Remove assertions that fail in the kcov docker container

Add historian demo

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "silk"
 description = "A silky smooth implementation of the Loom architecture"
-version = "0.1.3"
+version = "0.2.0"
 documentation = "https://docs.rs/silk"
 homepage = "http://loomprotocol.com/"
 repository = "https://github.com/loomprotocol/silk"
@@ -11,6 +11,10 @@ authors = [
 ]
 license = "Apache-2.0"
 
+[[bin]]
+name = "silk-demo"
+path = "src/bin/demo.rs"
+
 [badges]
 codecov = { repository = "loomprotocol/silk", branch = "master", service = "github" }
 

README.md

@@ -15,6 +15,54 @@ corresponding benchmarks are also added that demonstrate real performance boots.
 feature set here will always be a ways behind the loom repo, but that this is an implementation
 you can take to the bank, literally.
 
+# Usage
+
+Add the latest [silk package](https://crates.io/crates/silk) to the `[dependencies]` section
+of your Cargo.toml.
+
+Create a *Historian* and send it *events* to generate an *event log*, where each log *entry*
+is tagged with the historian's latest *hash*. Then ensure the order of events was not tampered
+with by verifying each entry's hash can be generated from the hash in the previous entry:
+
+```rust
+extern crate silk;
+
+use silk::historian::Historian;
+use silk::log::{verify_slice, Entry, Event};
+use std::{thread, time};
+use std::sync::mpsc::SendError;
+
+fn create_log(hist: &Historian) -> Result<(), SendError<Event>> {
+    hist.sender.send(Event::Tick)?;
+    thread::sleep(time::Duration::new(0, 100_000));
+    hist.sender.send(Event::UserDataKey(0xdeadbeef))?;
+    thread::sleep(time::Duration::new(0, 100_000));
+    hist.sender.send(Event::Tick)?;
+    Ok(())
+}
+
+fn main() {
+    let seed = 0;
+    let hist = Historian::new(seed);
+    create_log(&hist).expect("send error");
+    drop(hist.sender);
+    let entries: Vec<Entry> = hist.receiver.iter().collect();
+    for entry in &entries {
+        println!("{:?}", entry);
+    }
+    assert!(verify_slice(&entries, seed));
+}
+```
+
+Running the program should produce a log similar to:
+
+```
+Entry { num_hashes: 0, end_hash: 0, event: Tick }
+Entry { num_hashes: 245, end_hash: 11504657626326377539, event: UserDataKey(3735928559) }
+Entry { num_hashes: 154, end_hash: 13410333856574024888, event: Tick }
+```
+
+
 # Developing
 
 Building

src/bin/demo.rs

@@ -0,0 +1,27 @@
+extern crate silk;
+
+use silk::historian::Historian;
+use silk::log::{verify_slice, Entry, Event};
+use std::{thread, time};
+use std::sync::mpsc::SendError;
+
+fn create_log(hist: &Historian) -> Result<(), SendError<Event>> {
+    hist.sender.send(Event::Tick)?;
+    thread::sleep(time::Duration::new(0, 100_000));
+    hist.sender.send(Event::UserDataKey(0xdeadbeef))?;
+    thread::sleep(time::Duration::new(0, 100_000));
+    hist.sender.send(Event::Tick)?;
+    Ok(())
+}
+
+fn main() {
+    let seed = 0;
+    let hist = Historian::new(seed);
+    create_log(&hist).expect("send error");
+    drop(hist.sender);
+    let entries: Vec<Entry> = hist.receiver.iter().collect();
+    for entry in &entries {
+        println!("{:?}", entry);
+    }
+    assert!(verify_slice(&entries, seed));
+}

src/historian.rs

@@ -0,0 +1,137 @@
+//! The `historian` crate provides a microservice for generating a Proof-of-History.
+//! It logs Event items on behalf of its users. It continuously generates
+//! new hashes, only stopping to check if it has been sent an Event item. It
+//! tags each Event with an Entry and sends it back. The Entry includes the
+//! Event, the latest hash, and the number of hashes since the last event.
+//! The resulting stream of entries represents ordered events in time.
+
+use std::thread::JoinHandle;
+use std::sync::mpsc::{Receiver, Sender};
+use log::{hash, Entry, Event};
+
+pub struct Historian {
+    pub sender: Sender<Event>,
+    pub receiver: Receiver<Entry>,
+    pub thread_hdl: JoinHandle<(Entry, ExitReason)>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum ExitReason {
+    RecvDisconnected,
+    SendDisconnected,
+}
+
+fn log_events(
+    receiver: &Receiver<Event>,
+    sender: &Sender<Entry>,
+    num_hashes: u64,
+    end_hash: u64,
+) -> Result<u64, (Entry, ExitReason)> {
+    use std::sync::mpsc::TryRecvError;
+    let mut num_hashes = num_hashes;
+    loop {
+        match receiver.try_recv() {
+            Ok(event) => {
+                let entry = Entry {
+                    end_hash,
+                    num_hashes,
+                    event,
+                };
+                if let Err(_) = sender.send(entry.clone()) {
+                    return Err((entry, ExitReason::SendDisconnected));
+                }
+                num_hashes = 0;
+            }
+            Err(TryRecvError::Empty) => {
+                return Ok(num_hashes);
+            }
+            Err(TryRecvError::Disconnected) => {
+                let entry = Entry {
+                    end_hash,
+                    num_hashes,
+                    event: Event::Tick,
+                };
+                return Err((entry, ExitReason::RecvDisconnected));
+            }
+        }
+    }
+}
+
+/// A background thread that will continue tagging received Event messages and
+/// sending back Entry messages until either the receiver or sender channel is closed.
+pub fn create_logger(
+    start_hash: u64,
+    receiver: Receiver<Event>,
+    sender: Sender<Entry>,
+) -> JoinHandle<(Entry, ExitReason)> {
+    use std::thread;
+    thread::spawn(move || {
+        let mut end_hash = start_hash;
+        let mut num_hashes = 0;
+        loop {
+            match log_events(&receiver, &sender, num_hashes, end_hash) {
+                Ok(n) => num_hashes = n,
+                Err(err) => return err,
+            }
+            end_hash = hash(end_hash);
+            num_hashes += 1;
+        }
+    })
+}
+
+impl Historian {
+    pub fn new(start_hash: u64) -> Self {
+        use std::sync::mpsc::channel;
+        let (sender, event_receiver) = channel();
+        let (entry_sender, receiver) = channel();
+        let thread_hdl = create_logger(start_hash, event_receiver, entry_sender);
+        Historian {
+            sender,
+            receiver,
+            thread_hdl,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use log::*;
+
+    #[test]
+    fn test_historian() {
+        use std::thread::sleep;
+        use std::time::Duration;
+
+        let hist = Historian::new(0);
+
+        hist.sender.send(Event::Tick).unwrap();
+        sleep(Duration::new(0, 1_000_000));
+        hist.sender.send(Event::UserDataKey(0xdeadbeef)).unwrap();
+        sleep(Duration::new(0, 1_000_000));
+        hist.sender.send(Event::Tick).unwrap();
+
+        let entry0 = hist.receiver.recv().unwrap();
+        let entry1 = hist.receiver.recv().unwrap();
+        let entry2 = hist.receiver.recv().unwrap();
+
+        drop(hist.sender);
+        assert_eq!(
+            hist.thread_hdl.join().unwrap().1,
+            ExitReason::RecvDisconnected
+        );
+
+        assert!(verify_slice(&[entry0, entry1, entry2], 0));
+    }
+
+    #[test]
+    fn test_historian_closed_sender() {
+        let hist = Historian::new(0);
+        drop(hist.receiver);
+        hist.sender.send(Event::Tick).unwrap();
+        assert_eq!(
+            hist.thread_hdl.join().unwrap().1,
+            ExitReason::SendDisconnected
+        );
+    }
+}

src/lib.rs

@@ -1,4 +1,5 @@
 #![cfg_attr(feature = "unstable", feature(test))]
-pub mod event;
+pub mod log;
+pub mod historian;
 extern crate itertools;
 extern crate rayon;

src/log.rs

@@ -1,10 +1,10 @@
-//! The `event` crate provides the foundational data structures for Proof-of-History
+//! The `log` crate provides the foundational data structures for Proof-of-History,
+//! an ordered log of events in time.
 
-/// A Proof-of-History is an ordered log of events in time. Each entry contains three
-/// pieces of data. The 'num_hashes' field is the number of hashes performed since the previous
-/// entry.  The 'end_hash' field is the result of hashing 'end_hash' from the previous entry
-/// 'num_hashes' times.  The 'data' field is an optional foreign key (a hash) pointing to some
-/// arbitrary data that a client is looking to associate with the entry.
+/// Each log entry contains three pieces of data. The 'num_hashes' field is the number
+/// of hashes performed since the previous entry.  The 'end_hash' field is the result
+/// of hashing 'end_hash' from the previous entry 'num_hashes' times.  The 'event'
+/// field points to an Event that took place shortly after 'end_hash' was generated.
 ///
 /// If you divide 'num_hashes' by the amount of time it takes to generate a new hash, you
 /// get a duration estimate since the last event. Since processing power increases
@@ -12,31 +12,33 @@
 /// Though processing power varies across nodes, the network gives priority to the
 /// fastest processor. Duration should therefore be estimated by assuming that the hash
 /// was generated by the fastest processor at the time the entry was logged.
-pub struct Event {
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Entry {
     pub num_hashes: u64,
     pub end_hash: u64,
-    pub data: EventData,
+    pub event: Event,
 }
 
-/// When 'data' is Tick, the event represents a simple clock tick, and exists for the
+/// When 'event' is Tick, the event represents a simple clock tick, and exists for the
 /// sole purpose of improving the performance of event log verification. A tick can
 /// be generated in 'num_hashes' hashes and verified in 'num_hashes' hashes.  By logging
 /// a hash alongside the tick, each tick and be verified in parallel using the 'end_hash'
 /// of the preceding tick to seed its hashing.
-pub enum EventData {
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum Event {
     Tick,
     UserDataKey(u64),
 }
 
-impl Event {
-    /// Creates an Event from the number of hashes 'num_hashes' since the previous event
+impl Entry {
+    /// Creates a Entry from the number of hashes 'num_hashes' since the previous event
     /// and that resulting 'end_hash'.
     pub fn new_tick(num_hashes: u64, end_hash: u64) -> Self {
-        let data = EventData::Tick;
-        Event {
+        let event = Event::Tick;
+        Entry {
             num_hashes,
             end_hash,
-            data,
+            event,
         }
     }
 
@@ -46,36 +48,40 @@ impl Event {
     }
 }
 
-/// Creates the next Tick Event 'num_hashes' after 'start_hash'.
-pub fn next_tick(start_hash: u64, num_hashes: u64) -> Event {
+pub fn hash(val: u64) -> u64 {
     use std::collections::hash_map::DefaultHasher;
     use std::hash::{Hash, Hasher};
-    let mut end_hash = start_hash;
     let mut hasher = DefaultHasher::new();
+    val.hash(&mut hasher);
+    hasher.finish()
+}
+
+/// Creates the next Tick Entry 'num_hashes' after 'start_hash'.
+pub fn next_tick(start_hash: u64, num_hashes: u64) -> Entry {
+    let mut end_hash = start_hash;
     for _ in 0..num_hashes {
-        end_hash.hash(&mut hasher);
-        end_hash = hasher.finish();
+        end_hash = hash(end_hash);
     }
-    Event::new_tick(num_hashes, end_hash)
+    Entry::new_tick(num_hashes, end_hash)
 }
 
 /// Verifies the hashes and counts of a slice of events are all consistent.
-pub fn verify_slice(events: &[Event], start_hash: u64) -> bool {
+pub fn verify_slice(events: &[Entry], start_hash: u64) -> bool {
     use rayon::prelude::*;
-    let genesis = [Event::new_tick(0, start_hash)];
+    let genesis = [Entry::new_tick(0, start_hash)];
     let event_pairs = genesis.par_iter().chain(events).zip(events);
     event_pairs.all(|(x0, x1)| x1.verify(x0.end_hash))
 }
 
 /// Verifies the hashes and events serially. Exists only for reference.
-pub fn verify_slice_seq(events: &[Event], start_hash: u64) -> bool {
-    let genesis = [Event::new_tick(0, start_hash)];
+pub fn verify_slice_seq(events: &[Entry], start_hash: u64) -> bool {
+    let genesis = [Entry::new_tick(0, start_hash)];
     let mut event_pairs = genesis.iter().chain(events).zip(events);
     event_pairs.all(|(x0, x1)| x1.verify(x0.end_hash))
 }
 
 /// Create a vector of Ticks of length 'len' from 'start_hash' hash and 'num_hashes'.
-pub fn create_ticks(start_hash: u64, num_hashes: u64, len: usize) -> Vec<Event> {
+pub fn create_ticks(start_hash: u64, num_hashes: u64, len: usize) -> Vec<Entry> {
     use itertools::unfold;
     let mut events = unfold(start_hash, |state| {
         let event = next_tick(*state, num_hashes);
@@ -91,8 +97,8 @@ mod tests {
 
     #[test]
     fn test_event_verify() {
-        assert!(Event::new_tick(0, 0).verify(0)); // base case
-        assert!(!Event::new_tick(0, 0).verify(1)); // base case, bad
+        assert!(Entry::new_tick(0, 0).verify(0)); // base case
+        assert!(!Entry::new_tick(0, 0).verify(1)); // base case, bad
         assert!(next_tick(0, 1).verify(0)); // inductive step
         assert!(!next_tick(0, 1).verify(1)); // inductive step, bad
     }
@@ -102,10 +108,10 @@ mod tests {
         assert_eq!(next_tick(0, 1).num_hashes, 1)
     }
 
-    fn verify_slice_generic(verify_slice: fn(&[Event], u64) -> bool) {
+    fn verify_slice_generic(verify_slice: fn(&[Entry], u64) -> bool) {
         assert!(verify_slice(&vec![], 0)); // base case
-        assert!(verify_slice(&vec![Event::new_tick(0, 0)], 0)); // singleton case 1
-        assert!(!verify_slice(&vec![Event::new_tick(0, 0)], 1)); // singleton case 2, bad
+        assert!(verify_slice(&vec![Entry::new_tick(0, 0)], 0)); // singleton case 1
+        assert!(!verify_slice(&vec![Entry::new_tick(0, 0)], 1)); // singleton case 2, bad
         assert!(verify_slice(&create_ticks(0, 0, 2), 0)); // inductive step
 
         let mut bad_ticks = create_ticks(0, 0, 2);
@@ -129,23 +135,23 @@ mod tests {
 mod bench {
     extern crate test;
     use self::test::Bencher;
-    use event;
+    use log::*;
 
     #[bench]
     fn event_bench(bencher: &mut Bencher) {
         let start_hash = 0;
-        let events = event::create_ticks(start_hash, 100_000, 8);
+        let events = create_ticks(start_hash, 100_000, 8);
         bencher.iter(|| {
-            assert!(event::verify_slice(&events, start_hash));
+            assert!(verify_slice(&events, start_hash));
         });
     }
 
     #[bench]
     fn event_bench_seq(bencher: &mut Bencher) {
         let start_hash = 0;
-        let events = event::create_ticks(start_hash, 100_000, 8);
+        let events = create_ticks(start_hash, 100_000, 8);
         bencher.iter(|| {
-            assert!(event::verify_slice_seq(&events, start_hash));
+            assert!(verify_slice_seq(&events, start_hash));
         });
     }
 }