[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,

src/net/peerblk.c

@@ -270,6 +270,9 @@ static int peerblk_deliver ( struct peerdist_block *peerblk,
  */
 static void peerblk_done ( struct peerdist_block *peerblk, int rc ) {
 	struct digest_algorithm *digest = peerblk->digest;
+	struct peerdisc_segment *segment = peerblk->discovery.segment;
+	struct peerdisc_peer *head;
+	struct peerdisc_peer *peer;
 	uint8_t hash[digest->digestsize];
 	unsigned long now = peerblk_timestamp();
 
@@ -296,6 +299,11 @@ static void peerblk_done ( struct peerdist_block *peerblk, int rc ) {
 	profile_custom ( &peerblk_attempt_success_profiler,
 			 ( now - peerblk->attempted ) );
 
+	/* Report peer statistics */
+	head = list_entry ( &segment->peers, struct peerdisc_peer, list );
+	peer = ( ( peerblk->peer == head ) ? NULL : peerblk->peer );
+	peerdisc_stat ( &peerblk->xfer, peer, &segment->peers );
+
 	/* Close download */
 	peerblk_close ( peerblk, 0 );
 	return;

src/net/peerdisc.c

@@ -76,6 +76,36 @@ static struct peerdisc_segment * peerdisc_find ( const char *id );
 static int peerdisc_discovered ( struct peerdisc_segment *segment,
 				 const char *location );
 
+/******************************************************************************
+ *
+ * Statistics reporting
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Report peer discovery statistics
+ *
+ * @v intf		Interface
+ * @v peer		Selected peer (or NULL)
+ * @v peers		List of available peers
+ */
+void peerdisc_stat ( struct interface *intf, struct peerdisc_peer *peer,
+		     struct list_head *peers ) {
+	struct interface *dest;
+	peerdisc_stat_TYPE ( void * ) *op =
+		intf_get_dest_op ( intf, peerdisc_stat, &dest );
+	void *object = intf_object ( dest );
+
+	if ( op ) {
+		op ( object, peer, peers );
+	} else {
+		/* Default is to do nothing */
+	}
+
+	intf_put ( dest );
+}
+
 /******************************************************************************
  *
  * Discovery sockets

src/net/peermux.c

@@ -24,9 +24,11 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <errno.h>
 #include <ipxe/uri.h>
 #include <ipxe/xferbuf.h>
+#include <ipxe/job.h>
 #include <ipxe/peerblk.h>
 #include <ipxe/peermux.h>
 
@@ -74,6 +76,28 @@ static void peermux_close ( struct peerdist_multiplexer *peermux, int rc ) {
 	intf_shutdown ( &peermux->info, rc );
 }
 
+/**
+ * Report progress of PeerDist download
+ *
+ * @v peermux		PeerDist download multiplexer
+ * @v progress		Progress report to fill in
+ * @ret ongoing_rc	Ongoing job status code (if known)
+ */
+static int peermux_progress ( struct peerdist_multiplexer *peermux,
+			      struct job_progress *progress ) {
+	struct peerdist_statistics *stats = &peermux->stats;
+	unsigned int percentage;
+
+	/* Construct PeerDist status message */
+	if ( stats->total ) {
+		percentage = ( ( 100 * stats->local ) / stats->total );
+		snprintf ( progress->message, sizeof ( progress->message ),
+			   "%3d%% from %d peers", percentage, stats->peers );
+	}
+
+	return 0;
+}
+
 /**
  * Receive content information
  *
@@ -274,6 +298,35 @@ peermux_block_buffer ( struct peerdist_multiplexed_block *peermblk ) {
 	return xfer_buffer ( &peermux->xfer );
 }
 
+/**
+ * Record peer discovery statistics
+ *
+ * @v peermblk		PeerDist multiplexed block download
+ * @v peer		Selected peer (or NULL)
+ * @v peers		List of available peers
+ */
+static void peermux_block_stat ( struct peerdist_multiplexed_block *peermblk,
+				 struct peerdisc_peer *peer,
+				 struct list_head *peers ) {
+	struct peerdist_multiplexer *peermux = peermblk->peermux;
+	struct peerdist_statistics *stats = &peermux->stats;
+	struct peerdisc_peer *tmp;
+	unsigned int count = 0;
+
+	/* Record maximum number of available peers */
+	list_for_each_entry ( tmp, peers, list )
+		count++;
+	if ( count > stats->peers )
+		stats->peers = count;
+
+	/* Update block counts */
+	if ( peer )
+		stats->local++;
+	stats->total++;
+	DBGC2 ( peermux, "PEERMUX %p downloaded %d/%d from %d peers\n",
+		peermux, stats->local, stats->total, stats->peers );
+}
+
 /**
  * Close multiplexed block download
  *
@@ -303,6 +356,8 @@ static void peermux_block_close ( struct peerdist_multiplexed_block *peermblk,
 
 /** Data transfer interface operations */
 static struct interface_operation peermux_xfer_operations[] = {
+	INTF_OP ( job_progress, struct peerdist_multiplexer *,
+		  peermux_progress ),
 	INTF_OP ( intf_close, struct peerdist_multiplexer *, peermux_close ),
 };
 
@@ -330,6 +385,8 @@ static struct interface_operation peermux_block_operations[] = {
 		  peermux_block_deliver ),
 	INTF_OP ( xfer_buffer, struct peerdist_multiplexed_block *,
 		  peermux_block_buffer ),
+	INTF_OP ( peerdisc_stat, struct peerdist_multiplexed_block *,
+		  peermux_block_stat ),
 	INTF_OP ( intf_close, struct peerdist_multiplexed_block *,
 		  peermux_block_close ),
 };