core.app 3.0: tick method, advanced app linking features

lib/luajit/.gitignore

@@ -9,3 +9,12 @@
 *.dmp
 *.swp
 .tags
+*.dwo
+/src/lj_bcdef.h
+/src/lj_ffdef.h
+/src/lj_folddef.h
+/src/lj_libdef.h
+/src/lj_recdef.h
+/src/lj_vm.S
+/src/raptorjit
+/src/host/buildvm_arch.h

src/README.md

@@ -55,7 +55,7 @@ these in a desired way using *links* and finally pass the resulting app
 network on to the Snabb engine. The engine's job is to:
 
  * Pump traffic through the app network
- * Keep the app network running (e.g. restart failed apps)
+ * Apply, and inform apps of configuration and link changes
  * Report on the network status
 
 
@@ -117,11 +117,24 @@ will be used to validate the app’s arg when it is configured using
 `config.app`.
 
 
-— Method **myapp:link**
+— Method **myapp:link** *dir* *name*
 
-*Optional*. Called any time the app’s links may have been changed (including on
-start-up). Guaranteed to be called before `pull` and `push` are called with new
-links.
+*Optional*. Called during `engine.configure()` when a link of the app is
+added. Unless `unlink` is specified this method is also called when a link
+is removed.
+Guaranteed to be called before `pull` and `push` are called with new links. 
+
+*Dir* is either `'input'` or `'output'`, and *name* is the string name
+of the link. I.e., the added link can be accessed at `self[dir][name]`.
+
+
+— Method **myapp:unlink** *dir* *name*
+
+*Optional*. Called during `engine.configure()` when a link of the app is
+removed.
+
+*Dir* is either `'input'` or `'output'`, and *name* is the string name
+of the link.
 
 
 — Method **myapp:pull**
@@ -139,6 +152,53 @@ transmitting them to output ports.
 For example: Move packets from input ports to output ports or to a
 network adapter.
 
+— Field **myapp.push_link**
+
+*Optional*. When specified must be a table of per-link `push()` methods
+that take an input link as an argument. For example an app could specify
+a **push_link** method for its input link *foo*:
+
+```
+Myapp = { push_link={} }
+function Myapp.push_link:foo (input)
+  while not link.empty(input) do something() end
+end
+```
+
+**Push_link** methods are copied to a fresh table when the app is started,
+and it is valid to create **push_link** methods dynamically during `link()`,
+for example like so:
+
+```
+Myapp = { push_link={} }
+function Myapp:link (dir, name)
+  -- NB: Myapp.push_link ~= self.push_link
+  if dir == 'input' then
+    self.push_link[name] = function (self, input)
+      while not link.empty(input) do something() end
+    end
+  end
+end
+function Myapp:unlink (dir, name)
+  if dir == 'input' then
+    self.push_link[name] = nil
+  end
+end
+```
+
+**Push** is not called when an app has **push_link** methods
+for *all* of its input links. If, however, an app at least one input link
+without an associated **push_link** method then **push** is called
+in addition to the **push_link** methods.
+
+
+— Method **myapp:tick**
+
+*Optional*. Called periodically at **engine.tick_Hz** frequency.
+
+For example: Move packets from input ports to output ports or to a
+network adapter.
+
 
 — Method **myapp:reconfig** *arg*
 
@@ -285,6 +345,13 @@ how many times per second to poll.
 
 This setting is not used when engine.busywait is true.
 
+— Variable **engine.tick_Hz**
+
+Frequency at which to call **app:tick** methods. The default value is
+1000 (call `tick()`s every millisecond).
+
+A value of 0 effectively disables `tick()` methods.
+
 ## Link (core.link)
 
 A *link* is a [ring buffer](http://en.wikipedia.org/wiki/Circular_buffer)

src/apps/lwaftr/V4V6.lua

@@ -193,17 +193,19 @@ local function test_join ()
    config.app(c, 'v4v6', V4V6)
    config.app(c, 'sink', basic_apps.Sink)
 
-   config.link(c, 'source.output -> v4v6.v4')
-   config.link(c, 'source.output -> v4v6.v6')
+   config.link(c, 'source.v4 -> v4v6.v4')
+   config.link(c, 'source.v6 -> v4v6.v6')
    config.link(c, 'v4v6.output -> sink.input')
 
    engine.configure(c)
-   link.transmit(engine.app_table.source.output.output, arp_pkt())
-   link.transmit(engine.app_table.source.output.output, ipv4_pkt())
-   link.transmit(engine.app_table.source.output.output, ipv6_pkt())
+   for _, output in ipairs{'v4', 'v6'} do
+      link.transmit(engine.app_table.source.output[output], arp_pkt())
+      link.transmit(engine.app_table.source.output[output], ipv4_pkt())
+      link.transmit(engine.app_table.source.output[output], ipv6_pkt())
+   end
    engine.main({duration = 0.1, noreport = true})
 
-   assert(link.stats(engine.app_table.sink.input.input).rxpackets == 3)
+   assert(link.stats(engine.app_table.sink.input.input).rxpackets == 3*2)
 end
 
 function selftest ()

src/apps/packet_filter/pcap_filter.lua

@@ -135,8 +135,7 @@ function selftest_run (stateful, expected, tolerance, native)
 
    print(("Run for 1 second (stateful = %s)..."):format(stateful))
 
-   local deadline = lib.timeout(1.0)
-   repeat app.breathe() until deadline()
+   app.main{duration=1}
 
    app.report({showlinks=true})
    local sent     = link.stats(app.app_table.pcap_filter.input.input).rxpackets

src/apps/pcap/tap.lua

@@ -67,7 +67,7 @@ function selftest ()
       config.link(c, "source.output -> tap.input")
       config.link(c, "tap.output -> sink.input")
       app.configure(c)
-      while not app.app_table.source.done do app.breathe() end
+      app.main{done=function () return app.app_table.source.done end}
 
       local n = 0
       for packet, record in pcap.records(tmp) do n = n + 1 end

src/apps/rate_limiter/rate_limiter.lua

@@ -148,11 +148,7 @@ function selftest ()
       local snapshot = rl:get_stat_snapshot()
 
       -- push some packets through it
-      while seconds_to_run > 0 do
-         app.breathe()
-         timer.run()
-         C.usleep(10) -- avoid busy loop
-      end
+      app.main{duration=seconds_to_run}
       -- print final report
       app.report()
 
@@ -194,10 +190,7 @@ function selftest ()
       rl:reset(rate_busy_loop, bucket_size)
 
       local snapshot = rl:get_stat_snapshot()
-      for i = 1, 100000 do
-         app.breathe()
-         timer.run()
-      end
+      app.main{duration=0.1}
       local elapsed_time =
          (tonumber(C.get_time_ns()) - snapshot.time) / 1e9
       print("elapsed time ", elapsed_time, "seconds")

src/apps/test/match.lua

@@ -84,14 +84,16 @@ function selftest()
    engine.main({duration=0.0001})
    assert(#engine.app_table.sink:errors() > 0)
 
-   engine.configure(config.new())
+   local c = config.new()
    config.app(c, "sink", Match, {fuzzy=true})
+   config.app(c, "src", basic_apps.Source, 8)
    config.app(c, "comparator", basic_apps.Source, 8)
    config.app(c, "garbage", basic_apps.Source, 12)
    config.app(c, "join", basic_apps.Join)
    config.link(c, "src.output -> join.src")
    config.link(c, "garbage.output -> join.garbage")
    config.link(c, "join.output -> sink.rx")
+   config.link(c, "comparator.output -> sink.comparator")
    engine.configure(c)
    engine.main({duration=0.0001})
    assert(#engine.app_table.sink:errors() == 0)