feat: Multicall context manager

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add polygon network integration ([#1119](https://github.com/eth-brownie/brownie/pull/1119))
 - Fixed subcalls to empty accounts not appearing in the subcalls property of TransactionReceipts ([#1106](https://github.com/eth-brownie/brownie/pull/1106))
 - Add support for `POLYGONSCAN_TOKEN` env var ([#1135](https://github.com/eth-brownie/brownie/pull/1135))
+- Add Multicall context manager ([#1125](https://github.com/eth-brownie/brownie/pull/1125))
 
 ### Added
 - Added `LocalAccount.sign_message` method to sign `EIP712Message` objects ([#1097](https://github.com/eth-brownie/brownie/pull/1097))

MANIFEST.in

@@ -5,6 +5,7 @@ include requirements*.in
 include requirements*.txt
 include brownie/data/*.yaml
 include brownie/data/interfaces/*.json
+include brownie/data/contracts/*.sol
 
 recursive-exclude * __pycache__
 recursive-exclude * *.py[co]

brownie/__init__.py

@@ -8,11 +8,13 @@
 from brownie.convert import Fixed, Wei
 from brownie.network import accounts, alert, chain, history, rpc, web3
 from brownie.network.contract import Contract  # NOQA: F401
+from brownie.network import multicall as _multicall
 
 ETH_ADDRESS = "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"
 ZERO_ADDRESS = "0x0000000000000000000000000000000000000000"
 
 config = _CONFIG.settings
+multicall = _multicall.Multicall()
 
 __all__ = [
     "Contract",
@@ -22,6 +24,7 @@
     "alert",
     "chain",
     "history",  # history is a TxHistory singleton
+    "multicall",
     "network",
     "rpc",  # rpc is a Rpc singleton
     "web3",  # web3 is a Web3 instance

brownie/_cli/networks.py

@@ -39,7 +39,7 @@
 
 DEV_REQUIRED = ("id", "host", "cmd", "cmd_settings")
 PROD_REQUIRED = ("id", "host", "chainid")
-OPTIONAL = ("name", "explorer", "timeout")
+OPTIONAL = ("name", "explorer", "timeout", "multicall2")
 
 DEV_CMD_SETTINGS = (
     "port",

brownie/data/contracts/Multicall2.sol

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.5.0;
+pragma experimental ABIEncoderV2;
+
+/// @title Multicall2 - Aggregate results from multiple read-only function calls
+/// @author Michael Elliot <mike@makerdao.com>
+/// @author Joshua Levine <joshua@makerdao.com>
+/// @author Nick Johnson <arachnid@notdot.net>
+
+contract Multicall2 {
+    struct Call {
+        address target;
+        bytes callData;
+    }
+    struct Result {
+        bool success;
+        bytes returnData;
+    }
+
+    function aggregate(Call[] memory calls)
+        public
+        returns (uint256 blockNumber, bytes[] memory returnData)
+    {
+        blockNumber = block.number;
+        returnData = new bytes[](calls.length);
+        for (uint256 i = 0; i < calls.length; i++) {
+            (bool success, bytes memory ret) = calls[i].target.call(
+                calls[i].callData
+            );
+            require(success, "Multicall aggregate: call failed");
+            returnData[i] = ret;
+        }
+    }
+
+    function blockAndAggregate(Call[] memory calls)
+        public
+        returns (
+            uint256 blockNumber,
+            bytes32 blockHash,
+            Result[] memory returnData
+        )
+    {
+        (blockNumber, blockHash, returnData) = tryBlockAndAggregate(
+            true,
+            calls
+        );
+    }
+
+    function getBlockHash(uint256 blockNumber)
+        public
+        view
+        returns (bytes32 blockHash)
+    {
+        blockHash = blockhash(blockNumber);
+    }
+
+    function getBlockNumber() public view returns (uint256 blockNumber) {
+        blockNumber = block.number;
+    }
+
+    function getCurrentBlockCoinbase() public view returns (address coinbase) {
+        coinbase = block.coinbase;
+    }
+
+    function getCurrentBlockDifficulty()
+        public
+        view
+        returns (uint256 difficulty)
+    {
+        difficulty = block.difficulty;
+    }
+
+    function getCurrentBlockGasLimit() public view returns (uint256 gaslimit) {
+        gaslimit = block.gaslimit;
+    }
+
+    function getCurrentBlockTimestamp()
+        public
+        view
+        returns (uint256 timestamp)
+    {
+        timestamp = block.timestamp;
+    }
+
+    function getEthBalance(address addr) public view returns (uint256 balance) {
+        balance = addr.balance;
+    }
+
+    function getLastBlockHash() public view returns (bytes32 blockHash) {
+        blockHash = blockhash(block.number - 1);
+    }
+
+    function tryAggregate(bool requireSuccess, Call[] memory calls)
+        public
+        returns (Result[] memory returnData)
+    {
+        returnData = new Result[](calls.length);
+        for (uint256 i = 0; i < calls.length; i++) {
+            (bool success, bytes memory ret) = calls[i].target.call(
+                calls[i].callData
+            );
+
+            if (requireSuccess) {
+                require(success, "Multicall2 aggregate: call failed");
+            }
+
+            returnData[i] = Result(success, ret);
+        }
+    }
+
+    function tryBlockAndAggregate(bool requireSuccess, Call[] memory calls)
+        public
+        returns (
+            uint256 blockNumber,
+            bytes32 blockHash,
+            Result[] memory returnData
+        )
+    {
+        blockNumber = block.number;
+        blockHash = blockhash(block.number);
+        returnData = tryAggregate(requireSuccess, calls);
+    }
+}