From 5de6f3a621d11512a05429752cd6b0f1a9f232f8 Mon Sep 17 00:00:00 2001
From: Julien Desfossez <jdesfossez@efficios.com>
Date: Tue, 18 Nov 2014 10:27:42 -0500
Subject: [LTTNG-TOOLS PATCH 1/2] Test: implement a command to detach a viewer
 session

The LTTNG_VIEWER_DETACH_SESSION command allows the viewer to detach from
the session it is currently attached to without requiring it to close
the network connection.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
---
 src/bin/lttng-relayd/live.c             | 73 +++++++++++++++++++++++++++++++++
 src/bin/lttng-relayd/lttng-viewer-abi.h | 18 ++++++++
 2 files changed, 91 insertions(+)

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index 2940b2c..0b7ba88 100644
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -1752,6 +1752,76 @@ end:
 	return ret;
 }
 
+/*
+ * Detach a viewer session.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static
+int viewer_detach_session(struct relay_connection *conn)
+{
+	int ret, found;
+	struct lttng_viewer_detach_session_response resp;
+	struct lttng_viewer_detach_session_request request;
+	struct relay_session *session, *tmp_session;
+	uint64_t to_close;
+
+	DBG("Viewer detach session received");
+
+	assert(conn);
+
+	health_code_update();
+
+	/* Receive the request from the connected client. */
+	ret = recv_request(conn->sock, &request, sizeof(request));
+	if (ret < 0) {
+		goto end;
+	}
+	to_close = be64toh(request.session_id);
+
+	if (!conn->viewer_session) {
+		resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_ERR);
+		goto send_reply;
+	}
+
+	health_code_update();
+
+	memset(&resp, 0, sizeof(resp));
+	DBG("Cleaning connection of session ID %" PRIu64, to_close);
+
+	found = 0;
+	rcu_read_lock();
+	cds_list_for_each_entry_safe(session, tmp_session,
+			&conn->viewer_session->sessions_head,
+			viewer_session_list) {
+		if (session->id == to_close) {
+			DBG("Cleaning connection of session ID %" PRIu64, session->id);
+			cleanup_session(conn, session);
+			found = 1;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	if (!found) {
+		resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_ERR);
+	} else {
+		resp.status = htobe32(LTTNG_VIEWER_DETACH_SESSION_OK);
+	}
+
+send_reply:
+	health_code_update();
+	ret = send_response(conn->sock, &resp, sizeof(resp));
+	if (ret < 0) {
+		goto end;
+	}
+	health_code_update();
+	ret = 0;
+
+end:
+	return ret;
+}
+
 
 /*
  * live_relay_unknown_command: send -1 if received unknown command
@@ -1816,6 +1886,9 @@ int process_control(struct lttng_viewer_cmd *recv_hdr,
 	case LTTNG_VIEWER_CREATE_SESSION:
 		ret = viewer_create_session(conn);
 		break;
+	case LTTNG_VIEWER_DETACH_SESSION:
+		ret = viewer_detach_session(conn);
+		break;
 	default:
 		ERR("Received unknown viewer command (%u)", be32toh(recv_hdr->cmd));
 		live_relay_unknown_command(conn);
diff --git a/src/bin/lttng-relayd/lttng-viewer-abi.h b/src/bin/lttng-relayd/lttng-viewer-abi.h
index f9bce98..9b4bc1a 100644
--- a/src/bin/lttng-relayd/lttng-viewer-abi.h
+++ b/src/bin/lttng-relayd/lttng-viewer-abi.h
@@ -48,6 +48,7 @@ enum lttng_viewer_command {
 	LTTNG_VIEWER_GET_METADATA	= 6,
 	LTTNG_VIEWER_GET_NEW_STREAMS	= 7,
 	LTTNG_VIEWER_CREATE_SESSION	= 8,
+	LTTNG_VIEWER_DETACH_SESSION	= 9,
 };
 
 enum lttng_viewer_attach_return_code {
@@ -105,6 +106,11 @@ enum lttng_viewer_create_session_return_code {
 	LTTNG_VIEWER_CREATE_SESSION_ERR		= 2,
 };
 
+enum lttng_viewer_detach_session_return_code {
+	LTTNG_VIEWER_DETACH_SESSION_OK		= 1,
+	LTTNG_VIEWER_DETACH_SESSION_ERR		= 2,
+};
+
 struct lttng_viewer_session {
 	uint64_t id;
 	uint32_t live_timer;
@@ -232,4 +238,16 @@ struct lttng_viewer_create_session_response {
 	uint32_t status;
 } __attribute__((__packed__));
 
+/*
+ * LTTNG_VIEWER_DETACH_SESSION payload.
+ */
+struct lttng_viewer_detach_session_request {
+	uint64_t session_id;
+} __attribute__((__packed__));
+
+struct lttng_viewer_detach_session_response {
+	/* enum lttng_viewer_detach_session_return_code */
+	uint32_t status;
+} __attribute__((__packed__));
+
 #endif /* LTTNG_VIEWER_ABI_H */
-- 
1.9.1