[peerdist] Gather and report peer statistics during download

Record and report the number of peers (calculated as the maximum
number of peers discovered for a block's segment at the time that the
block download is complete), and the percentage of blocks retrieved
from peers rather than from the origin server.

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

src/include/ipxe/peerdisc.h

@@ -109,6 +109,12 @@ peerdisc_init ( struct peerdisc_client *peerdisc,
 
 extern unsigned int peerdisc_timeout_secs;
 
+extern void peerdisc_stat ( struct interface *intf, struct peerdisc_peer *peer,
+			    struct list_head *peers );
+#define peerdisc_stat_TYPE( object_type )				\
+	typeof ( void ( object_type, struct peerdisc_peer *peer,	\
+			struct list_head *peers ) )
+
 extern int peerdisc_open ( struct peerdisc_client *peerdisc, const void *id,
 			   size_t len );
 extern void peerdisc_close ( struct peerdisc_client *peerdisc );

src/include/ipxe/peermux.h

@@ -41,6 +41,16 @@ struct peerdist_multiplexed_block {
 	struct interface xfer;
 };
 
+/** PeerDist statistics */
+struct peerdist_statistics {
+	/** Maximum observed number of peers */
+	unsigned int peers;
+	/** Number of blocks downloaded in total */
+	unsigned int total;
+	/** Number of blocks downloaded from peers */
+	unsigned int local;
+};
+
 /** A PeerDist download multiplexer */
 struct peerdist_multiplexer {
 	/** Reference count */
@@ -65,6 +75,9 @@ struct peerdist_multiplexer {
 	struct list_head idle;
 	/** Block downloads */
 	struct peerdist_multiplexed_block block[PEERMUX_MAX_BLOCKS];
+
+	/** Statistics */
+	struct peerdist_statistics stats;
 };
 
 extern int peermux_filter ( struct interface *xfer, struct interface *info,