tracing-flat-json 0.1.1

use std::future::Future;

use opentelemetry::trace::TracerProvider;
use opentelemetry_sdk::error::OTelSdkResult;
use opentelemetry_sdk::trace::{SdkTracerProvider, SpanData, SpanExporter};
use tracing::{info, info_span};
use tracing_flat_json::FlatJsonLayer;
use tracing_subscriber::filter::LevelFilter;
use tracing_subscriber::layer::SubscriberExt;
use tracing_subscriber::util::SubscriberInitExt;

#[derive(Debug)]
struct NullExporter;

impl SpanExporter for NullExporter {
    fn export(&self, _batch: Vec<SpanData>) -> impl Future<Output = OTelSdkResult> + Send {
        std::future::ready(Ok(()))
    }
}

fn main() {
    tracing_subscriber::Registry::default()
        .with(LevelFilter::DEBUG)
        .with(FlatJsonLayer::new(std::io::stdout))
        .with({
            let provider = SdkTracerProvider::builder()
                .with_simple_exporter(NullExporter)
                .build();
            tracing_opentelemetry::layer().with_tracer(provider.tracer(env!("CARGO_PKG_NAME")))
        })
        .init();
    info!("tracing initialized");

    // Demonstrate external crate output.
    let _ = info_span!("external crate").in_scope(|| ureq::get("https://google.com").call());

    // Demonstrate span behavior.
    info!(first_event_field = 1, "no spans");
    let g1 = info_span!("first span", first_span_field = 1, dup_field = 1).entered();
    info!(second_event_field = 2, "one span");
    let g2 = info_span!("second span", second_span_field = 2, dup_field = 2).entered();
    info!(third_event_field = 3, "two spans");
    let g3 = info_span!("third span", third_span_field = 3, dup_field = 3).entered();
    info!(fourth_event_field = 4, "three spans");
    info!(dup_field = 4, "dup field");
    drop(g3);
    info!("two spans");
    drop(g2);
    info!("one span");
    drop(g1);
    info!("no spans");
}