nodedb 0.4.0

Local-first, real-time, edge-to-cloud hybrid database for multi-modal workloads
Documentation 
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// SPDX-License-Identifier: BUSL-1.1

//! Pre-`database_id` [`ReplicatedEntry`](super::types::ReplicatedEntry) shape.
//!
//! `ReplicatedEntry` is encoded as a plain positional zerompk array (no
//! `#[msgpack(map)]`), so decoding checks the array length exactly. Adding
//! `database_id` grew that array from 4 elements to 5, which means a Raft log
//! entry proposed by a leader running the previous binary (still emitting the
//! 4-element shape) would fail to decode on a follower running the new
//! binary. `LegacyReplicatedEntry` mirrors that old 4-field shape so
//! `ReplicatedEntry::from_bytes` can fall back to it and default
//! `database_id` to `0` (`DatabaseId::DEFAULT`), matching the same 0 → DEFAULT
//! convention the on-disk WAL header uses for its own `database_id` field.

use super::types::{ReplicatedEntry, ReplicatedWrite};

/// The `ReplicatedEntry` wire shape before `database_id` was added.
#[derive(Debug, Clone, zerompk::ToMessagePack, zerompk::FromMessagePack)]
pub struct LegacyReplicatedEntry {
    pub tenant_id: u64,
    pub vshard_id: u32,
    pub idempotency_key: u64,
    pub write: ReplicatedWrite,
}

impl LegacyReplicatedEntry {
    /// Number of positional elements in this shape's zerompk array encoding.
    /// Used by `ReplicatedEntry::from_bytes` to recognize an `ArrayLengthMismatch`
    /// against the current shape as "this is an old-leader entry", not corruption.
    pub const FIELD_COUNT: usize = 4;

    /// Upgrade to the current shape, defaulting `database_id` to `0`.
    pub fn into_current(self) -> ReplicatedEntry {
        ReplicatedEntry {
            tenant_id: self.tenant_id,
            database_id: 0,
            vshard_id: self.vshard_id,
            idempotency_key: self.idempotency_key,
            write: self.write,
        }
    }
}