X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fio%2Fio.h;h=9316dd180a9895adc2f60fdb6cdaeff6d77deb4a;hp=9b4797a558c241d43f2cf7723ed0b917997d195b;hb=aae40e493625a07f4ac95476664447546b28661a;hpb=0998955055e45ef980a2dfdbd302142269abdd26

diff --git a/ccan/io/io.h b/ccan/io/io.h
index 9b4797a5..9316dd18 100644
--- a/ccan/io/io.h
+++ b/ccan/io/io.h
@@ -1,72 +1,166 @@
 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
 #ifndef CCAN_IO_H
 #define CCAN_IO_H
+#include <ccan/tal/tal.h>
 #include <ccan/typesafe_cb/typesafe_cb.h>
-#include <ccan/time/time.h>
 #include <stdbool.h>
 #include <unistd.h>
 
+struct timers;
+struct timer;
+struct list_head;
+
 /**
- * struct io_plan - pointer to return from a setup function.
+ * struct io_plan - a plan for input or output.
  *
- * A plan of what IO to do, when.
+ * Each io_conn has zero to two of these active at any time.
  */
 struct io_plan;
 
+/**
+ * struct io_conn - a connection associated with an fd.
+ */
+struct io_conn;
+
 /**
  * io_new_conn - create a new connection.
+ * @ctx: the context to tal from (or NULL)
  * @fd: the file descriptor.
- * @start: the first function to call.
- * @finish: the function to call when it's closed or fails.
- * @arg: the argument to both @start and @finish.
- *
- * This creates a connection which owns @fd.  @start will be called on the
- * next return to io_loop(), and @finish will be called when an I/O operation
- * fails, or you call io_close() on the connection.
+ * @init: the function to call for a new connection
+ * @arg: the argument to @init.
  *
- * The @start function must call one of the io queueing functions
- * (eg. io_read, io_write) and return the next function to call once
- * that is done using io_next().  The alternative is to call io_close().
+ * This creates a connection which owns @fd, it then calls
+ * @init to initialize the connection, which sets up an io_plan.
  *
  * Returns NULL on error (and sets errno).
+ *
+ * Example:
+ * // Dumb init function to print string and tell conn to close.
+ * static struct io_plan *conn_init(struct io_conn *conn, const char *msg)
+ * {
+ *	printf("Created conn %p: %s", conn, msg);
+ *	return io_close(conn);
+ * }
+ *
+ * static void create_self_closing_pipe(void)
+ * {
+ *	int fd[2];
+ *	struct io_conn *conn;
+ *
+ *	pipe(fd);
+ *	conn = io_new_conn(NULL, fd[0], conn_init, (const char *)"hi!");
+ *	if (!conn)
+ *		exit(1);
+ * }
  */
-#define io_new_conn(fd, start, finish, arg)				\
-	io_new_conn_((fd),						\
+#define io_new_conn(ctx, fd, init, arg)					\
+	io_new_conn_((ctx), (fd),					\
 		     typesafe_cb_preargs(struct io_plan *, void *,	\
-					 (start), (arg), struct io_conn *), \
-		     typesafe_cb_preargs(void, void *, (finish), (arg),	\
-					 struct io_conn *),		\
-		     (arg))
-struct io_conn *io_new_conn_(int fd,
-			     struct io_plan *(*start)(struct io_conn *, void *),
-			     void (*finish)(struct io_conn *, void *),
+					 (init), (arg),			\
+					 struct io_conn *conn),		\
+		     (void *)(arg))
+
+struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
+			     struct io_plan *(*init)(struct io_conn *, void *),
 			     void *arg);
 
+/**
+ * io_set_finish - set finish function on a connection.
+ * @conn: the connection.
+ * @finish: the function to call when it's closed or fails.
+ * @arg: the argument to @finish.
+ *
+ * @finish will be called when an I/O operation fails, or you call
+ * io_close() on the connection.  errno will be set to the value
+ * after the failed I/O, or at the call to io_close().  The fd
+ * will be closed before @finish is called.
+ *
+ * Example:
+ * static void finish(struct io_conn *conn, const char *msg)
+ * {
+ *	// errno is not 0 after success, so this is a bit useless.
+ *	printf("Conn %p closed with errno %i (%s)\n", conn, errno, msg);
+ * }
+ *
+ * // Dumb init function to print string and tell conn to close.
+ * static struct io_plan *conn_init(struct io_conn *conn, const char *msg)
+ * {
+ *	io_set_finish(conn, finish, msg);
+ *	return io_close(conn);
+ * }
+ */
+#define io_set_finish(conn, finish, arg)				\
+	io_set_finish_((conn),						\
+		       typesafe_cb_preargs(void, void *,		\
+					   (finish), (arg),		\
+					   struct io_conn *),		\
+		       (void *)(arg))
+void io_set_finish_(struct io_conn *conn,
+		    void (*finish)(struct io_conn *, void *),
+		    void *arg);
+
+
 /**
  * io_new_listener - create a new accepting listener.
+ * @ctx: the context to tal from (or NULL)
  * @fd: the file descriptor.
- * @start: the first function to call on new connections.
- * @finish: the function to call when the connection is closed or fails.
- * @arg: the argument to both @start and @finish.
+ * @init: the function to call for a new connection
+ * @arg: the argument to @init.
  *
- * When @fd becomes readable, we accept() and turn that fd into a new
- * connection.
+ * When @fd becomes readable, we accept(), create a new connection,
+ * (tal'ocated off @ctx) and pass that to init().
  *
  * Returns NULL on error (and sets errno).
+ *
+ * Example:
+ * #include <sys/types.h>
+ * #include <sys/socket.h>
+ * #include <netdb.h>
+ *
+ * ...
+ *
+ * // Set up a listening socket, return it.
+ * static struct io_listener *do_listen(const char *port)
+ * {
+ *	struct addrinfo *addrinfo, hints;
+ *	int fd, on = 1;
+ *
+ *	memset(&hints, 0, sizeof(hints));
+ *	hints.ai_family = AF_UNSPEC;
+ *	hints.ai_socktype = SOCK_STREAM;
+ *	hints.ai_flags = AI_PASSIVE;
+ *	hints.ai_protocol = 0;
+ *
+ *	if (getaddrinfo(NULL, port, &hints, &addrinfo) != 0)
+ *		return NULL;
+ *
+ *	fd = socket(addrinfo->ai_family, addrinfo->ai_socktype,
+ *		    addrinfo->ai_protocol);
+ *	if (fd < 0)
+ *		return NULL;
+ *
+ *	freeaddrinfo(addrinfo);
+ *	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+ *	if (bind(fd, addrinfo->ai_addr, addrinfo->ai_addrlen) != 0) {
+ *		close(fd);
+ *		return NULL;
+ *	}
+ *	if (listen(fd, 1) != 0) {
+ *		close(fd);
+ *		return NULL;
+ *	}
+ *	return io_new_listener(NULL, fd, conn_init, (const char *)"listened!");
+ * }
  */
-#define io_new_listener(fd, start, finish, arg)				\
-	io_new_listener_((fd),						\
+#define io_new_listener(ctx, fd, init, arg)				\
+	io_new_listener_((ctx), (fd),					\
 			 typesafe_cb_preargs(struct io_plan *, void *,	\
-					     (start), (arg),		\
-					     struct io_conn *),		\
-			 typesafe_cb_preargs(void, void *, (finish),	\
-					     (arg), struct io_conn *),	\
-			 (arg))
-struct io_listener *io_new_listener_(int fd,
-				     struct io_plan *(*start)(struct io_conn *,
-							      void *arg),
-				     void (*finish)(struct io_conn *,
-						    void *arg),
+					     (init), (arg),		\
+					     struct io_conn *conn),	\
+			 (void *)(arg))
+struct io_listener *io_new_listener_(const tal_t *ctx, int fd,
+				     struct io_plan *(*init)(struct io_conn *,
+							     void *),
 				     void *arg);
 
 /**
@@ -74,223 +168,528 @@ struct io_listener *io_new_listener_(int fd,
  * @listener: the listener returned from io_new_listener.
  *
  * This closes the fd and frees @listener.
+ *
+ * Example:
+ * ...
+ *	struct io_listener *l = do_listen("8111");
+ *	if (l) {
+ *		io_loop(NULL, NULL);
+ *		io_close_listener(l);
+ *	}
  */
 void io_close_listener(struct io_listener *listener);
 
 /**
- * io_write - queue data to be written.
- * @conn: the current connection.
+ * io_write - output plan to write data.
+ * @conn: the connection that plan is for.
  * @data: the data buffer.
  * @len: the length to write.
- * @cb: function to call once it's done.
- * @arg: @cb argument
+ * @next: function to call output is done.
+ * @arg: @next argument
  *
- * This will queue the data buffer for writing.  Once it's all
- * written, the @cb function will be called: on an error, the finish
+ * This updates the output plan, to write out a data buffer.  Once it's all
+ * written, the @next function will be called: on an error, the finish
  * function is called instead.
  *
  * Note that the I/O may actually be done immediately.
+ *
+ * Example:
+ * static struct io_plan *write_to_conn(struct io_conn *conn, const char *msg)
+ * {
+ *	// Write message, then close.
+ *	return io_write(conn, msg, strlen(msg), io_close_cb, NULL);
+ * }
  */
-#define io_write(conn, data, len, cb, arg)				\
+#define io_write(conn, data, len, next, arg)				\
 	io_write_((conn), (data), (len),				\
 		  typesafe_cb_preargs(struct io_plan *, void *,		\
-				      (cb), (arg), struct io_conn *),	\
+				      (next), (arg), struct io_conn *),	\
 		  (arg))
-struct io_plan *io_write_(struct io_conn *conn, const void *data, size_t len,
-			  struct io_plan *(*cb)(struct io_conn *, void *),
+struct io_plan *io_write_(struct io_conn *conn,
+			  const void *data, size_t len,
+			  struct io_plan *(*next)(struct io_conn *, void *),
 			  void *arg);
 
 /**
- * io_read - queue buffer to be read.
- * @conn: the current connection.
+ * io_read - input plan to read data.
+ * @conn: the connection that plan is for.
  * @data: the data buffer.
  * @len: the length to read.
- * @cb: function to call once it's done.
- * @arg: @cb argument
+ * @next: function to call once input is done.
+ * @arg: @next argument
  *
- * This will queue the data buffer for reading.  Once it's all read,
- * the @cb function will be called: on an error, the finish function
- * is called instead.
+ * This creates a plan to read data into a buffer.  Once it's all
+ * read, the @next function will be called: on an error, the finish
+ * function is called instead.
  *
  * Note that the I/O may actually be done immediately.
+ *
+ * Example:
+ * static struct io_plan *read_from_conn(struct io_conn *conn, char *buf)
+ * {
+ *	// Read message, then close.
+ *	return io_read(conn, buf, 12, io_close_cb, NULL);
+ * }
  */
-#define io_read(conn, data, len, cb, arg)				\
+#define io_read(conn, data, len, next, arg)				\
 	io_read_((conn), (data), (len),					\
 		 typesafe_cb_preargs(struct io_plan *, void *,		\
-				     (cb), (arg), struct io_conn *),	\
+				     (next), (arg), struct io_conn *),	\
 		 (arg))
-struct io_plan *io_read_(struct io_conn *conn, void *data, size_t len,
-			 struct io_plan *(*cb)(struct io_conn *, void *),
+struct io_plan *io_read_(struct io_conn *conn,
+			 void *data, size_t len,
+			 struct io_plan *(*next)(struct io_conn *, void *),
 			 void *arg);
 
 
 /**
- * io_read_partial - queue buffer to be read (partial OK).
- * @conn: the current connection.
+ * io_read_partial - input plan to read some data.
+ * @conn: the connection that plan is for.
  * @data: the data buffer.
- * @len: the maximum length to read, set to the length actually read.
- * @cb: function to call once it's done.
- * @arg: @cb argument
+ * @maxlen: the maximum length to read
+ * @lenp: set to the length actually read.
+ * @next: function to call once input is done.
+ * @arg: @next argument
  *
- * This will queue the data buffer for reading.  Once any data is
- * read, @len is updated and the @cb function will be called: on an
+ * This creates a plan to read data into a buffer.  Once any data is
+ * read, @len is updated and the @next function will be called: on an
  * error, the finish function is called instead.
  *
  * Note that the I/O may actually be done immediately.
+ *
+ * Example:
+ * struct buf {
+ *	size_t len;
+ *	char buf[12];
+ * };
+ *
+ * static struct io_plan *dump(struct io_conn *conn, struct buf *b)
+ * {
+ *	printf("Partial read: '%*s'\n", (int)b->len, b->buf);
+ *	free(b);
+ *	return io_close(conn);
+ * }
+ *
+ * static struct io_plan *read_part(struct io_conn *conn, struct buf *b)
+ * {
+ *	// Read message, then dump and close.
+ *	return io_read_partial(conn, b->buf, sizeof(b->buf), &b->len, dump, b);
+ * }
  */
-#define io_read_partial(conn, data, len, cb, arg)			\
-	io_read_partial_((conn), (data), (len),				\
+#define io_read_partial(conn, data, maxlen, lenp, next, arg)		\
+	io_read_partial_((conn), (data), (maxlen), (lenp),		\
 			 typesafe_cb_preargs(struct io_plan *, void *,	\
-					     (cb), (arg), struct io_conn *), \
+					     (next), (arg),		\
+					     struct io_conn *),		\
 			 (arg))
-struct io_plan *io_read_partial_(struct io_conn *conn, void *data, size_t *len,
-				 struct io_plan *(*cb)(struct io_conn *, void *),
+struct io_plan *io_read_partial_(struct io_conn *conn,
+				 void *data, size_t maxlen, size_t *lenp,
+				 struct io_plan *(*next)(struct io_conn *,
+							 void *),
 				 void *arg);
 
 /**
- * io_write_partial - queue data to be written (partial OK).
- * @conn: the current connection.
+ * io_write_partial - output plan to write some data.
+ * @conn: the connection that plan is for.
  * @data: the data buffer.
- * @len: the maximum length to write, set to the length actually written.
- * @cb: function to call once it's done.
- * @arg: @cb argument
+ * @maxlen: the maximum length to write
+ * @lenp: set to the length actually written.
+ * @next: function to call once output is done.
+ * @arg: @next argument
  *
- * This will queue the data buffer for writing.  Once any data is
- * written, @len is updated and the @cb function will be called: on an
+ * This creates a plan to write data from a buffer.   Once any data is
+ * written, @len is updated and the @next function will be called: on an
  * error, the finish function is called instead.
  *
  * Note that the I/O may actually be done immediately.
+ *
+ * Example:
+ * struct buf {
+ *	size_t len;
+ *	char buf[12];
+ * };
+ *
+ * static struct io_plan *show_partial(struct io_conn *conn, struct buf *b)
+ * {
+ *	printf("Only wrote: '%*s'\n", (int)b->len, b->buf);
+ *	free(b);
+ *	return io_close(conn);
+ * }
+ *
+ * static struct io_plan *write_part(struct io_conn *conn, struct buf *b)
+ * {
+ *	// Write message, then dump and close.
+ *	strcpy(b->buf, "Hello world");
+ *	return io_write_partial(conn, b->buf, strlen(b->buf),
+ *				&b->len, show_partial, b);
+ * }
  */
-#define io_write_partial(conn, data, len, cb, arg)			\
-	io_write_partial_((conn), (data), (len),			\
+#define io_write_partial(conn, data, maxlen, lenp, next, arg)		\
+	io_write_partial_((conn), (data), (maxlen), (lenp),		\
 			  typesafe_cb_preargs(struct io_plan *, void *,	\
-					      (cb), (arg), struct io_conn *), \
+					      (next), (arg),		\
+					      struct io_conn *),	\
 			  (arg))
 struct io_plan *io_write_partial_(struct io_conn *conn,
-				  const void *data, size_t *len,
-				  struct io_plan *(*cb)(struct io_conn *, void*),
+				  const void *data, size_t maxlen, size_t *lenp,
+				  struct io_plan *(*next)(struct io_conn *,
+							  void*),
 				  void *arg);
 
+/**
+ * io_always - plan to immediately call next callback
+ * @conn: the connection that plan is for.
+ * @next: function to call.
+ * @arg: @next argument
+ *
+ * Sometimes it's neater to plan a callback rather than call it directly;
+ * for example, if you only need to read data for one path and not another.
+ *
+ * Example:
+ * static struct io_plan *init_conn_with_nothing(struct io_conn *conn,
+ *						 void *unused)
+ * {
+ *	// Silly example: close on next time around loop.
+ *	return io_always(conn, io_close_cb, NULL);
+ * }
+ */
+#define io_always(conn, next, arg)					\
+	io_always_((conn), typesafe_cb_preargs(struct io_plan *, void *, \
+					       (next), (arg),		\
+					       struct io_conn *),	\
+		   (arg))
+
+struct io_plan *io_always_(struct io_conn *conn,
+			   struct io_plan *(*next)(struct io_conn *, void *),
+			   void *arg);
 
 /**
- * io_idle - explicitly note that this connection will do nothing.
- * @conn: the current connection.
+ * 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 indicates the connection is idle: some other function will
- * later call io_read/io_write etc. (or io_close) on it, in which case
- * it will do that.
+ * 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.
  */
-struct io_plan *io_idle(struct io_conn *conn);
+#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_timeout - set timeout function if the callback doesn't fire.
- * @conn: the current connection.
- * @ts: how long until the timeout should be called.
- * @cb to call.
- * @arg: argument to @cb.
- *
- * If the usual next callback is not called for this connection before @ts,
- * this function will be called.  If next callback is called, the timeout
- * is automatically removed.
- *
- * Returns false on allocation failure.  A connection can only have one
- * timeout.
+ * io_connect - create an asynchronous connection to a listening socket.
+ * @conn: the connection that plan is for.
+ * @addr: where to connect.
+ * @init: function to call once it's connected
+ * @arg: @init argument
+ *
+ * This initiates a connection, and creates a plan for
+ * (asynchronously) completing it.  Once complete, the @init function
+ * will be called.
+ *
+ * Example:
+ * #include <sys/types.h>
+ * #include <sys/socket.h>
+ * #include <netdb.h>
+ *
+ * // Write, then close socket.
+ * static struct io_plan *init_connect(struct io_conn *conn,
+ *				       struct addrinfo *addrinfo)
+ * {
+ *	return io_connect(conn, addrinfo, io_close_cb, NULL);
+ * }
+ *
+ * ...
+ *
+ *	int fd;
+ *	struct addrinfo *addrinfo;
+ *
+ *	fd = socket(AF_INET, SOCK_STREAM, 0);
+ *	getaddrinfo("localhost", "8111", NULL, &addrinfo);
+ *	io_new_conn(NULL, fd, init_connect, addrinfo);
  */
-#define io_timeout(conn, ts, fn, arg)					\
-	io_timeout_((conn), (ts),					\
+struct addrinfo;
+#define io_connect(conn, addr, next, arg)				\
+	io_connect_((conn), (addr),					\
 		    typesafe_cb_preargs(struct io_plan *, void *,	\
-					(fn), (arg),			\
+					(next), (arg),			\
 					struct io_conn *),		\
 		    (arg))
-bool io_timeout_(struct io_conn *conn, struct timespec ts,
-		 struct io_plan *(*fn)(struct io_conn *, void *), void *arg);
+
+struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
+			    struct io_plan *(*next)(struct io_conn *, void *),
+			    void *arg);
 
 /**
- * io_duplex - split an fd into two connections.
- * @conn: a connection.
- * @start: the first function to call.
- * @finish: the function to call when it's closed or fails.
- * @arg: the argument to both @start and @finish.
+ * io_duplex - set plans for both input and output.
+ * @conn: the connection that plan is for.
+ * @in: the input plan
+ * @out: the output plan
+ *
+ * Most plans are either for input or output; io_duplex creates a plan
+ * which does both.  This is often used in the init function to create
+ * two independent streams, though it can be used once on any connection.
  *
- * Sometimes you want to be able to simultaneously read and write on a
- * single fd, but io forces a linear call sequence.  The solition is
- * to have two connections for the same fd, and use one for read
- * operations and one for write.
+ * Note that if either plan closes the connection, it will be closed.
  *
- * You must io_close() both of them to close the fd.
+ * Example:
+ * struct buf {
+ *	char in[100];
+ *	char out[100];
+ * };
+ *
+ * static struct io_plan *read_and_write(struct io_conn *conn, struct buf *b)
+ * {
+ *	return io_duplex(conn,
+ *			 io_read(conn, b->in, sizeof(b->in), io_close_cb, b),
+ *			 io_write(conn, b->out, sizeof(b->out), io_close_cb,b));
+ * }
  */
-#define io_duplex(conn, start, finish, arg)				\
-	io_duplex_((conn),						\
-		   typesafe_cb_preargs(struct io_plan *, void *,	\
-				       (start), (arg), struct io_conn *), \
-		   typesafe_cb_preargs(void, void *, (finish), (arg),	\
-				       struct io_conn *),		\
-		   (arg))
+#define io_duplex(conn, in_plan, out_plan) \
+	(io_duplex_prepare(conn), io_duplex_(in_plan, out_plan))
 
-struct io_conn *io_duplex_(struct io_conn *conn,
-			   struct io_plan *(*start)(struct io_conn *, void *),
-			   void (*finish)(struct io_conn *, void *),
-			   void *arg);
+struct io_plan *io_duplex_(struct io_plan *in_plan, struct io_plan *out_plan);
+void io_duplex_prepare(struct io_conn *conn);
 
 /**
- * io_wake - wake up and idle connection.
- * @conn: an idle connection.
- * @fn: the next function to call once queued IO is complete.
- * @arg: the argument to @next.
+ * io_halfclose - close half of an io_duplex connection.
+ * @conn: the connection that plan is for.
  *
- * This makes @conn run its @next function the next time around the
- * io_loop().
+ * It's common to want to close a duplex connection after both input and
+ * output plans have completed.  If either calls io_close() the connection
+ * closes immediately.  Instead, io_halfclose() needs to be called twice.
+ *
+ * Example:
+ * struct buf {
+ *	char in[100];
+ *	char out[100];
+ * };
+ *
+ * static struct io_plan *finish(struct io_conn *conn, struct buf *b)
+ * {
+ *	return io_halfclose(conn);
+ * }
+ *
+ * static struct io_plan *read_and_write(struct io_conn *conn, struct buf *b)
+ * {
+ *	return io_duplex(conn,
+ *			 io_read(conn, b->in, sizeof(b->in), finish, b),
+ *			 io_write(conn, b->out, sizeof(b->out), finish, b));
+ * }
+ */
+struct io_plan *io_halfclose(struct io_conn *conn);
+
+/**
+ * io_wait - leave a 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
+ *
+ * This leaves the input or output idle: io_wake(@waitaddr) will be
+ * called later to restart the connection.
+ *
+ * Example:
+ * // Silly example to wait then close.
+ * static struct io_plan *wait(struct io_conn *conn, void *b)
+ * {
+ *	return io_wait(conn, b, io_close_cb, NULL);
+ * }
  */
-#define io_wake(conn, fn, arg)						\
-	io_wake_((conn),						\
+#define io_wait(conn, waitaddr, next, arg)				\
+	io_wait_((conn), (waitaddr),					\
 		 typesafe_cb_preargs(struct io_plan *, void *,		\
-				     (fn), (arg), struct io_conn *),	\
+				     (next), (arg),			\
+				     struct io_conn *),			\
 		 (arg))
-void io_wake_(struct io_conn *conn,
-	      struct io_plan *(*fn)(struct io_conn *, void *), void *arg);
+
+struct io_plan *io_wait_(struct io_conn *conn,
+			 const void *wait,
+			 struct io_plan *(*next)(struct io_conn *, void *),
+			 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.
+ *
+ * All io_conns who have returned io_wait() on @waitaddr will move on
+ * to their next callback.
+ *
+ * Example:
+ * static struct io_plan *wake_it(struct io_conn *conn, void *b)
+ * {
+ *	io_wake(b);
+ *	return io_close(conn);
+ * }
+ */
+void io_wake(const void *wait);
 
 /**
  * io_break - return from io_loop()
- * @conn: the current connection.
  * @ret: non-NULL value to return from io_loop().
- * @cb: function to call once on return
- * @arg: @cb argument
  *
- * This breaks out of the io_loop.  As soon as the current @next
- * function returns, any io_closed()'d connections will have their
- * finish callbacks called, then io_loop() with return with @ret.
+ * This breaks out of the io_loop.  As soon as the current function
+ * returns, any io_close()'d connections will have their finish
+ * callbacks called, then io_loop() with return with @ret.
  *
- * If io_loop() is called again, then @cb will be called.
+ * If io_loop() is called again, then @plan will be carried out.
+ *
+ * Example:
+ *	static struct io_plan *fail_on_timeout(struct io_conn *conn, char *msg)
+ *	{
+ *		io_break(msg);
+ *		return io_close(conn);
+ *	}
  */
-#define io_break(conn, ret, fn, arg)					\
-	io_break_((conn), (ret),					\
-		  typesafe_cb_preargs(struct io_plan *, void *,		\
-				      (fn), (arg), struct io_conn *),	\
-		  (arg))
-struct io_plan *io_break_(struct io_conn *conn, void *ret,
-			  struct io_plan *(*fn)(struct io_conn *, void *),
-			  void *arg);
+void io_break(const void *ret);
+
+/**
+ * io_never - assert if callback is called.
+ * @conn: the connection that plan is for.
+ * @unused: an unused parameter to make this suitable for use as a callback.
+ *
+ * Sometimes you want to make it clear that a callback should never happen
+ * (eg. for io_break).  This will assert() if called.
+ *
+ * Example:
+ * static struct io_plan *break_out(struct io_conn *conn, void *unused)
+ * {
+ *	io_break(conn);
+ *	// We won't ever return from io_break
+ *	return io_never(conn, NULL);
+ * }
+ */
+struct io_plan *io_never(struct io_conn *conn, void *unused);
 
 /* FIXME: io_recvfrom/io_sendto */
 
 /**
- * io_close - terminate a connection.
- * @conn: any connection.
+ * io_close - plan to close a connection.
+ * @conn: the connection to close.
  *
- * The schedules a connection to be closed.  It can be done on any
- * connection, whether it has I/O queued or not (though that I/O may
- * be performed first).
+ * On return to io_loop, the connection will be closed.  It doesn't have
+ * to be the current connection and it doesn't need to be idle.  No more
+ * IO or callbacks will occur.
  *
- * It's common to 'return io_close(...)' from a @next function, but
- * io_close can also be used as an argument to io_next().
+ * You can close a connection twice without harmful effects.
+ *
+ * Example:
+ * static struct io_plan *close_on_timeout(struct io_conn *conn, const char *msg)
+ * {
+ *	printf("closing: %s\n", msg);
+ *	return io_close(conn);
+ * }
  */
-struct io_plan *io_close(struct io_conn *, void *unused);
+struct io_plan *io_close(struct io_conn *conn);
+
+/**
+ * io_close_cb - helper callback to close a connection.
+ * @conn: the connection.
+ *
+ * This schedules a connection to be closed; designed to be used as
+ * a callback function.
+ *
+ * Example:
+ *	#define close_on_timeout io_close_cb
+ */
+struct io_plan *io_close_cb(struct io_conn *, void *unused);
 
 /**
  * io_loop - process fds until all closed on io_break.
+ * @timers - timers which are waiting to go off (or NULL for none)
+ * @expired - an expired timer (can be NULL if @timers is)
  *
  * This is the core loop; it exits with the io_break() arg, or NULL if
- * all connections and listeners are closed.
+ * all connections and listeners are closed, or with @expired set to an
+ * expired timer (if @timers isn't NULL).
+ *
+ * Example:
+ *	io_loop(NULL, NULL);
+ */
+void *io_loop(struct timers *timers, struct timer **expired);
+
+/**
+ * io_conn_fd - get the fd from a connection.
+ * @conn: the connection.
+ *
+ * Sometimes useful, eg for getsockname().
+ */
+int io_conn_fd(const struct io_conn *conn);
+
+/**
+ * io_time_override - override the normal call for time.
+ * @nowfn: the function to call.
+ *
+ * io usually uses time_now() internally, but this forces it
+ * to use your function (eg. for debugging).  Returns the old
+ * one.
+ */
+struct timeabs (*io_time_override(struct timeabs (*now)(void)))(void);
+
+/**
+ * io_set_debug - set synchronous mode on a connection.
+ * @conn: the connection.
+ * @debug: whether to enable or disable debug.
+ *
+ * Once @debug is true on a connection, all I/O is done synchronously
+ * as soon as it is set, until it is unset or @conn is closed.  This
+ * makes it easy to debug what's happening with a connection, but note
+ * that other connections are starved while this is being done.
+ *
+ * See also: io_debug_complete()
+ *
+ * Example:
+ * // Dumb init function to set debug and tell conn to close.
+ * static struct io_plan *conn_init(struct io_conn *conn, const char *msg)
+ * {
+ *	io_set_debug(conn, true);
+ *	return io_close(conn);
+ * }
+ */
+void io_set_debug(struct io_conn *conn, bool debug);
+
+/**
+ * io_debug_complete - empty function called when conn is closing/waiting.
+ * @conn: the connection.
+ *
+ * This is for putting a breakpoint onto, when debugging.  It is called
+ * when a conn with io_set_debug() true can no longer be synchronous:
+ * 1) It is io_close()'d
+ * 2) It enters io_wait() (sychronous debug will resume after io_wake())
+ * 3) io_break() is called (sychronous debug will resume after io_loop())
  */
-void *io_loop(void);
+void io_debug_complete(struct io_conn *conn);
 #endif /* CCAN_IO_H */