fix(autoclose) only auto-close accepted connections

Only if a connection originates from accepting a connection request
on a server socket it will be auto-closed.

docs/index.html

@@ -103,8 +103,14 @@ <h2><a name="history"></a>History</h2>
     <dt><strong>Copas x.x.x</strong> [unreleased]</dt>
 	<dd><ul>
         <li>Fixed: yielding to the Copas scheduler from user-code now throws a proper error and
-        no longer breaks the loop. Breaking the loop could also happen if a thread terminated with
-        at leaast 2 return values.</li>
+        no longer breaks the loop. Breaking the loop could also happen if a thread returned with
+        at least 2 return values.</li>
+        <li>Fixed: wrongly auto-closing sockets. Upon exiting a coroutine, sockets would be automatically
+        closed. This should only be the case for accepted TCP connections on a TCP server socket. This caused issues
+        for sockets shared between threads.<br />
+        [breaking]: this changes behavior, auto-close is now determined when accepting the connection, and no longer when
+        terminating the handler thread. This will only affect users that dynamically change <code>copas.autoclose</code>
+        at runtime.</li>
         <li>Added: added <code>sempahore:destroy()</code></li>
         <li>Added: <code>copas.settimeouts</code>, to set separate timeouts for connect, send, receive</li>
         <li>Added: queue class, see module "copas.queue"</li>

docs/reference.html

@@ -157,7 +157,8 @@ <h3>Copas dispatcher main functions</h3>
     </dd>
 
     <dt><strong><code>copas.autoclose</code></strong></dt>
-    <dd>Constant that controls whether sockets are automatically closed.<br />
+    <dd>Constant that controls whether sockets are automatically closed. This only applies
+        to incoming connections accepted on a TCP server socket.<br />
         When a TCP handler function completes and terminates, then the client
         socket will be automatically closed when <code>copas.autoclose</code> is
         truthy.

src/copas.lua

@@ -267,6 +267,9 @@ end   -- _sleeping
 local _servers = newsocketset() -- servers being handled
 local _threads = setmetatable({}, {__mode = "k"})  -- registered threads added with addthread()
 local _canceled = setmetatable({}, {__mode = "k"}) -- threads that are canceled and pending removal
+local _autoclose = setmetatable({}, {__mode = "kv"}) -- sockets (value) to close when a thread (key) exits
+local _autoclose_r = setmetatable({}, {__mode = "kv"}) -- reverse: sockets (key) to close when a thread (value) exits
+
 
 -- for each socket we log the last read and last write times to enable the
 -- watchdog to follow up if it takes too long.
@@ -681,6 +684,14 @@ local function ssl_wrap(skt, wrap_params)
   copas.settimeouts(nskt, user_timeouts_connect[skt],
     user_timeouts_send[skt], user_timeouts_receive[skt]) -- copy copas user-timeout to newly wrapped one
 
+  local co = _autoclose_r[skt]
+  if co then
+    -- socket registered for autoclose, move registration to wrapped one
+    _autoclose[co] = nskt
+    _autoclose_r[skt] = nil
+    _autoclose_r[nskt] = co
+  end
+
   local sock_name = object_names[skt]
   if sock_name ~= tostring(skt) then
     -- socket had a custom name, so copy it over
@@ -1012,9 +1023,13 @@ local function _doTick (co, skt, ...)
     pcall(_errhandlers[co] or _deferror, res, co, skt)
   end
 
-  if skt and copas.autoclose and isTCP(skt) then
-    skt:close() -- do not auto-close UDP sockets, as the handler socket is also the server socket
+  local skt_to_close = _autoclose[co]
+  if skt_to_close then
+    skt_to_close:close()
+    _autoclose[co] = nil
+    _autoclose_r[skt_to_close] = nil
   end
+
   _errhandlers[co] = nil
 end
 
@@ -1036,6 +1051,12 @@ local _accept do
 
       local co = coroutine_create(handler)
       object_names[co] = object_names[server_skt] .. ":handler_" .. count
+
+      if copas.autoclose then
+        _autoclose[co] = client_skt
+        _autoclose_r[client_skt] = co
+      end
+
       _doTick(co, client_skt)
     end
   end