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// Copyright 2018 Google LLC
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.

use std::env;
use tracing_subscriber::{fmt::format::FmtSpan, prelude::*};

/// This is the service definition. It looks a lot like a trait definition.
/// It defines one RPC, hello, which takes one arg, name, and returns a String.
#[tarpc::service]
pub trait World {
    /// Returns a greeting for name.
    async fn hello(name: String) -> String;
}

/// Initializes an OpenTelemetry tracing subscriber with a Jaeger backend.
pub fn init_tracing(service_name: &str) -> anyhow::Result<()> {
    env::set_var("OTEL_BSP_MAX_EXPORT_BATCH_SIZE", "12");

    let tracer = opentelemetry_jaeger::new_pipeline()
        .with_service_name(service_name)
        .with_max_packet_size(2usize.pow(13))
        .install_batch(opentelemetry::runtime::Tokio)?;

    tracing_subscriber::registry()
        .with(tracing_subscriber::EnvFilter::from_default_env())
        .with(tracing_subscriber::fmt::layer().with_span_events(FmtSpan::NEW | FmtSpan::CLOSE))
        .with(tracing_opentelemetry::layer().with_tracer(tracer))
        .try_init()?;

    Ok(())
}