Add benchmarking tool for initial block download and indexing

(without DB writes)

src/bin/bench_index.rs

@@ -0,0 +1,47 @@
+extern crate electrs;
+
+extern crate error_chain;
+
+#[macro_use]
+extern crate log;
+
+use error_chain::ChainedError;
+
+use electrs::{config::Config,
+              daemon::Daemon,
+              errors::*,
+              index::Index,
+              store::{ReadStore, Row, WriteStore},
+              util::Bytes};
+
+struct FakeStore;
+
+impl ReadStore for FakeStore {
+    fn get(&self, _key: &[u8]) -> Option<Bytes> {
+        None
+    }
+    fn scan(&self, _prefix: &[u8]) -> Vec<Row> {
+        vec![]
+    }
+}
+
+impl WriteStore for FakeStore {
+    fn write(&self, _rows: Vec<Row>) {}
+}
+
+fn run() -> Result<()> {
+    let config = Config::from_args();
+    let daemon = Daemon::new(config.network_type)?;
+    debug!("{:?}", daemon.getblockchaininfo()?);
+    let fake_store = FakeStore {};
+    let index = Index::load(&fake_store);
+    let tip = index.update(&fake_store, &daemon)?;
+    info!("downloaded and indexed till {}", tip);
+    Ok(())
+}
+
+fn main() {
+    if let Err(e) = run() {
+        error!("{}", e.display_chain());
+    }
+}