http_driver: add 504 binding timeouts

src/syndicate/drivers/http_driver.nim

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: Unlicense
 
 import std/[httpcore, options, parseutils, sets, streams, strutils, tables, times, uri]
-import preserves, ../../syndicate, ../bags
+import preserves, ../../syndicate, ../bags, ./timers
 import ../protocols/http
 import taps
 
@@ -114,7 +114,7 @@ proc lenLine(chunk: Chunk): string =
 type
   Driver = ref object
     facet: Facet
-    ds: Cap
+    ds, timers: Cap
     bindings: Bag[Value]
       # cannot make a bag of HttpBinding, no `==` operator
     sequenceNumber: BiggestInt
@@ -128,6 +128,7 @@ type
     req: HttpRequest
     stream: StringStream
     mode: HttpResponseKind
+    active: bool
 
 proc send[T: byte|char](ses: Session; data: openarray[T]) =
   ses.conn.send(addr data[0], data.len, endOfMessage = false)
@@ -187,6 +188,7 @@ method message(e: Exchange; turn: var Turn; a: AssertionRef) =
 
     of HttpResponseKind.status:
       if e.mode == res.orKind:
+        e.active = true
         e.ses.conn.startBatch()
         e.stream.write(
             SupportedVersion, " ", res.status.code, " ", res.status.message, CRLF,
@@ -239,10 +241,21 @@ proc service(turn: var Turn; exch: Exchange) =
     if handler.isNone:
       stop(turn)
     else:
-      publish(turn, handler.get, HttpContext(
+      let
+        cap =  newCap(turn, exch)
+        ctx = publish(turn, handler.get, HttpContext(
           req: exch.req,
-          res: embed newCap(turn, exch),
+          res: embed cap,
         ))
+      const timeout = initDuration(seconds = 4)
+      after(turn, exch.ses.driver.timers, timeout) do (turn: var Turn):
+        if not exch.active:
+          var res = HttpResponse(orKind: HttpResponseKind.status)
+          res.status.code = 504
+          res.status.message = "Binding timeout"
+          message(turn, cap, res)
+          res = HttpResponse(orKind: HttpResponseKind.done)
+          message(turn, cap, res)
 
 proc service(ses: Session) =
   ## Service a connection to an HTTP client.
@@ -302,7 +315,8 @@ proc httpListen(turn: var Turn; driver: Driver; port: Port): Listener =
   listener
 
 proc httpDriver(turn: var Turn; ds: Cap) =
-  let driver = Driver(facet: turn.facet, ds: ds)
+  let driver = Driver(facet: turn.facet, ds: ds, timers: turn.newDataspace)
+  spawnTimerDriver(turn, driver.timers)
 
   during(turn, ds, HttpBinding?:{
         1: grab(),