An experimental pub/sub client and server project.
publisher now attempts to reconnect if the server is down (#15)
authored by
GitHub
af1f01d5
d623d510
+52
-5
+47
-5
client/publisher.go
+47
-5
client/publisher.go
···
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"log/slog"
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"net"
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"sync"
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"syscall"
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"github.com/willdot/messagebroker/internal/server"
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)
···
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type Publisher struct {
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conn net.Conn
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connMu sync.Mutex
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addr string
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}
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// NewPublisher connects to the server at the given address and registers as a publisher
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func NewPublisher(addr string) (*Publisher, error) {
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conn, err := connect(addr)
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if err != nil {
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return nil, fmt.Errorf("failed to connect to server: %w", err)
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}
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return &Publisher{
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conn: conn,
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addr: addr,
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}, nil
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}
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func connect(addr string) (net.Conn, error) {
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conn, err := net.Dial("tcp", addr)
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if err != nil {
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return nil, fmt.Errorf("failed to dial: %w", err)
···
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conn.Close()
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return nil, fmt.Errorf("failed to register publish to server: %w", err)
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}
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return &Publisher{
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conn: conn,
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}, nil
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return conn, nil
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}
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// Close cleanly shuts down the publisher
···
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// Publish will publish the given message to the server
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func (p *Publisher) PublishMessage(message *Message) error {
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return p.publishMessageWithRetry(message, 0)
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}
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func (p *Publisher) publishMessageWithRetry(message *Message, attempt int) error {
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op := func(conn net.Conn) error {
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// send topic first
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topic := fmt.Sprintf("topic:%s", message.Topic)
···
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return nil
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}
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return p.connOperation(op)
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err := p.connOperation(op)
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if err == nil {
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return nil
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}
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// we can handle a broken pipe by trying to reconnect, but if it's a different error return it
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if !errors.Is(err, syscall.EPIPE) {
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return err
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}
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slog.Info("error is broken pipe")
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if attempt >= 5 {
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return fmt.Errorf("failed to publish message after max attempts to reconnect (%d): %w", attempt, err)
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}
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slog.Error("failed to publish message", "error", err)
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conn, connectErr := connect(p.addr)
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if connectErr != nil {
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return fmt.Errorf("failed to reconnect after failing to publish message: %w", connectErr)
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}
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p.conn = conn
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return p.publishMessageWithRetry(message, attempt+1)
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}
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func (p *Publisher) connOperation(op connOpp) error {
+1
client/subscriber.go
+1
client/subscriber.go
+4
example/main.go
+4
example/main.go