Struct cadence::BufferedUnixMetricSink

pub struct BufferedUnixMetricSink { /* private fields */ }

Implementation of a MetricSink that buffers metrics before sending them to a Unix socket.

Metrics are line buffered, meaning that a trailing “\n” is added after each metric written to this sink. When the buffer is sufficiently full and a write is attempted, the contents of the buffer are flushed to a Unix socket and then the metric is written to the buffer. The buffer is also flushed when this sink is destroyed.

The default size of the buffer is 512 bytes. This is to be consistent with the default for the BufferedUdpMetricSink. The buffer size can be customized using the with_capacity method to create the sink if desired.

If a metric larger than the buffer is emitted, it will be written directly to the underlying Unix socket, bypassing the buffer.

Note that since metrics are buffered until a certain size is reached, it’s possible that they may sit in the buffer for a while for applications that do not emit metrics frequently or at a high volume. For these low- throughput use cases, it may make more sense to use the UnixMetricSink since it sends metrics immediately with no buffering.

Also note that unlike the UDP sinks, if there is no receiving socket at the path specified or nothing listening at the path, an error will be returned when metrics are emitted (though this may not happen on every write due to buffering).

Implementations

impl BufferedUnixMetricSink

pub fn from<P>(path: P, socket: UnixDatagram) -> BufferedUnixMetricSink

where P: AsRef<Path>,

Construct a new BufferedUnixMetricSink instance with a default buffer size of 512 bytes.

The socket does not need to be bound (i.e. UnixDatagram::unbound() is fine) but should have any desired configuration already applied (blocking vs non-blocking, timeouts, etc.).

Writes to this sink are automatically suffixed with a Unix newline (‘\n’) by the sink and stored in a 512 byte buffer until the buffer is full or this sink is destroyed, at which point the buffer will be flushed.

Example

use std::os::unix::net::UnixDatagram;
use cadence::BufferedUnixMetricSink;

let socket = UnixDatagram::unbound().unwrap();
let sink = BufferedUnixMetricSink::from("/run/statsd.sock", socket);

pub fn with_capacity<P>( path: P, socket: UnixDatagram, cap: usize ) -> BufferedUnixMetricSink

where P: AsRef<Path>,

Construct a new BufferedUnixMetricSink instance with a custom buffer size.

The socket does not need to be bound (i.e. UnixDatagram::unbound() is fine) but should have with any desired configuration already applied (blocking vs non-blocking, timeouts, etc.).

Writes to this sink are automatically suffixed with a Unix newline (‘\n’) by the sink and stored in a buffer until the buffer is full or this sink is destroyed, at which point the buffer will be flushed.

Example

use std::os::unix::net::UnixDatagram;
use cadence::BufferedUnixMetricSink;

let socket = UnixDatagram::unbound().unwrap();
let sink = BufferedUnixMetricSink::with_capacity("/run/statsd.sock", socket, 1432);

Trait Implementations

impl Debug for BufferedUnixMetricSink

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl MetricSink for BufferedUnixMetricSink

fn emit(&self, metric: &str) -> Result<usize>

Send the Statsd metric using this sink and return the number of bytes written or an I/O error.

fn flush(&self) -> Result<()>

Flush any currently buffered metrics to the underlying backend, returning an I/O error if they could not be written for some reason.

fn stats(&self) -> SinkStats

Return I/O telemetry like bytes / packets sent or dropped.