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//! Example of how to implement `KV` for a struct
//! to conveniently log data associated with it.
#[macro_use]
extern crate slog;
use slog::*;
mod common;
struct Peer {
host: String,
port: u32,
}
impl Peer {
fn new(host: String, port: u32) -> Self {
Peer {
host: host,
port: port,
}
}
}
// `KV` can be implemented for a struct
impl KV for Peer {
fn serialize(&self, _record: &Record, serializer: &mut Serializer) -> Result {
serializer.emit_u32(Key::from("peer-port"), self.port)?;
serializer.emit_str(Key::from("peer-host"), &self.host)?;
Ok(())
}
}
struct Server {
_host: String,
_port: u32,
// One approach is to create new `Logger` with struct data
// and embedded it into struct itself. This works when struct is mostly
// immutable.
log: Logger,
}
impl Server {
fn new(host: String, port: u32, log: Logger) -> Server {
let log = log.new(o!("server-host" => host.clone(), "server-port" => port));
Server {
_host: host,
_port: port,
log: log,
}
}
fn connection(&self, peer: &Peer) {
// Another approach is to add struct to a logging message when it's
// necessary. This might be necessary when struct data can change
// between different logging statements (not the case here for `Peer`).
info!(self.log, "new connection"; peer);
}
}
struct PeerCounter {
count: usize,
log: Logger,
}
impl PeerCounter {
fn new(log: Logger) -> Self {
PeerCounter { count: 0, log: log }
}
// A hybrid approach with `Logger` with parent logging-context embedded into
// a `struct` and a helper function adding mutable fields.
fn log_info(&self, msg: &str, kv: BorrowedKV) {
info!(self.log, "{}", msg; "current-count" => self.count, kv);
}
fn count(&mut self, peer: &Peer) {
self.count += 1;
self.log_info("counted peer", b!(peer));
}
}
fn main() {
let log = Logger::root(Fuse(common::PrintlnDrain), o!("build-id" => "7.3.3-abcdef"));
let server = Server::new("localhost".into(), 12345, log.clone());
let peer = Peer::new("1.2.3.4".into(), 999);
server.connection(&peer);
let mut counter = PeerCounter::new(log);
counter.count(&peer);
}
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