ccan/io: add io_out_wait() and io_out_always().

[ccan] / ccan / io / io.h

diff --git a/ccan/io/io.h b/ccan/io/io.h
index d0c0a39a3888526df10c4174ed4dd8e69b8e7153..1cf9d609973066c04c696f3412fd735ca241bf5d 100644 (file)
--- a/ccan/io/io.h
+++ b/ccan/io/io.h
@@ -362,6 +362,27 @@ struct io_plan *io_always_(struct io_conn *conn,
                           struct io_plan *(*next)(struct io_conn *, void *),
                           void *arg);
 
+/**
+ * io_out_always - output plan to immediately call next callback
+ * @conn: the connection that plan is for.
+ * @next: function to call.
+ * @arg: @next argument
+ *
+ * This is a variant of io_always() which uses the output plan; it only
+ * matters if you are using io_duplex, and thus have two plans running at
+ * once.
+ */
+#define io_out_always(conn, next, arg)                                 \
+       io_out_always_((conn), typesafe_cb_preargs(struct io_plan *, void *, \
+                                                  (next), (arg),       \
+                                                  struct io_conn *),   \
+                      (arg))
+
+struct io_plan *io_out_always_(struct io_conn *conn,
+                              struct io_plan *(*next)(struct io_conn *,
+                                                      void *),
+                              void *arg);
+
 /**
  * io_connect - create an asynchronous connection to a listening socket.
  * @conn: the connection that plan is for.
@@ -418,12 +439,6 @@ struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
  *
  * Note that if either plan closes the connection, it will be closed.
  *
- * Note that if one plan is io_wait or io_always, that causes a problem:
- * they look at the input and output plan slots to figure out which to
- * use, but if the other plan hasn't been evaluated yet, that will fail.
- * In this case, you'll need to ensure the other plan is evaluated first,
- * eg. "struct io_plan *r = io_read(...); return io_duplex(r, io_always(...))"
- *
  * Example:
  * struct buf {
  *     char in[100];
@@ -501,6 +516,30 @@ struct io_plan *io_wait_(struct io_conn *conn,
                         void *arg);
 
 
+/**
+ * io_out_wait - leave the output plan idle until something wakes us.
+ * @conn: the connection that plan is for.
+ * @waitaddr: the address to wait on.
+ * @next: function to call after waiting.
+ * @arg: @next argument
+ *
+ * io_wait() makes the input plan idle: if you're not using io_duplex it
+ * doesn't matter which plan is waiting.  Otherwise, you may need to use
+ * io_out_wait() instead, to specify explicitly that the output plan is
+ * waiting.
+ */
+#define io_out_wait(conn, waitaddr, next, arg)                         \
+       io_out_wait_((conn), (waitaddr),                                \
+                    typesafe_cb_preargs(struct io_plan *, void *,      \
+                                        (next), (arg),                 \
+                                        struct io_conn *),             \
+                    (arg))
+
+struct io_plan *io_out_wait_(struct io_conn *conn,
+                            const void *wait,
+                            struct io_plan *(*next)(struct io_conn *, void *),
+                            void *arg);
+
 /**
  * io_wake - wake up any connections waiting on @wait
  * @waitaddr: the address to trigger.