bgpd: move bgp i/o to a separate source file

After implement threading, bgp_packet.c was serving the double purpose
of consolidating packet parsing functionality and handling actual I/O
operations. This is somewhat messy and difficult to understand. I've
thus moved all code and data structures for handling threaded packet
writes to bgp_io.[ch].

Although bgp_io.[ch] only handles writes at the moment to keep the noise
on this commit series down, for organization purposes, it's probably
best to move bgp_read() and its trappings into here as well and
restructure that code so that read()'s happen in the pthread and packet
processing happens on the main thread.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/bgpd/bgp_io.h b/bgpd/bgp_io.h
new file mode 100644
index 0000000000..7b81b8ee3b
--- /dev/null
+++ b/bgpd/bgp_io.h
@@ -0,0 +1,104 @@
+/*
+  BGP I/O.
+  Implements a consumer thread to flush packets destined for remote peers.
+
+  Copyright (C) 2017  Cumulus Networks
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; see the file COPYING; if not, write to the
+  Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+  MA 02110-1301 USA
+ */
+
+#ifndef _FRR_BGP_IO_H
+#define _FRR_BGP_IO_H
+
+#include "bgpd/bgpd.h"
+
+/**
+ * Control variable for write thread.
+ *
+ * Setting this variable to false and calling peer_writes_wake() will
+ * eventually result in thread termination.
+ */
+extern bool bgp_packet_writes_thread_run;
+
+/**
+ * Initializes data structures and flags for the write thread.
+ *
+ * This function should be called from the main thread before
+ * peer_writes_start() is invoked.
+ */
+extern void peer_writes_init(void);
+
+/**
+ * Start function for write thread.
+ *
+ * This function should be passed to pthread_create() during BGP startup.
+ */
+extern void *peer_writes_start(void *arg);
+
+/**
+ * Start function for write thread.
+ *
+ * Uninitializes all resources and stops the thread.
+ *
+ * @param result -- where to store data result, unused
+ */
+extern int peer_writes_stop(void **result);
+
+/**
+ * Registers a peer with the write thread.
+ *
+ * This function adds the peer to an internal data structure, which must be
+ * locked for write access. This call will block until the structure can be
+ * locked.
+ *
+ * After this function is called, any packets placed on peer->obuf will be
+ * written to peer->fd at regular intervals.
+ *
+ * This function increments the peer reference counter with peer_lock().
+ *
+ * If the peer is already registered, nothing happens.
+ *
+ * @param peer - peer to register
+ */
+extern void peer_writes_on(struct peer *peer);
+
+/**
+ * Deregisters a peer with the write thread.
+ *
+ * This function removes the peer from an internal data structure, which must
+ * be locked for write access. This call will block until the structure can be
+ * locked.
+ *
+ * After this function is called, any packets placed on peer->obuf will not be
+ * written to peer->fd.
+ *
+ * This function decrements the peer reference counter with peer_unlock().
+ *
+ * If the peer is not registered, nothing happens.
+ *
+ * @param peer - peer to deregister
+ */
+extern void peer_writes_off(struct peer *peer);
+
+/**
+ * Notifies the write thread that there is work to be done.
+ *
+ * This function has the effect of waking the write thread if it is sleeping.
+ * If the thread is not sleeping, this signal will be ignored.
+ */
+extern void peer_writes_wake(void);
+
+#endif /* _FRR_BGP_IO_H */