Chainlink Integration

[jalextowle]

Resolved Issues

Fixes: #1104

Description

This PR adds a chainlink integration. This can be used with general price feeds, although the intended use is with price feeds like the wsteth-eth reference rate on Gnosis Chain. This integration uses the output of a given Chainlink aggregator as the vault share price. It doesn't support base as a deposit asset since the base token may not even exist. Some documentation is included in the implementation that describes how Chainlink downtime or deprecation will impact the instance.

Review Checklists

Please check each item before approving the pull request. While going
through the checklist, it is recommended to leave comments on items that are
referenced in the checklist to make sure that they are reviewed. If there are
multiple reviewers, copy the checklists into sections titled ## [Reviewer Name].
If the PR doesn't touch Solidity, the corresponding checklist can
be removed.

[[Reviewer Name]]

• Tokens
  • Do all approve calls use forceApprove?
  • Do all transfer calls use safeTransfer?
  • Do all transferFrom calls use msg.sender as the from address?
    • If not, is the function access restricted to prevent unauthorized
      token spend?
• Low-level calls (call, delegatecall, staticcall, transfer, send)
  • Is the returned success boolean checked to handle failed calls?
  • If using delegatecall, are there strict access controls on the
    addresses that can be called? It shouldn't be possible to delegatecall
    arbitrary addresses, so the list of possible targets should either be
    immutable or tightly controlled by an admin.
• Reentrancy
  • Are functions that make external calls or transfer ether marked as nonReentrant?
    • If not, is there documentation that explains why reentrancy is
      not a concern or how it's mitigated?
• Gas Optimizations
  • Is the logic as simple as possible?
  • Are the storage values that are used repeatedly cached in stack or
    memory variables?
  • If loops are used, are there guards in place to avoid out-of-gas
    issues?
• Visibility
  • Are all payable functions restricted to avoid stuck ether?
• Math
  • Is all of the arithmetic checked or guarded by if-statements that will
    catch underflows?
  • If Safe functions are altered, are potential underflows and
    overflows caught so that a failure flag can be thrown?
  • Are all of the rounding directions clearly documented?
• Testing
  • Are there new or updated unit or integration tests?
  • Do the tests cover the happy paths?
  • Do the tests cover the unhappy paths?
  • Are there an adequate number of fuzz tests to ensure that we are
    covering the full input space?

[coveralls]

Pull Request Test Coverage Report for Build 10483818456

Details

• 57 of 64 (89.06%) changed or added relevant lines in 20 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 90.7%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contracts/src/deployers/chainlink/ChainlinkHyperdriveDeployerCoordinator.sol	13	20	65.0%

Totals
Change from base Build 10483721874:	-0.04%
Covered Lines:	2292
Relevant Lines:	2527

---

💛 - Coveralls

[jrhea]

Nice work! I just had a couple of nits, but I will go ahead and approve. I would consider having @DannyDelott take a look at the PR in case he has any issues with the lack of a baseToken.

[mcclurejt]

awesome stuff! coolest integration yet imo

[github-actions]

Hyperdrive Gas Benchmark

Benchmark suite	Current: 8ae7cd9	Previous: 4f070b3	Deviation	Status
addLiquidity: min	33893 gas	33893 gas	0%	🟰
addLiquidity: avg	196852 gas	197337 gas	-0.2458%	✅
addLiquidity: max	474700 gas	474700 gas	0%	🟰
checkpoint: min	40316 gas	40316 gas	0%	🟰
checkpoint: avg	144443 gas	144535 gas	-0.0637%	✅
checkpoint: max	256108 gas	256108 gas	0%	🟰
closeLong: min	31384 gas	31384 gas	0%	🟰
closeLong: avg	135729 gas	135808 gas	-0.0582%	✅
closeLong: max	2539399 gas	2539399 gas	0%	🟰
closeShort: min	31327 gas	31327 gas	0%	🟰
closeShort: avg	131314 gas	131449 gas	-0.1027%	✅
closeShort: max	271272 gas	271272 gas	0%	🟰
initialize: min	31305 gas	31305 gas	0%	🟰
initialize: avg	352431 gas	352459 gas	-0.0079%	✅
initialize: max	418737 gas	418737 gas	0%	🟰
openLong: min	33370 gas	33370 gas	0%	🟰
openLong: avg	174007 gas	174093 gas	-0.0494%	✅
openLong: max	333737 gas	333737 gas	0%	🟰
openShort: min	33936 gas	33936 gas	0%	🟰
openShort: avg	174290 gas	174137 gas	0.0879%	🚨
openShort: max	415133 gas	415068 gas	0.0157%	🚨
redeemWithdrawalShares: min	31211 gas	31211 gas	0%	🟰
redeemWithdrawalShares: avg	74819 gas	74608 gas	0.2828%	🚨
redeemWithdrawalShares: max	305184 gas	305184 gas	0%	🟰
removeLiquidity: min	31217 gas	31217 gas	0%	🟰
removeLiquidity: avg	214368 gas	215105 gas	-0.3426%	✅
removeLiquidity: max	403247 gas	403526 gas	-0.0691%	✅

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