Add extra prom beacon chain metrics

beacon_node/store/src/lib.rs

@@ -7,18 +7,22 @@
 //!
 //! Provides a simple API for storing/retrieving all types that sometimes needs type-hints. See
 //! tests for implementation examples.
+#[macro_use]
+extern crate lazy_static;
 
 mod block_at_slot;
 mod errors;
 mod impls;
 mod leveldb_store;
 mod memory_store;
+mod metrics;
 
 pub mod iter;
 
 pub use self::leveldb_store::LevelDB as DiskStore;
 pub use self::memory_store::MemoryStore;
 pub use errors::Error;
+pub use metrics::scrape_for_metrics;
 pub use types::*;
 
 /// An object capable of storing and retrieving objects implementing `StoreItem`.

beacon_node/store/src/metrics.rs

@@ -0,0 +1,25 @@
+pub use lighthouse_metrics::{set_gauge, try_create_int_gauge, *};
+
+use std::fs;
+use std::path::PathBuf;
+
+lazy_static! {
+    pub static ref DISK_DB_SIZE: Result<IntGauge> =
+        try_create_int_gauge("database_size", "Size of the on-disk database (bytes)");
+}
+
+/// Updates the global metrics registry with store-related information.
+pub fn scrape_for_metrics(db_path: &PathBuf) {
+    let db_size = if let Ok(iter) = fs::read_dir(db_path) {
+        iter.filter_map(std::result::Result::ok)
+            .map(size_of_dir_entry)
+            .fold(0_u64, |sum, val| sum + val)
+    } else {
+        0
+    };
+    set_gauge(&DISK_DB_SIZE, db_size as i64);
+}
+
+fn size_of_dir_entry(dir: fs::DirEntry) -> u64 {
+    dir.metadata().map(|m| m.len()).unwrap_or(0)
+}