Concurrent imap

3 files changed, 176 insertions, 90 deletions

diff --git a/internal/imap/client.go b/internal/imap/client.go
index da06f54..5e2546b 100644
--- a/internal/imap/client.go
+++ b/internal/imap/client.go
@@ -3,6 +3,7 @@ package imap
 import (
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/emersion/go-imap"
@@ -11,20 +12,37 @@ import (
 	"github.com/Necoro/feed2imap-go/internal/log"
 )
 
-type Client struct {
-	c         *imapClient.Client
+const numberConns = 5
+
+type connConf struct {
 	host      string
-	mailboxes mailboxes
 	delimiter string
 	toplevel  Folder
+}
+
+type connection struct {
+	*connConf
+	mailboxes *mailboxes
+	c         *imapClient.Client
+}
+
+type mailboxes struct {
+	mb map[string]*imap.MailboxInfo
+	mu sync.RWMutex
+}
+
+type Client struct {
+	connConf
+	mailboxes mailboxes
 	commander *commander
+	connections [numberConns]*connection
+	nextFreeIndex int
 }
 
 type Folder struct {
 	str       string
 	delimiter string
 }
-type mailboxes map[string]*imap.MailboxInfo
 
 func (f Folder) String() string {
 	return f.str
@@ -40,21 +58,38 @@ func (f Folder) Append(other Folder) Folder {
 	}
 }
 
-func (mbs mailboxes) contains(elem Folder) bool {
-	_, ok := mbs[elem.str]
+func (mbs *mailboxes) contains(elem Folder) bool {
+	mbs.mu.RLock()
+	defer mbs.mu.RUnlock()
+
+	_, ok := mbs.mb[elem.str]
 	return ok
 }
 
-func (mbs mailboxes) add(elem *imap.MailboxInfo) {
-	mbs[elem.Name] = elem
+func (mbs *mailboxes) add(elem *imap.MailboxInfo) {
+	mbs.mu.Lock()
+	defer mbs.mu.Unlock()
+
+	mbs.mb[elem.Name] = elem
+}
+
+func (conn *connection) Disconnect() bool {
+	if conn != nil {
+		connected := (conn.c.State() & imap.ConnectedState) != 0
+		_ = conn.c.Logout()
+		return connected
+	}
+	return false
 }
 
 func (client *Client) Disconnect() {
 	if client != nil {
 		client.stopCommander()
 
-		connected := (client.c.State() & imap.ConnectedState) != 0
-		_ = client.c.Logout()
+		connected := false
+		for _, conn := range client.connections {
+			connected = conn.Disconnect() || connected
+		}
 
 		if connected {
 			log.Print("Disconnected from ", client.host)
@@ -73,13 +108,13 @@ func (client *Client) NewFolder(path []string) Folder {
 	return client.toplevel.Append(client.folderName(path))
 }
 
-func (client *Client) createFolder(folder string) error {
-	err := client.c.Create(folder)
+func (conn *connection) createFolder(folder string) error {
+	err := conn.c.Create(folder)
 	if err != nil {
 		return fmt.Errorf("creating folder '%s': %w", folder, err)
 	}
 
-	err = client.c.Subscribe(folder)
+	err = conn.c.Subscribe(folder)
 	if err != nil {
 		return fmt.Errorf("subscribing to folder '%s': %w", folder, err)
 	}
@@ -89,11 +124,11 @@ func (client *Client) createFolder(folder string) error {
 	return nil
 }
 
-func (client *Client) list(folder string) (*imap.MailboxInfo, int, error) {
+func (conn *connection) list(folder string) (*imap.MailboxInfo, int, error) {
 	mailboxes := make(chan *imap.MailboxInfo, 10)
 	done := make(chan error, 1)
 	go func() {
-		done <- client.c.List("", folder, mailboxes)
+		done <- conn.c.List("", folder, mailboxes)
 	}()
 
 	found := 0
@@ -112,24 +147,23 @@ func (client *Client) list(folder string) (*imap.MailboxInfo, int, error) {
 	return mbox, found, nil
 }
 
-func (client *Client) fetchDelimiter() error {
-	mbox, _, err := client.list("")
+func (conn *connection) fetchDelimiter() (string, error) {
+	mbox, _, err := conn.list("")
 	if err != nil {
-		return err
+		return "", err
 	}
 
-	client.delimiter = mbox.Delimiter
-	return nil
+	return mbox.Delimiter, nil
 }
 
-func (client *Client) ensureFolder(folder Folder) error {
-	if client.mailboxes.contains(folder) {
+func (conn *connection) ensureFolder(folder Folder) error {
+	if conn.mailboxes.contains(folder) {
 		return nil
 	}
 
 	log.Printf("Checking for folder '%s'", folder)
 
-	mbox, found, err := client.list(folder.str)
+	mbox, found, err := conn.list(folder.str)
 	if err != nil {
 		return err
 	}
@@ -140,20 +174,20 @@ func (client *Client) ensureFolder(folder Folder) error {
 
 	switch found {
 	case 0:
-		return client.createFolder(folder.str)
+		return conn.createFolder(folder.str)
 	case 1:
-		client.mailboxes.add(mbox)
+		conn.mailboxes.add(mbox)
 		return nil
 	default:
 		return fmt.Errorf("Found multiple folders matching '%s'.", folder)
 	}
 }
 
-func (client *Client) EnsureFolder(folder Folder, errorHandler ErrorHandler) {
-	client.commander.execute(ensureCommando{folder}, errorHandler)
+func (client *Client) EnsureFolder(folder Folder) error {
+	return client.commander.execute(ensureCommando{folder})
 }
 
-func (client *Client) putMessages(folder Folder, messages []string) error {
+func (conn *connection) putMessages(folder Folder, messages []string) error {
 	if len(messages) == 0 {
 		return nil
 	}
@@ -161,7 +195,7 @@ func (client *Client) putMessages(folder Folder, messages []string) error {
 	now := time.Now()
 	for _, msg := range messages {
 		reader := strings.NewReader(msg)
-		if err := client.c.Append(folder.str, nil, now, reader); err != nil {
+		if err := conn.c.Append(folder.str, nil, now, reader); err != nil {
 			return fmt.Errorf("uploading message to %s: %w", folder, err)
 		}
 	}
@@ -169,6 +203,51 @@ func (client *Client) putMessages(folder Folder, messages []string) error {
 	return nil
 }
 
-func (client *Client) PutMessages(folder Folder, messages []string, errorHandler ErrorHandler) {
-	client.commander.execute(addCommando{folder, messages}, errorHandler)
+func (client *Client) PutMessages(folder Folder, messages []string) error {
+	return client.commander.execute(addCommando{folder, messages})
+}
+
+func (client *Client) createConnection(c *imapClient.Client) *connection{
+	if client.nextFreeIndex >= len(client.connections) {
+		panic("Too many connections")
+	}
+
+	conn := &connection{
+		connConf:  &client.connConf,
+		mailboxes: &client.mailboxes,
+		c:         c,
+	}
+
+	client.connections[client.nextFreeIndex] = conn
+	client.nextFreeIndex++
+
+	return conn
+}
+
+func (conn *connection) startTls() error {
+	hasStartTls, err := conn.c.SupportStartTLS()
+	if err != nil {
+		return fmt.Errorf("checking for starttls for %s: %w", conn.host, err)
+	}
+
+	if hasStartTls {
+		if err = conn.c.StartTLS(nil); err != nil {
+			return fmt.Errorf("enabling starttls for %s: %w", conn.host, err)
+		}
+
+		log.Print("Connected to ", conn.host, " (STARTTLS)")
+	} else {
+		log.Print("Connected to ", conn.host, " (Plain)")
+	}
+
+	return nil
 }
+
+func NewClient() *Client {
+	return &Client{
+		mailboxes: mailboxes{
+			mb: map[string]*imap.MailboxInfo{},
+			mu: sync.RWMutex{},
+		},
+	}
+}
\ No newline at end of file
diff --git a/internal/imap/commando.go b/internal/imap/commando.go
index fbfeaec..171a507 100644
--- a/internal/imap/commando.go
+++ b/internal/imap/commando.go
@@ -1,7 +1,5 @@
 package imap
 
-import "github.com/Necoro/feed2imap-go/internal/log"
-
 const maxPipeDepth = 10
 
 type commander struct {
@@ -11,15 +9,12 @@ type commander struct {
 }
 
 type command interface {
-	execute(client *Client) error
+	execute(*connection) error
 }
 
-type ErrorHandler func(error) string
-
 type execution struct {
 	cmd          command
-	done         chan<- struct{}
-	errorHandler ErrorHandler
+	done         chan<- error
 }
 
 type addCommando struct {
@@ -27,25 +22,25 @@ type addCommando struct {
 	messages []string
 }
 
-func (cmd addCommando) execute(client *Client) error {
-	return client.putMessages(cmd.folder, cmd.messages)
+func (cmd addCommando) execute(conn *connection) error {
+	return conn.putMessages(cmd.folder, cmd.messages)
 }
 
 type ensureCommando struct {
 	folder Folder
 }
 
-func (cmd ensureCommando) execute(client *Client) error {
-	return client.ensureFolder(cmd.folder)
+func (cmd ensureCommando) execute(conn *connection) error {
+	return conn.ensureFolder(cmd.folder)
 }
 
-func (commander *commander) execute(command command, handler ErrorHandler) {
-	done := make(chan struct{})
-	commander.pipe <- execution{command, done, handler}
-	<-done
+func (commander *commander) execute(command command) error {
+	done := make(chan error)
+	commander.pipe <- execution{command, done}
+	return <-done
 }
 
-func executioner(client *Client, pipe <-chan execution, done <-chan struct{}) {
+func executioner(conn *connection, pipe <-chan execution, done <-chan struct{}) {
 	for {
 		select {
 		case <-done:
@@ -56,14 +51,8 @@ func executioner(client *Client, pipe <-chan execution, done <-chan struct{}) {
 				return
 			default:
 			}
-			if err := execution.cmd.execute(client); err != nil {
-				if execution.errorHandler == nil {
-					log.Error(err)
-				} else {
-					log.Error(execution.errorHandler(err))
-				}
-			}
-			close(execution.done)
+			err := execution.cmd.execute(conn)
+			execution.done <- err
 		}
 	}
 }
@@ -78,7 +67,11 @@ func (client *Client) startCommander() {
 
 	client.commander = &commander{client, pipe, done}
 
-	go executioner(client, pipe, done)
+	for _, conn := range client.connections {
+		if conn != nil {
+			go executioner(conn, pipe, done)
+		}
+	}
 }
 
 func (client *Client) stopCommander() {
diff --git a/internal/imap/imap.go b/internal/imap/imap.go
index 4965ca5..52c61f0 100644
--- a/internal/imap/imap.go
+++ b/internal/imap/imap.go
@@ -56,51 +56,34 @@ func sanitizeUrl(url *url.URL) {
 	setDefaultPort(url)
 }
 
-func Connect(url *url.URL) (*Client, error) {
-	var c *imapClient.Client
-	var err error
-
-	sanitizeUrl(url)
-
-	forceTls := forceTLS(url)
-
+func newImapClient(url *url.URL, forceTls bool) (*imapClient.Client,error) {
 	if forceTls {
-		c, err = imapClient.DialTLS(url.Host, nil)
+		c, err := imapClient.DialTLS(url.Host, nil)
 		if err != nil {
 			return nil, fmt.Errorf("connecting (TLS) to %s: %w", url.Host, err)
 		}
 		log.Print("Connected to ", url.Host, " (TLS)")
+		return c, nil
 	} else {
-		c, err = imapClient.Dial(url.Host)
+		c, err := imapClient.Dial(url.Host)
 		if err != nil {
 			return nil, fmt.Errorf("connecting to %s: %w", url.Host, err)
 		}
+		return c, nil
 	}
+}
 
-	var client = Client{c: c, host: url.Host, mailboxes: mailboxes{}}
+func (client *Client) connect(url *url.URL, forceTls bool) (*connection, error) {
+	c, err := newImapClient(url, forceTls)
+	if err != nil {
+		return nil, err
+	}
 
-	defer func() {
-		if err != nil {
-			client.Disconnect()
-		}
-	}()
+	conn := client.createConnection(c)
 
 	if !forceTls {
-		var hasStartTls bool // explicit to avoid shadowing err
-
-		hasStartTls, err = c.SupportStartTLS()
-		if err != nil {
-			return nil, fmt.Errorf("checking for starttls for %s: %w", url.Host, err)
-		}
-
-		if hasStartTls {
-			if err = c.StartTLS(nil); err != nil {
-				return nil, fmt.Errorf("enabling starttls for %s: %w", url.Host, err)
-			}
-
-			log.Print("Connected to ", url.Host, " (STARTTLS)")
-		} else {
-			log.Print("Connected to ", url.Host, " (Plain)")
+		if err = conn.startTls(); err != nil {
+			return nil, err
 		}
 	}
 
@@ -109,9 +92,33 @@ func Connect(url *url.URL) (*Client, error) {
 		return nil, fmt.Errorf("login to %s: %w", url.Host, err)
 	}
 
-	if err = client.fetchDelimiter(); err != nil {
+	return conn, nil
+}
+
+func Connect(url *url.URL) (*Client, error) {
+	var err error
+
+	sanitizeUrl(url)
+	forceTls := forceTLS(url)
+
+	client := NewClient()
+	client.host = url.Host
+	defer func() {
+		if err != nil {
+			client.Disconnect()
+		}
+	}()
+
+	var conn *connection // the main connection
+	if conn, err = client.connect(url, forceTls); err != nil {
+		return nil, err
+	}
+
+	delim, err := conn.fetchDelimiter()
+	if err != nil {
 		return nil, fmt.Errorf("fetching delimiter: %w", err)
 	}
+	client.delimiter = delim
 
 	toplevel := url.Path
 	if toplevel[0] == '/' {
@@ -121,11 +128,18 @@ func Connect(url *url.URL) (*Client, error) {
 
 	log.Printf("Determined '%s' as toplevel, with '%s' as delimiter", client.toplevel, client.delimiter)
 
-	if err = client.ensureFolder(client.toplevel); err != nil {
+	if err = conn.ensureFolder(client.toplevel); err != nil {
 		return nil, err
 	}
 
+	// the other connections
+	for i := 1; i < len(client.connections); i++ {
+		if _, err := client.connect(url, forceTls); err != nil { // explicitly new var 'err', b/c these are now harmless
+			log.Warnf("connecting #%d: %s", i, err)
+		}
+	}
+
 	client.startCommander()
 
-	return &client, nil
+	return client, nil
 }