Implement JSON-RPC batching

Cargo.toml

@@ -4,3 +4,6 @@ members = [
     "json",
     "client",
 ]
+
+[patch.crates-io]
+jsonrpc = { path = "/home/steven/code/rust/jsonrpc" }

client/examples/batching.rs

@@ -0,0 +1,42 @@
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software.
+// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+//
+
+extern crate bitcoin;
+extern crate bitcoincore_rpc;
+
+use bitcoincore_rpc::{Client, Error};
+
+fn main_result() -> Result<(), Error> {
+    let url = "http://localhost:18332/".to_owned();
+    let user = Some("rpcuser".to_owned());
+    let pass = Some("rpcpass".to_owned());
+
+    let rpc = Client::new(url, user, pass);
+
+    let mut batch = rpc.start_batch();
+
+    let blockchain_info = batch.get_blockchain_info()?;
+    let best_block_hash = batch.get_best_block_hash()?;
+    let best_block_count = batch.get_block_count()?;
+
+    println!("result ready: {}", blockchain_info.ready());
+    batch.execute()?;
+    println!("result ready: {}", blockchain_info.ready());
+
+    println!("chain: {}", blockchain_info.take()?.chain);
+    println!("best block hash: {}", best_block_hash.take()?);
+    println!("best block height: {}", best_block_count.take()?);
+
+    Ok(())
+}
+
+fn main() {
+    main_result().unwrap();
+}