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CryptopoolLPOracle

The source code of the CryptopoolLPOracle.vy contract can be found on GitHub. The contract is written with Vyper version 0.4.3.

Overview​

The CryptopoolLPOracle is a price oracle contract that provides LP token pricing for Curve cryptopools. It combines the LP token price from a Curve cryptopool with a price aggregator to return the LP token value in aggregated USD terms. This oracle is used by the Yield Basis protocol to determine the value of LP tokens for various calculations including debt limits, collateral values, and trading operations.

Oracle Principle and Reliability​

The oracle operates on a crvUSD price normalization principle that enhances reliability and reduces manipulation risks:

  1. Cryptopool components — the oracle reads POOL.virtual_price() and POOL.price_scale() directly. It does not call POOL.lp_price(); the formula is computed locally to avoid depending on any per-pool helper.
  2. Internal LP price: lp_price_internal = 2 · virtual_price · sqrt(price_scale · 1e18) / 1e18. This is the Curve LP price formula for a 2-coin pool, expressed in pool units (numeraire = coins(0), i.e. crvUSD).
  3. crvUSD aggregation: A price aggregator (AGG) provides the "real" price of crvUSD across multiple major liquidity pools.
  4. Final price: price = lp_price_internal · AGG.price() / 1e18 — LP value in aggregated USD.

This approach is reliable because:

  • Curve pools are battle-tested and the LP-price formula derives from the AMM invariant rather than an external helper.
  • crvUSD price aggregation uses multiple major liquidity pools to avoid price swings from any single source.
  • Local computation keeps the oracle independent of any future POOL.lp_price() behaviour change in the Twocrypto fork.

Function Documentation​

Public Variables​

Immutable Variables

  • POOL (Cryptopool) - Curve cryptopool contract address (immutable)
  • AGG (PriceOracle) - Price aggregator contract address (immutable)

lp_price() (internal)​

Description: Internal helper that computes the LP token's value in pool-numeraire units (coins(0) = crvUSD) directly from virtual_price and price_scale. Never reverts; never reads POOL.lp_price().

@internal
@view
def lp_price() -> uint256:
    virtual_price: uint256 = staticcall POOL.virtual_price()
    p_scale: uint256 = staticcall POOL.price_scale()
    return 2 * virtual_price * isqrt(p_scale * 10**18) // 10**18

price()​

Description: Returns the current LP token price in aggregated USD terms. View function — multiplies the internal LP price by the crvUSD aggregator's USD value.

Returns: uint256 - LP token price in aggregated USD (scaled by 10^18).

📄 View Source Code
@external
@view
def price() -> uint256:
    return self.lp_price() * staticcall AGG.price() // 10**18

price_w()​

Description: Returns the current LP token price in aggregated USD terms. Mutates the aggregator's EMA tick — used when fresh pricing is needed for state-mutating calls.

Returns: uint256 - LP token price in aggregated USD (scaled by 10^18).

📄 View Source Code
@external
def price_w() -> uint256:
    return self.lp_price() * extcall AGG.price_w() // 10**18