[PATCH v2 4/4] session: outdate a session of a closed connection

[Vladislav Shpilevoy]

Once a connection is closed, a long-running user
request can not learn about this occasion. Even
box.sesion.push() still works.

This patch makes such disconnected session 'rotten'.
So a user can determine if a connection is closed by
looking at session.fd() == -1, or checking for
errors from box.session.push().

Closes #3859
---
 src/box/iproto.cc      | 27 ++++++++++++++++++++---
 test/box/push.result   | 50 ++++++++++++++++++++++++++++++++++++++++++
 test/box/push.test.lua | 22 +++++++++++++++++++
 3 files changed, 96 insertions(+), 3 deletions(-)

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index e6eefc3d8..8fddc76ef 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -1239,14 +1239,35 @@ tx_fiber_init(struct session *session, uint64_t sync)
 	fiber_set_user(f, &session->credentials);
 }
 
+static int
+iproto_disconnected_session_push(struct session *session, uint64_t sync,
+				 struct port *port)
+{
+	(void) session;
+	(void) sync;
+	(void) port;
+	diag_set(ClientError, ER_NO_CONNECTION);
+	return -1;
+}
+
+static const struct session_vtab iproto_disconnected_session_vtab = {
+	/* .push = */ iproto_disconnected_session_push,
+	/* .fd = */ generic_session_fd,
+	/* .sync = */ generic_session_sync,
+};
+
 static void
 tx_process_disconnect(struct cmsg *m)
 {
 	struct iproto_connection *con =
 		container_of(m, struct iproto_connection, disconnect_msg);
-	if (con->session != NULL && !rlist_empty(&session_on_disconnect)) {
-		tx_fiber_init(con->session, 0);
-		session_run_on_disconnect_triggers(con->session);
+	if (con->session != NULL) {
+		session_set_type(con->session, SESSION_TYPE_BINARY,
+				 &iproto_disconnected_session_vtab);
+		if (! rlist_empty(&session_on_disconnect)) {
+			tx_fiber_init(con->session, 0);
+			session_run_on_disconnect_triggers(con->session);
+		}
 	}
 }
 
diff --git a/test/box/push.result b/test/box/push.result
index af730c1a7..6f858f38a 100644
--- a/test/box/push.result
+++ b/test/box/push.result
@@ -497,6 +497,56 @@ box.schema.func.drop('do_pushes')
 s:drop()
 ---
 ...
+--
+-- gh-3859: box.session.push() succeeds even after the connection
+-- is closed.
+--
+chan_push = fiber.channel()
+---
+...
+chan_disconnected = fiber.channel()
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function do_long_and_push()
+    box.session.on_disconnect(function() chan_disconnected:put(true) end)
+    chan_push:get()
+    ok, err = box.session.push(100)
+    chan_push:put(err)
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+box.schema.func.create('do_long_and_push')
+---
+...
+box.schema.user.grant('guest', 'execute', 'function', 'do_long_and_push')
+---
+...
+f = fiber.create(function() c:call('do_long_and_push') end)
+---
+...
 c:close()
 ---
 ...
+chan_disconnected:get()
+---
+- true
+...
+chan_push:put(true)
+---
+- true
+...
+chan_push:get()
+---
+- Connection is not established
+...
+box.schema.func.drop('do_long_and_push')
+---
+...
diff --git a/test/box/push.test.lua b/test/box/push.test.lua
index 893cf0153..514c08b3e 100644
--- a/test/box/push.test.lua
+++ b/test/box/push.test.lua
@@ -237,4 +237,26 @@ keys
 box.schema.func.drop('do_push_and_duplicate')
 box.schema.func.drop('do_pushes')
 s:drop()
+
+--
+-- gh-3859: box.session.push() succeeds even after the connection
+-- is closed.
+--
+chan_push = fiber.channel()
+chan_disconnected = fiber.channel()
+test_run:cmd("setopt delimiter ';'")
+function do_long_and_push()
+    box.session.on_disconnect(function() chan_disconnected:put(true) end)
+    chan_push:get()
+    ok, err = box.session.push(100)
+    chan_push:put(err)
+end;
+test_run:cmd("setopt delimiter ''");
+box.schema.func.create('do_long_and_push')
+box.schema.user.grant('guest', 'execute', 'function', 'do_long_and_push')
+f = fiber.create(function() c:call('do_long_and_push') end)
 c:close()
+chan_disconnected:get()
+chan_push:put(true)
+chan_push:get()
+box.schema.func.drop('do_long_and_push')
-- 
2.17.2 (Apple Git-113)