Merge pull request #128 from garious/faster-demo

Utilize parallelized accountant in demo

Cargo.toml

@@ -36,6 +36,10 @@ path = "src/bin/genesis-demo.rs"
 name = "solana-mint"
 path = "src/bin/mint.rs"
 
+[[bin]]
+name = "solana-mint-demo"
+path = "src/bin/mint-demo.rs"
+
 [badges]
 codecov = { repository = "solana-labs/solana", branch = "master", service = "github" }
 

README.md

@@ -39,25 +39,28 @@ $ cd solana
 The testnode server is initialized with a ledger from stdin and
 generates new ledger entries on stdout. To create the input ledger, we'll need
 to create *the mint* and use it to generate a *genesis ledger*. It's done in
-two steps because the mint.json file contains a private key that will be
+two steps because the mint-demo.json file contains private keys that will be
 used later in this demo.
 
 ```bash
-    $ echo 1000000000 | cargo run --release --bin solana-mint | tee mint.json
+    $ echo 1000000000 | cargo run --release --bin solana-mint-demo > mint-demo.json
-    $ cat mint.json | cargo run --release --bin solana-genesis | tee genesis.log
+    $ cat mint-demo.json | cargo run --release --bin solana-genesis-demo > genesis.log
 ```
 
 Now you can start the server:
 
 ```bash
-    $ cat genesis.log | cargo run --release --bin solana-testnode | tee transactions0.log
+    $ cat genesis.log | cargo run --release --bin solana-testnode > transactions0.log
 ```
 
+Wait a few seconds for the server to initialize. It will print "Ready." when it's safe
+to start sending it transactions.
+
 Then, in a separate shell, let's execute some transactions. Note we pass in
 the JSON configuration file here, not the genesis ledger.
 
 ```bash
-    $ cat mint.json | cargo run --release --bin solana-client-demo
+    $ cat mint-demo.json | cargo run --release --bin solana-client-demo
 ```
 
 Now kill the server with Ctrl-C, and take a look at the ledger. You should
@@ -73,14 +76,14 @@ Now restart the server from where we left off. Pass it both the genesis ledger,
 the transaction ledger.
 
 ```bash
-    $ cat genesis.log transactions0.log | cargo run --release --bin solana-testnode | tee transactions1.log
+    $ cat genesis.log transactions0.log | cargo run --release --bin solana-testnode > transactions1.log
 ```
 
 Lastly, run the client demo again, and verify that all funds were spent in the
 previous round, and so no additional transactions are added.
 
 ```bash
-    $ cat mint.json | cargo run --release --bin solana-client-demo
+    $ cat mint-demo.json | cargo run --release --bin solana-client-demo
 ```
 
 Stop the server again, and verify there are only Tick entries, and no Transaction entries.

src/accountant_skel.rs

@@ -33,6 +33,7 @@ pub struct AccountantSkel<W: Write + Send + 'static> {
     last_id: Hash,
     writer: W,
     historian: Historian,
+    entry_info_subscribers: Vec<SocketAddr>,
 }
 
 #[cfg_attr(feature = "cargo-clippy", allow(large_enum_variant))]
@@ -41,6 +42,19 @@ pub enum Request {
     Transaction(Transaction),
     GetBalance { key: PublicKey },
     GetLastId,
+    Subscribe { subscriptions: Vec<Subscription> },
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub enum Subscription {
+    EntryInfo,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct EntryInfo {
+    pub id: Hash,
+    pub num_hashes: u64,
+    pub num_events: u64,
 }
 
 impl Request {
@@ -56,7 +70,7 @@ impl Request {
 #[derive(Serialize, Deserialize, Debug)]
 pub enum Response {
     Balance { key: PublicKey, val: Option<i64> },
-    Entries { entries: Vec<Entry> },
+    EntryInfo(EntryInfo),
     LastId { id: Hash },
 }
 
@@ -68,6 +82,22 @@ impl<W: Write + Send + 'static> AccountantSkel<W> {
             last_id,
             writer,
             historian,
+            entry_info_subscribers: vec![],
+        }
+    }
+
+    fn notify_entry_info_subscribers(&mut self, entry: &Entry) {
+        // TODO: No need to bind().
+        let socket = UdpSocket::bind("127.0.0.1:0").expect("bind");
+
+        for addr in &self.entry_info_subscribers {
+            let entry_info = EntryInfo {
+                id: entry.id,
+                num_hashes: entry.num_hashes,
+                num_events: entry.events.len() as u64,
+            };
+            let data = serialize(&Response::EntryInfo(entry_info)).expect("serialize EntryInfo");
+            let _res = socket.send_to(&data, addr);
         }
     }
 
@@ -77,6 +107,7 @@ impl<W: Write + Send + 'static> AccountantSkel<W> {
             self.last_id = entry.id;
             self.acc.register_entry_id(&self.last_id);
             writeln!(self.writer, "{}", serde_json::to_string(&entry).unwrap()).unwrap();
+            self.notify_entry_info_subscribers(&entry);
         }
         self.last_id
     }
@@ -94,6 +125,14 @@ impl<W: Write + Send + 'static> AccountantSkel<W> {
             }
             Request::GetLastId => Some((Response::LastId { id: self.sync() }, rsp_addr)),
             Request::Transaction(_) => unreachable!(),
+            Request::Subscribe { subscriptions } => {
+                for subscription in subscriptions {
+                    match subscription {
+                        Subscription::EntryInfo => self.entry_info_subscribers.push(rsp_addr),
+                    }
+                }
+                None
+            }
         }
     }
 
@@ -242,7 +281,11 @@ impl<W: Write + Send + 'static> AccountantSkel<W> {
                 blob_sender.send(blobs)?;
             }
             packet_recycler.recycle(msgs);
+
+            // Write new entries to the ledger and notify subscribers.
+            obj.lock().unwrap().sync();
         }
+
         Ok(())
     }
 
@@ -286,8 +329,13 @@ impl<W: Write + Send + 'static> AccountantSkel<W> {
                 &packet_recycler,
                 &blob_recycler,
             );
-            if e.is_err() && exit.load(Ordering::Relaxed) {
+            if e.is_err() {
-                break;
+                // Assume this was a timeout, so sync any empty entries.
+                skel.lock().unwrap().sync();
+
+                if exit.load(Ordering::Relaxed) {
+                    break;
+                }
             }
         });
         Ok(vec![t_receiver, t_responder, t_server, t_verifier])
@@ -426,7 +474,7 @@ mod tests {
         let socket = UdpSocket::bind(send_addr).unwrap();
         socket.set_read_timeout(Some(Duration::new(5, 0))).unwrap();
 
-        let acc = AccountantStub::new(&addr, socket);
+        let mut acc = AccountantStub::new(&addr, socket);
         let last_id = acc.get_last_id().wait().unwrap();
 
         let tr = Transaction::new(&alice.keypair(), bob_pubkey, 500, last_id);

src/accountant_stub.rs

@@ -3,11 +3,12 @@
 //! this object instead of writing messages to the network directly. The binary
 //! encoding of its messages are unstable and may change in future releases.
 
-use accountant_skel::{Request, Response};
+use accountant_skel::{Request, Response, Subscription};
 use bincode::{deserialize, serialize};
-use futures::future::{err, ok, FutureResult};
+use futures::future::{ok, FutureResult};
 use hash::Hash;
 use signature::{KeyPair, PublicKey, Signature};
+use std::collections::HashMap;
 use std::io;
 use std::net::UdpSocket;
 use transaction::Transaction;
@@ -15,6 +16,9 @@ use transaction::Transaction;
 pub struct AccountantStub {
     pub addr: String,
     pub socket: UdpSocket,
+    last_id: Option<Hash>,
+    num_events: u64,
+    balances: HashMap<PublicKey, Option<i64>>,
 }
 
 impl AccountantStub {
@@ -22,9 +26,43 @@ impl AccountantStub {
     /// over `socket`. To receive responses, the caller must bind `socket`
     /// to a public address before invoking AccountantStub methods.
     pub fn new(addr: &str, socket: UdpSocket) -> Self {
-        AccountantStub {
+        let stub = AccountantStub {
             addr: addr.to_string(),
             socket,
+            last_id: None,
+            num_events: 0,
+            balances: HashMap::new(),
+        };
+        stub.init();
+        stub
+    }
+
+    pub fn init(&self) {
+        let subscriptions = vec![Subscription::EntryInfo];
+        let req = Request::Subscribe { subscriptions };
+        let data = serialize(&req).expect("serialize Subscribe");
+        let _res = self.socket.send_to(&data, &self.addr);
+    }
+
+    pub fn recv_response(&self) -> io::Result<Response> {
+        let mut buf = vec![0u8; 1024];
+        self.socket.recv_from(&mut buf)?;
+        let resp = deserialize(&buf).expect("deserialize balance");
+        Ok(resp)
+    }
+
+    pub fn process_response(&mut self, resp: Response) {
+        match resp {
+            Response::Balance { key, val } => {
+                self.balances.insert(key, val);
+            }
+            Response::LastId { id } => {
+                self.last_id = Some(id);
+            }
+            Response::EntryInfo(entry_info) => {
+                self.last_id = Some(entry_info.id);
+                self.num_events += entry_info.num_events;
+            }
         }
     }
 
@@ -52,42 +90,67 @@ impl AccountantStub {
     /// Request the balance of the user holding `pubkey`. This method blocks
     /// until the server sends a response. If the response packet is dropped
     /// by the network, this method will hang indefinitely.
-    pub fn get_balance(&self, pubkey: &PublicKey) -> FutureResult<i64, i64> {
+    pub fn get_balance(&mut self, pubkey: &PublicKey) -> FutureResult<i64, i64> {
         let req = Request::GetBalance { key: *pubkey };
         let data = serialize(&req).expect("serialize GetBalance");
         self.socket
             .send_to(&data, &self.addr)
             .expect("buffer error");
-        let mut buf = vec![0u8; 1024];
+        let mut done = false;
-        self.socket.recv_from(&mut buf).expect("buffer error");
+        while !done {
-        let resp = deserialize(&buf).expect("deserialize balance");
+            let resp = self.recv_response().expect("recv response");
-        if let Response::Balance { key, val } = resp {
+            if let &Response::Balance { ref key, .. } = &resp {
-            assert_eq!(key, *pubkey);
+                done = key == pubkey;
-            return match val {
+            }
-                Some(x) => ok(x),
+            self.process_response(resp);
-                _ => err(0),
-            };
         }
-        err(0)
+        ok(self.balances[pubkey].unwrap())
     }
 
     /// Request the last Entry ID from the server. This method blocks
     /// until the server sends a response. At the time of this writing,
     /// it also has the side-effect of causing the server to log any
     /// entries that have been published by the Historian.
-    pub fn get_last_id(&self) -> FutureResult<Hash, ()> {
+    pub fn get_last_id(&mut self) -> FutureResult<Hash, ()> {
         let req = Request::GetLastId;
         let data = serialize(&req).expect("serialize GetId");
         self.socket
             .send_to(&data, &self.addr)
             .expect("buffer error");
-        let mut buf = vec![0u8; 1024];
+        let mut done = false;
-        self.socket.recv_from(&mut buf).expect("buffer error");
+        while !done {
-        let resp = deserialize(&buf).expect("deserialize Id");
+            let resp = self.recv_response().expect("recv response");
-        if let Response::LastId { id } = resp {
+            if let &Response::LastId { .. } = &resp {
-            return ok(id);
+                done = true;
+            }
+            self.process_response(resp);
         }
-        ok(Default::default())
+        ok(self.last_id.unwrap_or(Hash::default()))
+    }
+
+    /// Return the number of transactions the server processed since creating
+    /// this stub instance.
+    pub fn transaction_count(&mut self) -> u64 {
+        // Wait for at least one EntryInfo.
+        let mut done = false;
+        while !done {
+            let resp = self.recv_response().expect("recv response");
+            if let &Response::EntryInfo(_) = &resp {
+                done = true;
+            }
+            self.process_response(resp);
+        }
+
+        // Then take the rest.
+        self.socket.set_nonblocking(true).expect("set nonblocking");
+        loop {
+            match self.recv_response() {
+                Err(_) => break,
+                Ok(resp) => self.process_response(resp),
+            }
+        }
+        self.socket.set_nonblocking(false).expect("set blocking");
+        self.num_events
     }
 }
 
@@ -128,7 +191,7 @@ mod tests {
         let socket = UdpSocket::bind(send_addr).unwrap();
         socket.set_read_timeout(Some(Duration::new(5, 0))).unwrap();
 
-        let acc = AccountantStub::new(addr, socket);
+        let mut acc = AccountantStub::new(addr, socket);
         let last_id = acc.get_last_id().wait().unwrap();
         let _sig = acc.transfer(500, &alice.keypair(), bob_pubkey, &last_id)
             .unwrap();

src/bin/client-demo.rs

@@ -4,21 +4,22 @@ extern crate isatty;
 extern crate rayon;
 extern crate serde_json;
 extern crate solana;
+extern crate untrusted;
 
 use futures::Future;
 use getopts::Options;
 use isatty::stdin_isatty;
 use rayon::prelude::*;
 use solana::accountant_stub::AccountantStub;
-use solana::mint::Mint;
+use solana::mint::MintDemo;
 use solana::signature::{KeyPair, KeyPairUtil};
 use solana::transaction::Transaction;
 use std::env;
 use std::io::{stdin, Read};
 use std::net::UdpSocket;
 use std::process::exit;
-use std::thread::sleep;
+use std::time::Instant;
-use std::time::{Duration, Instant};
+use untrusted::Input;
 
 fn print_usage(program: &str, opts: Options) {
     let mut brief = format!("Usage: cat <mint.json> | {} [options]\n\n", program);
@@ -75,74 +76,68 @@ fn main() {
         exit(1);
     }
 
-    let mint: Mint = serde_json::from_str(&buffer).unwrap_or_else(|e| {
+    println!("Parsing stdin...");
+    let demo: MintDemo = serde_json::from_str(&buffer).unwrap_or_else(|e| {
         eprintln!("failed to parse json: {}", e);
         exit(1);
     });
-    let mint_keypair = mint.keypair();
-    let mint_pubkey = mint.pubkey();
 
     let socket = UdpSocket::bind(&send_addr).unwrap();
-    println!("Stub new");
+    let mut acc = AccountantStub::new(&addr, socket);
-    let acc = AccountantStub::new(&addr, socket);
+
-    println!("Get last id");
+    println!("Get last ID...");
     let last_id = acc.get_last_id().wait().unwrap();
 
-    println!("Get Balance");
+    println!("Creating keypairs...");
-    let mint_balance = acc.get_balance(&mint_pubkey).wait().unwrap();
+    let txs = demo.users.len() / 2;
-    println!("Mint's Initial Balance {}", mint_balance);
+    let keypairs: Vec<_> = demo.users
+        .into_par_iter()
+        .map(|(pkcs8, _)| KeyPair::from_pkcs8(Input::from(&pkcs8)).unwrap())
+        .collect();
+    let keypair_pairs: Vec<_> = keypairs.chunks(2).collect();
 
     println!("Signing transactions...");
-    let txs = 1_000_000;
     let now = Instant::now();
-    let transactions: Vec<_> = (0..txs)
+    let transactions: Vec<_> = keypair_pairs
         .into_par_iter()
-        .map(|_| {
+        .map(|chunk| Transaction::new(&chunk[0], chunk[1].pubkey(), 1, last_id))
-            let rando_pubkey = KeyPair::new().pubkey();
-            Transaction::new(&mint_keypair, rando_pubkey, 1, last_id)
-        })
         .collect();
     let duration = now.elapsed();
-    let ns = duration.as_secs() * 2_000_000_000 + u64::from(duration.subsec_nanos());
+    let ns = duration.as_secs() * 1_000_000_000 + u64::from(duration.subsec_nanos());
-    let bsps = f64::from(txs) / ns as f64;
+    let bsps = txs as f64 / ns as f64;
-    let nsps = ns as f64 / f64::from(txs);
+    let nsps = ns as f64 / txs as f64;
     println!(
         "Done. {} thousand signatures per second, {}us per signature",
         bsps * 1_000_000_f64,
         nsps / 1_000_f64
     );
 
+    let initial_tx_count = acc.transaction_count();
+
     println!("Transfering {} transactions in {} batches", txs, threads);
     let now = Instant::now();
     let sz = transactions.len() / threads;
     let chunks: Vec<_> = transactions.chunks(sz).collect();
-    let _: Vec<_> = chunks
+    chunks.into_par_iter().for_each(|trs| {
-        .into_par_iter()
+        println!("Transferring 1 unit {} times...", trs.len());
-        .map(|trs| {
+        let send_addr = "0.0.0.0:0";
-            println!("Transferring 1 unit {} times...", trs.len());
+        let socket = UdpSocket::bind(send_addr).unwrap();
-            let send_addr = "0.0.0.0:0";
+        let acc = AccountantStub::new(&addr, socket);
-            let socket = UdpSocket::bind(send_addr).unwrap();
+        for tr in trs {
-            let acc = AccountantStub::new(&addr, socket);
+            acc.transfer_signed(tr.clone()).unwrap();
-            for tr in trs {
+        }
-                acc.transfer_signed(tr.clone()).unwrap();
+    });
-            }
+
-            ()
+    println!("Waiting for half the transactions to complete...",);
-        })
+    let mut tx_count = acc.transaction_count();
-        .collect();
+    while tx_count < transactions.len() as u64 / 2 {
-    println!("Waiting for last transaction to be confirmed...",);
+        tx_count = acc.transaction_count();
-    let mut val = mint_balance;
-    let mut prev = 0;
-    while val != prev {
-        sleep(Duration::from_millis(20));
-        prev = val;
-        val = acc.get_balance(&mint_pubkey).wait().unwrap();
     }
-    println!("Mint's Final Balance {}", val);
+    let txs = tx_count - initial_tx_count;
-    let txs = mint_balance - val;
+    println!("Transactions processed {}", txs);
-    println!("Successful transactions {}", txs);
 
     let duration = now.elapsed();
     let ns = duration.as_secs() * 1_000_000_000 + u64::from(duration.subsec_nanos());
     let tps = (txs * 1_000_000_000) as f64 / ns as f64;
-    println!("Done. {} tps!", tps);
+    println!("Done. {} tps", tps);
 }

src/bin/genesis-demo.rs

@@ -1,21 +1,23 @@
 extern crate isatty;
+extern crate rayon;
+extern crate ring;
 extern crate serde_json;
 extern crate solana;
+extern crate untrusted;
 
 use isatty::stdin_isatty;
-use solana::entry::create_entry;
+use rayon::prelude::*;
+use solana::accountant::MAX_ENTRY_IDS;
+use solana::entry::{create_entry, next_tick};
 use solana::event::Event;
-use solana::hash::Hash;
+use solana::mint::MintDemo;
-use solana::mint::Mint;
+use solana::signature::{KeyPair, KeyPairUtil};
-use solana::signature::{KeyPair, KeyPairUtil, PublicKey};
 use solana::transaction::Transaction;
 use std::io::{stdin, Read};
 use std::process::exit;
+use untrusted::Input;
 
-fn transfer(from: &KeyPair, (to, tokens): (PublicKey, i64), last_id: Hash) -> Event {
+// Generate a ledger with lots and lots of accounts.
-    Event::Transaction(Transaction::new(from, to, tokens, last_id))
-}
-
 fn main() {
     if stdin_isatty() {
         eprintln!("nothing found on stdin, expected a json file");
@@ -29,20 +31,39 @@ fn main() {
         exit(1);
     }
 
-    let mint: Mint = serde_json::from_str(&buffer).unwrap_or_else(|e| {
+    let demo: MintDemo = serde_json::from_str(&buffer).unwrap_or_else(|e| {
         eprintln!("failed to parse json: {}", e);
         exit(1);
     });
-    let mut entries = mint.create_entries();
 
-    let from = mint.keypair();
+    let num_accounts = demo.users.len();
-    let seed = mint.seed();
+    let last_id = demo.mint.last_id();
-    let alice = (KeyPair::new().pubkey(), 200);
+    let mint_keypair = demo.mint.keypair();
-    let bob = (KeyPair::new().pubkey(), 100);
-    let events = vec![transfer(&from, alice, seed), transfer(&from, bob, seed)];
-    entries.push(create_entry(&seed, 0, events));
 
-    for entry in entries {
+    eprintln!("Signing {} transactions...", num_accounts);
+    let events: Vec<_> = demo.users
+        .into_par_iter()
+        .map(|(pkcs8, tokens)| {
+            let rando = KeyPair::from_pkcs8(Input::from(&pkcs8)).unwrap();
+            let tr = Transaction::new(&mint_keypair, rando.pubkey(), tokens, last_id);
+            Event::Transaction(tr)
+        })
+        .collect();
+
+    for entry in demo.mint.create_entries() {
+        println!("{}", serde_json::to_string(&entry).unwrap());
+    }
+
+    eprintln!("Logging the creation of {} accounts...", num_accounts);
+    let entry = create_entry(&last_id, 0, events);
+    println!("{}", serde_json::to_string(&entry).unwrap());
+
+    eprintln!("Creating {} empty entries...", MAX_ENTRY_IDS);
+    // Offer client lots of entry IDs to use for each transaction's last_id.
+    let mut last_id = last_id;
+    for _ in 0..MAX_ENTRY_IDS {
+        let entry = next_tick(&last_id, 1);
+        last_id = entry.id;
         let serialized = serde_json::to_string(&entry).unwrap_or_else(|e| {
             eprintln!("failed to serialize: {}", e);
             exit(1);

src/bin/mint-demo.rs

@@ -0,0 +1,33 @@
+extern crate rayon;
+extern crate ring;
+extern crate serde_json;
+extern crate solana;
+
+use rayon::prelude::*;
+use ring::rand::SystemRandom;
+use solana::mint::{Mint, MintDemo};
+use solana::signature::KeyPair;
+use std::io;
+
+fn main() {
+    let mut input_text = String::new();
+    io::stdin().read_line(&mut input_text).unwrap();
+    let trimmed = input_text.trim();
+    let tokens = trimmed.parse::<i64>().unwrap();
+
+    let mint = Mint::new(tokens);
+    let tokens_per_user = 1_000;
+    let num_accounts = tokens / tokens_per_user;
+    let rnd = SystemRandom::new();
+
+    let users: Vec<_> = (0..num_accounts)
+        .into_par_iter()
+        .map(|_| {
+            let pkcs8 = KeyPair::generate_pkcs8(&rnd).unwrap().to_vec();
+            (pkcs8, tokens_per_user)
+        })
+        .collect();
+
+    let demo = MintDemo { mint, users };
+    println!("{}", serde_json::to_string(&demo).unwrap());
+}

src/bin/testnode.rs

@@ -62,6 +62,7 @@ fn main() {
         exit(1);
     }
 
+    eprintln!("Initializing...");
     let mut entries = buffer.lines().map(|line| {
         serde_json::from_str(&line).unwrap_or_else(|e| {
             eprintln!("failed to parse json: {}", e);
@@ -71,7 +72,7 @@ fn main() {
 
     // The first item in the ledger is required to be an entry with zero num_hashes,
     // which implies its id can be used as the ledger's seed.
-    entries.next().unwrap();
+    let entry0 = entries.next().unwrap();
 
     // The second item in the ledger is a special transaction where the to and from
     // fields are the same. That entry should be treated as a deposit, not a
@@ -84,11 +85,14 @@ fn main() {
     };
 
     let acc = Accountant::new_from_deposit(&deposit.unwrap());
+    acc.register_entry_id(&entry0.id);
+    acc.register_entry_id(&entry1.id);
 
     let mut last_id = entry1.id;
     for entry in entries {
         last_id = entry.id;
         acc.process_verified_events(entry.events).unwrap();
+        acc.register_entry_id(&last_id);
     }
 
     let historian = Historian::new(&last_id, Some(1000));
@@ -99,8 +103,8 @@ fn main() {
         stdout(),
         historian,
     )));
-    eprintln!("Listening on {}", addr);
     let threads = AccountantSkel::serve(&skel, &addr, exit.clone()).unwrap();
+    eprintln!("Ready. Listening on {}", addr);
     for t in threads {
         t.join().expect("join");
     }

src/entry.rs

@@ -61,7 +61,7 @@ fn add_event_data(hash_data: &mut Vec<u8>, event: &Event) {
 }
 
 /// Creates the hash `num_hashes` after `start_hash`. If the event contains
-/// signature, the final hash will be a hash of both the previous ID and
+/// a signature, the final hash will be a hash of both the previous ID and
 /// the signature.
 pub fn next_hash(start_hash: &Hash, num_hashes: u64, events: &[Event]) -> Hash {
     let mut id = *start_hash;
@@ -76,10 +76,12 @@ pub fn next_hash(start_hash: &Hash, num_hashes: u64, events: &[Event]) -> Hash {
     }
 
     if !hash_data.is_empty() {
-        return extend_and_hash(&id, &hash_data);
+        extend_and_hash(&id, &hash_data)
+    } else if num_hashes != 0 {
+        hash(&id)
+    } else {
+        id
     }
-
-    id
 }
 
 /// Creates the next Entry `num_hashes` after `start_hash`.
@@ -167,6 +169,8 @@ mod tests {
     #[test]
     fn test_next_tick() {
         let zero = Hash::default();
-        assert_eq!(next_tick(&zero, 1).num_hashes, 1)
+        let tick = next_tick(&zero, 1);
+        assert_eq!(tick.num_hashes, 1);
+        assert_ne!(tick.id, zero);
     }
 }

src/mint.rs

@@ -58,6 +58,12 @@ impl Mint {
     }
 }
 
+#[derive(Serialize, Deserialize, Debug)]
+pub struct MintDemo {
+    pub mint: Mint,
+    pub users: Vec<(Vec<u8>, i64)>,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;