Solana 日志、事件日志与历史交易查询

Solana 程序可以发出类似 Ethereum 事件的事件日志，但其设计和用途有所不同。本节将探讨 Solana 中的日志和事件日志，以及如何查询历史交易。

Solana 日志与事件日志

以下程序定义了两个事件日志：MyEvent 和 MySecondEvent，类似于 Ethereum 事件通过参数传递数据，Solana 使用结构体字段：

use anchor_lang::prelude::*;

declare_id!("8kSqq6R5YL4ZudFtnRH4xeRSP8xQNFdS4naWxunR5RKh");

#[program]
pub mod emit {
    use super::*;

    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
        emit!(MyEvent { value: 42 });
        emit!(MySecondEvent { value: 3, message: "hello world".to_string() });
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Initialize {}

#[event]
pub struct MyEvent {
    pub value: u64,
}

#[event]
pub struct MySecondEvent {
    pub value: u64,
    pub message: String,
}

事件日志会纳入 Solana 程序的 IDL，类似 Solidity 的事件定义在 ABI 中：

  "events": [
    {
      "name": "MyEvent",
      "fields": [
        {
          "name": "value",
          "type": "u64",
          "index": false
        }
      ]
    },
    {
      "name": "MySecondEvent",
      "fields": [
        {
          "name": "value",
          "type": "u64",
          "index": false
        },
        {
          "name": "message",
          "type": "string",
          "index": false
        }
      ]
    }
  ]

与 Ethereum 不同，Solana 没有“索引”或“非索引”字段的概念。

Solana 事件日志无法像 Ethereum 那样查询历史记录，只能实时监听。以下是监听示例：

import * as anchor from "@coral-xyz/anchor";
import { BorshCoder, EventParser, Program } from "@coral-xyz/anchor";
import { Emit } from "../target/types/emit";

describe("emit", () => {
  anchor.setProvider(anchor.AnchorProvider.env());

  const program = anchor.workspace.Emit as Program<Emit>;

  it("Is initialized!", async () => {
    const listenerMyEvent = program.addEventListener('MyEvent', (event, slot) => {
      console.log(`slot ${slot} event value ${event.value}`);
    });

    const listenerMySecondEvent = program.addEventListener('MySecondEvent', (event, slot) => {
      console.log(`slot ${slot} event value ${event.value} event message ${event.message}`);
    });

    await program.methods.initialize().rpc();

    await new Promise((resolve) => setTimeout(resolve, 5000));

    program.removeEv...