Try reconnect on EPIPE maybe fixes conn problems

internal/gncp/connection.go

@@ -15,7 +15,7 @@ type CpConn struct {
 // Destroy will close connection and release connection from connection pool.
 func (conn *CpConn) Destroy() error {
 	if conn.pool == nil {
-		return errors.New("Connection not belong any connection pool.")
+		return errors.New("Connection not belong any connection pool")
 	}
 	err := conn.pool.Remove(conn.Conn)
 	if err != nil {
@@ -28,7 +28,7 @@ func (conn *CpConn) Destroy() error {
 // Close will push connection back to connection pool. It will not close the real connection.
 func (conn *CpConn) Close() error {
 	if conn.pool == nil {
-		return errors.New("Connection not belong any connection pool.")
+		return errors.New("Connection not belong any connection pool")
 	}
 	return conn.pool.Put(conn.Conn)
 }

internal/gncp/pool.go

@@ -154,7 +154,7 @@ func (p *GncpPool) Put(conn net.Conn) error {
 		p.lock.Lock()
 		p.totalConnNum = p.totalConnNum - 1
 		p.lock.Unlock()
-		return errors.New("Cannot put nil to connection pool.")
+		return errors.New("Cannot put nil to connection pool")
 	}
 
 	select {

lql/client.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/gin-gonic/gin"
 	"github.com/webmeisterei/lql-api/internal/gncp"
@@ -170,13 +171,38 @@ func (c *Client) RequestRaw(context context.Context, request, outputFormat, auth
 	if err != nil {
 		return nil, err
 	}
-	defer c.pool.Put(conn)
 
 	c.logger.WithField("request", request).Debug("Writing request")
 	_, err = conn.Write([]byte(request))
-	if err != nil {
+	if err != nil && errors.Is(err, syscall.EPIPE) {
 		return nil, err
+	} else if errors.Is(err, syscall.EPIPE) {
+
+		// Destroy -> Create Connections until we don't get EPIPE.
+		numTries := 0
+		for errors.Is(err, syscall.EPIPE) {
+			conn.Close()
+			conn.(*gncp.CpConn).Destroy()
+
+			conn, err = c.pool.GetWithContext(context)
+			if err != nil {
+				return nil, err
+			}
+			conn.Close()
+
+			_, err = conn.Write([]byte(request))
+			if err != nil && errors.Is(err, syscall.EPIPE) {
+				return nil, err
+			}
+
+			numTries++
+			if numTries >= 20 {
+				// Bailout to much tries
+				return nil, err
+			}
+		}
 	}
+	defer conn.Close()
 
 	tmpBuff := make([]byte, 1024)
 	n, err := conn.Read(tmpBuff)