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101 lines
3.0 KiB
101 lines
3.0 KiB
8 years ago
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// Copyright 2013-2014 Apcera Inc. All rights reserved.
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package nats
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import (
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"errors"
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"reflect"
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)
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// This allows the functionality for network channels by binding send and receive Go chans
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// to subjects and optionally queue groups.
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// Data will be encoded and decoded via the EncodedConn and its associated encoders.
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// BindSendChan binds a channel for send operations to NATS.
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func (c *EncodedConn) BindSendChan(subject string, channel interface{}) error {
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chVal := reflect.ValueOf(channel)
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if chVal.Kind() != reflect.Chan {
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return ErrChanArg
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}
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go chPublish(c, chVal, subject)
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return nil
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}
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// Publish all values that arrive on the channel until it is closed or we
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// encounter an error.
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func chPublish(c *EncodedConn, chVal reflect.Value, subject string) {
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for {
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val, ok := chVal.Recv()
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if !ok {
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// Channel has most likely been closed.
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return
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}
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if e := c.Publish(subject, val.Interface()); e != nil {
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// Do this under lock.
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c.Conn.mu.Lock()
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defer c.Conn.mu.Unlock()
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if c.Conn.Opts.AsyncErrorCB != nil {
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// FIXME(dlc) - Not sure this is the right thing to do.
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// FIXME(ivan) - If the connection is not yet closed, try to schedule the callback
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if c.Conn.isClosed() {
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go c.Conn.Opts.AsyncErrorCB(c.Conn, nil, e)
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} else {
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c.Conn.ach <- func() { c.Conn.Opts.AsyncErrorCB(c.Conn, nil, e) }
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}
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}
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return
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}
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}
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}
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// BindRecvChan binds a channel for receive operations from NATS.
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func (c *EncodedConn) BindRecvChan(subject string, channel interface{}) (*Subscription, error) {
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return c.bindRecvChan(subject, _EMPTY_, channel)
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}
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// BindRecvQueueChan binds a channel for queue-based receive operations from NATS.
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func (c *EncodedConn) BindRecvQueueChan(subject, queue string, channel interface{}) (*Subscription, error) {
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return c.bindRecvChan(subject, queue, channel)
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}
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// Internal function to bind receive operations for a channel.
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func (c *EncodedConn) bindRecvChan(subject, queue string, channel interface{}) (*Subscription, error) {
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chVal := reflect.ValueOf(channel)
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if chVal.Kind() != reflect.Chan {
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return nil, ErrChanArg
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}
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argType := chVal.Type().Elem()
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cb := func(m *Msg) {
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var oPtr reflect.Value
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if argType.Kind() != reflect.Ptr {
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oPtr = reflect.New(argType)
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} else {
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oPtr = reflect.New(argType.Elem())
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}
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if err := c.Enc.Decode(m.Subject, m.Data, oPtr.Interface()); err != nil {
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c.Conn.err = errors.New("nats: Got an error trying to unmarshal: " + err.Error())
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if c.Conn.Opts.AsyncErrorCB != nil {
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c.Conn.ach <- func() { c.Conn.Opts.AsyncErrorCB(c.Conn, m.Sub, c.Conn.err) }
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}
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return
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}
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if argType.Kind() != reflect.Ptr {
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oPtr = reflect.Indirect(oPtr)
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}
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// This is a bit hacky, but in this instance we may be trying to send to a closed channel.
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// and the user does not know when it is safe to close the channel.
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defer func() {
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// If we have panicked, recover and close the subscription.
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if r := recover(); r != nil {
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m.Sub.Unsubscribe()
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}
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}()
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// Actually do the send to the channel.
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chVal.Send(oPtr)
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}
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return c.Conn.subscribe(subject, queue, cb, nil)
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}
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