adding CLI args to pelikan-rs

Adds CLI arguments to Rust Pelikan Backends to display usage,
version, and stats information.

Partially addresses twitter#361

Author: brayniac

Cargo.lock

@@ -96,6 +96,7 @@ mod process;
 mod threads;
 
 pub use process::{Process, ProcessBuilder};
+pub use threads::PERCENTILES;
 
 use metrics::{static_metrics, Counter};
 

src/rust/core/server/src/lib.rs

@@ -70,7 +70,7 @@ pub struct Admin {
     log_drain: Box<dyn Drain>,
 }
 
-static PERCENTILES: &[(&str, f64)] = &[
+pub static PERCENTILES: &[(&str, f64)] = &[
     ("p25", 25.0),
     ("p50", 50.0),
     ("p75", 75.0),

src/rust/core/server/src/threads/admin.rs

@@ -7,7 +7,7 @@ mod listener;
 mod traits;
 mod worker;
 
-pub use admin::Admin;
+pub use admin::{Admin, PERCENTILES};
 pub use listener::Listener;
 pub use traits::EventLoop;
 pub use worker::{MultiWorker, SingleWorker, StorageWorker};

src/rust/core/server/src/threads/mod.rs

@@ -38,6 +38,7 @@ debug = ["entrystore/debug"]
 
 [dependencies]
 backtrace = "0.3.56"
+clap = "2.33.3"
 config = { path = "../../config" }
 entrystore = { path = "../../entrystore" }
 logger = { path = "../../logger" }

src/rust/server/segcache/Cargo.toml

@@ -6,8 +6,11 @@
 extern crate logger;
 
 use backtrace::Backtrace;
+use clap::{App, Arg};
 use config::SegcacheConfig;
+use metrics::*;
 use pelikan_segcache_rs::Segcache;
+use server::PERCENTILES;
 
 fn main() {
     // custom panic hook to terminate whole process after unwinding
@@ -17,10 +20,68 @@ fn main() {
         std::process::exit(101);
     }));
 
+    // parse command line options
+    let matches = App::new(env!("CARGO_BIN_NAME"))
+        .version(env!("CARGO_PKG_VERSION"))
+        .version_short("v")
+        .long_about(
+            "One of the unified cache backends implemented in Rust. It \
+            uses segment-based storage to cache key/val pairs. It speaks the \
+            memcached ASCII protocol and supports some ASCII memcached \
+            commands.",
+        )
+        .arg(
+            Arg::with_name("stats")
+                .short("s")
+                .long("stats")
+                .help("List all metrics in stats")
+                .takes_value(false),
+        )
+        .arg(
+            Arg::with_name("CONFIG")
+                .help("Server configuration file")
+                .index(1),
+        )
+        .get_matches();
+
+    if matches.is_present("stats") {
+        println!("{:<31} {:<15} DESCRIPTION", "NAME", "TYPE");
+
+        let mut metrics = Vec::new();
+
+        for metric in &metrics::rustcommon_metrics::metrics() {
+            let any = match metric.as_any() {
+                Some(any) => any,
+                None => {
+                    continue;
+                }
+            };
+
+            if any.downcast_ref::<Counter>().is_some() {
+                metrics.push(format!("{:<31} counter", metric.name()));
+            } else if any.downcast_ref::<Gauge>().is_some() {
+                metrics.push(format!("{:<31} gauge", metric.name()));
+            } else if any.downcast_ref::<Heatmap>().is_some() {
+                for (label, _) in PERCENTILES {
+                    let name = format!("{}_{}", metric.name(), label);
+                    metrics.push(format!("{:<31} percentile", name));
+                }
+            } else {
+                continue;
+            }
+        }
+
+        metrics.sort();
+        for metric in metrics {
+            println!("{}", metric);
+        }
+        std::process::exit(0);
+    }
+
     // load config from file
-    let config = if let Some(file) = std::env::args().nth(1) {
+    let config = if let Some(file) = matches.value_of("CONFIG") {
         debug!("loading config: {}", file);
-        match SegcacheConfig::load(&file) {
+        match SegcacheConfig::load(file) {
             Ok(c) => c,
             Err(e) => {
                 error!("{}", e);