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-rw-r--r--modules/logging/netwriter.go56
1 files changed, 55 insertions, 1 deletions
diff --git a/modules/logging/netwriter.go b/modules/logging/netwriter.go
index 427bb75..a25ede7 100644
--- a/modules/logging/netwriter.go
+++ b/modules/logging/netwriter.go
@@ -18,6 +18,7 @@ import (
"fmt"
"io"
"net"
+ "sync"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
@@ -73,7 +74,15 @@ func (nw NetWriter) WriterKey() string {
// OpenWriter opens a new network connection.
func (nw NetWriter) OpenWriter() (io.WriteCloser, error) {
- return net.Dial(nw.addr.Network, nw.addr.JoinHostPort(0))
+ reconn := &redialerConn{nw: nw}
+ conn, err := reconn.dial()
+ if err != nil {
+ return nil, err
+ }
+ reconn.connMu.Lock()
+ reconn.Conn = conn
+ reconn.connMu.Unlock()
+ return reconn, nil
}
// UnmarshalCaddyfile sets up the handler from Caddyfile tokens. Syntax:
@@ -93,6 +102,51 @@ func (nw *NetWriter) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
return nil
}
+// redialerConn wraps an underlying Conn so that if any
+// writes fail, the connection is redialed and the write
+// is retried.
+type redialerConn struct {
+ net.Conn
+ connMu sync.RWMutex
+ nw NetWriter
+}
+
+// Write wraps the underlying Conn.Write method, but if that fails,
+// it will re-dial the connection anew and try writing again.
+func (reconn *redialerConn) Write(b []byte) (n int, err error) {
+ reconn.connMu.RLock()
+ conn := reconn.Conn
+ reconn.connMu.RUnlock()
+ if n, err = conn.Write(b); err == nil {
+ return
+ }
+
+ // problem with the connection - lock it and try to fix it
+ reconn.connMu.Lock()
+ defer reconn.connMu.Unlock()
+
+ // if multiple concurrent writes failed on the same broken conn, then
+ // one of them might have already re-dialed by now; try writing again
+ if n, err = reconn.Conn.Write(b); err == nil {
+ return
+ }
+
+ // we're the lucky first goroutine to re-dial the connection
+ conn2, err2 := reconn.dial()
+ if err2 != nil {
+ return
+ }
+ if n, err = conn2.Write(b); err == nil {
+ reconn.Conn.Close()
+ reconn.Conn = conn2
+ }
+ return
+}
+
+func (reconn *redialerConn) dial() (net.Conn, error) {
+ return net.Dial(reconn.nw.addr.Network, reconn.nw.addr.JoinHostPort(0))
+}
+
// Interface guards
var (
_ caddy.Provisioner = (*NetWriter)(nil)