Eliminate empty_pollset

1 files changed, 49 insertions, 106 deletions

diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index 48111cc07b..d9bd01d668 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -92,15 +92,14 @@ void grpc_pollset_global_shutdown(void) {
 
 /* main interface */
 
-static void become_empty_pollset(grpc_pollset *pollset);
-static void become_unary_pollset(grpc_pollset *pollset, grpc_fd *fd);
+static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null);
 
 void grpc_pollset_init(grpc_pollset *pollset) {
   gpr_mu_init(&pollset->mu);
   grpc_pollset_kick_init(&pollset->kick_state);
   pollset->in_flight_cbs = 0;
   pollset->shutting_down = 0;
-  become_empty_pollset(pollset);
+  become_basic_pollset(pollset, NULL);
 }
 
 void grpc_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
@@ -180,80 +179,8 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {
 }
 
 /*
- * empty_pollset - a vtable that provides polling for NO file descriptors
- */
-
-static void empty_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
-  become_unary_pollset(pollset, fd);
-}
-
-static void empty_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {}
-
-static int empty_pollset_maybe_work(grpc_pollset *pollset,
-                                    gpr_timespec deadline, gpr_timespec now,
-                                    int allow_synchronous_callback) {
-  struct pollfd pfd;
-  int timeout;
-  int r;
-
-  if (pollset->in_flight_cbs) {
-    /* Give do_promote priority so we don't starve it out */
-    return 1;
-  }
-  if (gpr_time_cmp(deadline, gpr_inf_future) == 0) {
-    timeout = -1;
-  } else {
-    timeout = gpr_time_to_millis(gpr_time_sub(deadline, now));
-    if (timeout <= 0) {
-      return 1;
-    }
-  }
-  pfd.fd = grpc_pollset_kick_pre_poll(&pollset->kick_state);
-  if (pfd.fd < 0) {
-    /* Already kicked */
-    return 1;
-  }
-  pfd.events = POLLIN;
-  pfd.revents = 0;
-  pollset->counter++;
-  gpr_mu_unlock(&pollset->mu);
-
-  /* poll fd count (argument 2) is shortened by one if we have no events
-     to poll on - such that it only includes the kicker */
-  r = poll(&pfd, 1, timeout);
-
-  if (r < 0) {
-    if (errno != EINTR) {
-      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
-    }
-  } else if (r == 0) {
-    /* do nothing */
-  } else {
-    if (pfd.revents & POLLIN) {
-      grpc_pollset_kick_consume(&pollset->kick_state);
-    }
-  }
-
-  grpc_pollset_kick_post_poll(&pollset->kick_state);
-
-  gpr_mu_lock(&pollset->mu);
-  pollset->counter--;
-  return 1;
-}
-
-static void empty_pollset_destroy(grpc_pollset *pollset) {}
-
-static const grpc_pollset_vtable empty_pollset = {
-    empty_pollset_add_fd, empty_pollset_del_fd, empty_pollset_maybe_work,
-    kick_using_pollset_kick, empty_pollset_destroy};
-
-static void become_empty_pollset(grpc_pollset *pollset) {
-  pollset->vtable = &empty_pollset;
-}
-
-/*
- * unary_poll_pollset - a vtable that provides polling for one file descriptor
- *                      via poll()
+ * basic_pollset - a vtable that provides polling for zero or one file 
+ *                 descriptor via poll()
  */
 
 
@@ -263,7 +190,7 @@ typedef struct grpc_unary_promote_args {
   grpc_fd *fd;
 } grpc_unary_promote_args;
 
-static void unary_poll_do_promote(void *args, int success) {
+static void basic_do_promote(void *args, int success) {
   grpc_unary_promote_args *up_args = args;
   const grpc_pollset_vtable *original_vtable = up_args->original_vtable;
   grpc_pollset *pollset = up_args->pollset;
@@ -283,7 +210,7 @@ static void unary_poll_do_promote(void *args, int success) {
   /* First we need to ensure that nobody is polling concurrently */
   while (pollset->counter != 0) {
     grpc_pollset_kick(pollset);
-    grpc_iomgr_add_callback(unary_poll_do_promote, up_args);
+    grpc_iomgr_add_callback(basic_do_promote, up_args);
     gpr_mu_unlock(&pollset->mu);
     return;
   }
@@ -329,12 +256,13 @@ static void unary_poll_do_promote(void *args, int success) {
     pollset->shutdown_done_cb(pollset->shutdown_done_arg);
   }
 
-  /* Matching ref in unary_poll_pollset_add_fd */
+  /* Matching ref in basic_pollset_add_fd */
   grpc_fd_unref(fd);
 }
 
-static void unary_poll_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
+static void basic_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
   grpc_unary_promote_args *up_args;
+  GPR_ASSERT(fd);
   if (fd == pollset->data.ptr) return;
 
   if (!pollset->counter) {
@@ -345,7 +273,10 @@ static void unary_poll_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
     fds[0] = pollset->data.ptr;
     fds[1] = fd;
 
-    if (!grpc_fd_is_orphaned(fds[0])) {
+    if (fds[0] == NULL) {
+      pollset->data.ptr = fd;
+      grpc_fd_ref(fd);
+    } else if (!grpc_fd_is_orphaned(fds[0])) {
       grpc_platform_become_multipoller(pollset, fds, GPR_ARRAY_SIZE(fds));
       grpc_fd_unref(fds[0]);
     } else {
@@ -366,19 +297,20 @@ static void unary_poll_pollset_add_fd(grpc_pollset *pollset, grpc_fd *fd) {
   up_args->pollset = pollset;
   up_args->fd = fd;
   up_args->original_vtable = pollset->vtable;
-  grpc_iomgr_add_callback(unary_poll_do_promote, up_args);
+  grpc_iomgr_add_callback(basic_do_promote, up_args);
 
   grpc_pollset_kick(pollset);
 }
 
-static void unary_poll_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {
+static void basic_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {
+  GPR_ASSERT(fd);
   if (fd == pollset->data.ptr) {
     grpc_fd_unref(pollset->data.ptr);
-    become_empty_pollset(pollset);
+    pollset->data.ptr = NULL;
   }
 }
 
-static int unary_poll_pollset_maybe_work(grpc_pollset *pollset,
+static int basic_pollset_maybe_work(grpc_pollset *pollset,
                                          gpr_timespec deadline,
                                          gpr_timespec now,
                                          int allow_synchronous_callback) {
@@ -387,16 +319,16 @@ static int unary_poll_pollset_maybe_work(grpc_pollset *pollset,
   grpc_fd_watcher fd_watcher;
   int timeout;
   int r;
+  int nfds;
 
   if (pollset->in_flight_cbs) {
     /* Give do_promote priority so we don't starve it out */
     return 1;
   }
   fd = pollset->data.ptr;
-  if (grpc_fd_is_orphaned(fd)) {
+  if (fd && grpc_fd_is_orphaned(fd)) {
     grpc_fd_unref(fd);
-    become_empty_pollset(pollset);
-    return 1;
+    fd = pollset->data.ptr = NULL;
   }
   if (gpr_time_cmp(deadline, gpr_inf_future) == 0) {
     timeout = -1;
@@ -413,19 +345,28 @@ static int unary_poll_pollset_maybe_work(grpc_pollset *pollset,
   }
   pfd[0].events = POLLIN;
   pfd[0].revents = 0;
-  pfd[1].fd = fd->fd;
-  pfd[1].revents = 0;
-  pollset->counter++;
-  gpr_mu_unlock(&pollset->mu);
-
-  pfd[1].events = grpc_fd_begin_poll(fd, pollset, POLLIN, POLLOUT, &fd_watcher);
+  nfds = 1;
+  if (fd) {
+    pfd[1].fd = fd->fd;
+    pfd[1].revents = 0;
+    pollset->counter++;
+    gpr_mu_unlock(&pollset->mu);
+    pfd[1].events = grpc_fd_begin_poll(fd, pollset, POLLIN, POLLOUT, &fd_watcher);
+    if (pfd[1].events != 0) {
+      nfds++;
+    }
+  } else {
+    gpr_mu_unlock(&pollset->mu);
+  }
 
   /* poll fd count (argument 2) is shortened by one if we have no events
      to poll on - such that it only includes the kicker */
-  r = poll(pfd, GPR_ARRAY_SIZE(pfd) - (pfd[1].events == 0), timeout);
+  r = poll(pfd, nfds, timeout);
   GRPC_TIMER_MARK(GRPC_PTAG_POLL_FINISHED, r);
 
-  grpc_fd_end_poll(&fd_watcher, pfd[1].revents & POLLIN, pfd[1].revents & POLLOUT);
+  if (fd) {
+    grpc_fd_end_poll(&fd_watcher, pfd[1].revents & POLLIN, pfd[1].revents & POLLOUT);
+  }
 
   if (r < 0) {
     if (errno != EINTR) {
@@ -452,21 +393,23 @@ static int unary_poll_pollset_maybe_work(grpc_pollset *pollset,
   return 1;
 }
 
-static void unary_poll_pollset_destroy(grpc_pollset *pollset) {
+static void basic_pollset_destroy(grpc_pollset *pollset) {
   GPR_ASSERT(pollset->counter == 0);
   grpc_fd_unref(pollset->data.ptr);
 }
 
-static const grpc_pollset_vtable unary_poll_pollset = {
-    unary_poll_pollset_add_fd, unary_poll_pollset_del_fd,
-    unary_poll_pollset_maybe_work, kick_using_pollset_kick,
-    unary_poll_pollset_destroy};
+static const grpc_pollset_vtable basic_pollset = {
+    basic_pollset_add_fd, basic_pollset_del_fd,
+    basic_pollset_maybe_work, kick_using_pollset_kick,
+    basic_pollset_destroy};
 
-static void become_unary_pollset(grpc_pollset *pollset, grpc_fd *fd) {
-  pollset->vtable = &unary_poll_pollset;
+static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null) {
+  pollset->vtable = &basic_pollset;
   pollset->counter = 0;
-  pollset->data.ptr = fd;
-  grpc_fd_ref(fd);
+  pollset->data.ptr = fd_or_null;
+  if (fd_or_null) {
+    grpc_fd_ref(fd_or_null);
+  }
 }
 
 #endif /* GPR_POSIX_POLLSET */