Merge pull request #66 from garious/conditional-plan

Simplify contract language

src/accountant.rs

@@ -5,7 +5,8 @@
 use hash::Hash;
 use entry::Entry;
 use event::Event;
-use transaction::{Action, Plan, Transaction};
+use plan::{Action, Plan, PlanEvent};
+use transaction::Transaction;
 use signature::{KeyPair, PublicKey, Signature};
 use mint::Mint;
 use historian::{reserve_signature, Historian};
@@ -30,7 +31,7 @@ pub struct Accountant {
     pub balances: HashMap<PublicKey, i64>,
     pub first_id: Hash,
     pub last_id: Hash,
-    pending: HashMap<Signature, Plan<i64>>,
+    pending: HashMap<Signature, Plan>,
     time_sources: HashSet<PublicKey>,
     last_time: DateTime<Utc>,
 }
@@ -83,15 +84,15 @@ impl Accountant {
         self.last_id
     }
 
-    fn is_deposit(allow_deposits: bool, from: &PublicKey, plan: &Plan<i64>) -> bool {
+    fn is_deposit(allow_deposits: bool, from: &PublicKey, plan: &Plan) -> bool {
         if let Plan::Action(Action::Pay(ref payment)) = *plan {
             allow_deposits && *from == payment.to
         } else {
             false
         }
     }
 
-    pub fn process_transaction(self: &mut Self, tr: Transaction<i64>) -> Result<()> {
+    pub fn process_transaction(self: &mut Self, tr: Transaction) -> Result<()> {
         if !tr.verify() {
             return Err(AccountingError::InvalidTransfer);
         }
@@ -112,7 +113,7 @@ impl Accountant {
     }
 
     /// Commit funds to the 'to' party.
-    fn complete_transaction(self: &mut Self, plan: &Plan<i64>) {
+    fn complete_transaction(self: &mut Self, plan: &Plan) {
         if let Plan::Action(Action::Pay(ref payment)) = *plan {
             if self.balances.contains_key(&payment.to) {
                 if let Some(x) = self.balances.get_mut(&payment.to) {
@@ -126,7 +127,7 @@ impl Accountant {
 
     fn process_verified_transaction(
         self: &mut Self,
-        tr: &Transaction<i64>,
+        tr: &Transaction,
         allow_deposits: bool,
     ) -> Result<()> {
         if !reserve_signature(&mut self.historian.signatures, &tr.sig) {
@@ -140,7 +141,7 @@ impl Accountant {
         }
 
         let mut plan = tr.plan.clone();
-        let actionable = plan.process_verified_timestamp(self.last_time);
+        let actionable = plan.process_event(PlanEvent::Timestamp(self.last_time));
 
         if !actionable {
             self.pending.insert(tr.sig, plan);
@@ -153,7 +154,7 @@ impl Accountant {
 
     fn process_verified_sig(&mut self, from: PublicKey, tx_sig: Signature) -> Result<()> {
         let actionable = if let Some(plan) = self.pending.get_mut(&tx_sig) {
-            plan.process_verified_sig(from)
+            plan.process_event(PlanEvent::Signature(from))
         } else {
             false
         };
@@ -185,7 +186,7 @@ impl Accountant {
         // Check to see if any timelocked transactions can be completed.
         let mut completed = vec![];
         for (key, plan) in &mut self.pending {
-            if plan.process_verified_timestamp(self.last_time) {
+            if plan.process_event(PlanEvent::Timestamp(self.last_time)) {
                 completed.push(key.clone());
             }
         }

src/accountant_skel.rs

@@ -19,7 +19,7 @@ pub struct AccountantSkel {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub enum Request {
-    Transaction(Transaction<i64>),
+    Transaction(Transaction),
     GetBalance { key: PublicKey },
     GetEntries { last_id: Hash },
     GetId { is_last: bool },

src/accountant_stub.rs

@@ -26,7 +26,7 @@ impl AccountantStub {
         }
     }
 
-    pub fn transfer_signed(&self, tr: Transaction<i64>) -> io::Result<usize> {
+    pub fn transfer_signed(&self, tr: Transaction) -> io::Result<usize> {
         let req = Request::Transaction(tr);
         let data = serialize(&req).unwrap();
         self.socket.send_to(&data, &self.addr)

src/event.rs

@@ -7,7 +7,7 @@ use bincode::serialize;
 
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
 pub enum Event {
-    Transaction(Transaction<i64>),
+    Transaction(Transaction),
     Signature {
         from: PublicKey,
         tx_sig: Signature,

src/lib.rs

@@ -1,6 +1,7 @@
 #![cfg_attr(feature = "unstable", feature(test))]
 pub mod signature;
 pub mod hash;
+pub mod plan;
 pub mod transaction;
 pub mod event;
 pub mod entry;

src/mint.rs

@@ -58,7 +58,7 @@ impl Mint {
 mod tests {
     use super::*;
     use log::verify_slice;
-    use transaction::{Action, Plan};
+    use plan::{Action, Plan};
 
     #[test]
     fn test_create_events() {

src/plan.rs

@@ -0,0 +1,188 @@
+//! The `plan` crate provides functionality for creating spending plans.
+
+use signature::PublicKey;
+use chrono::prelude::*;
+use std::mem;
+
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
+pub enum Condition {
+    Timestamp(DateTime<Utc>),
+    Signature(PublicKey),
+}
+
+pub enum PlanEvent {
+    Timestamp(DateTime<Utc>),
+    Signature(PublicKey),
+}
+
+impl Condition {
+    pub fn is_satisfied(&self, event: &PlanEvent) -> bool {
+        match (self, event) {
+            (&Condition::Signature(ref pubkey), &PlanEvent::Signature(ref from)) => pubkey == from,
+            (&Condition::Timestamp(ref dt), &PlanEvent::Timestamp(ref last_time)) => {
+                dt <= last_time
+            }
+            _ => false,
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
+pub enum Action {
+    Pay(Payment),
+}
+
+impl Action {
+    pub fn spendable(&self) -> i64 {
+        match *self {
+            Action::Pay(ref payment) => payment.asset,
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
+pub struct Payment {
+    pub asset: i64,
+    pub to: PublicKey,
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
+pub enum Plan {
+    Action(Action),
+    After(Condition, Action),
+    Race((Condition, Action), (Condition, Action)),
+}
+
+impl Plan {
+    pub fn new_payment(asset: i64, to: PublicKey) -> Self {
+        Plan::Action(Action::Pay(Payment { asset, to }))
+    }
+
+    pub fn new_authorized_payment(from: PublicKey, asset: i64, to: PublicKey) -> Self {
+        Plan::After(
+            Condition::Signature(from),
+            Action::Pay(Payment { asset, to }),
+        )
+    }
+
+    pub fn new_future_payment(dt: DateTime<Utc>, asset: i64, to: PublicKey) -> Self {
+        Plan::After(Condition::Timestamp(dt), Action::Pay(Payment { asset, to }))
+    }
+
+    pub fn new_cancelable_future_payment(
+        dt: DateTime<Utc>,
+        from: PublicKey,
+        asset: i64,
+        to: PublicKey,
+    ) -> Self {
+        Plan::Race(
+            (Condition::Timestamp(dt), Action::Pay(Payment { asset, to })),
+            (
+                Condition::Signature(from),
+                Action::Pay(Payment { asset, to: from }),
+            ),
+        )
+    }
+
+    pub fn verify(&self, spendable_assets: i64) -> bool {
+        match *self {
+            Plan::Action(ref action) => action.spendable() == spendable_assets,
+            Plan::After(_, ref action) => action.spendable() == spendable_assets,
+            Plan::Race(ref a, ref b) => {
+                a.1.spendable() == spendable_assets && b.1.spendable() == spendable_assets
+            }
+        }
+    }
+
+    pub fn process_event(&mut self, event: PlanEvent) -> bool {
+        let mut new_action = None;
+        match *self {
+            Plan::Action(_) => return true,
+            Plan::After(ref cond, ref action) => {
+                if cond.is_satisfied(&event) {
+                    new_action = Some(action.clone());
+                }
+            }
+            Plan::Race(ref a, ref b) => {
+                if a.0.is_satisfied(&event) {
+                    new_action = Some(a.1.clone());
+                } else if b.0.is_satisfied(&event) {
+                    new_action = Some(b.1.clone());
+                }
+            }
+        }
+
+        if let Some(action) = new_action {
+            mem::replace(self, Plan::Action(action));
+            true
+        } else {
+            false
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_signature_satisfied() {
+        let sig = PublicKey::default();
+        assert!(Condition::Signature(sig).is_satisfied(&PlanEvent::Signature(sig)));
+    }
+
+    #[test]
+    fn test_timestamp_satisfied() {
+        let dt1 = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
+        let dt2 = Utc.ymd(2014, 11, 14).and_hms(10, 9, 8);
+        assert!(Condition::Timestamp(dt1).is_satisfied(&PlanEvent::Timestamp(dt1)));
+        assert!(Condition::Timestamp(dt1).is_satisfied(&PlanEvent::Timestamp(dt2)));
+        assert!(!Condition::Timestamp(dt2).is_satisfied(&PlanEvent::Timestamp(dt1)));
+    }
+
+    #[test]
+    fn test_verify_plan() {
+        let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
+        let from = PublicKey::default();
+        let to = PublicKey::default();
+        assert!(Plan::new_payment(42, to).verify(42));
+        assert!(Plan::new_authorized_payment(from, 42, to).verify(42));
+        assert!(Plan::new_future_payment(dt, 42, to).verify(42));
+        assert!(Plan::new_cancelable_future_payment(dt, from, 42, to).verify(42));
+    }
+
+    #[test]
+    fn test_authorized_payment() {
+        let from = PublicKey::default();
+        let to = PublicKey::default();
+
+        let mut plan = Plan::new_authorized_payment(from, 42, to);
+        assert!(plan.process_event(PlanEvent::Signature(from)));
+        assert_eq!(plan, Plan::new_payment(42, to));
+    }
+
+    #[test]
+    fn test_future_payment() {
+        let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
+        let to = PublicKey::default();
+
+        let mut plan = Plan::new_future_payment(dt, 42, to);
+        assert!(plan.process_event(PlanEvent::Timestamp(dt)));
+        assert_eq!(plan, Plan::new_payment(42, to));
+    }
+
+    #[test]
+    fn test_cancelable_future_payment() {
+        let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
+        let from = PublicKey::default();
+        let to = PublicKey::default();
+
+        let mut plan = Plan::new_cancelable_future_payment(dt, from, 42, to);
+        assert!(plan.process_event(PlanEvent::Timestamp(dt)));
+        assert_eq!(plan, Plan::new_payment(42, to));
+
+        let mut plan = Plan::new_cancelable_future_payment(dt, from, 42, to);
+        assert!(plan.process_event(PlanEvent::Signature(from)));
+        assert_eq!(plan, Plan::new_payment(42, from));
+    }
+}