signal-desktop/ts/services/backups/util/CircularMessageCache.ts
2024-09-10 09:29:19 +10:00

80 lines
2.1 KiB
TypeScript

// Copyright 2024 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
import type {
ReadonlyMessageAttributesType,
MessageAttributesType,
} from '../../../model-types.d';
import { find } from '../../../util/iterables';
import { DataReader } from '../../../sql/Client';
export type CircularMessageCacheOptionsType = Readonly<{
size: number;
flush: () => Promise<void>;
}>;
export class CircularMessageCache {
private readonly flush: () => Promise<void>;
private readonly buffer: Array<MessageAttributesType | undefined>;
private readonly sentAtToMessages = new Map<
number,
Set<MessageAttributesType>
>();
private offset = 0;
constructor({ size, flush }: CircularMessageCacheOptionsType) {
this.flush = flush;
this.buffer = new Array(size);
}
public push(attributes: MessageAttributesType): void {
const stale = this.buffer[this.offset];
this.buffer[this.offset] = attributes;
this.offset = (this.offset + 1) % this.buffer.length;
let addedSet = this.sentAtToMessages.get(attributes.sent_at);
if (addedSet === undefined) {
addedSet = new Set();
this.sentAtToMessages.set(attributes.sent_at, addedSet);
}
addedSet.add(attributes);
if (stale === undefined) {
return;
}
const staleSet = this.sentAtToMessages.get(stale.sent_at);
if (staleSet === undefined) {
return;
}
staleSet.delete(stale);
if (staleSet.size === 0) {
this.sentAtToMessages.delete(stale.sent_at);
}
}
public async findBySentAt(
sentAt: number,
predicate: (attributes: ReadonlyMessageAttributesType) => boolean
): Promise<MessageAttributesType | undefined> {
const set = this.sentAtToMessages.get(sentAt);
if (set !== undefined) {
const cached = find(set.values(), predicate);
if (cached != null) {
return cached;
}
}
await this.flush();
const onDisk = await DataReader.getMessagesBySentAt(sentAt);
return onDisk.find(predicate);
}
// Just a stub to conform with the interface
public async upgradeSchema(
attributes: MessageAttributesType
): Promise<MessageAttributesType> {
return attributes;
}
}