Fast and extensible multi-platform HTTP/1-2-3 web server with automatic HTTPS
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Synced Nov 14, 05:15 UTC
logging: Net writer redials if write fails (#3453)
* logging: Net writer redials if write fails https://caddy.community/t/v2-log-output-net-does-not-reconnect-after-lost-connection/8386?u=matt * Only replace connection if redial succeeds * Fix error handling
Matt Holt committed
May 28, 2020 at 10:40 UTC
9415feca7cf0fe14b9d881c7318be2da20b2985f
1 file changed
+55
-1
modules/logging/netwriter.go
+55
-1
@@ -18,6 +18,7 @@ import (
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"fmt"
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"io"
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"net"
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+ "sync"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
@@ -73,7 +74,15 @@ func (nw NetWriter) WriterKey() string {
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// OpenWriter opens a new network connection.
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func (nw NetWriter) OpenWriter() (io.WriteCloser, error) {
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- return net.Dial(nw.addr.Network, nw.addr.JoinHostPort(0))
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+ reconn := &redialerConn{nw: nw}
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+ conn, err := reconn.dial()
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+ if err != nil {
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+ return nil, err
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+ }
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+ reconn.connMu.Lock()
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+ reconn.Conn = conn
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+ reconn.connMu.Unlock()
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+ return reconn, nil
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}
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// UnmarshalCaddyfile sets up the handler from Caddyfile tokens. Syntax:
@@ -93,6 +102,51 @@ func (nw *NetWriter) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
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return nil
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}
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+// redialerConn wraps an underlying Conn so that if any
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+// writes fail, the connection is redialed and the write
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+// is retried.
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+type redialerConn struct {
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+ net.Conn
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+ connMu sync.RWMutex
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+ nw NetWriter
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+}
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+
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+// Write wraps the underlying Conn.Write method, but if that fails,
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+// it will re-dial the connection anew and try writing again.
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+func (reconn *redialerConn) Write(b []byte) (n int, err error) {
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+ reconn.connMu.RLock()
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+ conn := reconn.Conn
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+ reconn.connMu.RUnlock()
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+ if n, err = conn.Write(b); err == nil {
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+ return
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+ }
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+
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+ // problem with the connection - lock it and try to fix it
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+ reconn.connMu.Lock()
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+ defer reconn.connMu.Unlock()
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+
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+ // if multiple concurrent writes failed on the same broken conn, then
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+ // one of them might have already re-dialed by now; try writing again
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+ if n, err = reconn.Conn.Write(b); err == nil {
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+ return
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+ }
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+
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+ // we're the lucky first goroutine to re-dial the connection
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+ conn2, err2 := reconn.dial()
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+ if err2 != nil {
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+ return
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+ }
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+ if n, err = conn2.Write(b); err == nil {
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+ reconn.Conn.Close()
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+ reconn.Conn = conn2
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+ }
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+ return
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+}
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+
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+func (reconn *redialerConn) dial() (net.Conn, error) {
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+ return net.Dial(reconn.nw.addr.Network, reconn.nw.addr.JoinHostPort(0))
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+}
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+
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// Interface guards
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var (
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_ caddy.Provisioner = (*NetWriter)(nil)