[sheepdog] [PATCH 1/4] sheep: don't send unnecessary data against read requests

[MORITA Kazutaka]

This will save network traffic.

Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
---
 sheep/gateway.c |   11 ++++++++---
 sheep/ops.c     |   17 ++++++++++++-----
 sheep/request.c |    2 ++
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/sheep/gateway.c b/sheep/gateway.c
index 3e8e673..2ed53d4 100644
--- a/sheep/gateway.c
+++ b/sheep/gateway.c
@@ -32,8 +32,10 @@ int gateway_read_obj(struct request *req)
 	uint64_t oid = req->rq.obj.oid;
 	int nr_copies, j;
 
-	if (is_object_cache_enabled() && !req->local && !bypass_object_cache(req))
-		return object_cache_handle_request(req);
+	if (is_object_cache_enabled() && !req->local && !bypass_object_cache(req)) {
+		ret = object_cache_handle_request(req);
+		goto out;
+	}
 
 	nr_copies = get_req_copy_number(req);
 	oid_to_vnodes(req->vinfo->vnodes, req->vinfo->nr_vnodes, oid,
@@ -44,7 +46,7 @@ int gateway_read_obj(struct request *req)
 			continue;
 		ret = peer_read_obj(req);
 		if (ret == SD_RES_SUCCESS)
-			return ret;
+			goto out;
 
 		eprintf("local read fail %x\n", ret);
 		break;
@@ -95,6 +97,9 @@ int gateway_read_obj(struct request *req)
 			sheep_put_sockfd(&v->nid, sfd);
 		}
 	}
+out:
+	if (ret != SD_RES_SUCCESS)
+		req->rp.data_length = 0;
 	return ret;
 }
 
diff --git a/sheep/ops.c b/sheep/ops.c
index 4c0426f..472fb00 100644
--- a/sheep/ops.c
+++ b/sheep/ops.c
@@ -401,8 +401,9 @@ static int local_get_store_list(struct request *req)
 		strbuf_addf(&buf, "%s ", driver->name);
 	}
 	strbuf_copyout(&buf, req->data, req->data_length);
-
 	strbuf_release(&buf);
+
+	req->rp.data_length = strlen(req->data) + 1;
 	return SD_RES_SUCCESS;
 }
 
@@ -676,12 +677,16 @@ static int local_get_snap_file(struct request *req)
 	int ret;
 	struct siocb iocb = { .buf = req->data };
 
-	if (sd_store->get_snap_file) {
+	if (sd_store->get_snap_file)
 		ret = sd_store->get_snap_file(&iocb);
-		req->rp.data_length = iocb.length;
-	} else
+	else
 		ret = SD_RES_NO_SUPPORT;
 
+	if (ret == SD_RES_SUCCESS)
+		req->rp.data_length = iocb.length;
+	else
+		req->rp.data_length = 0;
+
 	return ret;
 }
 
@@ -731,8 +736,10 @@ static int local_trace_read_buf(struct request *request)
 	int ret;
 
 	ret = trace_buffer_pop(request->data, req->data_length);
-	if (ret == -1)
+	if (ret == -1) {
+		rsp->data_length = 0;
 		return SD_RES_AGAIN;
+	}
 
 	rsp->data_length = ret;
 	dprintf("%u\n", rsp->data_length);
diff --git a/sheep/request.c b/sheep/request.c
index ae12bd3..40a49fc 100644
--- a/sheep/request.c
+++ b/sheep/request.c
@@ -123,6 +123,7 @@ static int check_request_epoch(struct request *req)
 		/* ask gateway to retry. */
 		req->rp.result = SD_RES_OLD_NODE_VER;
 		req->rp.epoch = sys->epoch;
+		req->rp.data_length = 0;
 		put_request(req);
 		return -1;
 	} else if (after(req->rq.epoch, sys->epoch)) {
@@ -394,6 +395,7 @@ static void queue_request(struct request *req)
 
 	return;
 done:
+	rsp->data_length = 0;
 	put_request(req);
 }
 
-- 
1.7.2.5