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Package latency

Variables

var (
    //Local simulates local network.
    Local = Network{0, 0, 0}
    //LAN simulates local area network network.
    LAN = Network{100 * 1024, 2 * time.Millisecond, 1500}
    //WAN simulates wide area network.
    WAN = Network{20 * 1024, 30 * time.Millisecond, 1500}
    //Longhaul simulates bad network.
    Longhaul = Network{1000 * 1024, 200 * time.Millisecond, 9000}
)

type ContextDialer ¶

ContextDialer is a function matching the signature of net.Dialer.DialContext.

type ContextDialer func(ctx context.Context, network, address string) (net.Conn, error)

type Dialer ¶

Dialer is a function matching the signature of net.Dial.

type Dialer func(network, address string) (net.Conn, error)

type Network ¶

Network represents a network with the given bandwidth, latency, and MTU (Maximum Transmission Unit) configuration, and can produce wrappers of net.Listeners, net.Conn, and various forms of dialing functions. The Listeners and Dialers/Conns on both sides of connections must come from this package, but need not be created from the same Network. Latency is computed when sending (in Write), and is injected when receiving (in Read). This allows senders' Write calls to be non-blocking, as in real-world applications.

Note: Latency is injected by the sender specifying the absolute time data should be available, and the reader delaying until that time arrives to provide the data. This package attempts to counter-act the effects of clock drift and existing network latency by measuring the delay between the sender's transmission time and the receiver's reception time during startup. No attempt is made to measure the existing bandwidth of the connection.

type Network struct {
    Kbps    int           // Kilobits per second; if non-positive, infinite
    Latency time.Duration // One-way latency (sending); if non-positive, no delay
    MTU     int           // Bytes per packet; if non-positive, infinite
}

func (*Network) Conn ¶

func (n *Network) Conn(c net.Conn) (net.Conn, error)

Conn returns a net.Conn that wraps c and injects n's latency into that connection. This function also imposes latency for connection creation. If n's Latency is lower than the measured latency in c, an error is returned.

func (*Network) ContextDialer ¶

func (n *Network) ContextDialer(d ContextDialer) ContextDialer

ContextDialer returns a ContextDialer that wraps d and injects n's latency in its connections. n's Latency is also injected to the connection's creation.

func (*Network) Dialer ¶

func (n *Network) Dialer(d Dialer) Dialer

Dialer returns a Dialer that wraps d and injects n's latency in its connections. n's Latency is also injected to the connection's creation.

func (*Network) Listener ¶

func (n *Network) Listener(l net.Listener) net.Listener

Listener returns a net.Listener that wraps l and injects n's latency in its connections.

func (*Network) TimeoutDialer ¶

func (n *Network) TimeoutDialer(d TimeoutDialer) TimeoutDialer

TimeoutDialer returns a TimeoutDialer that wraps d and injects n's latency in its connections. n's Latency is also injected to the connection's creation.

type TimeoutDialer ¶

TimeoutDialer is a function matching the signature of net.DialTimeout.

type TimeoutDialer func(network, address string, timeout time.Duration) (net.Conn, error)