package consul import ( "container/list" "crypto/tls" "fmt" "io" "net" "net/rpc" "sync" "sync/atomic" "time" "github.com/hashicorp/go-msgpack/codec" "github.com/hashicorp/yamux" "github.com/inconshreveable/muxado" ) // msgpackHandle is a shared handle for encoding/decoding of RPC messages var msgpackHandle = &codec.MsgpackHandle{} // muxSession is used to provide an interface for either muxado or yamux type muxSession interface { Open() (net.Conn, error) Close() error } type muxadoWrapper struct { m muxado.Session } func (w *muxadoWrapper) Open() (net.Conn, error) { return w.m.Open() } func (w *muxadoWrapper) Close() error { return w.m.Close() } // streamClient is used to wrap a stream with an RPC client type StreamClient struct { stream net.Conn client *rpc.Client } // Conn is a pooled connection to a Consul server type Conn struct { refCount int32 shouldClose int32 addr net.Addr session muxSession lastUsed time.Time version int pool *ConnPool clients *list.List clientLock sync.Mutex } func (c *Conn) Close() error { return c.session.Close() } // getClient is used to get a cached or new client func (c *Conn) getClient() (*StreamClient, error) { // Check for cached client c.clientLock.Lock() front := c.clients.Front() if front != nil { c.clients.Remove(front) } c.clientLock.Unlock() if front != nil { return front.Value.(*StreamClient), nil } // Open a new session stream, err := c.session.Open() if err != nil { return nil, err } // Create the RPC client cc := codec.GoRpc.ClientCodec(stream, msgpackHandle) client := rpc.NewClientWithCodec(cc) // Return a new stream client sc := &StreamClient{ stream: stream, client: client, } return sc, nil } // returnStream is used when done with a stream // to allow re-use by a future RPC func (c *Conn) returnClient(client *StreamClient) { didSave := false c.clientLock.Lock() if c.clients.Len() < c.pool.maxStreams && atomic.LoadInt32(&c.shouldClose) == 0 { c.clients.PushFront(client) didSave = true } c.clientLock.Unlock() if !didSave { client.stream.Close() } } // ConnPool is used to maintain a connection pool to other // Consul servers. This is used to reduce the latency of // RPC requests between servers. It is only used to pool // connections in the rpcConsul mode. Raft connections // are pooled seperately. type ConnPool struct { sync.Mutex // LogOutput is used to control logging logOutput io.Writer // The maximum time to keep a connection open maxTime time.Duration // The maximum number of open streams to keep maxStreams int // Pool maps an address to a open connection pool map[string]*Conn // TLS settings tlsConfig *tls.Config // Used to indicate the pool is shutdown shutdown bool shutdownCh chan struct{} } // NewPool is used to make a new connection pool // Maintain at most one connection per host, for up to maxTime. // Set maxTime to 0 to disable reaping. maxStreams is used to control // the number of idle streams allowed. // If TLS settings are provided outgoing connections use TLS. func NewPool(logOutput io.Writer, maxTime time.Duration, maxStreams int, tlsConfig *tls.Config) *ConnPool { pool := &ConnPool{ logOutput: logOutput, maxTime: maxTime, maxStreams: maxStreams, pool: make(map[string]*Conn), tlsConfig: tlsConfig, shutdownCh: make(chan struct{}), } if maxTime > 0 { go pool.reap() } return pool } // Shutdown is used to close the connection pool func (p *ConnPool) Shutdown() error { p.Lock() defer p.Unlock() for _, conn := range p.pool { conn.Close() } p.pool = make(map[string]*Conn) if p.shutdown { return nil } p.shutdown = true close(p.shutdownCh) return nil } // Acquire is used to get a connection that is // pooled or to return a new connection func (p *ConnPool) acquire(addr net.Addr, version int) (*Conn, error) { // Check for a pooled ocnn if conn := p.getPooled(addr, version); conn != nil { return conn, nil } // Create a new connection return p.getNewConn(addr, version) } // getPooled is used to return a pooled connection func (p *ConnPool) getPooled(addr net.Addr, version int) *Conn { p.Lock() c := p.pool[addr.String()] if c != nil { c.lastUsed = time.Now() atomic.AddInt32(&c.refCount, 1) } p.Unlock() return c } // getNewConn is used to return a new connection func (p *ConnPool) getNewConn(addr net.Addr, version int) (*Conn, error) { // Try to dial the conn conn, err := net.DialTimeout("tcp", addr.String(), 10*time.Second) if err != nil { return nil, err } // Cast to TCPConn if tcp, ok := conn.(*net.TCPConn); ok { tcp.SetKeepAlive(true) tcp.SetNoDelay(true) } // Check if TLS is enabled if p.tlsConfig != nil { // Switch the connection into TLS mode if _, err := conn.Write([]byte{byte(rpcTLS)}); err != nil { conn.Close() return nil, err } // Wrap the connection in a TLS client tlsConn, err := wrapTLSClient(conn, p.tlsConfig) if err != nil { conn.Close() return nil, err } conn = tlsConn } // Switch the multiplexing based on version var session muxSession if version < 2 { // Write the Consul multiplex byte to set the mode if _, err := conn.Write([]byte{byte(rpcMultiplex)}); err != nil { conn.Close() return nil, err } // Create a multiplexed session session = &muxadoWrapper{muxado.Client(conn)} } else { // Write the Consul multiplex byte to set the mode if _, err := conn.Write([]byte{byte(rpcMultiplexV2)}); err != nil { conn.Close() return nil, err } // Setup the logger conf := yamux.DefaultConfig() conf.LogOutput = p.logOutput // Create a multiplexed session session, _ = yamux.Client(conn, conf) } // Wrap the connection c := &Conn{ refCount: 1, addr: addr, session: session, clients: list.New(), lastUsed: time.Now(), version: version, pool: p, } // Track this connection, handle potential race condition p.Lock() if existing := p.pool[addr.String()]; existing != nil { c.Close() p.Unlock() return existing, nil } else { p.pool[addr.String()] = c p.Unlock() return c, nil } } // clearConn is used to clear any cached connection, potentially in response to an erro func (p *ConnPool) clearConn(conn *Conn) { // Ensure returned streams are closed atomic.StoreInt32(&conn.shouldClose, 1) // Clear from the cache p.Lock() if c, ok := p.pool[conn.addr.String()]; ok && c == conn { delete(p.pool, conn.addr.String()) } p.Unlock() // Close down immediately if idle if refCount := atomic.LoadInt32(&conn.refCount); refCount == 0 { conn.Close() } } // releaseConn is invoked when we are done with a conn to reduce the ref count func (p *ConnPool) releaseConn(conn *Conn) { refCount := atomic.AddInt32(&conn.refCount, -1) if refCount == 0 && atomic.LoadInt32(&conn.shouldClose) == 1 { conn.Close() } } // getClient is used to get a usable client for an address and protocol version func (p *ConnPool) getClient(addr net.Addr, version int) (*Conn, *StreamClient, error) { retries := 0 START: // Try to get a conn first conn, err := p.acquire(addr, version) if err != nil { return nil, nil, fmt.Errorf("failed to get conn: %v", err) } // Get a client client, err := conn.getClient() if err != nil { p.clearConn(conn) p.releaseConn(conn) // Try to redial, possible that the TCP session closed due to timeout if retries == 0 { retries++ goto START } return nil, nil, fmt.Errorf("failed to start stream: %v", err) } return conn, client, nil } // RPC is used to make an RPC call to a remote host func (p *ConnPool) RPC(addr net.Addr, version int, method string, args interface{}, reply interface{}) error { // Get a usable client conn, sc, err := p.getClient(addr, version) if err != nil { return fmt.Errorf("rpc error: %v", err) } // Make the RPC call err = sc.client.Call(method, args, reply) if err != nil { p.clearConn(conn) p.releaseConn(conn) return fmt.Errorf("rpc error: %v", err) } // Done with the connection conn.returnClient(sc) p.releaseConn(conn) return nil } // Reap is used to close conns open over maxTime func (p *ConnPool) reap() { for !p.shutdown { // Sleep for a while select { case <-time.After(time.Second): case <-p.shutdownCh: return } // Reap all old conns p.Lock() var removed []string now := time.Now() for host, conn := range p.pool { // Skip recently used connections if now.Sub(conn.lastUsed) < p.maxTime { continue } // Skip connections with active streams if atomic.LoadInt32(&conn.refCount) > 0 { continue } // Close the conn conn.Close() // Remove from pool removed = append(removed, host) } for _, host := range removed { delete(p.pool, host) } p.Unlock() } }