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Merge 22dab37 into 5357854
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@asselstine
asselstine committed Oct 14, 2021
2 parents 5357854 + 22dab37 commit d01ac24
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Showing 3 changed files with 52 additions and 53 deletions.
74 changes: 50 additions & 24 deletions contracts/Reserve.sol
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import "./interfaces/IReserve.sol";
import "./libraries/ObservationLib.sol";
import "./libraries/RingBufferLib.sol";

/**
* @title PoolTogether V4 Reserve
Expand All @@ -29,14 +30,16 @@ contract Reserve is IReserve, Manageable {

/// @notice Total withdraw amount from reserve
uint224 public withdrawAccumulator;
uint32 private _gap;

uint24 internal nextIndex;
uint24 internal cardinality;

/// @notice The maximum number of twab entries
uint24 internal constant MAX_CARDINALITY = 16777215; // 2**24
uint24 internal constant MAX_CARDINALITY = 16777215; // 2**24 - 1

ObservationLib.Observation[MAX_CARDINALITY] internal reserveAccumulators;

uint24 internal cardinality;

/* ============ Events ============ */

event Deployed(IERC20 indexed token);
Expand Down Expand Up @@ -74,25 +77,25 @@ contract Reserve is IReserve, Manageable {
{
require(_startTimestamp < _endTimestamp, "Reserve/start-less-then-end");
uint24 _cardinality = cardinality;
uint24 _nextIndex = nextIndex;

ObservationLib.Observation memory _newestObservation;

if (_cardinality > 0) {
_newestObservation = reserveAccumulators[_cardinality - 1];
}

ObservationLib.Observation memory _oldestObservation = reserveAccumulators[0];
(uint24 _newestIndex, ObservationLib.Observation memory _newestObservation) = _getNewestObservation(_nextIndex);
(uint24 _oldestIndex, ObservationLib.Observation memory _oldestObservation) = _getOldestObservation(_nextIndex);

uint224 _start = _getReserveAccumulatedAt(
_newestObservation,
_oldestObservation,
_newestIndex,
_oldestIndex,
_cardinality,
_startTimestamp
);

uint224 _end = _getReserveAccumulatedAt(
_newestObservation,
_oldestObservation,
_newestIndex,
_oldestIndex,
_cardinality,
_endTimestamp
);
Expand All @@ -118,6 +121,8 @@ contract Reserve is IReserve, Manageable {
* @dev Uses binary search if target timestamp is within ring buffer range.
* @param _newestObservation ObservationLib.Observation
* @param _oldestObservation ObservationLib.Observation
* @param _newestIndex The index of the newest observation
* @param _oldestIndex The index of the oldest observation
* @param _cardinality RingBuffer Range
* @param _timestamp Timestamp target
*
Expand All @@ -126,6 +131,8 @@ contract Reserve is IReserve, Manageable {
function _getReserveAccumulatedAt(
ObservationLib.Observation memory _newestObservation,
ObservationLib.Observation memory _oldestObservation,
uint24 _newestIndex,
uint24 _oldestIndex,
uint24 _cardinality,
uint32 _timestamp
) internal view returns (uint224) {
Expand Down Expand Up @@ -168,8 +175,8 @@ contract Reserve is IReserve, Manageable {
ObservationLib.Observation memory atOrAfter
) = ObservationLib.binarySearch(
reserveAccumulators,
_cardinality - 1,
0,
_newestIndex,
_oldestIndex,
_timestamp,
_cardinality,
timeNow
Expand All @@ -188,34 +195,37 @@ contract Reserve is IReserve, Manageable {
/// @notice Records the currently accrued reserve amount.
function _checkpoint() internal {
uint24 _cardinality = cardinality;
uint24 _nextIndex = nextIndex;
uint256 _balanceOfReserve = token.balanceOf(address(this));
uint224 _withdrawAccumulator = withdrawAccumulator; //sload
ObservationLib.Observation memory _newestObservation = _getNewestObservation(_cardinality);
(uint24 newestIndex, ObservationLib.Observation memory newestObservation) = _getNewestObservation(_nextIndex);

/**
* IF tokens have been deposited into Reserve contract since the last checkpoint
* create a new Reserve balance checkpoint. The will will update multiple times in a single block.
*/
if (_balanceOfReserve + _withdrawAccumulator > _newestObservation.amount) {
if (_balanceOfReserve + _withdrawAccumulator > newestObservation.amount) {
uint32 nowTime = uint32(block.timestamp);

// checkpointAccumulator = currentBalance + totalWithdraws
uint224 newReserveAccumulator = uint224(_balanceOfReserve) + _withdrawAccumulator;

// IF _newestObservation IS NOT in the current block.
// IF newestObservation IS NOT in the current block.
// CREATE observation in the accumulators ring buffer.
if (_newestObservation.timestamp != nowTime) {
reserveAccumulators[_cardinality] = ObservationLib.Observation({
if (newestObservation.timestamp != nowTime) {
reserveAccumulators[_nextIndex] = ObservationLib.Observation({
amount: newReserveAccumulator,
timestamp: nowTime
});

cardinality++;
nextIndex = uint24(RingBufferLib.nextIndex(_nextIndex, MAX_CARDINALITY));
if (_cardinality < MAX_CARDINALITY) {
cardinality = _cardinality + 1;
}
}
// ELSE IF _newestObservation IS in the current block.
// ELSE IF newestObservation IS in the current block.
// UPDATE the checkpoint previously created in block history.
else {
reserveAccumulators[_cardinality - 1] = ObservationLib.Observation({
reserveAccumulators[newestIndex] = ObservationLib.Observation({
amount: newReserveAccumulator,
timestamp: nowTime
});
Expand All @@ -225,12 +235,28 @@ contract Reserve is IReserve, Manageable {
}
}

function _getOldestObservation(uint24 _nextIndex)
internal
view
returns (uint24 index, ObservationLib.Observation memory observation)
{
index = _nextIndex;
observation = reserveAccumulators[index];

// If the TWAB is not initialized we go to the beginning of the TWAB circular buffer at index 0
if (observation.timestamp == 0) {
index = 0;
observation = reserveAccumulators[0];
}
}

/// @notice Retrieves the newest observation
function _getNewestObservation(uint24 _cardinality)
function _getNewestObservation(uint24 _nextIndex)
internal
view
returns (ObservationLib.Observation memory _observation)
returns (uint24 index, ObservationLib.Observation memory observation)
{
if (_cardinality > 0) _observation = reserveAccumulators[_cardinality - 1];
index = uint24(RingBufferLib.newestIndex(_nextIndex, MAX_CARDINALITY));
observation = reserveAccumulators[index];
}
}
18 changes: 2 additions & 16 deletions contracts/test/ReserveHarness.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -8,27 +8,13 @@ import "./ERC20Mintable.sol";
contract ReserveHarness is Reserve {
constructor(address _owner, IERC20 _token) Reserve(_owner, _token) {}

function getReserveAccumulatedAt(
ObservationLib.Observation memory _newestObservation,
ObservationLib.Observation memory _oldestObservation,
uint24 _cardinality,
uint32 timestamp
) public view returns (uint224) {
return
_getReserveAccumulatedAt(
_newestObservation,
_oldestObservation,
_cardinality,
timestamp
);
}

function setObservationsAt(ObservationLib.Observation[] calldata observations) external {
for (uint256 i = 0; i < observations.length; i++) {
reserveAccumulators[i] = observations[i];
}

cardinality = uint16(observations.length);
nextIndex = uint24(observations.length);
cardinality = uint24(observations.length);
}

function doubleCheckpoint(ERC20Mintable _token, uint256 _amount) external {
Expand Down
13 changes: 0 additions & 13 deletions test/Reserve.test.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -254,19 +254,6 @@ describe('Reserve', () => {
});
});

describe('_getReserveAccumulatedAt()', () => {
it('should return 0 if cardinality is equal to 0', async () => {
const newestObservation = { timestamp: 8, amount: 72 };
const oldestObservation = { timestamp: 5, amount: 70 };

await reserve.setObservationsAt([oldestObservation, newestObservation]);

expect(
await reserve.getReserveAccumulatedAt(newestObservation, oldestObservation, 0, 5),
).to.equal(0);
});
});

describe('withdrawTo()', () => {
it('should emit Checkpoint, Transfer and Withdrawn events', async () => {
await ticket.mint(reserve.address, toWei('100'));
Expand Down

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