Fix gh-1904: Issues in old net.box under scrunity

 * :close() didn't stop reconnect activity;
 * cancelling a fiber in the ceratin request stage leads to
   deadlock in subsequent :close().

src/box/lua/net_box.lua

@@ -598,7 +598,9 @@ local remote_methods = {
         for _, fid in pairs(list) do
             if fid ~= fiber.id() then
                 if self.ch.fid[fid] ~= nil then
-                    self.ch.fid[fid]:put(true)
+                    -- timeout=0 prevents deadlock if a client went away
+                    -- without removing the channel
+                    self.ch.fid[fid]:put(true, 0)
                     self.ch.fid[fid] = nil
                 end
             end
@@ -640,6 +642,9 @@ local remote_methods = {
                     return
                 end
                 fiber.sleep(self.opts.reconnect_after)
+                if self.state == 'closed' then
+                    return
+                end
             end
 
             self:_switch_state('connecting')

test/box/net.box.result

@@ -1016,6 +1016,23 @@ c.space.test:select{}
 box.space.test:drop()
 ---
 ...
+-- gh-1904 net.box hangs in :close() if a fiber was cancelled
+-- while blocked in :_wait_state() in :_request()
+options = {user = 'netbox', password = 'badpass', wait_connected = false, reconnect_after = 0.01}
+---
+...
+c = net:new(box.cfg.listen, options)
+---
+...
+f = fiber.create(function() c:call("") end)
+---
+...
+fiber.sleep(0.1)
+---
+...
+f:cancel(); c:close()
+---
+...
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
 ---
 ...

test/box/net.box.test.lua

@@ -399,5 +399,13 @@ c.space.test:upsert({2, 4, 'nothing'}, {{'+', 3, 100500}}) -- wrong operation
 c.space.test:select{}
 box.space.test:drop()
 
+-- gh-1904 net.box hangs in :close() if a fiber was cancelled
+-- while blocked in :_wait_state() in :_request()
+options = {user = 'netbox', password = 'badpass', wait_connected = false, reconnect_after = 0.01}
+c = net:new(box.cfg.listen, options)
+f = fiber.create(function() c:call("") end)
+fiber.sleep(0.1)
+f:cancel(); c:close()
+
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
 test_run:cmd("clear filter")