feat(socket): work without luasocket, using luasystem instead (#171)

All we need for the core scheduling tasks is:

-  a `sleep` function for a non-busy-loop wait
-  a `gettime` function to get actual time at usecond

So without using sockets, luasystem should be good enough. Removing LuaSocket from the rockspec is a breaking change, hence it is still installed by default. To be reviewed in a next major.

.github/workflows/unix_build.yml

@@ -37,6 +37,7 @@ jobs:
       run: |
         luarocks install luacov-coveralls
         luarocks install luasec
+        luarocks install luasystem
 
     - name: generate test certificates
       run: |

Makefile

@@ -50,6 +50,7 @@ test: certs
 	$(LUA) $(DELIM) $(PKGPATH) tests/largetransfer.lua
 	$(LUA) $(DELIM) $(PKGPATH) tests/lock.lua
 	$(LUA) $(DELIM) $(PKGPATH) tests/loop_starter.lua
+	$(LUA) $(DELIM) $(PKGPATH) tests/no_luasocket.lua
 	$(LUA) $(DELIM) $(PKGPATH) tests/pause.lua
 	$(LUA) $(DELIM) $(PKGPATH) tests/queue.lua
 	$(LUA) $(DELIM) $(PKGPATH) tests/removeserver.lua

docs/index.html

@@ -93,13 +93,19 @@ <h2><a name="download"></a>Download</h2>
 
 <h2><a name="dependencies"></a>Dependencies</h2>
 
-<p>Copas depends on
-LuaSocket, <a href="http://keplerproject.github.io/coxpcall/">Coxpcall</a> (only when using Lua 5.1), and (optionally) LuaSec.
-</p>
+<p>Copas depends on LuaSocket (or LuaSystem), <a href="http://keplerproject.github.io/coxpcall/">Coxpcall</a>
+(only when using Lua 5.1), and (optionally) LuaSec.</p>
 
 <h2><a name="history"></a>History</h2>
 
 <dl class="history">
+    <dt><strong>Copas 4.8.0</strong> unreleased</dt>
+	<dd><ul>
+        <li>Change: Copas no longer requires LuaSocket, if no sockets are needed, LuaSystem will be enough as a fallback.</li>
+        <li>Feat: added <code>copas.gettime()</code>, which transparently maps to either LuaSockets or
+        LuaSystems implementation, ensuring independence of the availability of either one of those.</li>
+    </ul></dd>
+
     <dt><strong>Copas 4.7.1</strong> [9/Mar/2024]</dt>
 	<dd><ul>
         <li>Fix: <code>copas.removethread</code> would not remove a sleeping thread immediately (it would not execute, but

docs/reference.html

@@ -210,6 +210,12 @@ <h3>Copas dispatcher main functions</h3>
         currently running coroutine.</p>
     </dd>
 
+    <dt><strong><code>number = copas.gettime()</code></strong></dt>
+    <dd>
+        <p>Returns the (fractional) number of seconds since the epoch. This directly
+        maps to either the LuaSocket or LuaSystem implementation of <code>gettime()</code>.</p>
+    </dd>
+
     <dt><strong><code>string = copas.gettraceback([msg], [co], [skt])</code></strong></dt>
     <dd>
         <p>Creates a traceback (string). Can be used from custom errorhandlers to create

src/copas.lua

@@ -20,14 +20,27 @@ if package.loaded["copas.http"] and (_VERSION=="Lua 5.1") then     -- obsolete:
   error("you must require copas before require'ing copas.http")
 end
 
+-- load either LuaSocket, or LuaSystem
+local socket, system do
+  if pcall(require, "socket") then
+    -- found LuaSocket
+    socket = require "socket"
+  else
+    -- fallback to LuaSystem
+    if pcall(require, "system") then
+      system = require "system"
+    else
+      error("Neither LuaSocket nor LuaSystem found, Copas requires at least one of them")
+    end
+  end
+end
 
-local socket = require "socket"
 local binaryheap = require "binaryheap"
-local gettime = socket.gettime
+local gettime = (socket or system).gettime
 local ssl -- only loaded upon demand
 
 local WATCH_DOG_TIMEOUT = 120
-local UDP_DATAGRAM_MAX = socket._DATAGRAMSIZE or 8192
+local UDP_DATAGRAM_MAX = (socket or {})._DATAGRAMSIZE or 8192
 local TIMEOUT_PRECISION = 0.1  -- 100ms
 local fnil = function() end
 
@@ -52,7 +65,7 @@ if _VERSION=="Lua 5.1" and not jit then     -- obsolete: only for Lua 5.1 compat
 end
 
 
-do
+if socket then
   -- Redefines LuaSocket functions with coroutine safe versions (pure Lua)
   -- (this allows the use of socket.http from within copas)
   local err_mt = {
@@ -126,6 +139,8 @@ copas.autoclose = true
 -- indicator for the loop running
 copas.running = false
 
+-- gettime method from either LuaSocket or LuaSystem: time in (fractional) seconds, since epoch.
+copas.gettime = gettime
 
 -------------------------------------------------------------------------------
 -- Object names, to track names of thread/coroutines and sockets
@@ -1355,6 +1370,7 @@ do
   local timeout_register = setmetatable({}, { __mode = "k" })
   local time_out_thread
   local timerwheel = require("timerwheel").new({
+      now = gettime,
       precision = TIMEOUT_PRECISION,
       ringsize = math.floor(60*60*24/TIMEOUT_PRECISION),  -- ring size 1 day
       err_handler = function(err)
@@ -1416,6 +1432,8 @@ end
 -- a task to check ready to read events
 local _readable_task = {} do
 
+  _readable_task._events = {}
+
   local function tick(skt)
     local handler = _servers[skt]
     if handler then
@@ -1439,6 +1457,8 @@ end
 -- a task to check ready to write events
 local _writable_task = {} do
 
+  _writable_task._events = {}
+
   local function tick(skt)
     _writing:remove(skt)
     _doTick(_writing:pop(skt), skt)
@@ -1502,59 +1522,65 @@ local _select_plain do
   local last_cleansing = 0
   local duration = function(t2, t1) return t2-t1 end
 
-  _select_plain = function(timeout)
-    local err
-    local now = gettime()
-
-    -- remove any closed sockets to prevent select from hanging on them
-    if _closed[1] then
-      for i, skt in ipairs(_closed) do
-        _closed[i] = { _reading:remove(skt), _writing:remove(skt) }
+  if not socket then
+    -- socket module unavailable, switch to luasystem sleep
+    _select_plain = system.sleep
+  else
+    -- use socket.select to handle socket-io
+    _select_plain = function(timeout)
+      local err
+      local now = gettime()
+
+      -- remove any closed sockets to prevent select from hanging on them
+      if _closed[1] then
+        for i, skt in ipairs(_closed) do
+          _closed[i] = { _reading:remove(skt), _writing:remove(skt) }
+        end
       end
-    end
 
-    _readable_task._events, _writable_task._events, err = socket.select(_reading, _writing, timeout)
-    local r_events, w_events = _readable_task._events, _writable_task._events
+      _readable_task._events, _writable_task._events, err = socket.select(_reading, _writing, timeout)
+      local r_events, w_events = _readable_task._events, _writable_task._events
 
-    -- inject closed sockets in readable/writeable task so they can error out properly
-    if _closed[1] then
-      for i, skts in ipairs(_closed) do
-        _closed[i] = nil
-        r_events[#r_events+1] = skts[1]
-        w_events[#w_events+1] = skts[2]
+      -- inject closed sockets in readable/writeable task so they can error out properly
+      if _closed[1] then
+        for i, skts in ipairs(_closed) do
+          _closed[i] = nil
+          r_events[#r_events+1] = skts[1]
+          w_events[#w_events+1] = skts[2]
+        end
       end
-    end
 
-    if duration(now, last_cleansing) > WATCH_DOG_TIMEOUT then
-      last_cleansing = now
-
-      -- Check all sockets selected for reading, and check how long they have been waiting
-      -- for data already, without select returning them as readable
-      for skt,time in pairs(_reading_log) do
-        if not r_events[skt] and duration(now, time) > WATCH_DOG_TIMEOUT then
-          -- This one timedout while waiting to become readable, so move
-          -- it in the readable list and try and read anyway, despite not
-          -- having been returned by select
-          _reading_log[skt] = nil
-          r_events[#r_events + 1] = skt
-          r_events[skt] = #r_events
+      if duration(now, last_cleansing) > WATCH_DOG_TIMEOUT then
+        last_cleansing = now
+
+        -- Check all sockets selected for reading, and check how long they have been waiting
+        -- for data already, without select returning them as readable
+        for skt,time in pairs(_reading_log) do
+          if not r_events[skt] and duration(now, time) > WATCH_DOG_TIMEOUT then
+            -- This one timedout while waiting to become readable, so move
+            -- it in the readable list and try and read anyway, despite not
+            -- having been returned by select
+            _reading_log[skt] = nil
+            r_events[#r_events + 1] = skt
+            r_events[skt] = #r_events
+          end
         end
-      end
 
-      -- Do the same for writing
-      for skt,time in pairs(_writing_log) do
-        if not w_events[skt] and duration(now, time) > WATCH_DOG_TIMEOUT then
-          _writing_log[skt] = nil
-          w_events[#w_events + 1] = skt
-          w_events[skt] = #w_events
+        -- Do the same for writing
+        for skt,time in pairs(_writing_log) do
+          if not w_events[skt] and duration(now, time) > WATCH_DOG_TIMEOUT then
+            _writing_log[skt] = nil
+            w_events[#w_events + 1] = skt
+            w_events[skt] = #w_events
+          end
         end
       end
-    end
 
-    if err == "timeout" and #r_events + #w_events > 0 then
-      return nil
-    else
-      return err
+      if err == "timeout" and #r_events + #w_events > 0 then
+        return nil
+      else
+        return err
+      end
     end
   end
 end

src/copas/lock.lua

@@ -1,5 +1,5 @@
 local copas = require("copas")
-local gettime = require("socket").gettime
+local gettime = copas.gettime
 
 local DEFAULT_TIMEOUT = 10
 

src/copas/queue.lua

@@ -1,5 +1,5 @@
 local copas = require "copas"
-local gettime = require("socket").gettime
+local gettime = copas.gettime
 local Sema = copas.semaphore
 local Lock = copas.lock
 

tests/close.lua

@@ -36,7 +36,7 @@ copas.loop(function()
       -- wait in the read/write queues
       copas.pause(2)
       -- now we're closing the connecting_socket
-      close_time = socket.gettime()
+      close_time = copas.gettime()
       print("closing client socket now, client receive and send operation should immediately error out now")
       client_socket:close()
 
@@ -55,7 +55,7 @@ copas.loop(function()
     copas.addthread(function()
       local data, err = client_socket:receive(1)
       print("receive result: ", tostring(data), tostring(err))
-      receive_end_time = socket.gettime()
+      receive_end_time = copas.gettime()
       print("receive took: ", receive_end_time - close_time)
       check_exit()
     end)
@@ -66,7 +66,7 @@ copas.loop(function()
         ok, err = client_socket:send(("hello world"):rep(100))
       end
       print("send result: ", tostring(ok), tostring(err))
-      send_end_time = socket.gettime()
+      send_end_time = copas.gettime()
       print("send took: ", send_end_time - close_time)
       check_exit()
     end)

tests/largetransfer.lua

@@ -12,7 +12,7 @@ local socket = require 'socket'
 -- copas.debug.start()
 
 local body = ("A"):rep(1024*1024*50) -- 50 mb string
-local start = socket.gettime()
+local start = copas.gettime()
 local done = 0
 local sparams, cparams
 
@@ -25,7 +25,7 @@ local function runtest()
       local res, err, part = skt:receive('*a')
       res = res or part
       if res ~= body then print("Received doesn't match send") end
-      print("Server reading port 49500... Done!", socket.gettime()-start, err, #res)
+      print("Server reading port 49500... Done!", copas.gettime()-start, err, #res)
       copas.removeserver(s1)
       done = done + 1
     end, sparams))
@@ -38,7 +38,7 @@ local function runtest()
       local res, err, part = skt:receive('*a')
       res = res or part
       if res ~= body then print("Received doesn't match send") end
-      print("Server reading port 49501... Done!", socket.gettime()-start, err, #res)
+      print("Server reading port 49501... Done!", copas.gettime()-start, err, #res)
       copas.removeserver(s2)
       done = done + 1
     end, sparams))
@@ -52,7 +52,7 @@ local function runtest()
       repeat
         last_byte_sent, err = skt:send(body, last_byte_sent or 1, -1)
       until last_byte_sent == nil or last_byte_sent == #body
-      print("Client writing port 49500... Done!", socket.gettime()-start, err, #body)
+      print("Client writing port 49500... Done!", copas.gettime()-start, err, #body)
       -- we're not closing the socket, so the Copas GC-when-idle can kick-in to clean up
       skt = nil -- luacheck: ignore
       done = done + 1
@@ -67,7 +67,7 @@ local function runtest()
       repeat
         last_byte_sent, err = skt:send(body, last_byte_sent or 1, -1)
       until last_byte_sent == nil or last_byte_sent == #body
-      print("Client writing port 49501... Done!", socket.gettime()-start, err, #body)
+      print("Client writing port 49501... Done!", copas.gettime()-start, err, #body)
       -- we're not closing the socket, so the Copas GC-when-idle can kick-in to clean up
       skt = nil -- luacheck: ignore
       done = done + 1
@@ -77,7 +77,7 @@ local function runtest()
       local i = 1
       while done ~= 4 do
         copas.pause(1)
-        print(i, "seconds:", socket.gettime()-start)
+        print(i, "seconds:", copas.gettime()-start)
         i = i + 1
         if i > 60 then
           print"timeout"
@@ -114,5 +114,5 @@ cparams = {
    options = {"all", "no_sslv2", "no_sslv3", "no_tlsv1"},
   }
 done = 0
-start = socket.gettime()
+start = copas.gettime()
 runtest()

tests/lock.lua

@@ -5,7 +5,7 @@ package.path = string.format("../src/?.lua;%s", package.path)
 
 local copas = require "copas"
 local Lock = copas.lock
-local gettime = require("socket").gettime
+local gettime = copas.gettime
 
 local test_complete = false
 copas.loop(function()

tests/no_luasocket.lua

@@ -0,0 +1,44 @@
+-- make sure we are pointing to the local copas first
+package.path = string.format("../src/?.lua;%s", package.path)
+
+print([[
+Testing to run Copas without LuaSocket, just LuaSystem
+=============================================================================
+]])
+
+-- patch require to no longer load luasocket
+local _require = require
+_G.require = function(name)
+  if name == "socket" then
+    error("luasocket is not allowed in this test")
+  end
+  return _require(name)
+end
+
+
+local copas = require "copas"
+local timer = copas.timer
+
+local successes = 0
+
+local t1 -- luacheck: ignore
+
+copas.loop(function()
+
+  t1 = timer.new({
+    delay = 0.1,
+    recurring = true,
+    callback = function(timer_obj, params)
+      successes = successes + 1  -- 6 to come
+      if successes == 6 then
+        timer_obj:cancel()
+      end
+    end,
+  })
+  -- succes count = 6
+
+end)
+
+
+assert(successes == 6, "number of successes didn't match! got: "..successes)
+print("test success!")