Refactor option handling APIs.

This makes the APIs use string keys, and largely eliminates the use of
integer option IDs altogether.  The underlying registration for options
is also now a bit richer, letting protcols and transports declare the
actual options they use, rather than calling down into each entry point
carte blanche and relying on ENOTSUP.

This code may not be as fast as the integers was, but it is more intuitive,
easier to extend, and is not on any hot code paths.  (If you're diddling
options on a hot code path you're doing something wrong.)

1 files changed, 41 insertions, 15 deletions

diff --git a/src/core/transport.h b/src/core/transport.h
index 2891d8a4..b82e2c92 100644
--- a/src/core/transport.h
+++ b/src/core/transport.h
@@ -29,11 +29,6 @@ struct nni_tran {
 	// tran_pipe links our pipe-specific operations.
 	const nni_tran_pipe *tran_pipe;
 
-	// tran_chkopt, if not NULL, is used to validate that the
-	// option data presented is valid. This allows an option to
-	// be set on a socket, even if no endpoints are configured.
-	int (*tran_chkopt)(int, const void *, size_t);
-
 	// tran_init, if not NULL, is called once during library
 	// initialization.
 	int (*tran_init)(void);
@@ -54,10 +49,31 @@ struct nni_tran {
 #define NNI_TRANSPORT_V0 0x54520000
 #define NNI_TRANSPORT_VERSION NNI_TRANSPORT_V0
 
+// Endpoint option handlers.
+struct nni_tran_ep_option {
+	// eo_name is the name of the option.
+	const char *eo_name;
+
+	// eo_getopt retrieves the value of the option.
+	int (*eo_getopt)(void *, void *, size_t *);
+
+	// eo_set sets the value of the option.  If the first argument
+	// (the endpoint) is NULL, then no actual set operation should be
+	// performed, but the option should be sanity tested for presence
+	// and size.  (This permits the core to validate that an option
+	// is reasonable and be set even before endpoints are created.)
+	int (*eo_setopt)(void *, const void *, size_t);
+};
+
 // Endpoint operations are called by the socket in a protocol-independent
 // fashion.  The socket makes individual calls, which are expected to block
-// if appropriate (except for destroy). Endpoints are unable to call back
-// into the socket, to prevent recusive entry and deadlock.
+// if appropriate (except for destroy), or run asynchronously if an aio
+// is provided. Endpoints are unable to call back into the socket, to prevent
+// recusive entry and deadlock.
+//
+// For a given endpoint, the framework holds a lock so that each entry
+// point is run exclusively of the others. (Transports must still guard
+// against any asynchronous operations they manage themselves, though.)
 struct nni_tran_ep {
 	// ep_init creates a vanilla endpoint. The value created is
 	// used for the first argument for all other endpoint functions.
@@ -86,11 +102,20 @@ struct nni_tran_ep {
 	// not affect pipes that have already been created.
 	void (*ep_close)(void *);
 
-	// ep_setopt sets an endpoint (transport-specific) option.
-	int (*ep_setopt)(void *, int, const void *, size_t);
+	// ep_options is an array of endpoint options.  The final element must
+	// have a NULL name. If this member is NULL, then no transport specific
+	// options are available.
+	nni_tran_ep_option *ep_options;
+};
+
+// Pipe option handlers.  We only have get for pipes; once a pipe is created
+// no options may be set on it.
+struct nni_tran_pipe_option {
+	// po_name is the name of the option.
+	const char *po_name;
 
-	// ep_getopt gets an endpoint (transport-specific) option.
-	int (*ep_getopt)(void *, int, void *, size_t *);
+	// po_getopt retrieves the value of the option.
+	int (*po_getopt)(void *, void *, size_t *);
 };
 
 // Pipe operations are entry points called by the socket. These may be called
@@ -132,15 +157,16 @@ struct nni_tran_pipe {
 	// transport specific manner is appropriate.
 	uint16_t (*p_peer)(void *);
 
-	// p_getopt gets an pipe (transport-specific) property.  These values
-	// may not be changed once the pipe is created.
-	int (*p_getopt)(void *, int, void *, size_t *);
+	// p_options is an array of pipe options.  The final element must have
+	// a NULL name. If this member is NULL, then no transport specific
+	// options are available.
+	nni_tran_pipe_option *p_options;
 };
 
 // These APIs are used by the framework internally, and not for use by
 // transport implementations.
 extern nni_tran *nni_tran_find(const char *);
-extern int       nni_tran_chkopt(int, const void *, size_t);
+extern int       nni_tran_chkopt(const char *, const void *, size_t);
 extern int       nni_tran_sys_init(void);
 extern void      nni_tran_sys_fini(void);
 extern int       nni_tran_register(const nni_tran *);