Alter snapshots logic (#39)

* take snapshots automatically

* fix: larger dt

* ci: some parallelisation

* test: new test for new features

* test: fix hardcoded init value check

* fix: get rid of balanceOf

* chore: commit format

.github/workflows/ci.yaml

@@ -55,4 +55,9 @@ jobs:
         env:
           ETH_RPC_URL: ${{ secrets.ETH_RPC_URL }}
           ETHERSCAN_API_KEY: ${{ secrets.ETHERSCAN_API_KEY }}
-        run: uv run pytest ${{ matrix.folder }}
+        run: |
+          if [ "${{ matrix.folder }}" == "tests/unitary" ]; then
+            uv run pytest ${{ matrix.folder }} -n=auto
+          else
+            uv run pytest ${{ matrix.folder }}
+          fi

contracts/RewardsHandler.vy

@@ -160,7 +160,7 @@ def __init__(
 
     twa.__init__(
         WEEK,  # twa_window = 1 week
-        1,  #  min_snapshot_dt_seconds = 1 second
+        600,  #  min_snapshot_dt_seconds = 600 seconds
     )
 
     self._set_minimum_weight(minimum_weight)
@@ -188,15 +188,22 @@ def take_snapshot():
     or the minimum amount of rewards can always be increased (if a malicious actor
     deflates the value of the snapshot).
     """
+    self._take_snapshot()
 
+
+@internal
+def _take_snapshot():
+    """
+    @notice Internal function to take a snapshot of the current deposited supply
+    ratio in the vault.
+    """
     # get the circulating supply from a helper contract.
     # supply in circulation = controllers' debt + peg keppers' debt
     circulating_supply: uint256 = staticcall self.stablecoin_lens.circulating_supply()
 
-    # obtain the supply of crvUSD contained in the vault by simply checking its
-    # balance since it's an ERC4626 vault. This will also take into account
-    # rewards that are not yet distributed.
-    supply_in_vault: uint256 = staticcall stablecoin.balanceOf(vault.address)
+    # obtain the supply of crvUSD contained in the vault by checking its totalAssets.
+    # This will not take into account rewards that are not yet distributed.
+    supply_in_vault: uint256 = staticcall vault.totalAssets()
 
     # here we intentionally reduce the precision of the ratio because the
     # dynamic weight interface expects a percentage in BPS.
@@ -206,11 +213,14 @@ def take_snapshot():
 
 
 @external
-def process_rewards():
+def process_rewards(take_snapshot: bool = True):
     """
     @notice Permissionless function that let anyone distribute rewards (if any) to
     the crvUSD vault.
     """
+    # optional (advised) snapshot before distributing the rewards
+    if take_snapshot:
+        self._take_snapshot()
 
     # prevent the rewards from being distributed untill the distribution rate
     # has been set

contracts/TWA.vy

@@ -107,7 +107,9 @@ def _take_snapshot(_value: uint256):
     @notice Stores a snapshot of the tracked value.
     @param _value The value to store.
     """
-    if self.last_snapshot_timestamp + self.min_snapshot_dt_seconds <= block.timestamp:
+    if (len(self.snapshots) == 0) or (  # First snapshot
+        self.last_snapshot_timestamp + self.min_snapshot_dt_seconds <= block.timestamp # after dt
+    ):
         self.last_snapshot_timestamp = block.timestamp
         self.snapshots.append(
             Snapshot(tracked_value=_value, timestamp=block.timestamp)

tests/unitary/rewards_handler/test_process_rewards.py

@@ -27,3 +27,23 @@ def test_no_rewards(rewards_handler, rate_manager):
 
     with boa.reverts("no rewards to distribute"):
         rewards_handler.process_rewards()
+
+
+def test_snapshots_taking(rewards_handler, rate_manager, crvusd):
+    rewards_handler.set_distribution_time(1234, sender=rate_manager)  # to enable process_rewards
+    assert rewards_handler.get_len_snapshots() == 0
+    boa.deal(crvusd, rewards_handler, 1)
+    rewards_handler.process_rewards()
+    assert crvusd.balanceOf(rewards_handler) == 0  # crvusd gone
+    assert rewards_handler.get_len_snapshots() == 1  # first snapshot taken
+
+    boa.deal(crvusd, rewards_handler, 1)
+    rewards_handler.process_rewards()
+    assert crvusd.balanceOf(rewards_handler) == 0  # crvusd gone (again)
+    assert rewards_handler.get_len_snapshots() == 1  # not changed since dt has not passed
+
+    boa.env.time_travel(seconds=rewards_handler.min_snapshot_dt_seconds())
+    boa.deal(crvusd, rewards_handler, 1)
+    rewards_handler.process_rewards()
+    assert crvusd.balanceOf(rewards_handler) == 0  # crvusd gone (they always go)
+    assert rewards_handler.get_len_snapshots() == 2  # changed since dt has passed

tests/unitary/rewards_handler/test_rh_constructor.py

@@ -33,4 +33,4 @@ def test_default_behavior(
     # eoa would be the deployer from which we revoke the role
     assert not rewards_handler.hasRole(rewards_handler.DEFAULT_ADMIN_ROLE(), boa.env.eoa)
     assert rewards_handler.eval("twa.twa_window") == 86_400 * 7
-    assert rewards_handler.eval("twa.min_snapshot_dt_seconds") == 1
+    assert rewards_handler.eval("twa.min_snapshot_dt_seconds") == 600  # 10 minutes

tests/unitary/rewards_handler/test_take_snapshot.py

@@ -0,0 +1,15 @@
+import pytest
+import boa
+
+
+@pytest.mark.gas_profile
+def test_take_snapshot_compute(rewards_handler):
+    n_days = 7
+    dt = 600
+    snaps_per_day = 86_400 // dt
+    for i_day in range(n_days):
+        for i_snap in range(snaps_per_day):
+            rewards_handler.take_snapshot()
+            boa.env.time_travel(seconds=dt)
+        twa = rewards_handler.compute_twa()
+        assert twa >= 0, f"Computed TWA is negative: {twa}"