feat_: Flush hystrix on going back online

When going offline, all the rpc calls fail making hystrix open all the
circuits.
This commit changes the behavior so that when we go back online, we
close all the circuits.
We should also avoid making rpc requests while offline, but this should
work for release.

Author: cammellos

api/geth_backend.go

@@ -15,6 +15,7 @@ import (
 
 	"go.uber.org/zap"
 
+	"github.com/afex/hystrix-go/hystrix"
 	"github.com/pkg/errors"
 
 	"github.com/imdario/mergo"
@@ -2434,6 +2435,12 @@ func (b *GethStatusBackend) ConnectionChange(typ string, expensive bool) {
 
 	b.log.Info("Network state change", "old", b.connectionState, "new", state)
 
+	if b.connectionState.Offline && !state.Offline {
+		//  flush hystrix if we are going again online, since it doesn't behave
+		// well when offline
+		hystrix.Flush()
+	}
+
 	b.connectionState = state
 	b.statusNode.ConnectionChanged(state)