golang tcp set timeout

golang tcp setting timeout

When using golang to write tcp network applications, if the timeout is not set, the network connection may be stuck for a long time, thereby affecting the performance and stability of the program. Therefore, in the golang tcp network programming process, it is also particularly important to set the timeout reasonably. This article will introduce how to set tcp timeout in golang to improve the reliability and stability of the program.

1. Set tcp connection timeout

1. DialTimeout and Dialer

There are two ways to set tcp connection timeout in golang: use DialTimeout or use Dialer . Among them, DialTimeout is a simplified version of Dialer.

The DialTimeout function is defined as follows:

func DialTimeout(network, address string, timeout time.Duration) (Conn, error)

The third parameter timeout specifies the connection timeout. If the connection is not established within this time, an error message will be returned.

Dialer can set the timeout more flexibly, which is defined as follows:

type Dialer struct {
    Timeout       time.Duration
    KeepAlive     time.Duration
    Resolver      *Resolver
    DualStack     bool
    FallbackDelay time.Duration
    Control       func(network, address string, c syscall.RawConn) error
}

Dialer's Timeout property is similar to the timeout parameter of the DialTimeout function, but is more flexible and can dynamically set the timeout.

2. Usage example

The following is an example of using the DialTimeout function to set the tcp connection timeout:

conn, err := net.DialTimeout("tcp", "127.0.0.1:9000", 3*time.Second)
if err != nil {
    fmt.Println("failed to connect:", err)
    return
}
defer conn.Close()

In the above code, the third parameter of the DialTimeout function 3*time.Second specifies a connection timeout of 3 seconds. If the connection is not established within this time, an error message will be returned.

If you use Dialer to implement tcp connection timeout, you can do this:

dialer := &net.Dialer{
    Timeout: 3 * time.Second,
}
conn, err := dialer.Dial("tcp", "127.0.0.1:9000")
if err != nil {
    fmt.Println("failed to connect:", err)
    return
}
defer conn.Close()

In the above code, the Dialer object dialer is used to set the connection timeout to 3 seconds, and through the dialer.Dial function to establish a tcp connection. If the connection is not established within 3 seconds, an error message will be returned.

2. Set tcp read and write timeout

After establishing a tcp connection, you also need to set the read and write timeout to avoid long waits or slow responses. The net package in golang provides SetReadDeadline and SetWriteDeadline functions for Conn to set read and write timeouts.

1. SetReadDeadline

The SetReadDeadline function is used to set the tcp read timeout. It is defined as:

func (c *TCPConn) SetReadDeadline(t time.Time) error

The parameter t of this function represents the set read timeout. If no data is received within this time, an error message will be returned.

Usage example:

conn, err := net.DialTimeout("tcp", "127.0.0.1:9000", 3*time.Second)
if err != nil {
    fmt.Println("failed to connect:", err)
    return
}
defer conn.Close()

_, err = conn.Write([]byte("hello"))
if err != nil {
    fmt.Println("failed to write:", err)
    return
}

if err = conn.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil {
    fmt.Println("failed to set read deadline:", err)
}

buf := make([]byte, 1024)
n, err := conn.Read(buf)
if err != nil {
    fmt.Println("failed to read:", err)
    return
}
fmt.Println(string(buf[:n]))

In the above code, the tcp read timeout is set to 3 seconds through the conn.SetReadDeadline function. If the connection does not receive data within this time, a will be returned. Timeout error message.

2. SetWriteDeadline

The SetWriteDeadline function is used to set the tcp write timeout. It is defined as:

func (c *TCPConn) SetWriteDeadline(t time.Time) error

The parameter t of this function represents the set write timeout time. If the data is not sent within this time, an error message will be returned.

Usage example:

conn, err := net.DialTimeout("tcp", "127.0.0.1:9000", 3*time.Second)
if err != nil {
    fmt.Println("failed to connect:", err)
    return
}
defer conn.Close()

if err = conn.SetWriteDeadline(time.Now().Add(3 * time.Second)); err != nil {
    fmt.Println("failed to set write deadline:", err)
}

_, err = conn.Write([]byte("hello"))
if err != nil {
    fmt.Println("failed to write:", err)
    return
}

In the above code, the tcp write timeout is set to 3 seconds through the conn.SetWriteDeadline function. If the connection does not finish sending data within this time, a will be returned. Timeout error message.

3. Reference link

1. net.Dialer: https://golang.org/pkg/net/#Dialer
2. net.Conn.SetReadDeadline: https ://golang.org/pkg/net/#Conn.SetReadDeadline
3. net.Conn.SetWriteDeadline: https://golang.org/pkg/net/#Conn.SetWriteDeadline
4. Golang TCP Client Example: https://www.linode.com/docs/guides/developing-udp-and-tcp-clients-and-servers-in-go/#golang-tcp-client-example

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