closure in the list.
+      Before enqueing for execution, this is usable for scratch data. */
+  gpr_uintptr final_data;
 };
 
 /** Initializes \a closure with \a cb and \a cb_arg. */
@@ -91,10 +88,10 @@ void grpc_closure_list_add(grpc_closure_list *list, grpc_closure *closure,
 /** append all closures from \a src to \a dst and empty \a src. */
 void grpc_closure_list_move(grpc_closure_list *src, grpc_closure_list *dst);
 
-/** pop (return and remove) the head closure from \a list. */
-grpc_closure *grpc_closure_list_pop(grpc_closure_list *list);
-
 /** return whether \a list is empty. */
 int grpc_closure_list_empty(grpc_closure_list list);
 
+/** return the next pointer for a queued closure list */
+grpc_closure *grpc_closure_next(grpc_closure *closure);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_CLOSURE_H */

src/core/iomgr/executor.c

@@ -63,8 +63,6 @@ void grpc_executor_init() {
 
 /* thread body */
 static void closure_exec_thread_func(void *ignored) {
-  grpc_closure *closure;
-
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (1) {
     gpr_mu_lock(&g_executor.mu);
@@ -72,16 +70,16 @@ static void closure_exec_thread_func(void *ignored) {
       gpr_mu_unlock(&g_executor.mu);
       break;
     }
-    closure = grpc_closure_list_pop(&g_executor.closures);
-    if (closure == NULL) {
+    if (grpc_closure_list_empty(g_executor.closures)) {
       /* no more work, time to die */
       GPR_ASSERT(g_executor.busy == 1);
       g_executor.busy = 0;
       gpr_mu_unlock(&g_executor.mu);
       break;
+    } else {
+      grpc_exec_ctx_enqueue_list(&exec_ctx, &g_executor.closures);
     }
     gpr_mu_unlock(&g_executor.mu);
-    closure->cb(&exec_ctx, closure->cb_arg, closure->success);
     grpc_exec_ctx_flush(&exec_ctx);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -125,7 +123,6 @@ void grpc_executor_enqueue(grpc_closure *closure, int success) {
 
 void grpc_executor_shutdown() {
   int pending_join;
-  grpc_closure *closure;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
   gpr_mu_lock(&g_executor.mu);
@@ -136,9 +133,7 @@ void grpc_executor_shutdown() {
    * list below because we aren't accepting new work */
 
   /* Execute pending callbacks, some may be performing cleanups */
-  while ((closure = grpc_closure_list_pop(&g_executor.closures)) != NULL) {
-    closure->cb(&exec_ctx, closure->cb_arg, closure->success);
-  }
+  grpc_exec_ctx_enqueue_list(&exec_ctx, &g_executor.closures);
   grpc_exec_ctx_finish(&exec_ctx);
   GPR_ASSERT(grpc_closure_list_empty(g_executor.closures));
   if (pending_join) {