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// Copyright 2026 Nowledge
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use crate::cache::ManifestGeneration;
/// The immutable identity of one published database read.
///
/// The logical commit epoch controls visibility. The physical generation only
/// identifies the checkpoint base beneath that logical snapshot; later commits
/// may be represented by an immutable delta without changing the base.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct PublishedReadView {
visible_commit_epoch: u64,
checkpoint_commit_epoch: Option<u64>,
physical_generation: Option<ManifestGeneration>,
}
impl PublishedReadView {
#[doc(hidden)]
pub fn new(
visible_commit_epoch: u64,
checkpoint_commit_epoch: Option<u64>,
physical_generation: Option<ManifestGeneration>,
) -> Self {
debug_assert_eq!(
checkpoint_commit_epoch.is_some(),
physical_generation.is_some(),
"checkpoint epoch and physical generation must be published together"
);
debug_assert!(
checkpoint_commit_epoch.is_none_or(|epoch| epoch <= visible_commit_epoch),
"checkpoint commit epoch must not exceed the visible commit epoch"
);
Self {
visible_commit_epoch,
checkpoint_commit_epoch,
physical_generation,
}
}
pub const fn visible_commit_epoch(self) -> u64 {
self.visible_commit_epoch
}
pub const fn checkpoint_commit_epoch(self) -> Option<u64> {
self.checkpoint_commit_epoch
}
pub const fn physical_generation(self) -> Option<ManifestGeneration> {
self.physical_generation
}
pub const fn physical_base_is_current(self) -> bool {
matches!(
self.checkpoint_commit_epoch,
Some(checkpoint_commit_epoch) if checkpoint_commit_epoch == self.visible_commit_epoch
)
}
pub const fn has_delta_after_physical_generation(self) -> bool {
matches!(
self.checkpoint_commit_epoch,
Some(checkpoint_commit_epoch) if checkpoint_commit_epoch < self.visible_commit_epoch
)
}
}