Allow the logger to inject Tick events on its own

README.md

@@ -45,7 +45,7 @@ fn create_log(hist: &Historian) -> Result<(), SendError<Event>> {
 
 fn main() {
     let seed = Sha256Hash::default();
-    let hist = Historian::new(&seed);
+    let hist = Historian::new(&seed, None);
     create_log(&hist).expect("send error");
     drop(hist.sender);
     let entries: Vec<Entry> = hist.receiver.iter().collect();

src/bin/demo.rs

@@ -16,7 +16,7 @@ fn create_log(hist: &Historian) -> Result<(), SendError<Event>> {
 
 fn main() {
     let seed = Sha256Hash::default();
-    let hist = Historian::new(&seed);
+    let hist = Historian::new(&seed, None);
     create_log(&hist).expect("send error");
     drop(hist.sender);
     let entries: Vec<Entry> = hist.receiver.iter().collect();

src/historian.rs

@@ -7,6 +7,7 @@
 
 use std::thread::JoinHandle;
 use std::sync::mpsc::{Receiver, Sender};
+use std::time::{Duration, SystemTime};
 use log::{extend_and_hash, hash, Entry, Event, Sha256Hash};
 
 pub struct Historian {
@@ -20,29 +21,48 @@ pub enum ExitReason {
     RecvDisconnected,
     SendDisconnected,
 }
+fn log_event(
+    sender: &Sender<Entry>,
+    num_hashes: &mut u64,
+    end_hash: &mut Sha256Hash,
+    event: Event,
+) -> Result<(), (Entry, ExitReason)> {
+    if let Event::UserDataKey(key) = event {
+        *end_hash = extend_and_hash(end_hash, &key);
+    }
+    let entry = Entry {
+        end_hash: *end_hash,
+        num_hashes: *num_hashes,
+        event,
+    };
+    if let Err(_) = sender.send(entry.clone()) {
+        return Err((entry, ExitReason::SendDisconnected));
+    }
+    *num_hashes = 0;
+    Ok(())
+}
 
 fn log_events(
     receiver: &Receiver<Event>,
     sender: &Sender<Entry>,
     num_hashes: &mut u64,
     end_hash: &mut Sha256Hash,
+    epoch: SystemTime,
+    num_ticks: &mut u64,
+    ms_per_tick: Option<u64>,
 ) -> Result<(), (Entry, ExitReason)> {
     use std::sync::mpsc::TryRecvError;
     loop {
+        if let Some(ms) = ms_per_tick {
+            let now = SystemTime::now();
+            if now > epoch + Duration::from_millis((*num_ticks + 1) * ms) {
+                log_event(sender, num_hashes, end_hash, Event::Tick)?;
+                *num_ticks += 1;
+            }
+        }
         match receiver.try_recv() {
             Ok(event) => {
-                if let Event::UserDataKey(key) = event {
-                    *end_hash = extend_and_hash(end_hash, &key);
-                }
-                let entry = Entry {
-                    end_hash: *end_hash,
-                    num_hashes: *num_hashes,
-                    event,
-                };
-                if let Err(_) = sender.send(entry.clone()) {
-                    return Err((entry, ExitReason::SendDisconnected));
-                }
-                *num_hashes = 0;
+                log_event(sender, num_hashes, end_hash, event)?;
             }
             Err(TryRecvError::Empty) => {
                 return Ok(());
@@ -63,6 +83,7 @@ fn log_events(
 /// sending back Entry messages until either the receiver or sender channel is closed.
 pub fn create_logger(
     start_hash: Sha256Hash,
+    ms_per_tick: Option<u64>,
     receiver: Receiver<Event>,
     sender: Sender<Entry>,
 ) -> JoinHandle<(Entry, ExitReason)> {
@@ -70,8 +91,18 @@ pub fn create_logger(
     thread::spawn(move || {
         let mut end_hash = start_hash;
         let mut num_hashes = 0;
+        let mut num_ticks = 0;
+        let epoch = SystemTime::now();
         loop {
-            if let Err(err) = log_events(&receiver, &sender, &mut num_hashes, &mut end_hash) {
+            if let Err(err) = log_events(
+                &receiver,
+                &sender,
+                &mut num_hashes,
+                &mut end_hash,
+                epoch,
+                &mut num_ticks,
+                ms_per_tick,
+            ) {
                 return err;
             }
             end_hash = hash(&end_hash);
@@ -81,11 +112,11 @@ pub fn create_logger(
 }
 
 impl Historian {
-    pub fn new(start_hash: &Sha256Hash) -> Self {
+    pub fn new(start_hash: &Sha256Hash, ms_per_tick: Option<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);
+        let thread_hdl = create_logger(*start_hash, ms_per_tick, event_receiver, entry_sender);
         Historian {
             sender,
             receiver,
@@ -105,7 +136,7 @@ mod tests {
         use std::time::Duration;
 
         let zero = Sha256Hash::default();
-        let hist = Historian::new(&zero);
+        let hist = Historian::new(&zero, None);
 
         hist.sender.send(Event::Tick).unwrap();
         sleep(Duration::new(0, 1_000_000));
@@ -129,7 +160,7 @@ mod tests {
     #[test]
     fn test_historian_closed_sender() {
         let zero = Sha256Hash::default();
-        let hist = Historian::new(&zero);
+        let hist = Historian::new(&zero, None);
         drop(hist.receiver);
         hist.sender.send(Event::Tick).unwrap();
         assert_eq!(