solana/src/accountant.rs

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