[pool] Add a generic concept of a pooled connection

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/pool.c

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 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; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/**
+ * @file
+ *
+ * Pooled connections
+ *
+ */
+
+#include <assert.h>
+#include <ipxe/pool.h>
+
+/**
+ * Recycle this connection after closing
+ *
+ * @v intf		Data transfer interface
+ */
+void pool_recycle ( struct interface *intf ) {
+
+	intf_poke ( intf, pool_recycle );
+}
+
+/**
+ * Reopen a defunct connection
+ *
+ * @v intf		Data transfer interface
+ */
+void pool_reopen ( struct interface *intf ) {
+
+	intf_poke ( intf, pool_reopen );
+}
+
+/**
+ * Add connection to pool
+ *
+ * @v pool		Pooled connection
+ * @v list		List of pooled connections
+ * @v expiry		Expiry time
+ */
+void pool_add ( struct pooled_connection *pool, struct list_head *list,
+		unsigned long expiry ) {
+
+	/* Sanity check */
+	assert ( list_empty ( &pool->list ) );
+	assert ( ! timer_running ( &pool->timer ) );
+
+	/* Add to list of pooled connections */
+	list_add_tail ( &pool->list, list );
+
+	/* Start expiry timer */
+	start_timer_fixed ( &pool->timer, expiry );
+}
+
+/**
+ * Remove connection from pool
+ *
+ * @v pool		Pooled connection
+ */
+void pool_del ( struct pooled_connection *pool ) {
+
+	/* Remove from list of pooled connections */
+	list_del ( &pool->list );
+	INIT_LIST_HEAD ( &pool->list );
+
+	/* Stop expiry timer */
+	stop_timer ( &pool->timer );
+
+	/* Mark as a freshly recycled connection */
+	pool->flags = POOL_RECYCLED;
+}
+
+/**
+ * Close expired pooled connection
+ *
+ * @v timer		Expiry timer
+ * @v over		Failure indicator
+ */
+void pool_expired ( struct retry_timer *timer, int over __unused ) {
+	struct pooled_connection *pool =
+		container_of ( timer, struct pooled_connection, timer );
+
+	/* Sanity check */
+	assert ( ! list_empty ( &pool->list ) );
+
+	/* Remove from connection pool */
+	list_del ( &pool->list );
+	INIT_LIST_HEAD ( &pool->list );
+
+	/* Close expired connection */
+	pool->expired ( pool );
+}

src/include/ipxe/pool.h

@@ -0,0 +1,127 @@
+#ifndef _IPXE_POOL_H
+#define _IPXE_POOL_H
+
+/** @file
+ *
+ * Pooled connections
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <ipxe/interface.h>
+#include <ipxe/list.h>
+#include <ipxe/retry.h>
+
+/** A pooled connection */
+struct pooled_connection {
+	/** List of pooled connections
+	 *
+	 * Note that each connecton in the pool has a running expiry
+	 * timer which holds a reference to the connection.  We
+	 * therefore do not require the connection pool list to hold a
+	 * reference for each pooled connection.
+	 */
+	struct list_head list;
+	/** Expiry timer */
+	struct retry_timer timer;
+	/** Close expired pooled connection
+	 *
+	 * @v pool		Pooled connection
+	 */
+	void ( * expired ) ( struct pooled_connection *pool );
+	/** Flags */
+	unsigned int flags;
+};
+
+/** Pooled connection flags */
+enum pooled_connection_flags {
+	/** Connection should be recycled after closing */
+	POOL_RECYCLABLE = 0x0001,
+	/** Connection has been recycled */
+	POOL_RECYCLED = 0x0002,
+	/** Connection is known to be alive */
+	POOL_ALIVE = 0x0004,
+};
+
+extern void pool_add ( struct pooled_connection *pool, struct list_head *list,
+		       unsigned long expiry );
+extern void pool_del ( struct pooled_connection *pool );
+extern void pool_expired ( struct retry_timer *timer, int over );
+
+/**
+ * Initialise a pooled connection
+ *
+ * @v pool		Pooled connection
+ * @v expired		Close expired pooled connection method
+ * @v refcnt		Containing object reference counter
+ */
+static inline __attribute__ (( always_inline )) void
+pool_init ( struct pooled_connection *pool,
+	    void ( * expired ) ( struct pooled_connection *pool ),
+	    struct refcnt *refcnt ) {
+
+	INIT_LIST_HEAD ( &pool->list );
+	timer_init ( &pool->timer, pool_expired, refcnt );
+	pool->expired = expired;
+}
+
+/**
+ * Mark pooled connection as recyclable
+ *
+ * @v pool		Pooled connection
+ */
+static inline __attribute__ (( always_inline )) void
+pool_recyclable ( struct pooled_connection *pool ) {
+
+	pool->flags |= POOL_RECYCLABLE;
+}
+
+/**
+ * Mark pooled connection as alive
+ *
+ * @v pool		Pooled connection
+ */
+static inline __attribute__ (( always_inline )) void
+pool_alive ( struct pooled_connection *pool ) {
+
+	pool->flags |= POOL_ALIVE;
+}
+
+/**
+ * Check if pooled connection is recyclable
+ *
+ * @v pool		Pooled connection
+ * @ret recyclable	Pooled connection is recyclable
+ */
+static inline __attribute__ (( always_inline )) int
+pool_is_recyclable ( struct pooled_connection *pool ) {
+
+	return ( pool->flags & POOL_RECYCLABLE );
+}
+
+/**
+ * Check if pooled connection is reopenable
+ *
+ * @v pool		Pooled connection
+ * @ret reopenable	Pooled connection is reopenable
+ */
+static inline __attribute__ (( always_inline )) int
+pool_is_reopenable ( struct pooled_connection *pool ) {
+
+	/* A connection is reopenable if it has been recycled but is
+	 * not yet known to be alive.
+	 */
+	return ( ( pool->flags & POOL_RECYCLED ) &
+		 ( ! ( pool->flags & POOL_ALIVE ) ) );
+}
+
+extern void pool_recycle ( struct interface *intf );
+#define pool_recycle_TYPE( object_type ) \
+	typeof ( void ( object_type ) )
+
+extern void pool_reopen ( struct interface *intf );
+#define pool_reopen_TYPE( object_type ) \
+	typeof ( void ( object_type ) )
+
+#endif /* _IPXE_POOL_H */