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
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78

use futures::Future;
use tokio::sync::mpsc;
use uuid::Uuid;

use crate::{
    event::{RecordedEvent, UnsavedEvent},
    event_bus::EventBusMessage,
    storage::StorageError,
    stream::Stream,
};

pub mod error;

pub trait Backend {
    fn backend_name() -> &'static str;

    #[doc(hidden)]
    fn direct_channel(&mut self, _notifier: mpsc::UnboundedSender<EventBusMessage>) {}

    /// Create a new stream with an identifier
    ///
    /// # Errors
    /// The stream creation can fail for multiple reasons:
    ///
    /// - pure storage failure (unable to create the stream on the backend)
    /// - The stream already exists
    fn create_stream(
        &mut self,
        stream: Stream,
        correlation_id: Uuid,
    ) -> std::pin::Pin<Box<dyn Future<Output = Result<Stream, StorageError>> + Send>>;

    /// Delete a stream from the `Backend`
    ///
    /// Do we need to provide a hard/soft deletion?
    ///
    /// # Errors
    /// The stream deletion can fail for multiple reasons:
    ///
    /// - pure storage failure (unable to delete the stream on the backend)
    /// - The stream doesn't exists
    fn delete_stream(
        &mut self,
        stream: &Stream,
        correlation_id: Uuid,
    ) -> std::pin::Pin<Box<dyn Future<Output = Result<(), StorageError>> + Send>>;

    fn append_to_stream(
        &mut self,
        stream_uuid: &str,
        events: &[UnsavedEvent],
        correlation_id: Uuid,
    ) -> std::pin::Pin<Box<dyn Future<Output = Result<Vec<Uuid>, StorageError>> + Send>>;

    // async fn read_stream(
    fn read_stream(
        &self,
        stream_uuid: String,
        version: usize,
        limit: usize,
        correlation_id: Uuid,
    ) -> std::pin::Pin<Box<dyn Future<Output = Result<Vec<RecordedEvent>, StorageError>> + Send>>;

    fn read_stream_info(
        &mut self,
        stream_uuid: String,
        correlation_id: Uuid,
    ) -> std::pin::Pin<Box<dyn Future<Output = Result<Stream, StorageError>> + Send>>;

    fn stream_forward(
        &self,
        stream_uuid: String,
        batch_size: usize,
        correlation_id: Uuid,
    ) -> std::pin::Pin<
        Box<dyn futures::Stream<Item = Result<Vec<RecordedEvent>, StorageError>> + Send>,
    >;
}