poc to reuse ldap connection

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

Author: butonic

identifier/backends/ldap/ldap.go

@@ -26,6 +26,7 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/go-ldap/ldap/v3"
@@ -71,6 +72,9 @@ type LDAPIdentifierBackend struct {
 
 	timeout int
 	limiter *rate.Limiter
+
+	connLock sync.Mutex
+	conn     *ldap.Conn
 }
 
 type ldapAttributeMapping map[string]string
@@ -372,7 +376,7 @@ func (b *LDAPIdentifierBackend) Logon(ctx context.Context, audience, username, p
 	if err != nil {
 		return false, nil, nil, nil, fmt.Errorf("ldap identifier backend logon connect error: %v", err)
 	}
-	defer l.Close()
+	//defer l.Close()
 
 	// Search for the given username.
 	entry, err := b.searchUsername(l, username, b.attributeMapping.attributes())
@@ -431,7 +435,7 @@ func (b *LDAPIdentifierBackend) ResolveUserByUsername(ctx context.Context, usern
 	if err != nil {
 		return nil, fmt.Errorf("ldap identifier backend resolve connect error: %v", err)
 	}
-	defer l.Close()
+	//defer l.Close()
 
 	// Search for the given username.
 	entry, err := b.searchUsername(l, username, b.attributeMapping.attributes())
@@ -464,7 +468,7 @@ func (b *LDAPIdentifierBackend) GetUser(ctx context.Context, entryID string, ses
 	if err != nil {
 		return nil, fmt.Errorf("ldap identifier backend get user connect error: %v", err)
 	}
-	defer l.Close()
+	//defer l.Close()
 
 	entry, err := b.getUser(l, entryID, b.attributeMapping.attributes())
 	if err != nil {
@@ -518,6 +522,12 @@ func (b *LDAPIdentifierBackend) Name() string {
 }
 
 func (b *LDAPIdentifierBackend) connect(parentCtx context.Context) (*ldap.Conn, error) {
+	b.connLock.Lock()
+	defer b.connLock.Unlock()
+
+	if b.conn != nil && !b.conn.IsClosing() {
+		return b.conn, nil
+	}
 	// A timeout for waiting for a limiter slot. The timeout also includes the
 	// time to connect to the LDAP server which as a consequence means that both
 	// getting a free slot and establishing the connection are one timeout.
@@ -556,9 +566,10 @@ func (b *LDAPIdentifierBackend) connect(parentCtx context.Context) (*ldap.Conn,
 		if err != nil {
 			return nil, err
 		}
+		b.conn = l
 	}
 
-	return l, nil
+	return b.conn, nil
 }
 
 func (b *LDAPIdentifierBackend) searchUsername(l *ldap.Conn, username string, attributes []string) (*ldap.Entry, error) {