Create a check mc command for testing connections to a server

Fixes #82

CHANGELOG.md

@@ -3,6 +3,8 @@
 ## v0.7.0 - unreleased
 
 - Build binaries for Linux Musl libc target. #83
+- Move "Bytes tx" under "Gets" and "Bytes rx" under "Sets". #84
+- Create a `check` subcommand for `mc` to test connections to a server. #86
 
 ## v0.6.9 - 2023-10-11
 

mtop/src/bin/mc.rs

@@ -1,9 +1,9 @@
 use clap::{Args, Parser, Subcommand, ValueHint};
+use mtop::check::{Checker, MeasurementBundle};
 use mtop_client::{MemcachedPool, Meta, PoolConfig, TLSConfig, Value};
-use std::error;
-use std::io;
 use std::path::PathBuf;
-use std::{env, process};
+use std::time::Duration;
+use std::{env, error, io, process};
 use tokio::io::{AsyncReadExt, AsyncWriteExt, BufReader, BufWriter};
 use tokio::runtime::Handle;
 use tracing::Level;
@@ -59,6 +59,23 @@ enum Action {
     Keys(KeysCommand),
     Set(SetCommand),
     Touch(TouchCommand),
+    Check(CheckCommand),
+}
+
+/// Run health checks against the cache.
+#[derive(Debug, Args)]
+struct CheckCommand {
+    /// How long to run the checks for in seconds.
+    #[arg(long, default_value_t = 60)]
+    time_secs: u64,
+
+    /// Timeout for each portion of the check (DNS, connection, set, get) in seconds.
+    #[arg(long, default_value_t = 5)]
+    timeout_secs: u64,
+
+    /// How long to wait between each health check in milliseconds.
+    #[arg(long, default_value_t = 100)]
+    delay_millis: u64,
 }
 
 /// Delete an item in the cache.
@@ -153,6 +170,17 @@ async fn main() -> Result<(), Box<dyn error::Error + Send + Sync>> {
     });
 
     match opts.mode {
+        Action::Check(c) => {
+            let checker = Checker::new(
+                &pool,
+                Duration::from_millis(c.delay_millis),
+                Duration::from_secs(c.timeout_secs),
+            );
+            let results = checker.run(&opts.host, Duration::from_secs(c.time_secs)).await;
+            if let Err(e) = print_check_results(&results).await {
+                tracing::warn!(message = "error writing output", error = %e);
+            }
+        }
         Action::Delete(c) => {
             if let Err(e) = client.delete(c.key.clone()).await {
                 tracing::error!(message = "unable to delete item", key = c.key, host = opts.host, error = %e);
@@ -220,15 +248,94 @@ async fn print_data(val: &Value) -> io::Result<()> {
 
 async fn print_keys(metas: &[Meta], show_details: bool) -> io::Result<()> {
     let mut output = BufWriter::new(tokio::io::stdout());
-    for meta in metas {
-        let line = if show_details {
-            format!("{}\t{}\t{}\n", meta.key, meta.expires, meta.size)
-        } else {
-            format!("{}\n", meta.key)
-        };
-
-        output.write_all(line.as_bytes()).await?;
+
+    if show_details {
+        for meta in metas {
+            output
+                .write_all(format!("{}\t{}\t{}\n", meta.key, meta.expires, meta.size).as_bytes())
+                .await?;
+        }
+    } else {
+        for meta in metas {
+            output.write_all(format!("{}\n", meta.key).as_bytes()).await?;
+        }
     }
 
     output.flush().await
 }
+
+async fn print_check_results(results: &MeasurementBundle) -> io::Result<()> {
+    let mut output = BufWriter::new(tokio::io::stdout());
+
+    output
+        .write_all(
+            format!(
+                "type=min total={:.9} dns={:.9} connection={:.9} set={:.9} get={:.9}\n",
+                results.total.min.as_secs_f64(),
+                results.dns.min.as_secs_f64(),
+                results.connections.min.as_secs_f64(),
+                results.sets.min.as_secs_f64(),
+                results.gets.min.as_secs_f64()
+            )
+            .as_bytes(),
+        )
+        .await?;
+
+    output
+        .write_all(
+            format!(
+                "type=max total={:.9} dns={:.9} connection={:.9} set={:.9} get={:.9}\n",
+                results.total.max.as_secs_f64(),
+                results.dns.max.as_secs_f64(),
+                results.connections.max.as_secs_f64(),
+                results.sets.max.as_secs_f64(),
+                results.gets.max.as_secs_f64(),
+            )
+            .as_bytes(),
+        )
+        .await?;
+
+    output
+        .write_all(
+            format!(
+                "type=avg total={:.9} dns={:.9} connection={:.9} set={:.9} get={:.9}\n",
+                results.total.avg.as_secs_f64(),
+                results.dns.avg.as_secs_f64(),
+                results.connections.avg.as_secs_f64(),
+                results.sets.avg.as_secs_f64(),
+                results.gets.avg.as_secs_f64()
+            )
+            .as_bytes(),
+        )
+        .await?;
+
+    output
+        .write_all(
+            format!(
+                "type=stddev total={:.9} dns={:.9} connection={:.9} set={:.9} get={:.9}\n",
+                results.total.std_dev.as_secs_f64(),
+                results.dns.std_dev.as_secs_f64(),
+                results.connections.std_dev.as_secs_f64(),
+                results.sets.std_dev.as_secs_f64(),
+                results.gets.std_dev.as_secs_f64()
+            )
+            .as_bytes(),
+        )
+        .await?;
+
+    output
+        .write_all(
+            format!(
+                "type=failures total={} dns={} connection={} set={} get={}\n",
+                results.failures.total,
+                results.failures.dns,
+                results.failures.connections,
+                results.failures.sets,
+                results.failures.gets,
+            )
+            .as_bytes(),
+        )
+        .await?;
+
+    output.flush().await
+}