mlg 0.1.0

An asynchronous Log for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45

use async_trait::async_trait;

mod file_log;

pub use file_log::FileLog;

/// The position of a record within a log, represented as an offset from the beginning of the log.
pub type Offset = u64;

/// A byte vector, used to represent binary data.
pub type Bytes = Vec<u8>;

/// Represents a single record within a log, consisting of a key, a value, and a timestamp.
struct Record {
    /// The length of the value of the log entry (in bytes).
    value_length: u64,

    /// The value of the log entry.
    value: Bytes,
}

/// An enumeration of possible errors that can occur during log operations.
#[derive(Debug)]
pub enum LogError {
    /// Represents an I/O error, typically encountered during file operations (read/write).
    IoError(std::io::Error),

    /// Represents an error encountered while attempting to read a record from the log
    /// that does not exist.
    IndexOutOfBounds,
}

#[async_trait]
pub trait Log {
    /// Appends a new record to the log, returning the offset of the newly appended record.
    async fn append(&self, entry: Bytes) -> Result<Offset, LogError>;

    /// Reads the record at the given offset, returning the record
    /// and the offset of the next record.
    async fn read(&self, offset: Offset) -> Result<(Bytes, Offset), LogError>;

    /// Reads records starting at the given offset, returning up to 'max_records' records,
    /// and the offset of the record after the last record read.
    async fn batch_read(&self, offset: Offset, max_records: usize) -> Result<(Vec<Bytes>, Offset), LogError>;
}