Add support for container messages. (#1822)

Co-authored-by: Kasper Lund <[email protected]>

lib/system/api/containers.toit

@@ -39,6 +39,9 @@ interface ContainerService:
   image-writer-commit handle/int flags/int data/int -> uuid.Uuid
   static IMAGE-WRITER-COMMIT-INDEX /int ::= 5
 
+  notify-background-state-changed new-state/any -> none
+  static NOTIFY-BACKGROUND-STATE-CHANGED-INDEX /int ::= 8
+
 class ContainerServiceClient extends ServiceClient implements ContainerService:
   static SELECTOR ::= ContainerService.SELECTOR
   constructor selector/ServiceSelector=SELECTOR:
@@ -75,3 +78,6 @@ class ContainerServiceClient extends ServiceClient implements ContainerService:
 
   image-writer-commit handle/int flags/int data/int -> uuid.Uuid:
     return uuid.Uuid (invoke_ ContainerService.IMAGE-WRITER-COMMIT-INDEX [handle, flags, data])
+
+  notify-background-state-changed new-state/bool -> none:
+    invoke_ ContainerService.NOTIFY-BACKGROUND-STATE-CHANGED-INDEX new-state

lib/system/containers.toit

@@ -43,6 +43,10 @@ start id/uuid.Uuid arguments/any=[] -> Container:
 uninstall id/uuid.Uuid -> none:
   _client_.uninstall-image id
 
+/** Notifies the system about a background-state change. */
+notify-background-state-changed new-state/bool -> none:
+  _client_.notify-background-state-changed new-state
+
 class ContainerImage:
   id/uuid.Uuid
   name/string?
@@ -51,6 +55,8 @@ class ContainerImage:
   constructor --.id --.name --.flags --.data:
 
 class Container extends ServiceResourceProxy:
+  static EVENT-BACKGROUND-STATE-CHANGE ::= 0
+
   // TODO(kasper): Rename this and document it.
   id/uuid.Uuid
 
@@ -70,6 +76,7 @@ class Container extends ServiceResourceProxy:
 
   result_/monitor.Latch ::= monitor.Latch
   on-stopped_/Lambda? := null
+  on-event_/Lambda? := null
 
   constructor.internal_ --handle/int --.id --.gid:
     super _client_ handle
@@ -101,14 +108,30 @@ class Container extends ServiceResourceProxy:
     else:
       on-stopped_ = lambda
 
-  on-notified_ code/int -> none:
-    result_.set code
-    on-stopped := on-stopped_
-    on-stopped_ = null
-    if on-stopped: on-stopped.call code
-    // We no longer expect or care about notifications, so
-    // close the resource.
-    close
+  on-event lambda/Lambda? -> none:
+    if not lambda:
+      on-event_ = null
+      return
+    if on-event_: throw "ALREADY_IN_USE"
+    on-event_ = lambda
+
+  on-notified_ notification/any -> none:
+    if notification is int:
+      code/int := notification
+      result_.set code
+      on-stopped := on-stopped_
+      on-stopped_ = null
+      if on-stopped: on-stopped.call code
+      // We no longer expect or care about notifications, so
+      // close the resource.
+      close
+    else if on-event_:
+      if notification is not List or notification.size != 2 or notification[0] is not int:
+        // Discard unknown event.
+        return
+      event-kind := notification[0]
+      event-value := notification[1]
+      on-event_.call event-kind event-value
 
 class ContainerImageWriter extends ServiceResourceProxy:
   size/int ::= ?

system/containers.toit

@@ -23,6 +23,7 @@ import encoding.tison
 import system.assets
 import system.services show ServiceHandler ServiceProvider ServiceResource
 import system.api.containers show ContainerService
+import system.containers as system-containers
 
 import .flash.allocation
 import .flash.image-writer
@@ -45,8 +46,7 @@ class Container:
 
   start arguments/any=image.default-arguments -> none:
     if pids_: throw "Already started"
-    pids_ = {}
-    pids_.add (image.spawn this arguments)
+    pids_ = {image.spawn this arguments}
 
   stop -> none:
     if not pids_: throw "Not started"
@@ -56,6 +56,11 @@ class Container:
     image.manager.on-container-stop_ this 0
     resources.do: it.on-container-stop 0
 
+  send-event event/any:
+    if not pids_: throw "Not started"
+    if pids_.is-empty: return
+    resources.do: it.send-event event
+
   on-stop_ -> none:
     pids_.do: on-process-stop_ it 0
 
@@ -91,6 +96,10 @@ class ContainerResource extends ServiceResource:
     if is-closed: return
     notify_ code
 
+  send-event event/List -> none:
+    if is-closed: return
+    notify_ event
+
   on-closed -> none:
     container.resources.remove this
 
@@ -177,6 +186,7 @@ class ContainerImageFlash extends ContainerImage:
 
 abstract class ContainerServiceProvider extends ServiceProvider
     implements ContainerService ServiceHandler:
+
   constructor:
     super "system/containers" --major=0 --minor=2
     provides ContainerService.SELECTOR --handler=this
@@ -203,12 +213,17 @@ abstract class ContainerServiceProvider extends ServiceProvider
     if index == ContainerService.IMAGE-WRITER-COMMIT-INDEX:
       writer ::= (resource client arguments[0]) as ContainerImageWriter
       return (image-writer-commit writer arguments[1] arguments[2]).to-byte-array
+    if index == ContainerService.NOTIFY-BACKGROUND-STATE-CHANGED-INDEX:
+      return send-container-event --gid=gid
+          system-containers.Container.EVENT-BACKGROUND-STATE-CHANGE
+          arguments
     unreachable
 
   abstract image-registry -> FlashRegistry
   abstract images -> List
   abstract add-flash-image allocation/FlashAllocation -> ContainerImage
   abstract lookup-image id/uuid.Uuid -> ContainerImage?
+  abstract send-container-event --gid/int event-kind/int event-value/any -> none
 
   list-images -> List:
     names := {:}
@@ -263,6 +278,9 @@ abstract class ContainerServiceProvider extends ServiceProvider
     image := add-flash-image allocation
     return image.id
 
+  notify-background-state-changed new-state/bool:
+    unreachable  // Here to satisfy the checker.
+
 class ContainerManager extends ContainerServiceProvider implements SystemMessageHandler_:
   image-registry/FlashRegistry ::= ?
   service-manager_/SystemServiceManager ::= ?
@@ -366,6 +384,10 @@ class ContainerManager extends ContainerServiceProvider implements SystemMessage
     else:
       unreachable
 
+  send-container-event --gid/int event-kind/int event-value/any -> none:
+    container/Container? := lookup-container gid
+    if container: container.send-event [event-kind, event-value]
+
 trace-using-print message/ByteArray --from=0 --to=message.size:
   // Print a trace message on output so that that you can easily decode.
   // The message is base64 encoded to limit the output size.

tests/containers-test.toit

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
+import monitor
 import system.containers
 import expect show *
 
@@ -15,6 +16,7 @@ main arguments:
 
   test-images
   test-start
+  test-background-state-changed
 
 test-images:
   images/List := containers.images
@@ -58,5 +60,19 @@ test-start:
   expect-equals 0 lambda4-value
   expect-equals 0 sub4.wait
 
+test-background-state-changed:
+  sub := containers.start containers.current { "background-state-test": true }
+  channel := monitor.Channel 1
+  sub.on-event:: | event-id/int value |
+    expect-equals containers.Container.EVENT-BACKGROUND-STATE-CHANGE event-id
+    channel.send value
+
+  expect_equals true channel.receive
+  expect_equals false channel.receive
+
 main-child arguments/Map:
+  if arguments.contains "background-state-test":
+    sleep --ms=10
+    containers.notify-background-state-changed true
+    containers.notify-background-state-changed false
   sleep --ms=100

tests/negative/gold/illegal-system-call-test.gold

@@ -1,6 +1,6 @@
 As check failed: null is not a ServiceResource.
   0: ServiceProvider.resource  <sdk>/system/services.toit:401:5
-  1: ContainerServiceProvider.handle <...>/system/containers.toit:201:19
+  1: ContainerServiceProvider.handle <...>/system/containers.toit:211:19
   2: ServiceManager_.<lambda>  <sdk>/system/services.toit:634:15
   3: RpcRequest_.process.<block> <sdk>/rpc/broker.toit:98:26
   4: RpcRequest_.process       <sdk>/rpc/broker.toit:95:3