internal: copy opts on Connect

The copy is not an honest deepcopy because, for example, copying logger
or channel will break the logic.

Part of #120

Author: DifferentialOrange

Diff for: connection.go

@@ -293,6 +293,14 @@ type SslOpts struct {
 	Ciphers string
 }
 
+// Copy returns the copy of an Opts object.
+// Beware that Notify channel, Logger and Handle are not copied.
+func (opts Opts) Copy() Opts {
+	optsCopy := opts
+
+	return optsCopy
+}
+
 // Connect creates and configures a new Connection.
 //
 // Address could be specified in following ways:
@@ -319,7 +327,7 @@ func Connect(addr string, opts Opts) (conn *Connection, err error) {
 		contextRequestId: 1,
 		Greeting:         &Greeting{},
 		control:          make(chan struct{}),
-		opts:             opts,
+		opts:             opts.Copy(),
 		dec:              newDecoder(&smallBuf{}),
 	}
 	maxprocs := uint32(runtime.GOMAXPROCS(-1))
@@ -344,9 +352,9 @@ func Connect(addr string, opts Opts) (conn *Connection, err error) {
 		}
 	}
 
-	if opts.RateLimit > 0 {
-		conn.rlimit = make(chan struct{}, opts.RateLimit)
-		if opts.RLimitAction != RLimitDrop && opts.RLimitAction != RLimitWait {
+	if conn.opts.RateLimit > 0 {
+		conn.rlimit = make(chan struct{}, conn.opts.RateLimit)
+		if conn.opts.RLimitAction != RLimitDrop && conn.opts.RLimitAction != RLimitWait {
 			return nil, errors.New("RLimitAction should be specified to RLimitDone nor RLimitWait")
 		}
 	}

Diff for: connection_pool/connection_pool.go

@@ -125,7 +125,7 @@ func ConnectWithOpts(addrs []string, connOpts tarantool.Opts, opts OptsPool) (co
 
 	connPool = &ConnectionPool{
 		addrs:    make([]string, 0, len(addrs)),
-		connOpts: connOpts,
+		connOpts: connOpts.Copy(),
 		opts:     opts,
 		state:    unknownState,
 		done:     make(chan struct{}),

Diff for: multi/multi.go

@@ -88,7 +88,7 @@ func ConnectWithOpts(addrs []string, connOpts tarantool.Opts, opts OptsMulti) (c
 	connOpts.Notify = notify
 	connMulti = &ConnectionMulti{
 		addrs:    addrs,
-		connOpts: connOpts,
+		connOpts: connOpts.Copy(),
 		opts:     opts,
 		notify:   notify,
 		control:  make(chan struct{}),