fixed some performance issues when pulling a large amount of messages

Signed-off-by: Michael <michael.lindman@gmail.com>

go.mod

@@ -5,6 +5,6 @@ go 1.16
 require (
 	github.com/emersion/go-imap v1.2.0
 	github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac // indirect
-	golang.org/x/net v0.0.0-20211209124913-491a49abca63
+	golang.org/x/net v0.0.0-20220114011407-0dd24b26b47d
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 )

mail/mail.go

@@ -3,11 +3,11 @@ package mail
 import (
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
 	"strconv"
-	"time"
 
 	"github.com/emersion/go-imap"
 	"github.com/emersion/go-imap/client"
@@ -18,19 +18,6 @@ type Mail struct {
 	Client *client.Client
 }
 
-type Message struct {
-	SeqNum  uint32
-	Subject string
-	To      []*imap.Address
-	From    []*imap.Address
-	Date    time.Time
-	Body    imap.Literal
-}
-
-type Messages struct {
-	Message []Message
-}
-
 type Conn struct {
 	Addr     string
 	Username string
@@ -76,20 +63,19 @@ func Login(conn Conn) (mail *Mail, err error) {
 	return mail, nil
 }
 
-func (mail *Mail) GetMessages(mailbox string, msgs int32) (*Messages, error) {
+func (mail *Mail) GetMessages(mailbox string, path string) error {
-	var messages Messages
 	mbox, err := mail.Client.Select(mailbox, true)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if mbox.Messages == 0 {
-		return nil, errors.New("no messages in mailbox")
+		return errors.New("no messages in mailbox")
 	}
 	seqSet := new(imap.SeqSet)
 	seqSet.AddRange(1, mbox.Messages)
 	var section imap.BodySectionName
 
-	imapMessages := make(chan *imap.Message, msgs)
+	imapMessages := make(chan *imap.Message, mbox.Messages)
 	done := make(chan error, 1)
 	go func() {
 		done <- mail.Client.Fetch(seqSet, []imap.FetchItem{imap.FetchEnvelope, section.FetchItem()}, imapMessages)
@@ -98,33 +84,26 @@ func (mail *Mail) GetMessages(mailbox string, msgs int32) (*Messages, error) {
 	for msg := range imapMessages {
 		body := msg.GetBody(&section)
 		if body == nil {
-			return nil, errors.New("server didn't returned message body")
+			return errors.New("server didn't returned message body")
 		}
-		message := Message{
+		fmt.Println(msg.Envelope.Subject)
-			SeqNum:  msg.SeqNum,
+		if err := Write(path, msg, body); err != nil {
-			Subject: msg.Envelope.Subject,
+			return err
-			To:      msg.Envelope.To,
-			From:    msg.Envelope.From,
-			Date:    msg.Envelope.Date,
-			Body:    body,
 		}
-		messages.Message = append(messages.Message, message)
 	}
 	if err := <-done; err != nil {
-		return nil, err
-	}
-	return &messages, nil
-}
-
-func WriteMessages(path string, messages *Messages) error {
-	for _, msg := range messages.Message {
-		body, err := ioutil.ReadAll(msg.Body)
-		if err != nil {
 		return err
 	}
-		if err := ioutil.WriteFile(path+"/"+strconv.Itoa(int(msg.SeqNum))+"_"+msg.Date.String()+".eml", body, 0644); err != nil {
+	return nil
-			return err
+}
-		}
+
-	}
+func Write(path string, msg *imap.Message, literal imap.Literal) error {
+	body, err := io.ReadAll(literal)
+	if err != nil {
+		return err
+	}
+	if err := ioutil.WriteFile(path+"/"+strconv.Itoa(int(msg.SeqNum))+"_"+msg.Envelope.Date.String()+".eml", body, 0644); err != nil {
+		return err
+	}
 	return nil
 }

main.go

@@ -11,7 +11,7 @@ import (
 )
 
 func main() {
-	cfgFile, mailbox, msgs := ui()
+	cfgFile, mailbox := ui()
 	cfg := NewConfig(*cfgFile)
 	chErr, chDone := make(chan error), make(chan bool)
 	for _, account := range cfg.Account {
@@ -34,17 +34,13 @@ func main() {
 				}
 			}
 			defer conn.Client.Logout()
-			messages, err := conn.GetMessages(*mailbox, int32(*msgs))
-			if err != nil {
-				chErr <- err
-			}
 			path := cfg.Path + username + "/" + time.Now().Format("2006-01-02-15:04:05")
 			for _, p := range []string{cfg.Path + username, path} {
 				if _, err := os.Stat(p); os.IsNotExist(err) {
 					os.Mkdir(p, 0775)
 				}
 			}
-			if err := mail.WriteMessages(path, messages); err != nil {
+			if err = conn.GetMessages(*mailbox, path); err != nil {
 				chErr <- err
 			}
 		}(account.Addr, account.Username, account.Password, chErr, chDone)
@@ -59,7 +55,7 @@ func main() {
 	}
 }
 
-func ui() (cfgFile, mailbox *string, msgs *int) {
+func ui() (cfgFile, mailbox *string) {
 	flag.Usage = func() {
 		fmt.Printf("Usage of %s:\n", os.Args[0])
 		flag.PrintDefaults()
@@ -70,8 +66,7 @@ func ui() (cfgFile, mailbox *string, msgs *int) {
 	}
 	cfgFile = flag.String("cfgFile", home+"/.config/gomail/config.yaml", "path to config file")
 	mailbox = flag.String("mailbox", "inbox", "mailbox to scan messages")
-	msgs = flag.Int("msgs", 100, "Number of messages to pull")
 
 	flag.Parse()
-	return cfgFile, mailbox, msgs
+	return cfgFile, mailbox
 }