208 lines
6.2 KiB
Rust
208 lines
6.2 KiB
Rust
//! The `accountant` is a client of the `historian`. It uses the historian's
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//! event log to record transactions. Its users can deposit funds and
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//! transfer funds to other users.
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use hash::Hash;
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use entry::Entry;
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use event::Event;
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use transaction::Transaction;
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use signature::{KeyPair, PublicKey, Signature};
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use mint::Mint;
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use historian::{reserve_signature, Historian};
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use std::sync::mpsc::SendError;
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use std::collections::HashMap;
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use std::result;
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#[derive(Debug, PartialEq, Eq)]
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pub enum AccountingError {
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InsufficientFunds,
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InvalidTransfer,
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InvalidTransferSignature,
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SendError,
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}
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pub type Result<T> = result::Result<T, AccountingError>;
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pub struct Accountant {
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pub historian: Historian,
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pub balances: HashMap<PublicKey, i64>,
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pub first_id: Hash,
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pub last_id: Hash,
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}
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impl Accountant {
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pub fn new_from_entries<I>(entries: I, ms_per_tick: Option<u64>) -> Self
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where
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I: IntoIterator<Item = Entry>,
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{
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let mut entries = entries.into_iter();
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// The first item in the log is required to be an entry with zero num_hashes,
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// which implies its id can be used as the log's seed.
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let entry0 = entries.next().unwrap();
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let start_hash = entry0.id;
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let hist = Historian::new(&start_hash, ms_per_tick);
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let mut acc = Accountant {
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historian: hist,
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balances: HashMap::new(),
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first_id: start_hash,
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last_id: start_hash,
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};
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// The second item in the log is a special transaction where the to and from
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// fields are the same. That entry should be treated as a deposit, not a
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// transfer to oneself.
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let entry1 = entries.next().unwrap();
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acc.process_verified_event(&entry1.event, true).unwrap();
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for entry in entries {
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acc.process_verified_event(&entry.event, false).unwrap();
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}
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acc
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}
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pub fn new(mint: &Mint, ms_per_tick: Option<u64>) -> Self {
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Self::new_from_entries(mint.create_entries(), ms_per_tick)
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}
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pub fn sync(self: &mut Self) -> Hash {
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while let Ok(entry) = self.historian.receiver.try_recv() {
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self.last_id = entry.id;
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}
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self.last_id
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}
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fn is_deposit(allow_deposits: bool, from: &PublicKey, to: &PublicKey) -> bool {
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allow_deposits && from == to
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}
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pub fn process_transaction(self: &mut Self, tr: Transaction<i64>) -> Result<()> {
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if !tr.verify() {
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return Err(AccountingError::InvalidTransfer);
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}
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if self.get_balance(&tr.from).unwrap_or(0) < tr.asset {
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return Err(AccountingError::InsufficientFunds);
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}
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self.process_verified_transaction(&tr, false)?;
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if let Err(SendError(_)) = self.historian.sender.send(Event::Transaction(tr)) {
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return Err(AccountingError::SendError);
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}
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Ok(())
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}
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fn process_verified_transaction(
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self: &mut Self,
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tr: &Transaction<i64>,
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allow_deposits: bool,
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) -> Result<()> {
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if !reserve_signature(&mut self.historian.signatures, &tr.sig) {
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return Err(AccountingError::InvalidTransferSignature);
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}
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if !Self::is_deposit(allow_deposits, &tr.from, &tr.to) {
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if let Some(x) = self.balances.get_mut(&tr.from) {
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*x -= tr.asset;
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}
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}
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if self.balances.contains_key(&tr.to) {
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if let Some(x) = self.balances.get_mut(&tr.to) {
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*x += tr.asset;
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}
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} else {
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self.balances.insert(tr.to, tr.asset);
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}
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Ok(())
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}
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fn process_verified_event(self: &mut Self, event: &Event, allow_deposits: bool) -> Result<()> {
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match *event {
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Event::Tick => Ok(()),
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Event::Transaction(ref tr) => self.process_verified_transaction(tr, allow_deposits),
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}
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}
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pub fn transfer(
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self: &mut Self,
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n: i64,
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keypair: &KeyPair,
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to: PublicKey,
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) -> Result<Signature> {
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let tr = Transaction::new(keypair, to, n, self.last_id);
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let sig = tr.sig;
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self.process_transaction(tr).map(|_| sig)
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}
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pub fn get_balance(self: &Self, pubkey: &PublicKey) -> Option<i64> {
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self.balances.get(pubkey).map(|x| *x)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use signature::KeyPairUtil;
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use logger::ExitReason;
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#[test]
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fn test_accountant() {
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let alice = Mint::new(10_000);
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let bob_pubkey = KeyPair::new().pubkey();
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let mut acc = Accountant::new(&alice, Some(2));
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acc.transfer(1_000, &alice.keypair(), bob_pubkey).unwrap();
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assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_000);
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acc.transfer(500, &alice.keypair(), bob_pubkey).unwrap();
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assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_500);
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drop(acc.historian.sender);
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assert_eq!(
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acc.historian.thread_hdl.join().unwrap(),
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ExitReason::RecvDisconnected
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);
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}
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#[test]
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fn test_invalid_transfer() {
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let alice = Mint::new(11_000);
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let mut acc = Accountant::new(&alice, Some(2));
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let bob_pubkey = KeyPair::new().pubkey();
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acc.transfer(1_000, &alice.keypair(), bob_pubkey).unwrap();
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assert_eq!(
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acc.transfer(10_001, &alice.keypair(), bob_pubkey),
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Err(AccountingError::InsufficientFunds)
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);
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let alice_pubkey = alice.keypair().pubkey();
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assert_eq!(acc.get_balance(&alice_pubkey).unwrap(), 10_000);
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assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_000);
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drop(acc.historian.sender);
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assert_eq!(
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acc.historian.thread_hdl.join().unwrap(),
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ExitReason::RecvDisconnected
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);
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}
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#[test]
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fn test_transfer_to_newb() {
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let alice = Mint::new(10_000);
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let mut acc = Accountant::new(&alice, Some(2));
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let alice_keypair = alice.keypair();
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let bob_pubkey = KeyPair::new().pubkey();
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acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
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assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 500);
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drop(acc.historian.sender);
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assert_eq!(
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acc.historian.thread_hdl.join().unwrap(),
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ExitReason::RecvDisconnected
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);
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}
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}
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