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plugin/forward: make Yield not block (#3336)

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* plugin/forward: may Yield not block

Yield may block when we're super busy with creating (and looking) for
connection. Set a small timeout on Yield, to skip putting the connection
back in the queue.

Use persistentConn troughout the socket handling code to be more
consistent.

Signed-off-by: Miek Gieben <miek@miek.nl>

Dont do

Signed-off-by: Miek Gieben <miek@miek.nl>

* Set used in Yield

This gives one central place where we update used in the persistConns

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2019-10-01 16:39:42 +01:00
committed by GitHub
parent 7b69dfebb5
commit 2d98d520b5
8 changed files with 53 additions and 105 deletions
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34
plugin/forward/connect.go
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@@ -44,17 +44,17 @@ func (t *Transport) updateDialTimeout(newDialTime time.Duration) {
}
// Dial dials the address configured in transport, potentially reusing a connection or creating a new one.
func (t *Transport) Dial(proto string) (*dns.Conn, bool, error) {
func (t *Transport) Dial(proto string) (*persistConn, bool, error) {
// If tls has been configured; use it.
if t.tlsConfig != nil {
proto = "tcp-tls"
}
t.dial <- proto
c := <-t.ret
pc := <-t.ret
if c != nil {
return c, true, nil
if pc != nil {
return pc, true, nil
}
reqTime := time.Now()
@@ -62,11 +62,11 @@ func (t *Transport) Dial(proto string) (*dns.Conn, bool, error) {
if proto == "tcp-tls" {
conn, err := dns.DialTimeoutWithTLS("tcp", t.addr, t.tlsConfig, timeout)
t.updateDialTimeout(time.Since(reqTime))
return conn, false, err
return &persistConn{c: conn}, false, err
}
conn, err := dns.DialTimeout(proto, t.addr, timeout)
t.updateDialTimeout(time.Since(reqTime))
return conn, false, err
return &persistConn{c: conn}, false, err
}
// Connect selects an upstream, sends the request and waits for a response.
@@ -83,20 +83,20 @@ func (p *Proxy) Connect(ctx context.Context, state request.Request, opts options
proto = state.Proto()
}
conn, cached, err := p.transport.Dial(proto)
pc, cached, err := p.transport.Dial(proto)
if err != nil {
return nil, err
}
// Set buffer size correctly for this client.
conn.UDPSize = uint16(state.Size())
if conn.UDPSize < 512 {
conn.UDPSize = 512
pc.c.UDPSize = uint16(state.Size())
if pc.c.UDPSize < 512 {
pc.c.UDPSize = 512
}
conn.SetWriteDeadline(time.Now().Add(maxTimeout))
if err := conn.WriteMsg(state.Req); err != nil {
conn.Close() // not giving it back
pc.c.SetWriteDeadline(time.Now().Add(maxTimeout))
if err := pc.c.WriteMsg(state.Req); err != nil {
pc.c.Close() // not giving it back
if err == io.EOF && cached {
return nil, ErrCachedClosed
}
@@ -104,11 +104,11 @@ func (p *Proxy) Connect(ctx context.Context, state request.Request, opts options
}
var ret *dns.Msg
conn.SetReadDeadline(time.Now().Add(readTimeout))
pc.c.SetReadDeadline(time.Now().Add(readTimeout))
for {
ret, err = conn.ReadMsg()
ret, err = pc.c.ReadMsg()
if err != nil {
conn.Close() // not giving it back
pc.c.Close() // not giving it back
if err == io.EOF && cached {
return nil, ErrCachedClosed
}
@@ -120,7 +120,7 @@ func (p *Proxy) Connect(ctx context.Context, state request.Request, opts options
}
}
p.transport.Yield(conn)
p.transport.Yield(pc)
rc, ok := dns.RcodeToString[ret.Rcode]
if !ok {