Request cancellations support added to Middlewares.

Some core functions refactored as middlewares.
Fixed race condition in exporting system. Now, only one goroutine will be responsible for exporting. This fixes concurrency issues on writing.

exporter/csv.go

@@ -3,7 +3,6 @@ package exporter
 import (
 	"encoding/csv"
 	"fmt"
-	"github.com/geziyor/geziyor"
 	"log"
 	"os"
 	"reflect"
@@ -19,7 +18,8 @@ type CSVExporter struct {
 	writer *csv.Writer
 }
 
-func (e *CSVExporter) Export(response *geziyor.Response) {
+// Export exports response data as CSV streaming file
+func (e *CSVExporter) Export(exports chan interface{}) {
 
 	// Default filename
 	if e.FileName == "" {
@@ -37,7 +37,7 @@ func (e *CSVExporter) Export(response *geziyor.Response) {
 	})
 
 	// Export data as responses came
-	for res := range response.Exports {
+	for res := range exports {
 		var values []string
 
 		// Detect type and extract CSV values
@@ -57,14 +57,9 @@ func (e *CSVExporter) Export(response *geziyor.Response) {
 		}
 
 		// Write to file
-		e.mut.Lock()
 		if err := e.writer.Write(values); err != nil {
 			log.Printf("CSV writing error on exporter: %v\n", err)
 		}
-		e.mut.Unlock()
 	}
-
-	e.mut.Lock()
 	e.writer.Flush()
-	e.mut.Unlock()
 }