From 46c4db6b1a0ba507a186b0d491a1cd5d1e485ed6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Musab=20G=C3=BCltekin?= <gultekinmusab@gmail.com>
Date: Wed, 14 Apr 2021 09:30:17 +0300
Subject: [PATCH] Exporters now need to return error. This is done because of
 simple error logging.

---
 export/csv.go    |  7 ++++---
 export/export.go |  2 +-
 export/json.go   | 32 +++++++++++++++++++-------------
 geziyor.go       | 11 +++++++----
 4 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/export/csv.go b/export/csv.go
index 4d91bfd..03f9d33 100644
--- a/export/csv.go
+++ b/export/csv.go
@@ -17,13 +17,12 @@ type CSV struct {
 }
 
 // Export exports response data as CSV streaming file
-func (e *CSV) Export(exports chan interface{}) {
+func (e *CSV) Export(exports chan interface{}) error {
 
 	// Create or append file
 	file, err := os.OpenFile(internal.DefaultString(e.FileName, "out.csv"), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
 	if err != nil {
-		internal.Logger.Printf("Output file creation error: %v\n", err)
-		return
+		return fmt.Errorf("output file creation error: %w", err)
 	}
 	defer file.Close()
 
@@ -53,4 +52,6 @@ func (e *CSV) Export(exports chan interface{}) {
 		}
 	}
 	writer.Flush()
+
+	return nil
 }
diff --git a/export/export.go b/export/export.go
index 8f50bd3..90ff313 100644
--- a/export/export.go
+++ b/export/export.go
@@ -3,5 +3,5 @@ package export
 // Exporter interface is for extracting data to external resources.
 // Export functions should wait for new data from exports chan.
 type Exporter interface {
-	Export(exports chan interface{})
+	Export(exports chan interface{}) error
 }
diff --git a/export/json.go b/export/json.go
index ffeadda..7565a17 100644
--- a/export/json.go
+++ b/export/json.go
@@ -3,6 +3,7 @@ package export
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"github.com/geziyor/geziyor/internal"
 	"os"
 )
@@ -16,13 +17,12 @@ type JSONLine struct {
 }
 
 // Export exports response data as JSON streaming file
-func (e *JSONLine) Export(exports chan interface{}) {
+func (e *JSONLine) Export(exports chan interface{}) error {
 
 	// Create or append file
 	file, err := os.OpenFile(internal.DefaultString(e.FileName, "out.json"), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
 	if err != nil {
-		internal.Logger.Printf("Output file creation error: %v\n", err)
-		return
+		return fmt.Errorf("output file creation error: %w", err)
 	}
 	defer file.Close()
 
@@ -36,6 +36,8 @@ func (e *JSONLine) Export(exports chan interface{}) {
 			internal.Logger.Printf("JSON encoding error on exporter: %v\n", err)
 		}
 	}
+
+	return nil
 }
 
 // JSON exports response data as JSON
@@ -45,17 +47,19 @@ type JSON struct {
 }
 
 // Export exports response data as JSON
-func (e *JSON) Export(exports chan interface{}) {
+func (e *JSON) Export(exports chan interface{}) error {
 
 	// Create or append file
 	file, err := os.OpenFile(internal.DefaultString(e.FileName, "out.json"), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
 	if err != nil {
-		internal.Logger.Printf("Output file creation error: %v\n", err)
-		return
+		return fmt.Errorf("output file creation error: %w", err)
 	}
 	defer file.Close()
 
-	file.Write([]byte("[\n"))
+	_, err = file.Write([]byte("[\n"))
+	if err != nil {
+		return fmt.Errorf("file write error: %w", err)
+	}
 
 	// Export data as responses came
 	for res := range exports {
@@ -64,16 +68,18 @@ func (e *JSON) Export(exports chan interface{}) {
 			internal.Logger.Printf("JSON encoding error on exporter: %v\n", err)
 			continue
 		}
-		file.Write(data)
+		_, err = file.Write(data)
+		if err != nil {
+			return fmt.Errorf("file write error: %w", err)
+		}
 	}
 
-	// Override on last comma
-	stat, err := file.Stat()
+	_, err = file.Write([]byte("]\n"))
 	if err != nil {
-		file.Write([]byte("]\n"))
-		return
+		return fmt.Errorf("file write error: %w", err)
 	}
-	file.WriteAt([]byte("\n]\n"), stat.Size()-2)
+
+	return nil
 }
 
 // jsonMarshalLine adds tab and comma around actual data
diff --git a/geziyor.go b/geziyor.go
index 6625219..7285ecc 100644
--- a/geziyor.go
+++ b/geziyor.go
@@ -3,6 +3,7 @@ package geziyor
 import (
 	"github.com/geziyor/geziyor/cache"
 	"github.com/geziyor/geziyor/client"
+	"github.com/geziyor/geziyor/export"
 	"github.com/geziyor/geziyor/internal"
 	"github.com/geziyor/geziyor/metrics"
 	"github.com/geziyor/geziyor/middleware"
@@ -139,11 +140,13 @@ func (g *Geziyor) Start() {
 	// Start Exporters
 	if len(g.Opt.Exporters) != 0 {
 		g.wgExporters.Add(len(g.Opt.Exporters))
-		for _, exp := range g.Opt.Exporters {
-			go func() {
+		for _, exporter := range g.Opt.Exporters {
+			go func(exporter export.Exporter) {
 				defer g.wgExporters.Done()
-				exp.Export(g.Exports)
-			}()
+				if err := exporter.Export(g.Exports); err != nil {
+					internal.Logger.Printf("exporter error: %s\n", err)
+				}
+			}(exporter)
 		}
 	} else {
 		g.wgExporters.Add(1)