feat(checkpoint): add mysql checkpoint

[postbird]

Add a new checkpoint implementation based on Mysql.

Follow up the table structure of checkpoint-postgresql, adding the adaptation for mysql.

I passed all the tests using Vitest's test scripts and conducted actual application tests for the local agent (including human-in-the-loop).

For usage:

import { MySQLSaver } from "@langchain/langgraph-checkpoint-mysql";

const writeConfig = {
  configurable: {
    thread_id: "1",
    checkpoint_ns: "",
  },
};
const readConfig = {
  configurable: {
    thread_id: "1",
  },
};

// you can optionally pass a configuration object as the second parameter
const checkpointer = MySQLSaver.fromConnString("mysql://...");

// or you can initialize the sequelize instance first
// const sequelize = new Sequelize({
//   database: 'testdb',
//   username: 'root',
//   password: '123456',
//   host: '127.0.0.1',
//   port: 3306,
//   dialect: 'mysql',
// });

// const checkpointer = new MySQLSaver(sequelize);

// You should call .setup() the first time you use the checkpointer:
await checkpointer.setup();

// or you can set the table manually by using the sql in `/src/migration.sql`

const checkpoint = {
  v: 1,
  ts: "2024-07-31T20:14:19.804150+00:00",
  id: "1ef4f797-8335-6428-8001-8a1503f9b875",
  channel_values: {
    my_key: "meow",
    node: "node",
  },
  channel_versions: {
    __start__: 2,
    my_key: 3,
    "start:node": 3,
    node: 3,
  },
  versions_seen: {
    __input__: {},
    __start__: {
      __start__: 1,
    },
    node: {
      "start:node": 2,
    },
  },
  pending_sends: [],
};

// store checkpoint
await checkpointer.put(writeConfig, checkpoint, {}, {});

// load checkpoint
await checkpointer.get(readConfig);

// list checkpoints
for await (const checkpoint of checkpointer.list(readConfig)) {
  console.log(checkpoint);
}

[changeset-bot]

⚠️ No Changeset found

Latest commit: f8ea777

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[postbird]

Different from the postgresql implementation:

• Use sequelize@6 as the ORM framework, and provide the DDL sqls.
• Use JSON to replace JSONB
• Use LONGBLOB to replace `BINARY
• Support mysql 5.7+ (for JSON type)

[postbird]

The testing includes human-in-the-loopand resume operation.

Locally testing result in DB:

checkpoints

checkpoint_writes

checkpoint_migrations

checkpoint_blobs