From cce7cf2c1428d174dd49177358dc52b234e97e5c Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Mon, 22 Dec 2014 15:51:30 +0100
Subject: [SERVER] Configurable client timeout, adaptive replication speed (to
 be tested against varying bw/latency), retry sendfile call if ret <= len

---
 src/server/uplink.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

(limited to 'src/server/uplink.c')

diff --git a/src/server/uplink.c b/src/server/uplink.c
index 0a60ff1..6c604c1 100644
--- a/src/server/uplink.c
+++ b/src/server/uplink.c
@@ -55,6 +55,7 @@ int uplink_init(dnbd3_image_t *image, int sock, dnbd3_host_t *host)
 	link->queueLen = 0;
 	link->fd = -1;
 	link->signal = -1;
+	link->replicationHandle = 0;
 	if ( sock >= 0 ) {
 		link->betterFd = sock;
 		link->betterServer = *host;
@@ -250,10 +251,11 @@ static void* uplink_mainloop(void *data)
 			if ( link->image->crc32 == NULL ) {
 				uplink_addCrc32( link );
 			}
-			// Re-send all pending requests
-			uplink_send_requests( link, FALSE );
 			link->betterFd = -1;
 			link->currentServer = link->betterServer;
+			link->replicationHandle = 0;
+			// Re-send all pending requests
+			uplink_send_requests( link, FALSE );
 			link->image->working = TRUE;
 			buffer[0] = '@';
 			if ( host_to_string( &link->currentServer, buffer + 1, sizeof(buffer) - 1 ) ) {
@@ -331,8 +333,6 @@ static void* uplink_mainloop(void *data)
 			}
 		}
 		// Done handling epoll sockets
-		// Replicate missing blocks from the image so the proxy will eventually have a full copy
-		uplink_sendReplicationRequest( link );
 		// See if we should trigger an RTT measurement
 		if ( link->rttTestResult == RTT_IDLE || link->rttTestResult == RTT_DONTCHANGE ) {
 			const time_t now = time( NULL );
@@ -373,6 +373,7 @@ static void* uplink_mainloop(void *data)
 		}
 #ifdef _DEBUG
 		if ( link->fd != -1 && !link->shutdown ) {
+			int resend = FALSE;
 			time_t deadline = time( NULL ) - 10;
 			spin_lock( &link->queueLock );
 			for (i = 0; i < link->queueLen; ++i) {
@@ -381,12 +382,15 @@ static void* uplink_mainloop(void *data)
 							"%s\n(from %" PRIu64 " to %" PRIu64 ", status: %d)\n", link->queue[i].client->image->lower_name,
 							link->queue[i].from, link->queue[i].to, link->queue[i].status );
 					link->queue[i].status = ULR_NEW;
+					resend = TRUE;
 					spin_unlock( &link->queueLock );
 					printf("%s", buffer);
 					spin_lock( &link->queueLock );
 				}
 			}
 			spin_unlock( &link->queueLock );
+			if ( resend )
+				uplink_send_requests( link,  TRUE );
 		}
 #endif
 	}
@@ -458,27 +462,24 @@ static void uplink_sendReplicationRequest(dnbd3_connection_t *link)
 	if ( link == NULL || link->fd == -1 ) return;
 	dnbd3_image_t * const image = link->image;
 	if ( image == NULL || image->cache_map == NULL || image->filesize < DNBD3_BLOCK_SIZE ) return;
-	const time_t now = time( NULL );
-	if ( now <= link->lastReplication + 1 ) return;
-	link->lastReplication = now;
 	spin_lock( &image->lock );
-	if ( image == NULL || image->cache_map == NULL ) {
+	if ( image == NULL || image->cache_map == NULL || link->replicationHandle != 0 ) {
 		spin_unlock( &image->lock );
 		return;
 	}
 	dnbd3_request_t request;
 	request.magic = dnbd3_packet_magic;
-	int sent = 0;
 	const size_t len = IMGSIZE_TO_MAPBYTES( image->filesize ) - 1;
 	for (int i = 0; i <= len; ++i) {
-		if ( image->cache_map == NULL || link->fd == -1 || sent > 20 ) break;
+		if ( image->cache_map == NULL || link->fd == -1 ) break;
 		if ( image->cache_map[i] == 0xff || (i == len && link->replicatedLastBlock) ) continue;
 		if ( i == len ) link->replicatedLastBlock = TRUE;
+		link->replicationHandle = 1; // Prevent race condition
 		spin_unlock( &image->lock );
 		// Unlocked - do not break or continue here...
-		++sent;
 		request.cmd = CMD_GET_BLOCK;
-		request.offset = request.handle = (uint64_t)i * DNBD3_BLOCK_SIZE * (uint64_t)8;
+		// Needs to be 8 (bit->byte, bitmap)
+		link->replicationHandle = request.offset = request.handle = (uint64_t)i * DNBD3_BLOCK_SIZE * (uint64_t)8;
 		request.size = DNBD3_BLOCK_SIZE * (uint64_t)8;
 		if ( request.offset + request.size > image->filesize ) {
 			request.size = image->filesize - request.offset;
@@ -489,10 +490,10 @@ static void uplink_sendReplicationRequest(dnbd3_connection_t *link)
 			printf( "[DEBUG] Error sending background replication request to uplink server!\n" );
 			return;
 		}
-		// Lock again...
-		spin_lock( &image->lock );
+		return; // Request was sent, bail out, nothing is locked
 	}
 	spin_unlock( &image->lock );
+	// Replication might be complete, uplink_mainloop should take care....
 }
 
 /**
@@ -592,15 +593,21 @@ static void uplink_handle_receive(dnbd3_connection_t *link)
 			writev( client->sock, iov, 2 );
 			pthread_mutex_unlock( &client->sendMutex );
 			spin_lock( &link->queueLock );
-			if ( i > 20 && i == link->queueLen - 1 ) link->queueLen--;
+			if ( i == link->queueLen - 1 ) link->queueLen--;
 		}
 		spin_unlock( &link->queueLock );
+		if ( start == link->replicationHandle ) link->replicationHandle = 0;
+	}
+	if ( link->queueLen == 0 ) {
+		uplink_sendReplicationRequest( link );
 	}
 	error_cleanup: ;
 	altservers_serverFailed( &link->currentServer );
 	const int fd = link->fd;
 	link->fd = -1;
+	link->replicationHandle = 0;
 	if ( fd != -1 ) close( fd );
+	altservers_findUplink( link ); // Can we just call it here?
 }
 
 /**
-- 
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