Attributes for action and connection buffers (#198)

* This PR adds attributes for specifying the max num pending events for actions and the max buffer size for connections

* Simple formatting

Author: erlingrj

lfc/core/src/main/java/org/lflang/AttributeUtils.java

@@ -26,6 +26,7 @@
 package org.lflang;
 
 import static org.lflang.ast.ASTUtils.factory;
+import static org.lflang.ast.ASTUtils.toInteger;
 
 import java.util.HashMap;
 import java.util.List;
@@ -290,6 +291,24 @@ public static List<Attribute> getInterfaceAttributes(Instantiation node) {
     return findAttributesByNameStartingWith(node, "interface");
   }
 
+  public static int getMaxNumberOfPendingEvents(Action node) {
+    Attribute attr = findAttributeByName(node, "max_pending_events");
+    if (attr != null) {
+      return Integer.valueOf(attr.getAttrParms().get(0).getValue());
+    } else {
+      return -1;
+    }
+  }
+
+  public static int getConnectionBufferSize(Connection node) {
+    Attribute attr = findAttributeByName(node, "buffer");
+    if (attr != null) {
+      return Integer.valueOf(attr.getAttrParms().get(0).getValue());
+    } else {
+      return -1;
+    }
+  }
+
   public static Attribute getLinkAttribute(Connection node) {
     return findAttributeByName(node, "link");
   }

lfc/core/src/main/java/org/lflang/validation/AttributeSpec.java

@@ -243,6 +243,14 @@ enum AttrParamType {
     ATTRIBUTE_SPECS_BY_NAME.put(
         "_networkReactor",
         new AttributeSpec(List.of(new AttrParamSpec(VALUE_ATTR, AttrParamType.STRING, false))));
+    // @max_pending_event(<value>)
+    ATTRIBUTE_SPECS_BY_NAME.put(
+            "max_pending_events",
+            new AttributeSpec(List.of(new AttrParamSpec(VALUE_ATTR, AttrParamType.INT, false))));
+    // @buffer(<value>)
+    ATTRIBUTE_SPECS_BY_NAME.put(
+            "buffer",
+            new AttributeSpec(List.of(new AttrParamSpec(VALUE_ATTR, AttrParamType.INT, false))));
     // @interface:tcp(name="string", address="string") e.g. @interface:tcp(name="if1", address="127.0.0.1")
     ATTRIBUTE_SPECS_BY_NAME.put(
             "interface_tcp",

lfc/core/src/main/kotlin/org/lflang/generator/uc/UcActionGenerator.kt

@@ -9,13 +9,17 @@ import org.lflang.generator.uc.UcReactorGenerator.Companion.codeType
 import org.lflang.generator.uc.UcReactorGenerator.Companion.getEffects
 import org.lflang.generator.uc.UcReactorGenerator.Companion.getObservers
 import org.lflang.generator.uc.UcReactorGenerator.Companion.getSources
+import org.lflang.AttributeUtils.getMaxNumberOfPendingEvents
 import org.lflang.lf.*
 
 class UcActionGenerator(private val reactor: Reactor) {
 
     companion object {
         public val Action.maxNumPendingEvents
-            get(): Int = 12 // FIXME: This should be annotated in the LF code
+            get(): Int {
+                val num = getMaxNumberOfPendingEvents(this)
+                return if (num > 0) num else 1
+            }
     }
 
     /** Returns the C Enum representing the type of action.*/

lfc/core/src/main/kotlin/org/lflang/generator/uc/UcConnectionUtils.kt

@@ -1,6 +1,6 @@
 package org.lflang.generator.uc
 
-import org.lflang.AttributeUtils.getLinkAttribute
+import org.lflang.AttributeUtils.*
 import org.lflang.generator.orNever
 import org.lflang.generator.uc.UcInstanceGenerator.Companion.codeWidth
 import org.lflang.generator.uc.UcInstanceGenerator.Companion.width
@@ -58,7 +58,7 @@ open class UcGroupedConnection(
             channels.groupingBy { Pair(it.src.getCodePortIdx(), it.src.getCodeBankIdx()) }.eachCount()
         frequencyMap.values.maxOrNull() ?: 0
     }
-    val maxNumPendingEvents = 16 // FIXME: Must be derived from the program
+    val maxNumPendingEvents = if (getConnectionBufferSize(lfConn) > 0) getConnectionBufferSize(lfConn) else 1
 
     fun assignUid(id: Int) {
         uid = id

src/action.c

@@ -52,7 +52,7 @@ lf_ret_t Action_schedule(Action *self, interval_t offset, const void *value) {
   }
 
   if (self->events_scheduled >= self->max_pending_events) {
-    LF_ERR(TRIG, "Too many pending events. Capacity is %i", self->max_pending_events);
+    LF_ERR(TRIG, "Action event buffer is full, dropping event. Capacity is %i", self->max_pending_events);
     return LF_ERR;
   }
 

src/connection.c

@@ -142,7 +142,11 @@ void DelayedConnection_trigger_downstreams(Connection *_self, const void *value,
   EventPayloadPool *pool = trigger->payload_pool;
   if (self->staged_payload_ptr == NULL) {
     ret = pool->allocate(pool, &self->staged_payload_ptr);
-    validate(ret == LF_OK); // FIME: Trigger_downstreams should return lf_ret_t
+    if (ret != LF_OK) {
+      LF_ERR(CONN, "No more space in event buffer for delayed connection %p, dropping. Capacity is %d", _self,
+             self->payload_pool.capacity);
+      return;
+    }
   }
   memcpy(self->staged_payload_ptr, value, value_size);
   sched->register_for_cleanup(sched, &_self->super);

test/lf/src/Action.lf

@@ -3,6 +3,7 @@ target uC {
 }
 
 main reactor {
+  @max_pending_events(10)
   logical action a:int
   state cnt:int=0
   state cnt2:int=0

test/lf/src/ActionBuffer.lf

@@ -0,0 +1,26 @@
+target uC {
+  platform: Native
+}
+
+main reactor {
+
+  @max_pending_events(10)
+  logical action a:int
+
+  state received:int=0
+
+  reaction(startup) -> a {=
+    for (int i = 0; i<10; i++) {
+      lf_schedule(a, MSEC(i), i);
+    }
+  =}
+
+  reaction(a) {=
+    validate(a->value == self->received++);
+    printf("Action scheduled wtih %d\n", a->value);
+  =}
+
+  reaction(shutdown) {=
+    validate(self->received == 10);
+  =}
+}

test/lf/src/Connections.lf

@@ -19,25 +19,32 @@ reactor R1 {
 }
 
 
-reactor R2 {
+reactor R2(expected: int = 0) {
     input in:int
 
+    state cnt:int = 0
+
     reaction(startup) {=
       printf("Hi from other guy at startup\n");
-
     =}
 
     reaction(in) {=
         printf("Got %d\n", in->value);
+        self->cnt++;
+    =}
+
+    reaction(shutdown) {=
+      validate(self->cnt == self->expected);
     =}
 }
 
 main reactor {
   r1 = new R1()
-  r2 = new R2()
+  r2 = new R2(expected = 11)
   r1.out -> r2.in
 
   r3 = new R1()
-  r4 = new R2()
-  r3.out -> r4.in after 100 msec
+  r4 = new R2(expected = 10)
+  
+  r3.out -> r4.in after 10 msec
 }

test/lf/src/DelayedConnectionBuffer.lf

@@ -0,0 +1,38 @@
+target uC {
+  platform: Native,
+  timeout: 200 msec
+}
+
+reactor R1 {
+  output out: int
+  timer t(0, 10 msec)
+  state cnt: int = 0;
+
+  reaction(t) -> out {=
+    if (self->cnt < 10) {
+      printf("Hello from R1 at %ld\n", env->get_elapsed_physical_time(env));
+      lf_set(out, self->cnt++);
+    }
+  =}
+}
+
+reactor R2 {
+    input in:int
+    state cnt:int = 0
+    reaction(in) {=
+        printf("Got %d\n", in->value);
+        validate(in->value == self->cnt++);
+    =}
+
+    reaction(shutdown) {=
+      validate(self->cnt == 10);
+    =}
+}
+
+main reactor {
+  r1 = new R1()
+  r2 = new R2()
+
+  @buffer(10)
+  r1.out -> r2.in after 100 msec
+}