Optimized v2 oracle implementation [SC-1132]

[simplyoptimistic]

before:
gasUsed VelodromeV2Oracle WETH -> USDC 160768
gasUsed VelodromeV2Oracle USDC -> WETH 160928
gasUsed VelodromeV2Oracle WETH -> OP -> USDC 267972

after:
gasUsed VelodromeV2Oracle WETH -> USDC 50244
gasUsed VelodromeV2Oracle USDC -> WETH 50313
gasUsed VelodromeV2Oracle WETH -> OP -> USDC 75466

Achieved by:

• Not iterating through the factory registry (different pool types require different oracles).
• Generate pool address without external call.
• Fetch reserves directly from pool, without additional external call to router.

[zZoMROT]

// ✔ OffchainOracle with 1 connector, WETH -> USDC price
gasUsed offchainOracle current version 196073
gasUsed offchainOracle new version 192270 // diff oracles for diff factories
gasUsed offchainOracle new version 183686 // 1 oracle
gasUsed offchainOracle new version 164376 // 1 oracle w/o Slipstream factory

// ✔ OffchainOracle with 2 connector, WETH -> USDC price
gasUsed offchainOracle current version 419621
gasUsed offchainOracle new version 398382 // diff oracles for diff factories
gasUsed offchainOracle new version 386564 // 1 oracle
gasUsed offchainOracle new version 328625 // 1 oracle w/o Slipstream factory

[zZoMROT]

Good point! 👍
I've tweaked your idea a bit to enhance its functionality even further.
Thank you for your contribution to improving the service!

[zZoMROT]

Before deploying the new oracle, I noticed that one of the factories is the first Velodrome Finance, and the other is also a fork of Solidly. This indicates that the oracle for the factory pool_factory does not require a separate oracle; instead, we can reuse the SolidlyOracle, which turns out to be more cost-effective:

gasUsed offchainOracleNew (1 connector) WETH -> USDC 98666
gasUsed offchainOracleNew (2 connector) WETH -> USDC 157936

Check PR