diff options
Diffstat (limited to 'modules/logging')
-rw-r--r-- | modules/logging/netwriter.go | 56 |
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) |