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//
// Copyright 2016 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#ifndef CORE_PROTOCOL_H
#define CORE_PROTOCOL_H
// Protocol implementation details. Protocols must implement the
// interfaces in this file. Note that implementing new protocols is
// not necessarily intended to be a trivial task. The protocol developer
// must understand the nature of nng, as they are responsible for handling
// most of the logic. The protocol generally does most of the work for
// locking, and calls into the transport's pipe functions to do actual
// work, and the pipe functions generally assume no locking is needed.
// As a consequence, most of the concurrency in nng exists in the protocol
// implementations.
// nni_proto_pipe contains protocol-specific per-pipe operations.
struct nni_proto_pipe {
// pipe_init creates the protocol-specific per pipe data structure.
// The last argument is the per-socket protocol private data.
int (*pipe_init)(void **, nni_pipe *, void *);
// pipe_fini releases any pipe data structures. This is called after
// the pipe has been removed from the protocol, and the generic
// pipe threads have been stopped.
void (*pipe_fini)(void *);
// pipe_add is called to register a pipe with the protocol. The
// protocol can reject this, for example if another pipe is already
// active on a 1:1 protocol. The protocol may not block during this,
// as the socket lock is held.
int (*pipe_add)(void *);
// pipe_rem is called to unregister a pipe from the protocol.
// Threads may still acccess data structures, so the protocol
// should not free anything yet. This is called with the socket
// lock held, so the protocol may not call back into the socket, and
// must not block.
void (*pipe_rem)(void *);
// pipe_send is a function run in a thread per pipe, to process
// send activity. This can be NULL.
void (*pipe_send)(void *);
// pipe_recv is a function run in a thread per pipe, to process
// receive activity. While this can be NULL, it should NOT be, as
// otherwise the protocol may not be able to discover the closure of
// the underlying transport (such as a remote disconnect).
void (*pipe_recv)(void *);
};
struct nni_proto {
uint16_t proto_self; // our 16-bit protocol ID
uint16_t proto_peer; // who we peer with (ID)
const char * proto_name; // string version of our name
const nni_proto_pipe * proto_pipe; // Per-pipe operations.
// Create protocol instance, which will be stored on the socket.
int (*proto_init)(void **, nni_sock *);
// Destroy the protocol instance.
void (*proto_fini)(void *);
// Option manipulation. These may be NULL.
int (*proto_setopt)(void *, int, const void *,
size_t);
int (*proto_getopt)(void *, int, void *, size_t *);
// Receive filter. This may be NULL, but if it isn't, then
// messages coming into the system are routed here just before being
// delivered to the application. To drop the message, the prtocol
// should return NULL, otherwise the message (possibly modified).
nni_msg * (*proto_recv_filter)(void *, nni_msg *);
// Send filter. This may be NULL, but if it isn't, then messages
// here are filtered just after they come from the application.
nni_msg * (*proto_send_filter)(void *, nni_msg *);
};
// These functions are not used by protocols, but rather by the socket
// core implementation. The lookups can be used by transports as well.
extern nni_proto *nni_proto_find(uint16_t);
extern const char *nni_proto_name(uint16_t);
extern uint16_t nni_proto_number(const char *);
extern uint16_t nni_proto_peer(uint16_t);
#endif // CORE_PROTOCOL_H
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