io: io_always, and zero-length operations support.
[ccan] / ccan / io / poll.c
index f9221d1ff6d91fc398563def5d24d33ec626bdcf..d7b9eb56b950b5a1b4772525c86bb944b3a60c6f 100644 (file)
@@ -7,11 +7,56 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <limits.h>
+#include <errno.h>
 
-static size_t num_fds = 0, max_fds = 0, num_next = 0, num_finished = 0, num_waiting = 0;
+static size_t num_fds = 0, max_fds = 0, num_closing = 0, num_waiting = 0;
+static bool some_always = false;
 static struct pollfd *pollfds = NULL;
 static struct fd **fds = NULL;
 static struct timers timeouts;
+#ifdef DEBUG
+static unsigned int io_loop_level;
+static struct io_conn *free_later;
+static void io_loop_enter(void)
+{
+       io_loop_level++;
+}
+static void io_loop_exit(void)
+{
+       io_loop_level--;
+       if (io_loop_level == 0) {
+               /* Delayed free. */
+               while (free_later) {
+                       struct io_conn *c = free_later;
+                       free_later = c->finish_arg;
+                       io_alloc.free(c);
+               }
+       }
+}
+static void free_conn(struct io_conn *conn)
+{
+       /* Only free on final exit: chain via finish. */
+       if (io_loop_level > 1) {
+               struct io_conn *c;
+               for (c = free_later; c; c = c->finish_arg)
+                       assert(c != conn);
+               conn->finish_arg = free_later;
+               free_later = conn;
+       } else
+               io_alloc.free(conn);
+}
+#else
+static void io_loop_enter(void)
+{
+}
+static void io_loop_exit(void)
+{
+}
+static void free_conn(struct io_conn *conn)
+{
+       io_alloc.free(conn);
+}
+#endif
 
 static bool add_fd(struct fd *fd, short events)
 {
@@ -20,19 +65,23 @@ static bool add_fd(struct fd *fd, short events)
                struct fd **newfds;
                size_t num = max_fds ? max_fds * 2 : 8;
 
-               newpollfds = realloc(pollfds, sizeof(*newpollfds) * num);
+               newpollfds = io_alloc.realloc(pollfds, sizeof(*newpollfds)*num);
                if (!newpollfds)
                        return false;
                pollfds = newpollfds;
-               newfds = realloc(fds, sizeof(*newfds) * num);
+               newfds = io_alloc.realloc(fds, sizeof(*newfds) * num);
                if (!newfds)
                        return false;
                fds = newfds;
                max_fds = num;
        }
 
-       pollfds[num_fds].fd = fd->fd;
        pollfds[num_fds].events = events;
+       /* In case it's idle. */
+       if (!events)
+               pollfds[num_fds].fd = -fd->fd;
+       else
+               pollfds[num_fds].fd = fd->fd;
        pollfds[num_fds].revents = 0; /* In case we're iterating now */
        fds[num_fds] = fd;
        fd->backend_info = num_fds;
@@ -57,10 +106,18 @@ static void del_fd(struct fd *fd)
                fds[n] = fds[num_fds-1];
                assert(fds[n]->backend_info == num_fds-1);
                fds[n]->backend_info = n;
+               /* If that happens to be a duplex, move that too. */
+               if (!fds[n]->listener) {
+                       struct io_conn *c = (void *)fds[n];
+                       if (c->duplex) {
+                               assert(c->duplex->fd.backend_info == num_fds-1);
+                               c->duplex->fd.backend_info = n;
+                       }
+               }
        } else if (num_fds == 1) {
                /* Free everything when no more fds. */
-               free(pollfds);
-               free(fds);
+               io_alloc.free(pollfds);
+               io_alloc.free(fds);
                pollfds = NULL;
                fds = NULL;
                max_fds = 0;
@@ -77,66 +134,78 @@ bool add_listener(struct io_listener *l)
        return true;
 }
 
-static void adjust_counts(enum io_state state)
+void backend_plan_changed(struct io_conn *conn)
 {
-       if (state == IO_NEXT)
-               num_next++;
-       else if (state == IO_FINISHED)
-               num_finished++;
-}
+       struct pollfd *pfd;
 
-static void update_pollevents(struct io_conn *conn)
-{
-       struct pollfd *pfd = &pollfds[conn->fd.backend_info];
+       /* This can happen with debugging and delayed free... */
+       if (conn->fd.backend_info == -1)
+               return;
+
+       pfd = &pollfds[conn->fd.backend_info];
 
        if (pfd->events)
                num_waiting--;
 
-       pfd->events = conn->plan.pollflag;
+       pfd->events = conn->plan.pollflag & (POLLIN|POLLOUT);
        if (conn->duplex) {
-               int mask = conn->duplex->plan.pollflag;
+               int mask = conn->duplex->plan.pollflag & (POLLIN|POLLOUT);
                /* You can't *both* read/write. */
                assert(!mask || pfd->events != mask);
                pfd->events |= mask;
        }
-       if (pfd->events)
+       if (pfd->events) {
                num_waiting++;
+               pfd->fd = conn->fd.fd;
+       } else
+               pfd->fd = -conn->fd.fd;
+
+       if (!conn->plan.next)
+               num_closing++;
 
-       adjust_counts(conn->plan.state);
+       if (conn->plan.pollflag == POLLALWAYS)
+               some_always = true;
 }
 
 bool add_conn(struct io_conn *c)
 {
-       if (!add_fd(&c->fd, c->plan.pollflag))
+       if (!add_fd(&c->fd, c->plan.pollflag & (POLLIN|POLLOUT)))
                return false;
-       adjust_counts(c->plan.state);
+       /* Immediate close is allowed. */
+       if (!c->plan.next)
+               num_closing++;
+       if (c->plan.pollflag == POLLALWAYS)
+               some_always = true;
        return true;
 }
 
 bool add_duplex(struct io_conn *c)
 {
        c->fd.backend_info = c->duplex->fd.backend_info;
-       update_pollevents(c);
+       backend_plan_changed(c);
        return true;
 }
 
-static void del_conn(struct io_conn *conn)
+void backend_del_conn(struct io_conn *conn)
 {
-       if (conn->finish)
+       if (conn->finish) {
+               /* Saved by io_close */
+               errno = conn->plan.u1.s;
                conn->finish(conn, conn->finish_arg);
+       }
        if (timeout_active(conn))
                backend_del_timeout(conn);
-       free(conn->timeout);
+       io_alloc.free(conn->timeout);
        if (conn->duplex) {
                /* In case fds[] pointed to the other one. */
+               assert(conn->duplex->fd.backend_info == conn->fd.backend_info);
                fds[conn->fd.backend_info] = &conn->duplex->fd;
                conn->duplex->duplex = NULL;
+               conn->fd.backend_info = -1;
        } else
                del_fd(&conn->fd);
-       if (conn->plan.state == IO_FINISHED)
-               num_finished--;
-       else if (conn->plan.state == IO_NEXT)
-               num_next--;
+       num_closing--;
+       free_conn(conn);
 }
 
 void del_listener(struct io_listener *l)
@@ -144,15 +213,10 @@ void del_listener(struct io_listener *l)
        del_fd(&l->fd);
 }
 
-static void backend_set_state(struct io_conn *conn, struct io_plan plan)
+static void set_plan(struct io_conn *conn, struct io_plan plan)
 {
        conn->plan = plan;
-       update_pollevents(conn);
-}
-
-void backend_wakeup(struct io_conn *conn)
-{
-       update_pollevents(conn);
+       backend_plan_changed(conn);
 }
 
 static void accept_conn(struct io_listener *l)
@@ -166,36 +230,31 @@ static void accept_conn(struct io_listener *l)
 }
 
 /* It's OK to miss some, as long as we make progress. */
-static void finish_and_next(bool finished_only)
+static bool finish_conns(struct io_conn **ready)
 {
        unsigned int i;
 
        for (i = 0; !io_loop_return && i < num_fds; i++) {
                struct io_conn *c, *duplex;
 
-               if (!num_finished) {
-                       if (finished_only || num_next == 0)
-                               break;
-               }
+               if (!num_closing)
+                       break;
+
                if (fds[i]->listener)
                        continue;
                c = (void *)fds[i];
                for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
-                       if (c->plan.state == IO_FINISHED) {
-                               del_conn(c);
-                               free(c);
+                       if (!c->plan.next) {
+                               if (doing_debug_on(c) && ready) {
+                                       *ready = c;
+                                       return true;
+                               }
+                               backend_del_conn(c);
                                i--;
-                       } else if (!finished_only && c->plan.state == IO_NEXT) {
-                               backend_set_state(c, c->plan.next(c, c->plan.next_arg));
-                               num_next--;
                        }
                }
        }
-}
-
-static void ready(struct io_conn *c)
-{
-       backend_set_state(c, do_ready(c));
+       return false;
 }
 
 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
@@ -214,14 +273,37 @@ void backend_del_timeout(struct io_conn *conn)
        conn->timeout->conn = NULL;
 }
 
+static void handle_always(void)
+{
+       int i;
+
+       some_always = false;
+
+       for (i = 0; i < num_fds && !io_loop_return; i++) {
+               struct io_conn *c = (void *)fds[i];
+
+               if (fds[i]->listener)
+                       continue;
+
+               if (c->plan.pollflag == POLLALWAYS)
+                       io_ready(c);
+
+               if (c->duplex && c->duplex->plan.pollflag == POLLALWAYS)
+                       io_ready(c->duplex);
+       }
+}
+
 /* This is the main loop. */
-void *io_loop(void)
+void *do_io_loop(struct io_conn **ready)
 {
        void *ret;
 
+       io_loop_enter();
+
        while (!io_loop_return) {
                int i, r, timeout = INT_MAX;
                struct timespec now;
+               bool some_timeouts = false;
 
                if (timeouts.base) {
                        struct timespec first;
@@ -236,7 +318,9 @@ void *io_loop(void)
                                struct io_conn *conn = t->conn;
                                /* Clear, in case timer re-adds */
                                t->conn = NULL;
-                               backend_set_state(conn, t->next(conn, t->next_arg));
+                               set_current(conn);
+                               set_plan(conn, t->next(conn, t->next_arg));
+                               some_timeouts = true;
                        }
 
                        /* Now figure out how long to wait for the next one. */
@@ -247,12 +331,23 @@ void *io_loop(void)
                        }
                }
 
-               if (num_finished || num_next) {
-                       finish_and_next(false);
+               if (num_closing) {
+                       /* If this finishes a debugging con, return now. */
+                       if (finish_conns(ready))
+                               return NULL;
                        /* Could have started/finished more. */
                        continue;
                }
 
+               /* debug can recurse on io_loop; anything can change. */
+               if (doing_debug() && some_timeouts)
+                       continue;
+
+               if (some_always) {
+                       handle_always();
+                       continue;
+               }
+
                if (num_fds == 0)
                        break;
 
@@ -280,28 +375,59 @@ void *io_loop(void)
                                if (c->duplex) {
                                        int mask = c->duplex->plan.pollflag;
                                        if (events & mask) {
-                                               ready(c->duplex);
+                                               if (doing_debug_on(c->duplex)
+                                                       && ready) {
+                                                       *ready = c->duplex;
+                                                       return NULL;
+                                               }
+                                               io_ready(c->duplex);
                                                events &= ~mask;
-                                               if (!(events&(POLLIN|POLLOUT)))
+                                               /* debug can recurse;
+                                                * anything can change. */
+                                               if (doing_debug())
+                                                       break;
+
+                                               /* If no events, or it closed
+                                                * the duplex, continue. */
+                                               if (!(events&(POLLIN|POLLOUT))
+                                                   || !c->plan.next)
                                                        continue;
                                        }
                                }
-                               ready(c);
-                       } else if (events & POLLHUP) {
+                               if (doing_debug_on(c) && ready) {
+                                       *ready = c;
+                                       return NULL;
+                               }
+                               io_ready(c);
+                               /* debug can recurse; anything can change. */
+                               if (doing_debug())
+                                       break;
+                       } else if (events & (POLLHUP|POLLNVAL|POLLERR)) {
                                r--;
-                               backend_set_state(c, io_close(c, NULL));
-                               if (c->duplex)
-                                       backend_set_state(c->duplex,
-                                                         io_close(c->duplex,
-                                                                  NULL));
+                               set_current(c);
+                               errno = EBADF;
+                               set_plan(c, io_close());
+                               if (c->duplex) {
+                                       set_current(c->duplex);
+                                       set_plan(c->duplex, io_close());
+                               }
                        }
                }
        }
 
-       while (num_finished)
-               finish_and_next(true);
+       while (num_closing && !io_loop_return) {
+               if (finish_conns(ready))
+                       return NULL;
+       }
 
        ret = io_loop_return;
        io_loop_return = NULL;
+
+       io_loop_exit();
        return ret;
 }
+
+void *io_loop(void)
+{
+       return do_io_loop(NULL);
+}