Add updatePriceIfNecessary method (#23)

* Add updatePriceIfNecessary method
* Bump version to 0.5.1 (not breaking change)

Co-authored-by: Tom Pointon <[email protected]>

Author: ali-behjati

AbstractPyth.sol

@@ -5,7 +5,9 @@ import "./PythStructs.sol";
 import "./IPyth.sol";
 
 abstract contract AbstractPyth is IPyth {
-
+    /// @notice Returns the price feed with given id.
+    /// @dev Reverts if the price does not exist.
+    /// @param id The Pyth Price Feed ID of which to fetch the current price and confidence interval.
     function queryPriceFeed(bytes32 id) public view virtual returns (PythStructs.PriceFeed memory priceFeed);
 
     function getCurrentPrice(bytes32 id) external view override returns (PythStructs.Price memory price) {
@@ -59,4 +61,22 @@ abstract contract AbstractPyth is IPyth {
             return y - x;
         }
     }
+
+    // Access modifier is overridden to public to be able to call it locally.
+    function updatePriceFeeds(bytes[] memory updateData) public virtual payable override;
+
+    function updatePriceFeedsIfNecessary(bytes[] memory updateData, bytes32[] memory priceIds, uint64[] memory publishTimes) external payable override {
+        require(priceIds.length == publishTimes.length, "priceIds and publishTimes arrays should have same length");
+
+        bool updateNeeded = false;
+        for(uint i = 0; i < priceIds.length; i++) {
+            if (queryPriceFeed(priceIds[i]).publishTime < publishTimes[i]) {
+                updateNeeded = true;
+            }
+        }
+
+        require(updateNeeded, "no prices in the submitted batch have fresh prices, so this update will have no effect");
+
+        updatePriceFeeds(updateData);
+    }
 }

IPyth.sol

@@ -74,6 +74,23 @@ interface IPyth {
     /// @param updateData Array of price update data.
     function updatePriceFeeds(bytes[] memory updateData) external payable;
 
+    /// @notice Wrapper around updatePriceFeeds that rejects fast if a price update is not necessary. A price update is
+    /// necessary if the current on-chain publishTime is older than the given publishTime. It relies solely on the
+    /// given `publishTimes` for the price feeds and does not read the actual price update publish time within `updateData`.
+    ///
+    /// This method requires the caller to pay a fee in wei; the required fee can be computed by calling
+    /// `getUpdateFee` with the length of the `updateData` array.
+    ///
+    /// `priceIds` and `publishTimes` are two arrays with the same size that correspond to senders known publishTime
+    /// of each priceId when calling this method. If all of price feeds within `priceIds` have updated and have
+    /// a newer or equal publish time than the given publish time, it will reject the transaction to save gas.
+    /// Otherwise, it calls updatePriceFeeds method to update the prices.
+    ///
+    /// @dev Reverts if update is not needed or the transferred fee is not sufficient or the updateData is invalid.
+    /// @param updateData Array of price update data.
+    /// @param priceIds Array of price ids.
+    /// @param publishTimes Array of publishTimes. `publishTimes[i]` corresponds to known `publishTime` of `priceIds[i]`
+    function updatePriceFeedsIfNecessary(bytes[] memory updateData, bytes32[] memory priceIds, uint64[] memory publishTimes) external payable;
 
     /// @notice Returns the required fee to update an array of price updates.
     /// @param updateDataSize Number of price updates.

MockPyth.sol

@@ -15,6 +15,7 @@ contract MockPyth is AbstractPyth {
     }
 
     function queryPriceFeed(bytes32 id) public override view returns (PythStructs.PriceFeed memory priceFeed) {
+        require(priceFeeds[id].id != 0, "no price feed found for the given price id");
         return priceFeeds[id];
     }
 

abis/AbstractPyth.json

@@ -386,5 +386,28 @@
     "outputs": [],
     "stateMutability": "payable",
     "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "bytes[]",
+        "name": "updateData",
+        "type": "bytes[]"
+      },
+      {
+        "internalType": "bytes32[]",
+        "name": "priceIds",
+        "type": "bytes32[]"
+      },
+      {
+        "internalType": "uint64[]",
+        "name": "publishTimes",
+        "type": "uint64[]"
+      }
+    ],
+    "name": "updatePriceFeedsIfNecessary",
+    "outputs": [],
+    "stateMutability": "payable",
+    "type": "function"
   }
 ]

abis/IPyth.json

@@ -295,5 +295,28 @@
     "outputs": [],
     "stateMutability": "payable",
     "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "bytes[]",
+        "name": "updateData",
+        "type": "bytes[]"
+      },
+      {
+        "internalType": "bytes32[]",
+        "name": "priceIds",
+        "type": "bytes32[]"
+      },
+      {
+        "internalType": "uint64[]",
+        "name": "publishTimes",
+        "type": "uint64[]"
+      }
+    ],
+    "name": "updatePriceFeedsIfNecessary",
+    "outputs": [],
+    "stateMutability": "payable",
+    "type": "function"
   }
 ]

abis/MockPyth.json

@@ -466,5 +466,28 @@
     "outputs": [],
     "stateMutability": "payable",
     "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "bytes[]",
+        "name": "updateData",
+        "type": "bytes[]"
+      },
+      {
+        "internalType": "bytes32[]",
+        "name": "priceIds",
+        "type": "bytes32[]"
+      },
+      {
+        "internalType": "uint64[]",
+        "name": "publishTimes",
+        "type": "uint64[]"
+      }
+    ],
+    "name": "updatePriceFeedsIfNecessary",
+    "outputs": [],
+    "stateMutability": "payable",
+    "type": "function"
   }
 ]

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@pythnetwork/pyth-sdk-solidity",
-  "version": "0.5.0",
+  "version": "0.5.1",
   "description": "Read prices from the Pyth oracle",
   "repository": {
     "type": "git",