filtering can be disabled with -tags nofilter

it will make your binaries way smaller

cmd/circolog-tail/main.go

@@ -75,7 +75,7 @@ func main() {
 				log.Println("invalid BSON", err)
 				continue
 			}
-			if filter.Node != nil && !filter.Validate(parsed) {
+			if !filter.Validate(parsed) {
 				continue
 			}
 			if err := formatter.WriteFormatted(os.Stdout, formatter.FormatSyslog, parsed); err != nil {

filtering/filter.go

@@ -1,3 +1,5 @@
+// +build !nofilter
+
 package filtering
 
 import (
@@ -11,38 +13,38 @@ import (
 )
 
 type ExprValue struct {
-	Node       expr.Node
-	Expression string
+	node       expr.Node
+	expression string
 }
 
 func (e *ExprValue) String() string {
-	if e.Node != nil {
-		return e.Node.String()
+	if e.node != nil {
+		return e.node.String()
 	} else {
 		return "<Empty Expression>"
 	}
 }
 func (e *ExprValue) Set(value string) error {
 	if value == "" {
-		e.Node = nil
-		e.Expression = value
+		e.node = nil
+		e.expression = value
 		return nil
 	}
 	ast, err := expr.ParseExpression(value)
 	if err != nil {
 		return err
 	}
-	e.Node = ast
-	e.Expression = value
+	e.node = ast
+	e.expression = value
 	return nil
 }
 
 func (e *ExprValue) Validate(line map[string]interface{}) bool {
-	if e.Node == nil {
+	if e.node == nil {
 		return true
 	}
 	context := datasource.NewContextSimpleNative(line)
-	val, ok := vm.Eval(context, e.Node)
+	val, ok := vm.Eval(context, e.node)
 	if !ok || val == nil { // errors when evaluating
 		return false
 	}

filtering/filter_fake.go

@@ -0,0 +1,17 @@
+// +build nofilter
+
+package filtering
+
+type ExprValue struct {
+}
+
+func (e *ExprValue) String() string {
+	return "<filtering disabled>"
+}
+
+func (e *ExprValue) Set(value string) error {
+	return nil
+}
+func (e *ExprValue) Validate(line map[string]interface{}) bool {
+	return true
+}

hub.go

@@ -144,7 +144,7 @@ func (h *Hub) Run() {
 				cmd.Response <- CommandResponse{Value: map[string]interface{}{
 					"size":   h.circbuf.Len(),
 					"paused": !active,
-					"filter": filter.Expression,
+					"filter": filter.String(),
 				}}
 			case CommandNewFilter:
 				if err := filter.Set(cmd.Parameters["where"].(string)); err != nil {