Solana秘籍

账户映射

在编程中，我们经常使用映射（Map）这种数据结构，将一个键与某种值关联起来。键和值可以是任意类型的数据，键用作标识要保存的特定值的标识符。通过键，我们可以高效地插入、检索和更新这些值。

正如我们所了解的，Solana的账户模型要求程序数据和相关状态数据存储在不同的账户中。这些账户都有与之关联的地址，这本身就有映射的作用！在这里open in new window了解更多关于Solana账户模型的信息。

因此，将值存储在单独的账户中，以其地址作为检索值所需的键是有意义的。但这也带来了一些问题，比如：

*上述地址很可能不是理想的键，你可能难以记住并检索所需的值。

*上述地址是不同Keypair的公钥，每个公钥（或地址）都有与之关联的私钥。如果需要，这个私钥将用于对不同的指令进行签名，这意味着我们需要在某个地方存储私钥，这绝对不是推荐的做法！

这给许多Solana开发者带来了一个问题，即如何在他们的程序中实现类似Map的逻辑。让我们看看几种解决这个问题的方法。

派生PDA

PDA的全称是“程序派生地址” - Program Derived Addressopen in new window，简而言之，它们是从一组种子和程序ID（或地址）派生出来的地址。

PDAs的独特之处在于，这些地址不与任何私钥相关联。这是因为这些地址不位于ED25519曲线上。因此，只有派生此地址的程序可以使用提供的密钥和种子对指令进行签名。在这里了解更多信息。

现在我们对PDAs有了一个概念，让我们使用它们来映射一些账户！我们以一个博客程序作为示例，演示如何实现这一点。

在这个博客程序中，我们希望每个User都拥有一个Blog。这个博客可以有任意数量的Posts。这意味着我们将每个用户映射到一个博客，每个帖子映射到某个博客。

简而言之，用户和他/她的博客之间是1:1的映射，而博客和其帖子之间是1:N的映射。

对于1:1的映射，我们希望一个博客的地址仅从其用户派生，这样我们可以通过其权限（或用户）来检索博客。因此，博客的种子将包括其权限的密钥，可能还有一个前缀博客，作为类型标识符。

对于1:N的映射，我们希望每个帖子的地址不仅从它所关联的博客派生，还从另一个标识符派生，以区分博客中的多个帖子。在下面的示例中，每个帖子的地址是从博客的密钥、一个用于标识每个帖子的slug和一个前缀帖子派生出来的，作为类型标识符。

代码如下所示：

Press </> button to view full source
use anchor_lang::prelude::*;

declare_id!("2vD2HBhLnkcYcKxnxLjFYXokHdcsgJnyEXGnSpAX376e");

#[program]
pub mod mapping_pda {
    use super::*;
    pub fn initialize_blog(ctx: Context<InitializeBlog>, _blog_account_bump: u8, blog: Blog) -> ProgramResult {
        ctx.accounts.blog_account.set_inner(blog);
        Ok(())
    }

    pub fn create_post(ctx: Context<CreatePost>, _post_account_bump: u8, post: Post) -> ProgramResult {
        if (post.title.len() > 20) || (post.content.len() > 50) {
            return Err(ErrorCode::InvalidContentOrTitle.into());
        }

        ctx.accounts.post_account.set_inner(post);
        ctx.accounts.blog_account.post_count += 1;

        Ok(())
    }
}

#[derive(Accounts)]
#[instruction(blog_account_bump: u8)]
pub struct InitializeBlog<'info> {
    #[account(
        init,
        seeds = [
            b"blog".as_ref(),
            authority.key().as_ref()
        ],
        bump = blog_account_bump,
        payer = authority,
        space = Blog::LEN
    )]
    pub blog_account: Account<'info, Blog>,

    #[account(mut)]
    pub authority: Signer<'info>,

    pub system_program: Program<'info, System>
}

#[derive(Accounts)]
#[instruction(post_account_bump: u8, post: Post)]
pub struct CreatePost<'info> {
    #[account(mut, has_one = authority)]
    pub blog_account: Account<'info, Blog>,

    #[account(
        init,
        seeds = [
            b"post".as_ref(),
            blog_account.key().as_ref(),
            post.slug.as_ref(),
        ],
        bump = post_account_bump,
        payer = authority,
        space = Post::LEN
    )]
    pub post_account: Account<'info, Post>,

    #[account(mut)]
    pub authority: Signer<'info>,
    
    pub system_program: Program<'info, System>
}

#[account]
pub struct Blog {
    pub authority: Pubkey,
    pub bump: u8,
    pub post_count: u8,
}

#[account]
pub struct Post {
    pub author: Pubkey,
    pub slug: String, // 10 characters max
    pub title: String, // 20 characters max
    pub content: String // 50 characters max
}

impl Blog {
    const LEN: usize = 8 + 32 + 1 + (4 + (10 * 32));
}

impl Post {
    const LEN: usize = 8 + 32 + 32 + (4 + 10) + (4 + 20) + (4 + 50); 
}

#[error]
pub enum ErrorCode {
    #[msg("Invalid Content or Title.")]
    InvalidContentOrTitle,
}

use std::convert::TryInto;
use borsh::{BorshDeserialize, BorshSerialize};
use solana_program::{
    sysvar::{rent::Rent, Sysvar},
    borsh::try_from_slice_unchecked,
    account_info::{AccountInfo, next_account_info},
    entrypoint,
    entrypoint::ProgramResult, 
    pubkey::Pubkey, 
    msg,
    program_error::ProgramError, system_instruction, program::invoke_signed,
};
use thiserror::Error;


entrypoint!(process_instruction);
fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    Processor::process(program_id, accounts, instruction_data)
}

pub enum BlogInstruction {

    /// Accounts expected:
    /// 
    /// 0. `[signer]` User account who is creating the blog
    /// 1. `[writable]` Blog account derived from PDA
    /// 2. `[]` The System Program
    InitBlog {},

    /// Accounts expected:
    /// 
    /// 0. `[signer]` User account who is creating the post
    /// 1. `[writable]` Blog account for which post is being created
    /// 2. `[writable]` Post account derived from PDA
    /// 3. `[]` System Program
    CreatePost {
        slug: String,
        title: String,
        content: String,
    }
}

pub struct Processor;
impl Processor {
    pub fn process(program_id: &Pubkey, accounts: &[AccountInfo], instruction_data: &[u8]) -> ProgramResult {
        
        let instruction = BlogInstruction::unpack(instruction_data)?;

        match instruction {
            BlogInstruction::InitBlog {} => {
                msg!("Instruction: InitBlog");
                Self::process_init_blog(accounts, program_id)
            },
            BlogInstruction::CreatePost { slug, title, content} => {
                msg!("Instruction: CreatePost");
                Self::process_create_post(accounts, slug, title, content, program_id)
            }
        }
    }

    fn process_create_post(
        accounts: &[AccountInfo],
        slug: String,
        title: String,
        content: String,
        program_id: &Pubkey
    ) -> ProgramResult {
        if slug.len() > 10 || content.len() > 20 || title.len() > 50 {
            return Err(BlogError::InvalidPostData.into())
        }

        let account_info_iter = &mut accounts.iter();

        let authority_account = next_account_info(account_info_iter)?;
        let blog_account = next_account_info(account_info_iter)?;
        let post_account = next_account_info(account_info_iter)?;
        let system_program = next_account_info(account_info_iter)?;

        if !authority_account.is_signer {
            return Err(ProgramError::MissingRequiredSignature);
        }

        let (blog_pda, _blog_bump) = Pubkey::find_program_address(
            &[b"blog".as_ref(), authority_account.key.as_ref()],
            program_id
        );
        if blog_pda != *blog_account.key || !blog_account.is_writable || blog_account.data_is_empty() {
            return Err(BlogError::InvalidBlogAccount.into())
        }

        let (post_pda, post_bump) = Pubkey::find_program_address(
            &[b"post".as_ref(), slug.as_ref(), authority_account.key.as_ref()],
            program_id
        );
        if post_pda != *post_account.key {
            return Err(BlogError::InvalidPostAccount.into())
        }

        let post_len: usize = 32 + 32 + 1 + (4 + slug.len()) + (4 + title.len()) + (4 + content.len());

        let rent = Rent::get()?;
        let rent_lamports = rent.minimum_balance(post_len);

        let create_post_pda_ix = &system_instruction::create_account(
            authority_account.key,
            post_account.key,
            rent_lamports,
            post_len.try_into().unwrap(),
            program_id
        );
        msg!("Creating post account!");
        invoke_signed(
            create_post_pda_ix, 
            &[
                authority_account.clone(),
                post_account.clone(),
                system_program.clone()
            ],
            &[&[
                b"post".as_ref(),
                slug.as_ref(),
                authority_account.key.as_ref(),
                &[post_bump]
            ]]
        )?;

        let mut post_account_state = try_from_slice_unchecked::<Post>(&post_account.data.borrow()).unwrap();
        post_account_state.author = *authority_account.key;
        post_account_state.blog = *blog_account.key;
        post_account_state.bump = post_bump;
        post_account_state.slug = slug;
        post_account_state.title = title;
        post_account_state.content = content;

        msg!("Serializing Post data");
        post_account_state.serialize(&mut &mut post_account.data.borrow_mut()[..])?;


        let mut blog_account_state = Blog::try_from_slice(&blog_account.data.borrow())?;
        blog_account_state.post_count += 1;

        msg!("Serializing Blog data");
        blog_account_state.serialize(&mut &mut blog_account.data.borrow_mut()[..])?;

        Ok(())
    }

    fn process_init_blog(
        accounts: &[AccountInfo],
        program_id: &Pubkey
    ) -> ProgramResult {
        let account_info_iter = &mut accounts.iter();
        
        let authority_account = next_account_info(account_info_iter)?;
        let blog_account = next_account_info(account_info_iter)?;
        let system_program = next_account_info(account_info_iter)?;

        if !authority_account.is_signer {
            return Err(ProgramError::MissingRequiredSignature);
        }

        let (blog_pda, blog_bump) = Pubkey::find_program_address(
            &[b"blog".as_ref(), authority_account.key.as_ref()],
            program_id 
        );
        if blog_pda != *blog_account.key {
            return Err(BlogError::InvalidBlogAccount.into())
        }

        let rent = Rent::get()?;
        let rent_lamports = rent.minimum_balance(Blog::LEN);
        
        let create_blog_pda_ix = &system_instruction::create_account(
            authority_account.key,
            blog_account.key,
            rent_lamports,
            Blog::LEN.try_into().unwrap(),
            program_id
        );
        msg!("Creating blog account!");
        invoke_signed(
            create_blog_pda_ix, 
            &[
                authority_account.clone(),
                blog_account.clone(),
                system_program.clone()
            ],
            &[&[
                b"blog".as_ref(),
                authority_account.key.as_ref(),
                &[blog_bump]
            ]]
        )?;

        let mut blog_account_state = Blog::try_from_slice(&blog_account.data.borrow())?;
        blog_account_state.authority = *authority_account.key;
        blog_account_state.bump = blog_bump;
        blog_account_state.post_count = 0;
        blog_account_state.serialize(&mut &mut blog_account.data.borrow_mut()[..])?;
        

        Ok(())
    }
}



#[derive(BorshDeserialize, Debug)]
struct PostIxPayload {
    slug: String,
    title: String,
    content: String
}


impl BlogInstruction {
    pub fn unpack(input: &[u8]) -> Result<Self, ProgramError> {
        let (variant, rest) = input.split_first().ok_or(BlogError::InvalidInstruction)?;
        let payload = PostIxPayload::try_from_slice(rest).unwrap();

        Ok(match variant {
            0 => Self::InitBlog {},
            1 => Self::CreatePost {
                slug: payload.slug,
                title: payload.title,
                content: payload.content
            },
            _ => return Err(BlogError::InvalidInstruction.into()),
        })
    }
}

#[derive(BorshSerialize, BorshDeserialize, Debug, Clone)]
pub struct Blog {
    pub authority: Pubkey,
    pub bump: u8,
    pub post_count: u8 // 10 posts max
}

#[derive(BorshSerialize, BorshDeserialize, Debug, Clone)]
pub struct Post {
    pub author: Pubkey,
    pub blog: Pubkey,
    pub bump: u8,
    pub slug: String, // 10 chars max
    pub title: String, // 20 chars max
    pub content: String, // 50 chars max
}

impl Blog {
    pub const LEN: usize = 32 + 1 + 1;
}

#[derive(Error, Debug, Copy, Clone)]
pub enum BlogError {
    #[error("Invalid Instruction")]
    InvalidInstruction,

    #[error("Invalid Blog Account")]
    InvalidBlogAccount,

    #[error("Invalid Post Account")]
    InvalidPostAccount,

    #[error("Invalid Post Data")]
    InvalidPostData,

    #[error("Account not Writable")]
    AccountNotWritable,
}

impl From<BlogError> for ProgramError {
    fn from(e: BlogError) -> Self {
        return ProgramError::Custom(e as u32);
    }
}

在客户端，你可以使用PublicKey.findProgramAddress()来获取所需的Blog 和Post账户地址，然后将其传递给connection.getAccountInfo()来获取账户数据。下面是一个示例：

Press </> button to view full source
import * as borsh from "@project-serum/borsh";
import { PublicKey } from "@solana/web3.js";

export const BLOG_ACCOUNT_DATA_LAYOUT = borsh.struct([
  borsh.publicKey("authorityPubkey"),
  borsh.u8("bump"),
  borsh.u8("postCount"),
]);

export const POST_ACCOUNT_DATA_LAYOUT = borsh.struct([
  borsh.publicKey("author"),
  borsh.publicKey("blog"),
  borsh.u8("bump"),
  borsh.str("slug"),
  borsh.str("title"),
  borsh.str("content"),
]);

async () => {
  const connection = new Connection("http://localhost:8899", "confirmed");

  const [blogAccount] = await PublicKey.findProgramAddress(
    [Buffer.from("blog"), user.publicKey.toBuffer()],
    MY_PROGRAM_ID
  );

  const [postAccount] = await PublicKey.findProgramAddress(
    [Buffer.from("post"), Buffer.from("slug-1"), user.publicKey.toBuffer()],
    MY_PROGRAM_ID
  );

  const blogAccountInfo = await connection.getAccountInfo(blogAccount);
  const blogAccountState = BLOG_ACCOUNT_DATA_LAYOUT.decode(
    blogAccountInfo.data
  );
  console.log("Blog account state: ", blogAccountState);

  const postAccountInfo = await connection.getAccountInfo(postAccount);
  const postAccountState = POST_ACCOUNT_DATA_LAYOUT.decode(
    postAccountInfo.data
  );
  console.log("Post account state: ", postAccountState);
};

单个映射账户

另一种实现映射的方法是在单个账户中显式存储一个BTreeMap数据结构。这个账户的地址本身可以是一个PDA，或者是生成的Keypair的公钥。

这种账户映射的方法并不理想，原因如下：

*首先，你需要初始化存储BTreeMap的账户，然后才能向其中插入必要的键值对。然后，你还需要将这个账户的地址存储在某个地方，以便每次更新时进行更新。

*账户存在内存限制，每个账户的最大大小为10兆字节，这限制了BTreeMap存储大量键值对的能力。

因此，在考虑你的用例后，可以按照以下方式实现这种方法：

Press </> button to view full source
use std::{collections::BTreeMap};
use thiserror::Error;
use borsh::{BorshSerialize, BorshDeserialize};
use num_traits::FromPrimitive;
use solana_program::{sysvar::{rent::Rent, Sysvar}, entrypoint, entrypoint::ProgramResult, pubkey::Pubkey, account_info::{AccountInfo, next_account_info}, program_error::ProgramError, system_instruction, msg, program::{invoke_signed}, borsh::try_from_slice_unchecked};

entrypoint!(process_instruction);

fn process_instruction(
    program_id: &Pubkey,
    accounts: &[AccountInfo],
    instruction_data: &[u8],
) -> ProgramResult {
    msg!("instruction_data: {:?}", instruction_data);
    Processor::process(program_id, accounts, instruction_data)
}

pub struct Processor;

impl Processor {
    pub fn process(
        program_id: &Pubkey,
        accounts: &[AccountInfo],
        instruction_data: &[u8]
    ) -> ProgramResult {
        let instruction = FromPrimitive::from_u8(instruction_data[0]).ok_or(ProgramError::InvalidInstructionData)?;

        match instruction {
            0 => {
                msg!("Initializing map!");
                Self::process_init_map(accounts, program_id)?;
            },
            1 => {
                msg!("Inserting entry!");
                Self::process_insert_entry(accounts, program_id)?;
            },
            _ => {
                return Err(ProgramError::InvalidInstructionData)
            }
        }
        Ok(())
    }

    fn process_init_map(accounts: &[AccountInfo], program_id: &Pubkey) -> ProgramResult {
        let account_info_iter = &mut accounts.iter();

        let authority_account = next_account_info(account_info_iter)?;
        let map_account = next_account_info(account_info_iter)?;
        let system_program = next_account_info(account_info_iter)?;

        if !authority_account.is_signer {
            return Err(ProgramError::MissingRequiredSignature)
        }

        let (map_pda, map_bump) = Pubkey::find_program_address(
            &[b"map".as_ref()],
            program_id
        );

        if map_pda != *map_account.key || !map_account.is_writable || !map_account.data_is_empty() {
            return Err(BlogError::InvalidMapAccount.into())
        }

        let rent = Rent::get()?;
        let rent_lamports = rent.minimum_balance(MapAccount::LEN);

        let create_map_ix = &system_instruction::create_account(
            authority_account.key, 
            map_account.key, 
            rent_lamports, 
            MapAccount::LEN.try_into().unwrap(), 
            program_id
        );

        msg!("Creating MapAccount account");
        invoke_signed(
            create_map_ix, 
            &[
                authority_account.clone(),
                map_account.clone(),
                system_program.clone()
            ],
            &[&[
                b"map".as_ref(),
                &[map_bump]
            ]]
        )?;

        msg!("Deserializing MapAccount account");
        let mut map_state = try_from_slice_unchecked::<MapAccount>(&map_account.data.borrow()).unwrap();
        let empty_map: BTreeMap<Pubkey, Pubkey> = BTreeMap::new();

        map_state.is_initialized = 1;
        map_state.map = empty_map;

        msg!("Serializing MapAccount account");
        map_state.serialize(&mut &mut map_account.data.borrow_mut()[..])?;

        Ok(())
    }

    fn process_insert_entry(accounts: &[AccountInfo], program_id: &Pubkey) -> ProgramResult {
        
        let account_info_iter = &mut accounts.iter();

        let a_account = next_account_info(account_info_iter)?;
        let b_account = next_account_info(account_info_iter)?;
        let map_account = next_account_info(account_info_iter)?;

        if !a_account.is_signer {
            return Err(ProgramError::MissingRequiredSignature)
        }

        if map_account.data.borrow()[0] == 0 || *map_account.owner != *program_id {
            return Err(BlogError::InvalidMapAccount.into())
        }

        msg!("Deserializing MapAccount account");
        let mut map_state = try_from_slice_unchecked::<MapAccount>(&map_account.data.borrow())?;

        if map_state.map.contains_key(a_account.key) {
            return Err(BlogError::AccountAlreadyHasEntry.into())
        }

        map_state.map.insert(*a_account.key, *b_account.key);
        
        msg!("Serializing MapAccount account");
        map_state.serialize(&mut &mut map_account.data.borrow_mut()[..])?;

        Ok(())
    }
}

#[derive(BorshSerialize, BorshDeserialize, Clone, Debug)]
pub struct MapAccount {
    pub is_initialized: u8,
    pub map: BTreeMap<Pubkey, Pubkey> // 100
}

impl MapAccount {
    const LEN: usize = 1 + (4 + (10 * 64)); // 10 user -> blog
}

#[derive(Error, Debug, Copy, Clone)]
pub enum BlogError {
    #[error("Invalid MapAccount account")]
    InvalidMapAccount,

    #[error("Invalid Blog account")]
    InvalidBlogAccount,

    #[error("Account already has entry in Map")]
    AccountAlreadyHasEntry,
}

impl From<BlogError> for ProgramError {
    fn from(e: BlogError) -> Self {
        return ProgramError::Custom(e as u32);
    }
}

上述程序的客户端测试代码可能如下所示：

Press </> button to view full source
import {
  Connection,
  Keypair,
  LAMPORTS_PER_SOL,
  PublicKey,
  SystemProgram,
  Transaction,
  TransactionInstruction,
} from "@solana/web3.js";

import * as borsh from "@project-serum/borsh";

const MY_PROGRAM_ID = new PublicKey(
  "FwcG3yKuAkCfX68q9GPykNWDaaPjdZFaR1Tgr8qSxaEa"
);

const MAP_DATA_LAYOUT = borsh.struct([
  borsh.u8("is_initialized"),
  borsh.map(borsh.publicKey("user_a"), borsh.publicKey("user_b"), "blogs"),
]);

async () => {
  const connection = new Connection("http://localhost:8899", "confirmed");

  const userA = Keypair.generate();
  const userB = Keypair.generate();
  const userC = Keypair.generate();

  const [mapKey] = await PublicKey.findProgramAddress(
    [Buffer.from("map")],
    MY_PROGRAM_ID
  );

  const airdropASig = await connection.requestAirdrop(
    userA.publicKey,
    5 * LAMPORTS_PER_SOL
  );
  const airdropBSig = await connection.requestAirdrop(
    userB.publicKey,
    5 * LAMPORTS_PER_SOL
  );
  const airdropCSig = await connection.requestAirdrop(
    userC.publicKey,
    5 * LAMPORTS_PER_SOL
  );
  const promiseA = connection.confirmTransaction(airdropASig);
  const promiseB = connection.confirmTransaction(airdropBSig);
  const promiseC = connection.confirmTransaction(airdropCSig);

  await Promise.all([promiseA, promiseB, promiseC]);

  const initMapIx = new TransactionInstruction({
    programId: MY_PROGRAM_ID,
    keys: [
      {
        pubkey: userA.publicKey,
        isSigner: true,
        isWritable: true,
      },
      {
        pubkey: mapKey,
        isSigner: false,
        isWritable: true,
      },
      {
        pubkey: SystemProgram.programId,
        isSigner: false,
        isWritable: false,
      },
    ],
    data: Buffer.from(Uint8Array.of(0)),
  });

  const insertABIx = new TransactionInstruction({
    programId: MY_PROGRAM_ID,
    keys: [
      {
        pubkey: userA.publicKey,
        isSigner: true,
        isWritable: true,
      },
      {
        pubkey: userB.publicKey,
        isSigner: false,
        isWritable: false,
      },
      {
        pubkey: mapKey,
        isSigner: false,
        isWritable: true,
      },
    ],
    data: Buffer.from(Uint8Array.of(1)),
  });

  const insertBCIx = new TransactionInstruction({
    programId: MY_PROGRAM_ID,
    keys: [
      {
        pubkey: userB.publicKey,
        isSigner: true,
        isWritable: true,
      },
      {
        pubkey: userC.publicKey,
        isSigner: false,
        isWritable: false,
      },
      {
        pubkey: mapKey,
        isSigner: false,
        isWritable: true,
      },
    ],
    data: Buffer.from(Uint8Array.of(1)),
  });

  const insertCAIx = new TransactionInstruction({
    programId: MY_PROGRAM_ID,
    keys: [
      {
        pubkey: userC.publicKey,
        isSigner: true,
        isWritable: true,
      },
      {
        pubkey: userA.publicKey,
        isSigner: false,
        isWritable: false,
      },
      {
        pubkey: mapKey,
        isSigner: false,
        isWritable: true,
      },
    ],
    data: Buffer.from(Uint8Array.of(1)),
  });

  const tx = new Transaction();
  tx.add(initMapIx);
  tx.add(insertABIx);
  tx.add(insertBCIx);
  tx.add(insertCAIx);

  const sig = await connection.sendTransaction(tx, [userA, userB, userC], {
    skipPreflight: false,
    preflightCommitment: "confirmed",
  });
  await connection.confirmTransaction(sig);

  const mapAccount = await connection.getAccountInfo(mapKey);
  const mapData = MAP_DATA_LAYOUT.decode(mapAccount.data);
  console.log("MapData: ", mapData);
};
Last Updated:
Contributors: lillianrf