From 0cc786a1e5277f96cbd7fe64b55a6f633045c32f Mon Sep 17 00:00:00 2001
From: Ignotus Peverell <igno.peverell@protonmail.com>
Date: Fri, 23 Dec 2016 12:15:36 -0800
Subject: [PATCH] Refactored server to share the same struct whether futures
 are exposed or not. Multi-server test now properly waits for a block instead
 of a timer.

---
 grin/src/lib.rs        |  2 +-
 grin/src/server.rs     | 48 +++++++++---------------------------------
 grin/tests/simulnet.rs | 44 ++++++++++++++++++++++++++++++++++----
 3 files changed, 51 insertions(+), 43 deletions(-)

diff --git a/grin/src/lib.rs b/grin/src/lib.rs
index 6cf508e9..de97889d 100644
--- a/grin/src/lib.rs
+++ b/grin/src/lib.rs
@@ -40,4 +40,4 @@ mod adapters;
 mod miner;
 mod server;
 
-pub use server::{Server, ServerFut, ServerConfig};
+pub use server::{Server, ServerConfig};
diff --git a/grin/src/server.rs b/grin/src/server.rs
index b26483a9..5602ce13 100644
--- a/grin/src/server.rs
+++ b/grin/src/server.rs
@@ -108,43 +108,8 @@ impl Server {
 		})
 	}
 
-	/// Asks the server to connect to a peer at the provided network address.
-	pub fn connect_peer(&self, addr: SocketAddr) -> Result<(), Error> {
-		let handle = self.evt_handle.clone();
-		handle.spawn(self.p2p.connect_peer(addr, handle.clone()).map_err(|_| ()));
-		Ok(())
-	}
-
-	/// Start mining for blocks on a separate thread. Relies on a toy miner,
-	/// mostly for testing.
-	pub fn start_miner(&self) {
-		let miner = miner::Miner::new(self.chain_head.clone(),
-		                              self.chain_store.clone(),
-		                              self.chain_adapter.clone());
-		thread::spawn(move || {
-			miner.run_loop();
-		});
-	}
-}
-
-/// Implementation of the server that doesn't take control of the event loop
-/// and returns futures instead.
-pub struct ServerFut {
-	config: ServerConfig,
-	/// handle to our network server
-	p2p: Arc<p2p::Server>,
-	/// the reference copy of the current chain state
-	chain_head: Arc<Mutex<chain::Tip>>,
-	/// data store access
-	chain_store: Arc<chain::ChainStore>,
-	/// chain adapter to net, required for miner and anything that submits
-	/// blocks
-	chain_adapter: Arc<ChainToNetAdapter>,
-}
-
-impl ServerFut {
-	/// Instantiates and starts a new server.
-	pub fn start(config: ServerConfig, evt_handle: &reactor::Handle) -> Result<Server, Error> {
+	/// Instantiates a new server associated with the provided future reactor.
+	pub fn future(config: ServerConfig, evt_handle: &reactor::Handle) -> Result<Server, Error> {
 		let (chain_store, head) = try!(store_head(&config));
 		let shared_head = Arc::new(Mutex::new(head));
 
@@ -169,7 +134,8 @@ impl ServerFut {
 	}
 
 	/// Asks the server to connect to a peer at the provided network address.
-	pub fn connect_peer(&self, addr: SocketAddr, handle: &reactor::Handle) -> Result<(), Error> {
+	pub fn connect_peer(&self, addr: SocketAddr) -> Result<(), Error> {
+		let handle = self.evt_handle.clone();
 		handle.spawn(self.p2p.connect_peer(addr, handle.clone()).map_err(|_| ()));
 		Ok(())
 	}
@@ -184,6 +150,12 @@ impl ServerFut {
 			miner.run_loop();
 		});
 	}
+
+	pub fn head(&self) -> chain::Tip {
+		let head = self.chain_head.clone();
+		let h = head.lock().unwrap();
+		h.clone()
+	}
 }
 
 // Helper function to create the chain storage and check if it already has a
diff --git a/grin/tests/simulnet.rs b/grin/tests/simulnet.rs
index bfcb765b..5d20837b 100644
--- a/grin/tests/simulnet.rs
+++ b/grin/tests/simulnet.rs
@@ -25,7 +25,8 @@ use std::io;
 use std::thread;
 use std::time;
 
-use futures::Future;
+use futures::{Future, Poll, Async};
+use futures::task::park;
 use tokio_core::reactor;
 
 #[test]
@@ -38,7 +39,7 @@ fn simulate_servers() {
   // instantiates 5 servers on different ports
   let mut servers = vec![];
   for n in 0..5 {
-      let s = grin::ServerFut::start(
+      let s = grin::Server::future(
           grin::ServerConfig{
             db_root: format!("target/grin-{}", n),
             cuckoo_size: 12,
@@ -58,7 +59,42 @@ fn simulate_servers() {
 
   // start mining
   servers[0].start_miner();
+  let original_height = servers[0].head().height;
 
-  let timeout = reactor::Timeout::new(time::Duration::new(10, 0), &handle.clone()).unwrap();
-  evtlp.run(timeout);
+  // monitor for a change of head on a different server and check we 
+  evtlp.run(change(&servers[4]).and_then(|tip| {
+    assert!(tip.height == original_height+1);
+    Ok(())
+  }));
+}
+
+// Builds the change future, monitoring for a change of head on the provided server
+fn change<'a>(s: &'a grin::Server) -> HeadChange<'a> {
+  let start_head = s.head();
+  HeadChange {
+    server: s,
+    original: start_head,
+  }
+}
+
+/// Future that monitors when a server has had its head updated.
+struct HeadChange<'a> {
+  server: &'a grin::Server,
+  original:  chain::Tip,
+}
+
+impl<'a> Future for HeadChange<'a> {
+  type Item = chain::Tip;
+  type Error = ();
+
+  fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+    let new_head = self.server.head();
+    if new_head.last_block_h != self.original.last_block_h {
+      Ok(Async::Ready(new_head))
+    } else {
+      // egregious polling, asking the task to schedule us every iteration
+      park().unpark();
+      Ok(Async::NotReady)
+    }
+  }
 }