[pool] Add a generic concept of a pooled connection

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

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 */