sqlite_diff_rs/wire/
source.rs

1//! [`WireSource`]: sealed marker trait for CDC wire formats.
2
3use core::hash::Hash;
4
5use super::sealed::Sealed;
6
7/// Per-format marker naming a CDC wire source.
8///
9/// Implementors are unit structs owned by each format module
10/// (`PgWalstream`, `Wal2Json`, `Maxwell`). The associated types describe
11/// the format's per-column payload and its native type-identity key.
12///
13/// # Type keys
14///
15/// - `PgWalstream::TypeKey = pg_walstream::Oid` (u32 alias).
16/// - `Wal2Json::TypeKey = alloc::sync::Arc<str>` (Postgres type name).
17/// - `Maxwell::TypeKey = alloc::sync::Arc<str>` (MySQL type name; empty
18///   string when the Maxwell daemon runs without `--include_types`).
19pub trait WireSource: Sealed {
20    /// Per-column payload the format hands to a decoder.
21    ///
22    /// Every payload struct carries a `column_name: &'a str` so decoder
23    /// errors are self-describing without an outer wrapping layer.
24    type Payload<'a>;
25
26    /// Type identity as seen on this source's wire.
27    type TypeKey: Hash + Eq + Clone;
28
29    /// Extract the type key from a payload for dispatch.
30    fn type_key(payload: &Self::Payload<'_>) -> Self::TypeKey;
31
32    /// Extract the column name from a payload for diagnostic messages.
33    fn column_name<'a>(payload: &'a Self::Payload<'_>) -> &'a str;
34}
35
36/// Schema-side source-native type key for one column of one table.
37pub trait WireColumnTypes<Src: WireSource> {
38    /// Type key for the column at `column_index`.
39    fn column_type_key(&self, column_index: usize) -> Src::TypeKey;
40}
41
42/// Table-name lookup for the [`DiffSetBuilder::digest`](crate::DiffSetBuilder::digest) entry point.
43pub trait WireSchema<Src: WireSource> {
44    /// Concrete schema type for one table.
45    type Table: crate::schema::NamedColumns + WireColumnTypes<Src>;
46
47    /// Resolve a table name to its schema entry.
48    fn get(&self, table_name: &str) -> Option<&Self::Table>;
49}
50
51/// One CDC wire event digested via [`DiffSetBuilder::digest`](crate::DiffSetBuilder::digest).
52///
53/// Implemented in-crate for `pg_walstream::EventType`, `wal2json::MessageV2`,
54/// `wal2json::ChangeV1`, and `maxwell::Message` (each times both formats).
55pub trait Digestable<F, T, S, B>
56where
57    F: crate::builders::Format<S, B>,
58    T: crate::schema::NamedColumns + WireColumnTypes<Self::Src>,
59{
60    /// Wire source this event came from.
61    type Src: WireSource;
62
63    /// Failure mode raised on schema lookup or decode failure.
64    type Error;
65
66    /// Fold this event into `builder`, resolving affected tables via `schema`
67    /// and decoding column payloads via `adapter`.
68    ///
69    /// # Errors
70    ///
71    /// Any per-source `ConversionError`.
72    fn digest_into<Sch, A>(
73        &self,
74        builder: crate::builders::DiffSetBuilder<F, T, S, B>,
75        schema: &Sch,
76        adapter: &A,
77    ) -> Result<crate::builders::DiffSetBuilder<F, T, S, B>, Self::Error>
78    where
79        Sch: WireSchema<Self::Src, Table = T>,
80        A: super::WireAdapter<Self::Src, S, B>;
81}
sqlite_diff_rs/wire/source.rs

sqlite_diff_rs/wire/
source.rs
