add LivelinessQuerier

examples/examples/z_querier_liveliness.rs

@@ -0,0 +1,75 @@
+//
+// Copyright (c) 2023 ZettaScale Technology
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+//
+// Contributors:
+//   ZettaScale Zenoh Team, <[email protected]>
+//
+use std::time::Duration;
+
+use clap::Parser;
+use tokio::time::sleep;
+use zenoh::{key_expr::KeyExpr, Config};
+use zenoh_examples::CommonArgs;
+
+#[tokio::main]
+async fn main() {
+    // initiate logging
+    zenoh::init_log_from_env_or("error");
+
+    let (config, key_expr, timeout) = parse_args();
+
+    println!("Opening session...");
+    let session = zenoh::open(config).await.unwrap();
+
+    println!("Declaring Liveliness Querier on '{}'...", &key_expr);
+    let querier = session
+        .liveliness()
+        .declare_querier(key_expr)
+        .timeout(timeout)
+        .await
+        .unwrap();
+
+    println!("Press CTRL-C to quit...");
+    loop {
+        println!("Sending Liveliness Query '{}'...", querier.key_expr());
+        let replies = querier.get().await.unwrap();
+        while let Ok(reply) = replies.recv_async().await {
+            match reply.result() {
+                Ok(sample) => println!(">> Alive token ('{}')", sample.key_expr().as_str(),),
+                Err(err) => {
+                    let payload = err
+                        .payload()
+                        .try_to_string()
+                        .unwrap_or_else(|e| e.to_string().into());
+                    println!(">> Received (ERROR: '{}')", payload);
+                }
+            }
+        }
+        sleep(Duration::from_secs(1)).await;
+    }
+}
+
+#[derive(Parser, Clone, Debug)]
+struct Args {
+    #[arg(short, long, default_value = "group1/**")]
+    /// The key expression matching liveliness tokens to query.
+    key_expr: KeyExpr<'static>,
+    #[arg(short = 'o', long, default_value = "10000")]
+    /// The query timeout in milliseconds.
+    timeout: u64,
+    #[command(flatten)]
+    common: CommonArgs,
+}
+
+fn parse_args() -> (Config, KeyExpr<'static>, Duration) {
+    let args = Args::parse();
+    let timeout = Duration::from_millis(args.timeout);
+    (args.common.into(), args.key_expr, timeout)
+}