More cleanup

Far fewer branches when we process transfers outside the context
of events.

src/accountant.rs

@@ -3,7 +3,8 @@
 //! transfer funds to other users.
 
 use log::{Entry, Sha256Hash};
-use event::{get_pubkey, sign_transaction_data, verify_event, Event, PublicKey, Signature, Transfer};
+use event::{get_pubkey, sign_transaction_data, verify_transfer, Event, PublicKey, Signature,
+            Transfer};
 use genesis::Genesis;
 use historian::{reserve_signature, Historian};
 use ring::signature::Ed25519KeyPair;
@@ -14,7 +15,8 @@ use std::result;
 #[derive(Debug, PartialEq, Eq)]
 pub enum AccountingError {
     InsufficientFunds,
-    InvalidEvent,
+    InvalidTransfer,
+    InvalidTransferSignature,
     SendError,
 }
 
@@ -74,20 +76,44 @@ impl Accountant {
         allow_deposits && from == to
     }
 
-    pub fn process_event(self: &mut Self, event: Event<i64>) -> Result<()> {
-        if !verify_event(&event) {
-            return Err(AccountingError::InvalidEvent);
+    pub fn process_transfer(self: &mut Self, tr: Transfer<i64>) -> Result<()> {
+        if !verify_transfer(&tr) {
+            return Err(AccountingError::InvalidTransfer);
         }
 
-        if let Event::Transaction(Transfer { from, data, .. }) = event {
-            if self.get_balance(&from).unwrap_or(0) < data {
-                return Err(AccountingError::InsufficientFunds);
+        if self.get_balance(&tr.from).unwrap_or(0) < tr.data {
+            return Err(AccountingError::InsufficientFunds);
+        }
+
+        self.process_verified_transfer(&tr, false)?;
+        if let Err(SendError(_)) = self.historian.sender.send(Event::Transaction(tr)) {
+            return Err(AccountingError::SendError);
+        }
+
+        Ok(())
+    }
+
+    fn process_verified_transfer(
+        self: &mut Self,
+        tr: &Transfer<i64>,
+        allow_deposits: bool,
+    ) -> Result<()> {
+        if !reserve_signature(&mut self.historian.signatures, &tr.sig) {
+            return Err(AccountingError::InvalidTransferSignature);
+        }
+
+        if !Self::is_deposit(allow_deposits, &tr.from, &tr.to) {
+            if let Some(x) = self.balances.get_mut(&tr.from) {
+                *x -= tr.data;
             }
         }
 
-        self.process_verified_event(&event, false)?;
-        if let Err(SendError(_)) = self.historian.sender.send(event) {
-            return Err(AccountingError::SendError);
+        if self.balances.contains_key(&tr.to) {
+            if let Some(x) = self.balances.get_mut(&tr.to) {
+                *x += tr.data;
+            }
+        } else {
+            self.balances.insert(tr.to, tr.data);
         }
 
         Ok(())
@@ -98,26 +124,10 @@ impl Accountant {
         event: &Event<i64>,
         allow_deposits: bool,
     ) -> Result<()> {
-        if !reserve_signature(&mut self.historian.signatures, event) {
-            return Err(AccountingError::InvalidEvent);
+        match *event {
+            Event::Tick => Ok(()),
+            Event::Transaction(ref tr) => self.process_verified_transfer(tr, allow_deposits),
         }
-
-        if let Event::Transaction(Transfer { from, to, data, .. }) = *event {
-            if !Self::is_deposit(allow_deposits, &from, &to) {
-                if let Some(x) = self.balances.get_mut(&from) {
-                    *x -= data;
-                }
-            }
-
-            if self.balances.contains_key(&to) {
-                if let Some(x) = self.balances.get_mut(&to) {
-                    *x += data;
-                }
-            } else {
-                self.balances.insert(to, data);
-            }
-        }
-        Ok(())
     }
 
     pub fn transfer(
@@ -129,14 +139,14 @@ impl Accountant {
         let from = get_pubkey(keypair);
         let last_id = self.last_id;
         let sig = sign_transaction_data(&n, keypair, &to, &last_id);
-        let event = Event::Transaction(Transfer {
+        let tr = Transfer {
             from,
             to,
             data: n,
             last_id,
             sig,
-        });
-        self.process_event(event).map(|_| sig)
+        };
+        self.process_transfer(tr).map(|_| sig)
     }
 
     pub fn get_balance(self: &Self, pubkey: &PublicKey) -> Option<i64> {

src/accountant_skel.rs

@@ -31,9 +31,8 @@ impl AccountantSkel {
 
     pub fn process_request(self: &mut Self, msg: Request) -> Option<Response> {
         match msg {
-            Request::Transaction(transfer) => {
-                let event = Event::Transaction(transfer);
-                if let Err(err) = self.acc.process_event(event) {
+            Request::Transaction(tr) => {
+                if let Err(err) = self.acc.process_transfer(tr) {
                     eprintln!("Transfer error: {:?}", err);
                 }
                 None

src/event.rs

@@ -34,6 +34,18 @@ pub struct Transfer<T> {
     pub sig: Signature,
 }
 
+impl<T> Transfer<T> {
+    pub fn new_claim(to: PublicKey, data: T, last_id: Sha256Hash, sig: Signature) -> Self {
+        Transfer {
+            from: to,
+            to,
+            data,
+            last_id,
+            sig,
+        }
+    }
+}
+
 /// 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
@@ -47,14 +59,7 @@ pub enum Event<T> {
 
 impl<T> Event<T> {
     pub fn new_claim(to: PublicKey, data: T, last_id: Sha256Hash, sig: Signature) -> Self {
-        let transfer = Transfer {
-            from: to,
-            to,
-            data,
-            last_id,
-            sig,
-        };
-        Event::Transaction(transfer)
+        Event::Transaction(Transfer::new_claim(to, data, last_id, sig))
     }
 }
 

src/historian.rs

@@ -7,7 +7,7 @@ use std::sync::mpsc::{sync_channel, Receiver, SyncSender};
 use std::time::Instant;
 use log::{hash, Entry, Sha256Hash};
 use logger::{ExitReason, Logger};
-use event::{get_signature, Event, Signature};
+use event::{Event, Signature};
 use serde::Serialize;
 use std::fmt::Debug;
 
@@ -55,13 +55,11 @@ impl<T: 'static + Serialize + Clone + Debug + Send> Historian<T> {
     }
 }
 
-pub fn reserve_signature<T>(sigs: &mut HashSet<Signature>, event: &Event<T>) -> bool {
-    if let Some(sig) = get_signature(&event) {
-        if sigs.contains(&sig) {
-            return false;
-        }
-        sigs.insert(sig);
+pub fn reserve_signature(sigs: &mut HashSet<Signature>, sig: &Signature) -> bool {
+    if sigs.contains(sig) {
+        return false;
     }
+    sigs.insert(*sig);
     true
 }
 
@@ -116,10 +114,10 @@ mod tests {
         let data = b"hello, world";
         let zero = Sha256Hash::default();
         let sig = sign_claim_data(&data, &keypair, &zero);
-        let event0 = Event::new_claim(to, &data, zero, sig);
+        let tr0 = Transfer::new_claim(to, &data, zero, sig);
         let mut sigs = HashSet::new();
-        assert!(reserve_signature(&mut sigs, &event0));
-        assert!(!reserve_signature(&mut sigs, &event0));
+        assert!(reserve_signature(&mut sigs, &tr0.sig));
+        assert!(!reserve_signature(&mut sigs, &tr0.sig));
     }
 
     #[test]