# mysql_cdc

[![crates.io](https://img.shields.io/crates/v/mysql_cdc.svg)](https://crates.io/crates/mysql_cdc)
[![docs.rs](https://docs.rs/mysql_cdc/badge.svg)](https://docs.rs/mysql_cdc)

MySQL/MariaDB binlog replication client for Rust

## Limitations
Please note the lib currently has the following limitations:
- Supports only standard auth plugins `mysql_native_password` and `caching_sha2_password`.
- **Currently, the library doesn't support SSL encryption.**
- **Doesn't handle split packets (16MB and more).**

## Binlog event stream replication
Real-time replication client works the following way.
```rust
use mysql_cdc::binlog_client::BinlogClient;
use mysql_cdc::binlog_options::BinlogOptions;
use mysql_cdc::errors::Error;
use mysql_cdc::providers::mariadb::gtid::gtid_list::GtidList;
use mysql_cdc::providers::mysql::gtid::gtid_set::GtidSet;
use mysql_cdc::replica_options::ReplicaOptions;
use mysql_cdc::ssl_mode::SslMode;

fn main() -> Result<(), Error> {
    // Start replication from MariaDB GTID
    let _options = BinlogOptions::from_mariadb_gtid(GtidList::parse("0-1-270")?);

    // Start replication from MySQL GTID
    let gtid_set =
        "d4c17f0c-4f11-11ea-93e3-325d3e1cd1c8:1-107, f442510a-2881-11ea-b1dd-27916133dbb2:1-7";
    let _options = BinlogOptions::from_mysql_gtid(GtidSet::parse(gtid_set)?);

    // Start replication from the position
    let _options = BinlogOptions::from_position(String::from("mysql-bin.000008"), 195);

    // Start replication from last master position.
    // Useful when you are only interested in new changes.
    let _options = BinlogOptions::from_end();

    // Start replication from first event of first available master binlog.
    // Note that binlog files by default have expiration time and deleted.
    let options = BinlogOptions::from_start();

    let options = ReplicaOptions {
        username: String::from("root"),
        password: String::from("Qwertyu1"),
        blocking: true,
        ssl_mode: SslMode::Disabled,
        binlog: options,
        ..Default::default()
    };

    let mut client = BinlogClient::new(options);

    for result in client.replicate()? {
        let (header, event) = result?;
        println!("{:#?}", header);
        println!("{:#?}", event);

        // You process an event here

        // After you processed the event, you need to update replication position
        client.commit(&header, &event);
    }
    Ok(())
}
```
A typical transaction has the following structure.
1. `GtidEvent` if gtid mode is enabled.
2. One or many `TableMapEvent` events.
   - One or many `WriteRowsEvent` events.
   - One or many `UpdateRowsEvent` events.
   - One or many `DeleteRowsEvent` events.
3. `XidEvent` indicating commit of the transaction.

**It's best practice to use GTID replication with the `from_gtid` method.** Using the approach you can correctly perform replication failover.
Note that in GTID mode `from_gtid` has the following behavior:
- `from_gtid(@@gtid_purged)` acts like `from_start()`
- `from_gtid(@@gtid_executed)` acts like `from_end()`

## Reading binlog files offline
In some cases you will need to read binlog files offline from the file system.
This can be done using `BinlogReader` class.
```rust
use mysql_cdc::{binlog_reader::BinlogReader, errors::Error};
use std::fs::File;

const PATH: &str = "mysql-bin.000001";

fn main() -> Result<(), Error> {
    let file = File::open(PATH)?;
    let reader = BinlogReader::new(file)?;

    for result in reader.read_events() {
        let (header, event) = result?;
        println!("{:#?}", header);
        println!("{:#?}", event);
    }
    Ok(())
}
```