Allow optional metrics collection

Can be disable by `--no-default-features`.

Also, enable RocksDB ZSTD compression (removing the feature).

Cargo.lock

@@ -720,9 +720,16 @@ dependencies = [
  "memchr",
  "parking_lot",
  "procfs",
+ "protobuf",
  "thiserror",
 ]
 
+[[package]]
+name = "protobuf"
+version = "2.23.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "45604fc7a88158e7d514d8e22e14ac746081e7a70d7690074dd0029ee37458d6"
+
 [[package]]
 name = "quick-error"
 version = "1.2.3"

Cargo.toml

@@ -13,7 +13,8 @@ edition = "2018"
 build = "build.rs"
 
 [features]
-default = ["rocksdb/zstd", "prometheus/process"]
+default = ["metrics"]
+metrics = ["prometheus"]
 
 [package.metadata.configure_me]
 spec = "internal/config_specification.toml"
@@ -28,9 +29,9 @@ dirs-next = "2.0"
 env_logger = "0.7"
 hyper = "0.10"
 log = "0.4"
-prometheus = { version = "0.12", default-features = false }
+prometheus = { version = "0.12", features = ["process"], optional = true }
 rayon = "1.5"
-rocksdb = { git = "https://github.com/romanz/rust-rocksdb", rev = "4554d19b2ff2e34493564b4d868454097c74b693", default-features = false }  # to support building with Rust 1.41.1 and https://github.com/romanz/electrs/issues/403
+rocksdb = { git = "https://github.com/romanz/rust-rocksdb", rev = "4554d19b2ff2e34493564b4d868454097c74b693", features = ["zstd"] }  # to support building with Rust 1.41.1 and https://github.com/romanz/electrs/issues/403
 rust-crypto = "0.2"
 serde = "1.0"
 serde_derive = "1.0"

src/config.rs

@@ -208,6 +208,13 @@ impl Config {
             (DEFAULT_SERVER_ADDRESS, default_electrum_port).into(),
             ResolvAddr::resolve_or_exit,
         );
+        #[cfg(not(feature = "metrics"))]
+        {
+            assert!(
+                config.monitoring_addr.is_none(),
+                "Enable \"metrics\" feature to specify monitoring_addr"
+            );
+        }
         let monitoring_addr: SocketAddr = config.monitoring_addr.map_or(
             (DEFAULT_SERVER_ADDRESS, default_monitoring_port).into(),
             ResolvAddr::resolve_or_exit,

src/electrum.rs

@@ -79,11 +79,10 @@ pub struct Rpc {
 
 impl Rpc {
     pub fn new(config: &Config, tracker: Tracker) -> Result<Self> {
-        let rpc_duration = tracker.metrics().histogram_vec(
-            "rpc_duration",
-            "RPC duration (in seconds)",
-            &["method"],
-        );
+        let rpc_duration =
+            tracker
+                .metrics()
+                .histogram_vec("rpc_duration", "RPC duration (in seconds)", "method");
         Ok(Self {
             tracker,
             cache: Cache::default(),

src/index.rs

@@ -25,30 +25,30 @@ impl Stats {
             update_duration: metrics.histogram_vec(
                 "index_update_duration",
                 "Index update duration (in seconds)",
-                &["step"],
+                "step",
             ),
             update_size: metrics.histogram_vec(
                 "index_update_size",
                 "Index update size (in bytes)",
-                &["step"],
+                "step",
             ),
             lookup_duration: metrics.histogram_vec(
                 "index_lookup_duration",
                 "Index lookup duration (in seconds)",
-                &["step"],
+                "step",
             ),
         }
     }
 
     fn report_stats(&self, batch: &db::WriteBatch) {
         self.update_size
-            .observe_size("write_funding_rows", db_rows_size(&batch.funding_rows));
+            .observe("write_funding_rows", db_rows_size(&batch.funding_rows));
         self.update_size
-            .observe_size("write_spending_rows", db_rows_size(&batch.spending_rows));
+            .observe("write_spending_rows", db_rows_size(&batch.spending_rows));
         self.update_size
-            .observe_size("write_txid_rows", db_rows_size(&batch.txid_rows));
+            .observe("write_txid_rows", db_rows_size(&batch.txid_rows));
         self.update_size
-            .observe_size("write_header_rows", db_rows_size(&batch.header_rows));
+            .observe("write_header_rows", db_rows_size(&batch.header_rows));
         debug!(
             "writing {} funding and {} spending rows from {} transactions, {} blocks",
             batch.funding_rows.len(),

src/metrics.rs

@@ -1,89 +1,129 @@
-use anyhow::{Context, Result};
-use hyper::server::{Handler, Listening, Request, Response, Server};
-use prometheus::{self, Encoder, HistogramOpts, HistogramVec, Registry};
+#[cfg(feature = "metrics")]
+mod metrics_impl {
+    use anyhow::{Context, Result};
+    use hyper::server::{Handler, Listening, Request, Response, Server};
+    use prometheus::process_collector::ProcessCollector;
+    use prometheus::{self, Encoder, HistogramOpts, HistogramVec, Registry};
 
-#[cfg(feature = "process_collector")]
-use prometheus::process_collector::ProcessCollector;
+    use std::net::SocketAddr;
 
-use std::net::SocketAddr;
+    pub struct Metrics {
+        reg: Registry,
+        listen: Listening,
+    }
 
-pub struct Metrics {
-    reg: Registry,
-    listen: Listening,
-}
+    impl Metrics {
+        pub fn new(addr: SocketAddr) -> Result<Self> {
+            let reg = Registry::new();
 
-impl Drop for Metrics {
-    fn drop(&mut self) {
-        debug!("closing Prometheus server");
-        if let Err(e) = self.listen.close() {
-            warn!("failed to stop Prometheus server: {}", e);
+            reg.register(Box::new(ProcessCollector::for_self()))
+                .expect("failed to register ProcessCollector");
+
+            let listen = Server::http(addr)?
+                .handle(RegistryHandler { reg: reg.clone() })
+                .with_context(|| format!("failed to serve on {}", addr))?;
+            info!("serving Prometheus metrics on {}", addr);
+            Ok(Self { reg, listen })
+        }
+
+        pub fn histogram_vec(&self, name: &str, desc: &str, label: &str) -> Histogram {
+            let opts = HistogramOpts::new(name, desc);
+            let hist = HistogramVec::new(opts, &[label]).unwrap();
+            self.reg
+                .register(Box::new(hist.clone()))
+                .expect("failed to register Histogram");
+            Histogram { hist }
+        }
+    }
+
+    impl Drop for Metrics {
+        fn drop(&mut self) {
+            debug!("closing Prometheus server");
+            if let Err(e) = self.listen.close() {
+                warn!("failed to stop Prometheus server: {}", e);
+            }
+        }
+    }
+
+    #[derive(Clone)]
+    pub struct Histogram {
+        hist: HistogramVec,
+    }
+
+    impl Histogram {
+        pub fn observe(&self, label: &str, value: usize) {
+            self.hist.with_label_values(&[label]).observe(value as f64);
+        }
+
+        pub fn observe_duration<F, T>(&self, label: &str, func: F) -> T
+        where
+            F: FnOnce() -> T,
+        {
+            self.hist
+                .with_label_values(&[label])
+                .observe_closure_duration(func)
+        }
+    }
+
+    struct RegistryHandler {
+        reg: Registry,
+    }
+
+    impl RegistryHandler {
+        fn gather(&self) -> Result<Vec<u8>> {
+            let mut buffer = vec![];
+            prometheus::TextEncoder::new()
+                .encode(&self.reg.gather(), &mut buffer)
+                .context("failed to encode metrics")?;
+            Ok(buffer)
+        }
+    }
+
+    impl Handler for RegistryHandler {
+        fn handle(&self, req: Request, res: Response) {
+            trace!("{} {}", req.method, req.uri);
+            let buffer = self.gather().expect("failed to gather metrics");
+            res.send(&buffer).expect("failed to send metrics");
         }
     }
 }
 
-#[derive(Clone)]
-pub struct Histogram {
-    hist: HistogramVec,
-}
+#[cfg(feature = "metrics")]
+pub use metrics_impl::{Histogram, Metrics};
 
-impl Histogram {
-    pub fn observe_size(&self, label: &str, value: usize) {
-        self.hist.with_label_values(&[label]).observe(value as f64);
+#[cfg(not(feature = "metrics"))]
+mod metrics_fake {
+    use anyhow::Result;
+
+    use std::net::SocketAddr;
+
+    pub struct Metrics {}
+
+    impl Metrics {
+        pub fn new(_addr: SocketAddr) -> Result<Self> {
+            debug!("metrics collection is disabled");
+            Ok(Self {})
+        }
+
+        pub fn histogram_vec(&self, _name: &str, _desc: &str, _label: &str) -> Histogram {
+            Histogram {}
+        }
     }
 
-    pub fn observe_duration<F, T>(&self, label: &str, func: F) -> T
-    where
-        F: FnOnce() -> T,
-    {
-        self.hist
-            .with_label_values(&[label])
-            .observe_closure_duration(func)
+    #[derive(Clone)]
+    pub struct Histogram {}
+
+    impl Histogram {
+        pub fn observe(&self, _label: &str, _value: usize) {}
+
+        pub fn observe_duration<F, T>(&self, _label: &str, func: F) -> T
+        where
+            F: FnOnce() -> T,
+        {
+            func()
+        }
     }
 }
 
-struct RegistryHandler {
-    reg: Registry,
-}
-
-impl RegistryHandler {
-    fn gather(&self) -> Result<Vec<u8>> {
-        let mut buffer = vec![];
-        prometheus::TextEncoder::new()
-            .encode(&self.reg.gather(), &mut buffer)
-            .context("failed to encode metrics")?;
-        Ok(buffer)
-    }
-}
-
-impl Handler for RegistryHandler {
-    fn handle(&self, req: Request, res: Response) {
-        trace!("{} {}", req.method, req.uri);
-        let buffer = self.gather().expect("failed to gather metrics");
-        res.send(&buffer).expect("send failed");
-    }
-}
-
-impl Metrics {
-    pub fn new(addr: SocketAddr) -> Result<Self> {
-        let reg = Registry::new();
-
-        #[cfg(feature = "prometheus/process")]
-        reg.register(Box::new(ProcessCollector::for_self()))
-            .expect("failed to register ProcessCollector");
-
-        let listen = Server::http(addr)?
-            .handle(RegistryHandler { reg: reg.clone() })
-            .with_context(|| format!("failed to serve on {}", addr))?;
-        info!("serving Prometheus metrics on {}", addr);
-        Ok(Self { reg, listen })
-    }
-
-    pub fn histogram_vec(&self, name: &str, desc: &str, labels: &[&str]) -> Histogram {
-        let opts = HistogramOpts::new(name, desc);
-        let hist = HistogramVec::new(opts, labels).unwrap();
-        self.reg
-            .register(Box::new(hist.clone()))
-            .expect("failed to register Histogram");
-        Histogram { hist }
-    }
-}
+#[cfg(not(feature = "metrics"))]
+pub use metrics_fake::{Histogram, Metrics};