在乙太坊區塊鏈中儲存每個 IPFS 雜湊需要多少錢

我查看了一些有關計算 Gas 成本的資源，例如我在這個執行緒上找到的這個電子表格。但是電子表格只有計算氣體成本，但沒有儲存散列。我有點困惑，在區塊鏈合約中儲存 IPFS 雜湊的方式也基於這個執行緒有點不同。我認為它必須儲存字元串或字節是直截了當的，但它需要在 Struct 中？任何人都可以幫助我。* 抱歉，我還是智能合約程式的新手

在乙太坊區塊鏈上儲存數據時，每個計算任務都有成本（以氣體單位為單位），您通常希望盡可能降低應用程序的交易成本。

您想 在智能合約中儲存 IPFS 雜湊（或 Multihash）（或 CID），例如QmWATWQ7fVPP2EFGu71UkfnqhYXDYH566qy47CnJDgvs8u

第一：閱讀本文 以了解多雜湊

---

這是儲存 IPFS 雜湊與相關氣體成本的三種解決方案。

Assuming gasPrice: 20 000 000 000 (wei)

1. 將其儲存為字元串

智能合約：

contract IPFSStorage {
   string hash;
   function storeCIDAsString(string _hash) public {
       hash = _hash;
   }
}

松露測試：

it('should store the IPFS CID as a string', async () => {

   instance.storeCIDAsString(cid, {'from': accounts[0]}).then(function(txReceipt) {
       console.log('# should store the IPFS CID as a string');

       let gasUsed = txReceipt.receipt.gasUsed;
       console.log("gasUsed: " + gasUsed + " units");

       let gasCost = gasUsed*gasPrice;
       console.log("gasCost (wei): " + gasCost + " wei");

       let gasCostEth = web3.fromWei(gasCost, 'ether')
       console.log("gasCost (ether): " + gasCostEth + " ether");
   }).catch(function (error) {
       console.log(error);
   });
});

結果：

# should store the IPFS CID as a string
gasUsed: 85986 units
gasCost (wei): 1719720000000000 wei
gasCost (ether): 0.00171972 ether

2. 將其儲存為結構

智能合約：

contract IPFSStorage {
   struct Multihash {
       bytes32 hash;
       bytes2 hash_function;
       uint8 size;
   }

   Multihash multihash;

   function storeCIDAsStruct(bytes32 _hash, bytes2 _hash_function, uint8 _size) public {

       Multihash memory multihashMemory;
       multihash.hash = _hash;
       multihash.hash_function = _hash_function;
       multihash.size = _size;

       multihash = multihashMemory;
   }
}

松露測試：

it('should store the IPFS CID as a struct', async () => {

   let mh = multihashes.fromB58String(Buffer.from(cid))
   let args = {
     hashFunction: '0x' + mh.slice(0, 2).toString('hex'),
     digest: '0x' + mh.slice(2).toString('hex'),
     size: mh.length - 2
   }

   instance.storeCIDAsStruct(args.digest, args.hashFunction, args.size, {'from': accounts[0]}).then(function(txReceipt) {
       console.log('# should store the IPFS CID as a struct');

       let gasUsed = txReceipt.receipt.gasUsed;
       console.log("gasUsed: " + gasUsed + " units");

       let gasCost = gasUsed*gasPrice;
       console.log("gasCost (wei): " + gasCost + " wei");

       let gasCostEth = web3.fromWei(gasCost, 'ether')
       console.log("gasCost (ether): " + gasCostEth + " ether");
   }).catch(function (error) {
       console.log(error);
   });
});

結果：

# should store the IPFS CID as a struct
gasUsed: 55600 units
gasCost (wei): 1112000000000000 wei
gasCost (ether): 0.001112 ether

3. 將其儲存在事件日誌中

智能合約：

contract IPFSStorage {
   event CIDStoredInTheLog(string _hash);

   function storeCIDInTheLog(string _hash) public {

       emit CIDStoredInTheLog(_hash);
   }
}

松露測試：

it('should store the IPFS CID in the logs', async () => {

   instance.storeCIDInTheLog(cid, {'from': accounts[0]}).then(function(txReceipt) {
       console.log('# should store the IPFS CID in the logs');

       let gasUsed = txReceipt.receipt.gasUsed;
       console.log("gasUsed: " + gasUsed + " units");

       let gasCost = gasUsed*gasPrice;
       console.log("gasCost (wei): " + gasCost + " wei");

       let gasCostEth = web3.fromWei(gasCost, 'ether')
       console.log("gasCost (ether): " + gasCostEth + " ether");
   }).catch(function (error) {
       console.log(error);
   });
});

結果：

# should store the IPFS CID in the logs
gasUsed: 27501 units
gasCost (wei): 550020000000000 wei
gasCost (ether): 0.00055002 ether

---

如您所見，每個解決方案都有效，唯一的區別是在區塊鏈中儲存 IPFS 雜湊的交易的氣體成本。

你可以在這裡找到程式碼（Truffle 項目）

引用自：https://ethereum.stackexchange.com/questions/61100