rpc: pass `outCapacity` to `eventBus#Subscribe` when subscribing using a l… (#4279)

* pass `outCapacity` to `eventBus#Subscribe` when subscribing using a local client

Fixes #4256

* use outCap directly

CHANGELOG_PENDING.md

@@ -142,3 +142,4 @@ program](https://hackerone.com/tendermint).
   efforts of @gchaincl and @ancazamfir)
 - [p2p] \#4140 `SecretConnection`: use the transcript solely for authentication (i.e. MAC)
 - [consensus/types] \#4243 fix BenchmarkRoundStateDeepCopy panics (@cuonglm)
+- [rpc] \#4256 Pass `outCapacity` to `eventBus#Subscribe` when subscribing using a local client

rpc/client/localclient.go

@@ -177,16 +177,22 @@ func (c *Local) Subscribe(
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to parse query")
 	}
-	sub, err := c.EventBus.Subscribe(ctx, subscriber, q)
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to subscribe")
-	}
 
 	outCap := 1
 	if len(outCapacity) > 0 {
 		outCap = outCapacity[0]
 	}
 
+	var sub types.Subscription
+	if outCap > 0 {
+		sub, err = c.EventBus.Subscribe(ctx, subscriber, q, outCap)
+	} else {
+		sub, err = c.EventBus.SubscribeUnbuffered(ctx, subscriber, q)
+	}
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to subscribe")
+	}
+
 	outc := make(chan ctypes.ResultEvent, outCap)
 	go c.eventsRoutine(sub, subscriber, q, outc)