本文主要介绍了如何使用truffle + Atom
进行拍卖环节1:胜利者选择智能合约的编写,以及如何使用ganache-cli
进行智能合约的交互测试。
1 Trueffle框架编写代码
相关细节可以查看另一篇文章以太坊公开拍卖智能合约(truffle + ganache-cli)。本文主要介绍合约实现,以及一些新的点。
1.1 建立项目
PS H:\TestContract> mkdir ReverseAuction
PS H:\TestContract\ReverseAuction> cd contracts
PS H:\TestContract\ReverseAuction\contracts> truffle create contract ReverseAuction
-
\contracts
:存放智能合约源代码的地方,可以看到里面已经有一个sol
文件,我们开发的ReverseAuction.sol
文件就存放在这个文件夹。 -
\migrations
:这是Truffle
用来部署智能合约的功能,待会儿我们会新建一个类似1_initial_migration.js
的文件来部署ReverseAuction.sol
。 -
\test
:测试智能合约的代码放在这里,支持js
与sol
测试。 -
truffle-config.js
和truffle.js
:Truffle
的配置文件,需要配置要连接的以太坊网络。
1.2 创建合约
需求:
请实现一个拍卖协议,在该协议中,每个用户可以提交自己的出价。
根据边际成本排序,每次选择边际成本最低的报价,直到所有的任务被包含。
详细算法可以看参考文献[1],算法有什么不对的请轻拍,我现在只是测试一下能不能用智能合约写出一个简单的拍卖。
pragma solidity ^0.4.22;
contract ReverseAuction {
struct Bid{
address id; // identity of employee
uint k; // k-th bid of user i
// bool selected; // whether it is selected
uint[] Q; // a subset of sensing tasks that employees are willing to sense
uint bid; // corresponding bid
uint increaseR;
}
uint[] public tasks; // published tasks
address public provider; // task provider
uint public amount; // amount of tasks
//mapping (address => Bid[]) public bids; // mapping from address to bid
Bid[] public bids;
// mapping (address => Bid[]) public selected_bids; // winning bids
Bid[] public selected_bids;
uint public selected_bids_num;
Bid[] public backup_bids;
uint[] public currentQ; // tasks set currently included in the selected bids
uint public utility; // social welfare
event AuctionEnded(uint utility); // auction end event
event LogBid(address, uint, uint[], uint, uint);
function log(address id, uint k, uint[] Q, uint bid, uint r) internal {
emit LogBid(id, k, Q, bid, r);
}
constructor(address _provider) {
provider = _provider;
amount = 0;
selected_bids_num = 0;
utility = 0;
}
function setTasks(uint _amount, uint[] _tasks) public {
amount = _amount;
tasks = new uint[](_amount);
for (uint i = 0; i < amount; i++){
tasks[i] = _tasks[i];
}
}
function getTasks() constant public returns(uint[]){
return tasks;
}
function addBid(uint _k, uint[] _Q, uint _bid) public {
require(_Q.length > 0 && _bid > 0);
bids.push(Bid({id: msg.sender, k: _k, Q: _Q, bid: _bid, increaseR: 0}));
}
function getAllBidsNum() constant public returns (uint) {
return bids.length;
}
function getAllBids(uint index) constant public returns(address, uint, uint[], uint, uint) {
return (bids[index].id, bids[index].k, bids[index].Q, bids[index].bid, bids[index].increaseR);
}
function getBackupBids(uint index) constant public returns(address, uint, uint[], uint, uint) {
return (backup_bids[index].id, backup_bids[index].k, backup_bids[index].Q, backup_bids[index].bid, backup_bids[index].increaseR);
}
function getSocialWelfare() constant public returns (uint) {
return utility;
}
function getSelectedBidsNum() constant public returns(uint) {
return selected_bids.length;
}
function getSelectedBids(uint index) constant public returns(address, uint, uint[], uint, uint) {
return (selected_bids[index].id, selected_bids[index].k, selected_bids[index].Q, selected_bids[index].bid, selected_bids[index].increaseR);
}
function getCurrentQNum() constant public returns (uint) {
return currentQ.length;
}
function selectWinners() public returns (uint[]) {
require(bids.length != 0 && currentQ.length != amount);
backupAllBids();
while (currentQ.length != amount) {
// compute r(bid) for each bid
computeIncreaseR(bids, currentQ);
// sort increaseR in nondecreasing order
// and return the top bid
sortBidByIncreaseR(bids, int(0), int(bids.length-1));
// increasing order
Bid memory bid = Bid({id: bids[0].id, k: bids[0].k, Q: bids[0].Q, bid:bids[0].bid, increaseR: bids[0].increaseR});
selected_bids.push(bid);
utility += bid.bid;
// find union of currentQ and bid.Q, then put into the currentQ
setUnion(currentQ, bid.Q);
// remove the selected bid from B
removeBid(0, bids);
// delete bids that conflict with the selected bid
deleteConflictBids(bid);
}
return currentQ;
}
// print all bid
function printAllBids() public {
require(bids.length > 0);
for (uint i = 0; i < bids.length; i++) {
emit LogBid(bids[i].id, bids[i].k, bids[i].Q, bids[i].bid, bids[i].increaseR);
}
}
function testCopy(uint[] _Q) public returns (address, uint, uint[], uint, uint){
bid1 = Bid({id: msg.sender, k: 0, Q:_Q, bid: 6, increaseR:0});
bid2 = bid1;
// copyBid(bid2, bid1);
return (bid2.id, bid2.k, bid2.Q, bid2.bid, bid2.increaseR);
}
// backup the original bids
function backupAllBids() internal {
uint length = bids.length;
// backup_bids = new Bid[](length);
delete backup_bids;
for (uint i = 0; i < length; i++) {
backup_bids.push(bids[i]);
}
}
// compute r(bid) for each bid
function computeIncreaseR(Bid[] storage _bids, uint[] _currentQ) internal {
for (uint i = 0; i < _bids.length; i++) {
uint diffNum = isSubsetOfcurrentQ(_bids[i].Q, _currentQ); // |Q-currentQ|
// Q is subset of currentQ, delete the bid contains Q
if (diffNum == 0) {
removeBid(i, _bids);
i--;
continue;
}
_bids[i].increaseR = _bids[i].bid / diffNum;
}
}
// if Q is the subset of currentQ, delete Q
// otherwise, compute the marginal benefit of Q
function isSubsetOfcurrentQ(uint[] _Q, uint[] _currentQ) internal returns (uint){
uint count = _Q.length;
for (uint i = 0; i < _Q.length; i++) {
for (uint j = 0; j < _currentQ.length; j++) {
if(_Q[i] == _currentQ[j]) {
count--;
break; // jump out of the loop as soon as you find the same one
}
}
}
return count;
}
// delete the bid at the specified location
function removeBid(uint index, Bid[] storage _bids) internal {
uint length = _bids.length;
if (index < 0 || index > length) return;
for (uint i = index; i < length - 1; i++) {
_bids[i] = _bids[i+1];
/*
_bids[i].id = _bids[i+1].id;
_bids[i].k = _bids[i+1].k;
_bids[i].Q = _bids[i+1].Q;
_bids[i].bid = _bids[i+1].bid;
_bids[i].increaseR = _bids[i+1].increaseR;
*/
}
delete _bids[length - 1];
_bids.length--;
}
function sortBidByIncreaseR(Bid[] storage R, int i, int j) internal {
if (R.length == 0) return;
quickSort(R, i, j);
}
function quickSort(Bid[] storage R, int i, int j) internal {
if (i < j) {
int pivot = partition(R, i, j);
quickSort(R, i, pivot - 1);
quickSort(R, pivot + 1, j);
}
}
function partition(Bid[] storage R, int i, int j) internal returns(int){
// Bid temp = R[i];
Bid memory temp = Bid({id: R[uint(i)].id, k: R[uint(i)].k, Q: R[uint(i)].Q, bid:R[uint(i)].bid, increaseR: R[uint(i)].increaseR});
// copyBid(temp, R[i]);
while (i < j) {
while (i < j && R[uint(j)].increaseR >= temp.increaseR)
j--;
if (i < j) {
R[uint(i)] = R[uint(j)];
i++;
}
while (i < j && R[uint(i)].increaseR <= temp.increaseR)
i++;
if (i < j) {
R[uint(j)] = R[uint(i)];
j--;
}
}
// copyBid(R[i] , temp);
R[uint(i)] = Bid({id: temp.id, k: temp.k, Q: temp.Q, bid: temp.bid, increaseR: temp.increaseR});
delete temp;
return i;
}
// find the union of two sets
function setUnion(uint[] storage v1, uint[] v2) internal {
for (uint i = 0; i < v2.length; i++) {
if (isElementInSet(v1, v2[i])) continue;
v1.push(v2[i]);
}
}
// check whether element is in set v
function isElementInSet(uint[] v, uint element) internal returns(bool){
for (uint i = 0; i < v.length; i++) {
if (v[i] == element) return true;
}
return false;
}
// delete conflict bids conflict with the bid
function deleteConflictBids(Bid bid) internal {
uint length = bid.Q.length;
int i = 0;
while (uint(i) < bids.length) {
// Bid temp = bids[i];
Bid memory temp = Bid({id: bids[uint(i)].id, k: bids[uint(i)].k, Q: bids[uint(i)].Q, bid:bids[uint(i)].bid, increaseR: bids[uint(i)].increaseR});
//copyBid(temp, bids[i]);
i++;
// no conflict
if (temp.Q.length != length) continue;
// may have conflict
uint flag = isConflictBid(temp, bid);
if (flag == 0) {
--i;
removeBid(uint(i), bids);
}
}
// delete temp;
}
// check if this two bids conflict
function isConflictBid(Bid bid, Bid baseBid) internal returns(uint) {
uint length = baseBid.Q.length;
uint flag = length;
for (uint i = 0; i < length; i++) {
for (uint j = 0; j < length; j++) {
if (bid.Q[i] == baseBid.Q[j]) {
flag--;
break;
}
}
}
return flag;
}
}
常见错误
ufixed
和uint
最开始,我是定义ufixed increaseR;
虽然Solidity从0.4.20开始支持浮点数,然而这些编译器并不支持,会报错UnimplementedFeatureError: Not yet implemented - FixedPointType.
。所以只好改成了uint
无符号整型。即使会影响精度,但这也是没有办法的事,只能等待EVM的更新了。
memory
和storage
变量类型,可以在网上找到一些关于他们的介绍,如:Solidity的数据位置特性深入详解。简单的理解,智能合约中的状态变量,也可以说是全局变量吧,都是storage
的,而函数中声明的大多数变量都是memory
类型的。看源代码
function backupAllBids() {}
函数中被注释掉的一句话backup_bids = new Bid[] (length);
最开始我写了一个函数,函数中会调用很多子函数,通过truffle编译后,只会报出
UnimplementedFeatureError: Copying of type struct ReverseAuction.Bid memory[] memory to storage not yet supported.
错误。
backup_bids
是storage
类型的,这里的new Bid[] (length)却是memory
的。不过我这里有一个疑惑是,在function setTasks() {}
函数中,我同样使用了tasks = new uint[] (_amount);
,这句话却是正确的,我也不理解是为什么。可能是因为Bid
是我自定义的比较复杂的结构体吧。不过不需要自己分配空间,智能合约也依然可以使用,所以目前比较好的方法就是直接删掉这句话。EVM无法进行debug, 我也尝试了利用
event
事件函数来打印log,不过没有成功,所以很难找出错误在哪儿。只好一个个写测试函数,在cmd中不断重新构造对象,进行单元测试。虽然这一次能找到,但是下一次依然很麻烦,希望赶紧出一个简单方便的以太坊调试工具。
uint
和int
在我将上面的问题都解决后,我还是决定先把所有调用的子函数都测试完再将它们整合起来,这时候,function deleteConflictBids() {}
函数就报错了,EVM的特性,不会告诉你错在哪儿的,,只给出一句话Error: VM Exception while processing transaction: invalid opcode
,就只能自己找了。我大概记得之前曾经看到过智能合约中进行排序或者类似
i--
这种类型的语句,很有可能会越界,因为定义的是uint
类型的虽然我们并不会用到i = -1
这种,但是当i == 0
时,有时候还会进行一次i--
操作才会跳出函数,因此这种情况下会报错。然而在智能合约中,所有的数组取值操作,下标
data[i]
这里的i
必须是uint
类型的,不然会报错。所以就需要自己多次进行类型转换。如:定义int i;
使用时bids[uint(i)]
。如上方的源代码那样修改之后,函数调用成功。
单元测试 & 集成测试
我发现单独测试将winner
加入selected_bids
,以及将selected_bids_num++
这几句代码仿佛直接被编译器跳过了,无论重新编译几次,也不会执行。这也导致了后面函数的调用失败。我想可能是编译器自己的原因,就直接将函数整合了,重新编译,进行整体的集成测试,然后函数完全运行成功。
所以有网友说直接用自带
remix
编译成abi
,然后自己部署,不要用类似truffle
之类的工具,毕竟也是其他开发者自己编写的,会有很多bug。remix会实时编译,也挺方便。但是使用框架毕竟要容易一点,目前还能忍受一些小小的错误。如何用
remix
编译部署的方法,我另一篇文章也有简单介绍Windows搭建私有链,创建部署Hello world智能合约,自己可以自由组合用什么工具写编译智能合约(atom+truffle, remix, wallet...) ,再用什么方法部署智能合约(truffle, 自己创建的私有链,wallet...)。网上的方法也挺多的。
1.3 编译合约
同样可以参考之前的文章,有详细说明。
在项目根目录ReverseAuction
的powershell中执行truffle compile
命令:
PS H:\TestContract\ReverseAuction> truffle compile
Compiling .\contracts\Migrations.sol...
Compiling .\contracts\ReverseAuction.sol...
Compilation warnings encountered:
....
Writing artifacts to .\build\contracts
2 Ganache-cli 部署测试智能合约
2.1 启动ganache-cli
打开powershell
终端,可以看到ganache-cli
启动后自动建立了10
个账号(Accounts),与每个账号对应的私钥(Private Key)。每个账号中都有100
个测试用的以太币(Ether)。
Note. ganache-cli仅运行在内存中,因此每次重开时都会回到全新的状态。
C:\Users\aby>ganache-cli
2.2 部署合约
(1)migrations
目录下创建一个名字叫做2_deploy_contracts.js
的文件。文件中的内容为:
var ReverseAuction = artifacts.require('./ReverseAuction');
module.exports = function(deployer){
deployer.deploy(ReverseAuction, '0x540dcc00853f82dcba9d5871e1013d55d3bd9461')
}
(2)修改truffle.js
文件,连接本地ganache-cli
环境。参数在最开初始化ganache-cli
环境的窗口可以看到。
module.exports = {
// See
// to customize your Truffle configuration!
networks: {
development: {
host: '127.0.0.1',
port: 8545,
network_id: "*" // match any network id
}
}
};
(3)现在执行truffle migrate
命令,我们可以将ReverseAuction.sol
原始码编译成Ethereum bytecode
。
PS H:\TestContract\ReverseAuction> truffle migrate --reset
Using network 'development'.
Running migration: 1_initial_migration.js
Deploying Migrations...
...
Saving artifacts...
2.3 与合约交互
truffle
提供命令行工具,执行truffle console
命令后,可用Javascript
来和刚刚部署的合约互动。
PS H:\TestContract\SimpleAuction> truffle console
truffle(development)>
2.3.1 参与拍卖的账户
我们需要准备一些测试账户。
它会把第一个帐户的地址分配给变量account0
,第二个帐户分配给变量account1
。Web3
是一个JavaScript API
,它将RPC
调用包装起来以方便我们与区块链进行交互。
我在这里将第9个账户作为部署合约初始化的拍卖发起人。
其余5个账户会进行报价。
PS H:\TestContract\ReverseAuction> truffle console
truffle(development)> address = web3.eth.accounts[9];
'0x540dcc00853f82dcba9d5871e1013d55d3bd9461'
truffle(development)> a1 = web3.eth.accounts[1];
'0x68e8a5c2041d181b83b45e6d43bd6632c2fbd4c1'
truffle(development)> a2 = web3.eth.accounts[2];
'0x05f5daeb06b8c9d4e158b9fa0ce3c36805a2542a'
truffle(development)> a3 = web3.eth.accounts[3];
'0x1e78baa740a7241fc92f5d47ae13d6a5f304b516'
truffle(development)> a4 = web3.eth.accounts[4];
'0x489fbcee812f313596ed7fdc816b588383b9c3f7'
truffle(development)> a5 = web3.eth.accounts[5];
'0x6125b3b7e1bf338696eae491df24710ae13258eb'
2.3.2 启动拍卖
现在我们需要先启动一个拍卖,才能进行接下来的操作。
truffle(development)> let contract
undefined
truffle(development)> ReverseAuction.deployed().then(instance => contract = instance);
任务提供者设置任务。
truffle(development)> tasks = [1,2,3,4,5,6];
[ 1, 2, 3, 4, 5, 6 ]
truffle(development)> contract.setTasks(6,tasks,{from:address});
truffle(development)> contract.getTasks.call();
[ BigNumber { s: 1, e: 0, c: [ 1 ] },
BigNumber { s: 1, e: 0, c: [ 2 ] },
BigNumber { s: 1, e: 0, c: [ 3 ] },
BigNumber { s: 1, e: 0, c: [ 4 ] },
BigNumber { s: 1, e: 0, c: [ 5 ] },
BigNumber { s: 1, e: 0, c: [ 6 ] } ]
2.3.3 开始报价
此时我们用5个账号分别调用addBid()
进行报价。
truffle(development)> contract.addBid(0,[1,3,4],12,{from:a1});
truffle(development)> contract.addBid(0,[1,5],6,{from:a2});
truffle(development)> contract.addBid(0,[2,3,4],15,{from:a3});
truffle(development)> contract.addBid(0,[3,4,5,6],16,{from:a4});
truffle(development)> contract.addBid(0,[2,4,6],9,{from:a5});
并且查看此时a1
报价(注释是我写文章的时候加的,为了方便查看,命令行中并没有)。
truffle(development)> contract.getAllBids.call(0)
[ '0x68e8a5c2041d181b83b45e6d43bd6632c2fbd4c1', // id
BigNumber { s: 1, e: 0, c: [ 0 ] }, // k
[ BigNumber { s: 1, e: 0, c: [Array] }, // Q
BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] } ],
BigNumber { s: 1, e: 1, c: [ 12 ] }, // bid
BigNumber { s: 1, e: 0, c: [ 0 ] } ] // increaseR
2.3.4 启动winner selection算法
调用function selectWinners() {}
函数进行winner selection。
truffle(development)> contract.selectWinners({from:address})
{ tx: '0x376316e4346743675be052b07323b5ebac115d92a80e9cf0571203d5f0207b72',
receipt:
{ transactionHash: '0x376316e4346743675be052b07323b5ebac115d92a80e9cf0571203d5f0207b72',
transactionIndex: 0,
blockHash: '0x8e71731c25b51e8561483cbdeabaaaf8f7eefe7a3a9496f5990bc65043b951c3',
blockNumber: 11,
gasUsed: 2515856,
cumulativeGasUsed: 2515856,
contractAddress: null,
logs: [],
status: '0x1',
logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000' },
logs: [] }
然后查看当前原始Bidsbids
中没被选中的报价数。
truffle(development)> contract.getAllBidsNum.call()
BigNumber { s: 1, e: 0, c: [ 2 ] }
再看看selected_bids
中被选中的报价数。
truffle(development)> contract.getSelectedBidsNum.call()
BigNumber { s: 1, e: 0, c: [ 3 ] }
最后分别查看selected_bids
中每个被选中报价的详情。
truffle(development)> contract.getSelectedBids.call(0)
[ '0x6125b3b7e1bf338696eae491df24710ae13258eb',
BigNumber { s: 1, e: 0, c: [ 0 ] },
[ BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] } ],
BigNumber { s: 1, e: 0, c: [ 9 ] },
BigNumber { s: 1, e: 0, c: [ 3 ] } ]
truffle(development)> contract.getSelectedBids.call(1)
[ '0x05f5daeb06b8c9d4e158b9fa0ce3c36805a2542a',
BigNumber { s: 1, e: 0, c: [ 0 ] },
[ BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] } ],
BigNumber { s: 1, e: 0, c: [ 6 ] },
BigNumber { s: 1, e: 0, c: [ 3 ] } ]
truffle(development)> contract.getSelectedBids.call(2)
[ '0x68e8a5c2041d181b83b45e6d43bd6632c2fbd4c1',
BigNumber { s: 1, e: 0, c: [ 0 ] },
[ BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] },
BigNumber { s: 1, e: 0, c: [Array] } ],
BigNumber { s: 1, e: 1, c: [ 12 ] },
BigNumber { s: 1, e: 1, c: [ 12 ] } ]
最后看一看是否已经覆盖了全部的任务,同时打印social welfare
。
truffle(development)> contract.getCurrentQNum.call()
BigNumber { s: 1, e: 0, c: [ 6 ] }
truffle(development)> contract.getSocialWelfare.call()
BigNumber { s: 1, e: 1, c: [ 27 ] }
可以看出所有任务都被覆盖到。
结果与我用c++
跑出来的结果一样。
下一篇文章,将会用智能合约实现参考文献[1]的第二部分critical payment
算法。
本文作者:Joyce
文章来源:https://www.jianshu.com/p/8bd49c1d5c39
版权声明:转载请注明出处!
2018年7月26日
Reference
-
TRAC: Truthful Auction for Location-Aware Collaborative Sensing in Mobile Crowdsourcing ↩ ↩