PlatON Cross | PlatON上的WASM智能合约开发（二）——跨合约调用

本文转载自微信公众号 PlatON Cross

原创作者：PlatON Cross小编

基于PlatON进行生态开发，智能合约是关键。这篇文章将会为大家介绍PlatON WASM智能合约的跨合约调用。本教程将用到我们在智能合约开发（一）的教程内容，如果还没有安装开发环境，或者还未进行合约部署，可以参考上一篇文章。

合约开发

● 编写合约

代码

在contracts目录下新建文件Cross.cpp，合约内容如下

#undef NDEBUG
#include <platon/platon.hpp>
#include <string>
using namespace platon;
CONTRACT Cross : public platon::Contract
{
public:
ACTION void init(){}
ACTION void add_message(std::string a, std::string b, std::string c)
{
auto address_pair = make_address(“lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h”);
char param[50];
sprintf(param, “[[[\”&s\”], \”&s\”, \”&s\”]]”, a.c_str(), b.c_str(), c.c_str());
auto result = platon_call(address_pair.first, uint32_t(0), uint32_t(0), “add_message”, std::string(param));
if (!result)
{
internal::platon_throw(“add_message fail”);
}
}
CONST uint8_t get_message_size()
{
auto address_pair = make_address(“lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h”);
if (address_pair.second)
{
DEBUG(“address”, address_pair.first.toString())
}
else
{
DEBUG(“address error”)
}
auto result = platon_call_with_return_value<uint8_t>(address_pair.first,
uint32_t(0), uint32_t(0), “get_message_size”);
if (!result.second)
{
internal::platon_throw(“cross call fail”);
}
return result.first;
}
CONST std::string get_message_body(const uint8_t index)
{
auto address_pair = make_address(“lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h”);
auto result = platon_call_with_return_value<std::string>(address_pair.first, uint32_t(0), uint32_t(0), “get_message_body”, index);
if (!result.second)
{
internal::platon_throw(“cross call fail”);
}
return result.first;
}
};
PLATON_DISPATCH(Cross, (init)(add_message)(get_message_size)(get_message_body))

代码说明

● 代码中我们用到了platon_call和platon_call_with_return_value方法，分别表示无返回调用和有返回合约调用。

● 更多的接口可以在~/.config/truffle/compilers/platon-cdt/platon.cdt/include/platon目录中找到，如合约调用文件为cross_call.hpp。

● make_address填入的地址是HelloWorld教程中部署的合约地址。

● make_address函数返回的是一个pair，需要根据second值判断地址是否获取成功。

● DEBUG可以用于调试输出，可以在节点日志中看到输出信息。

● 需要修改”lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h”为之前部署的HelloWorld合约地址

● 编译

注意

官方目前只发布了alaya版本的wasm编译器，在涉及到跨合约调用的时候，会出现地址编码问题，因此需要手动编译和安装platon版本的wasm编译器。

项目链接：

https://github.com/PlatONnetwork/PlatON-CDT/tree/feature/wasm

我们已经编译了最新版本的platon版本的wasm编译器，有需要的朋友可以下载并解压到~/.config/truffle/compilers目录下。

下载链接：

http://111.231.58.192/platon-cdt.zip

执行编译命令

platon-truffle compile

● 部署

platon-truffle deploy –wasm –contract-name Cross

部署成功后，将看到类似如下信息：

receipt: { blockHash:
‘0x8602678fc1f9e1934e9505fc291e3021e5eff70513d37156bc9b9b87273cfb69’,
blockNumber: 3957166,
contractAddress: ‘lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d’,
cumulativeGasUsed: 322472,
from: ‘lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n’,
gasUsed: 322472,
logs: [],
logsBloom:
‘0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000’,
status: true,
to: null,
transactionHash:
‘0xf0a04748ca277ec7ceecc2910753bec270f802632d2743843b43cc8030a73bd8’,
transactionIndex: 0 }
contract Cross deployed successfully
======================
> transactionHash: 0xf0a04748ca277ec7ceecc2910753bec270f802632d2743843b43cc8030a73bd8
> contract address: lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d
> block number: 3957166
> block timestamp: 1619603861743
> account: lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n
> balance: 7199474719087690925044
> gas limit: 9424776
> gas used: 322472
> gas price: 0.00000002 LAT
> total cost: 0.00644944 LAT

● 测试

1）进入platon-truffle控制台

platon-truffle console

* 以下调用查询将在truffle控制台中进行

2）构建合约对象

var abi = [{“constant”:true,”input”:[],”name”:”get_message_size”,”output”:”uint8″,”type”:”Action”},{“constant”:false,”input”:[],”name”:”init”,”output”:”void”,”type”:”Action”},{“constant”:false,”input”:[{“name”:”a”,”type”:”string”},{“name”:”b”,”type”:”string”},{“name”:”c”,”type”:”string”}],”name”:”add_message”,”output”:”void”,”type”:”Action”},{“constant”:true,”input”:[{“name”:”index”,”type”:”uint8″}],”name”:”get_message_body”,”output”:”string”,”type”:”Action”}];
var contractAddr = ‘lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d’;
var cross = new web3.platon.Contract(abi,contractAddr,{vmType: 1 });

说明：

● abi是合约提供给外部调用时的接口，每个合约对应的abi在编译后的文件中，如：HelloWorld/build/contracts/Cross.abi.json中可以找到

● contractAddr在部署合约成功后有一个contract address

● cross就是构建出来与链上合约交互的合约对象抽象

3）调用合约

cross.methods.add_message(“10”, “11”, “12”).send({
from: ‘lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n’,gas: 999999
}).on(‘receipt’, function(receipt) {
console.log(receipt);
}).on(‘error’, console.error);

调用合约命令说明：

● cross是之前构建的合约对象

● methods固定语法,后面紧跟合约的方法名

● add_message是我们Cross合约中的一个方法，有3个std::string类型的入参

● from调用者的钱包地址

● gasgas值

● on是监听合约处理结果事件，此处如果成功将打印回执，失败输出错误日志

函数调用成功，将会看到如下信息：

{ blockHash:
‘0x50fac24f50f871260663997d66f99e7d4e66bd09edc3002cc00d2be8c0021bdc’,
blockNumber: 3957919,
contractAddress: null,
cumulativeGasUsed: 137365,
from: ‘lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n’,
gasUsed: 137365,
logsBloom:
‘0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000’,
status: true,
to: ‘lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d’,
transactionHash:
‘0x8196f89cca8161b940b649008211c1cccea40edf0581d5088961c344382d3f31’,
transactionIndex: 0,
events: {} }

4）查询合约