Simplify DB
This commit is contained in:
parent
9244e5d220
commit
3177691e13
2 changed files with 98 additions and 316 deletions
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@ -4,7 +4,7 @@ import { Database, createEmptyDatabase } from "./database";
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test("current state keeps absent optional fields absent across save and reload", async () => {
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const initial = createEmptyDatabase("vault");
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initial.local = { local: "local.md", remote: "remote.md" };
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initial.actualFileManifest = { local: "local.md", remote: "remote.md" };
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initial.documents = {
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local: { observedHash: "local" },
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remote: { remote: { vaultUpdateId: 1, contentSize: 3 } },
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@ -29,7 +29,7 @@ test("current state keeps absent optional fields absent across save and reload",
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test("current reset state is restored after an uncertain save", async () => {
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const saved = createEmptyDatabase("vault");
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saved.local = { note: "note.md" };
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saved.actualFileManifest = { note: "note.md" };
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saved.documents.note = {
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base: { vaultUpdateId: null, hash: "clean" },
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observedHash: "clean"
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@ -43,6 +43,6 @@ test("current reset state is restored after an uncertain save", async () => {
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async () => structuredClone(saved)
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);
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await assert.rejects(db.save(), /interrupted/);
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await db.recoverPersistence();
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await db.reloadFromSave();
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assert.deepEqual(db.state, saved);
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});
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@ -1,374 +1,156 @@
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import type { Logger } from "../tracing/logger";
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import { EMPTY_HASH } from "../utils/hash";
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import { CoveredValues } from "../utils/data-structures/min-covered";
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import { awaitAll } from "../utils/await-all";
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import { removeFromArray } from "../utils/remove-from-array";
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import type { PendingRequest } from "./requests";
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import type { FileManifest } from "../services/types/FileManifest";
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import type { FileManifestEntries } from "../types/file-manifest-entries";
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export type VaultUpdateId = number;
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export type DocumentId = string;
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export type RelativePath = string;
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export interface DocumentMetadata {
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parentVersionId: VaultUpdateId;
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hash: string;
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remoteRelativePath?: RelativePath;
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export interface ContentHead {
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vaultUpdateId: VaultUpdateId;
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contentSize: number;
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}
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export interface StoredDocumentMetadata {
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relativePath: RelativePath;
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documentId: DocumentId;
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parentVersionId: VaultUpdateId;
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remoteRelativePath?: RelativePath;
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hash: string;
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export interface DocumentState {
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// A null version retains only the clean hash after a server history reset.
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base?: { vaultUpdateId: VaultUpdateId | null; hash: string };
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// Last observed disk hash; an empty string means a notification awaits scanning.
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observedHash?: string;
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// A remote version still to be incorporated, including excluded downloads.
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remote?: ContentHead;
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}
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export type { PendingRequest } from "./requests";
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export interface StoredDatabase {
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documents: StoredDocumentMetadata[];
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lastSeenUpdateId: VaultUpdateId | undefined;
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hasInitialSyncCompleted: boolean;
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readonly vaultKey: string;
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// Last incorporated server manifest; the base for the next three-way path merge.
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parentFileManifest: FileManifest;
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// Current local document IDs and paths, including files awaiting upload or download.
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actualFileManifest: FileManifestEntries;
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// Per-document merge bases and observations; content bytes are not stored here.
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documents: Record<DocumentId, DocumentState>;
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// Absent until a vault snapshot is applied; also marks a durable history reset.
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lastSeenUpdateId?: VaultUpdateId;
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// Exact request to resolve before observing a newer remote base.
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pending?: PendingRequest;
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// Commits consumption of the saved notification queue with the identity map.
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lastAppliedLocalChangeId?: string;
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// Server path at the start of exclusion, retained as the path-merge base.
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// null means the document was absent from the server manifest at that time.
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excluded?: Record<DocumentId, RelativePath | null>;
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}
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/**
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* Represents a document in the database.
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*
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* It is mutable and its content should always represent the latest
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* state of the document on disk based on the update events we have seen.
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*/
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export interface DocumentRecord {
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relativePath: RelativePath;
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documentId: DocumentId;
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metadata: DocumentMetadata | undefined;
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isDeleted: boolean;
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updates: Promise<unknown>[];
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parallelVersion: number;
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export function createEmptyDatabase(vaultKey: string): StoredDatabase {
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return {
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vaultKey,
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parentFileManifest: { fileManifestId: 0, entries: {} },
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actualFileManifest: {},
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documents: {}
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};
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}
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function canBindToAnotherVault(state: StoredDatabase): boolean {
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return (
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state.lastSeenUpdateId === undefined &&
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!state.pending &&
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Object.keys(state.actualFileManifest).length === 0
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);
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}
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export class Database {
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private documents: DocumentRecord[];
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private lastSeenUpdateIds: CoveredValues;
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private hasInitialSyncCompleted: boolean;
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public state: StoredDatabase;
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private needsReload = false;
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public constructor(
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private readonly logger: Logger,
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initialState: Partial<StoredDatabase> | undefined,
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private readonly saveData: (data: StoredDatabase) => Promise<void>
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initial: StoredDatabase | undefined,
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private readonly saveData: (data: StoredDatabase) => Promise<void>,
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vaultKey: string,
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private readonly loadData: () => Promise<StoredDatabase | undefined>
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) {
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initialState ??= {};
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const state =
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initial === undefined
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? createEmptyDatabase(vaultKey)
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: structuredClone(initial);
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this.documents =
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initialState.documents?.map(
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({ relativePath, documentId, ...metadata }) => ({
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relativePath,
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documentId,
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metadata,
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isDeleted: false,
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updates: [],
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parallelVersion: 0
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})
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) ?? [];
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if (state.vaultKey !== vaultKey && !canBindToAnotherVault(state)) {
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throw new Error(
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"Incompatible vault identity. Preserve it for recovery and initialize a separate state store."
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);
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}
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this.ensureConsistency();
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this.logger.debug(`Loaded ${this.documents.length} documents`);
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const { lastSeenUpdateId } = initialState;
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this.logger.debug(`Loaded last seen update id: ${lastSeenUpdateId}`);
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this.lastSeenUpdateIds = new CoveredValues(
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Math.max(0, lastSeenUpdateId ?? 0) // the first updateId will be 1 which is the first integer after -1
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);
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this.documents.forEach((doc) => {
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this.lastSeenUpdateIds.add(doc.metadata?.parentVersionId);
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});
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this.hasInitialSyncCompleted =
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initialState.hasInitialSyncCompleted ?? false;
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this.logger.debug(
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`Loaded hasInitialSyncCompleted: ${this.hasInitialSyncCompleted}`
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);
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this.state = { ...state, vaultKey };
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}
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public get length(): number {
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return this.documents.length;
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return Object.keys(this.state.actualFileManifest).length;
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}
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public get resolvedDocuments(): DocumentRecord[] {
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const paths = new Map<string, DocumentRecord[]>();
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this.documents
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// eslint-disable-next-line no-restricted-syntax -- Type narrowing, not removing a specific item
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.filter(({ metadata }) => metadata !== undefined)
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.forEach((record) =>
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paths.set(record.relativePath, [
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record,
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...(paths.get(record.relativePath) ?? [])
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])
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);
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return Array.from(paths.values()).map((records) => {
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records.sort(
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(a, b) => b.parallelVersion - a.parallelVersion // descending
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);
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if (
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records.length > 1 &&
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records.some((current, i) =>
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i === 0
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? false
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: records[i - 1].parallelVersion ===
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current.parallelVersion
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)
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) {
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throw new Error(
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`Multiple documents with the same parallel version and path at ${records[0].relativePath}`
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);
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}
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return records[0];
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});
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}
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public updateDocumentMetadata(
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metadata: {
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parentVersionId: VaultUpdateId;
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hash: string;
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remoteRelativePath: RelativePath;
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},
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toUpdate: DocumentRecord
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): void {
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if (!this.documents.includes(toUpdate)) {
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throw new Error("Document not found in database");
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}
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toUpdate.metadata = metadata;
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this.saveInTheBackground();
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}
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public removeDocumentPromise(promise: Promise<unknown>): void {
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const entry = this.documents.find(({ updates }) =>
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updates.includes(promise)
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);
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if (entry === undefined) {
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// This method should be idempotent and tolerant of
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// stragglers calling it after the databse has been reset.
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// Bind an empty database to the configured vault.
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public async bindVault(vaultKey: string): Promise<void> {
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if (this.state.vaultKey === vaultKey) {
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return;
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}
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removeFromArray(entry.updates, promise);
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// No need to save as Promises don't get serialized
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}
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public removeDocument(find: DocumentRecord): void {
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removeFromArray(this.documents, find);
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this.saveInTheBackground();
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}
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public getLatestDocumentByRelativePath(
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find: RelativePath
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): DocumentRecord | undefined {
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const candidates = this.documents.filter(
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({ relativePath }) => relativePath === find
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);
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candidates.sort((a, b) => b.parallelVersion - a.parallelVersion); // descending
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return candidates[0];
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}
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public async getResolvedDocumentByRelativePath(
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relativePath: RelativePath,
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promise: Promise<unknown>
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): Promise<DocumentRecord> {
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const entry = this.getLatestDocumentByRelativePath(relativePath);
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if (entry === undefined) {
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if (!canBindToAnotherVault(this.state)) {
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throw new Error(
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`Document not found by relative path: ${relativePath}, ${JSON.stringify(
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this.documents,
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null,
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2
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)}`
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"Incompatible vault identity. Preserve it for recovery and initialize a separate state store."
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);
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}
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const currentPromises = entry.updates;
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entry.updates = [...currentPromises, promise];
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await awaitAll(currentPromises);
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return entry;
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await this.commit({ ...this.state, vaultKey });
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}
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public createNewPendingDocument(
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documentId: DocumentId,
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relativePath: RelativePath,
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promise: Promise<unknown>
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): DocumentRecord {
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this.logger.debug(
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`Creating new pending document: ${relativePath} (${documentId})`
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public async commit(next: StoredDatabase): Promise<void> {
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const snapshot = structuredClone(next);
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if (this.needsReload) {
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throw new Error(
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"Reload saved state before retrying an uncertain save"
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);
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}
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this.needsReload = true;
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await this.saveData(snapshot);
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this.state = snapshot;
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this.needsReload = false;
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}
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public findDocumentId(path: RelativePath): DocumentId | undefined {
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return Object.keys(this.state.actualFileManifest).find(
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(id) => this.state.actualFileManifest[id] === path
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);
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const previousEntry =
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this.getLatestDocumentByRelativePath(relativePath);
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const entry = {
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relativePath,
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documentId,
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metadata: undefined,
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isDeleted: false,
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updates: [promise],
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parallelVersion:
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previousEntry?.parallelVersion === undefined
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? 0
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: previousEntry.parallelVersion + 1
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};
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this.documents.push(entry);
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this.saveInTheBackground();
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return entry;
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}
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public createNewEmptyDocument(
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documentId: DocumentId,
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parentVersionId: VaultUpdateId,
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relativePath: RelativePath
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): DocumentRecord {
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const entry = {
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relativePath,
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documentId,
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metadata: {
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parentVersionId,
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hash: EMPTY_HASH,
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remoteRelativePath: relativePath
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},
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isDeleted: false,
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updates: [],
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parallelVersion: 0
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};
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this.documents.push(entry);
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this.saveInTheBackground();
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return entry;
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}
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public getDocumentByDocumentId(
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find: DocumentId
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): DocumentRecord | undefined {
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return this.documents.find(({ documentId }) => documentId === find);
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}
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public move(
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oldRelativePath: RelativePath,
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newRelativePath: RelativePath
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): void {
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const oldDocument =
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this.getLatestDocumentByRelativePath(oldRelativePath);
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if (oldDocument === undefined) {
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public async reloadFromSave(): Promise<void> {
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if (!this.needsReload) {
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return;
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}
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const newDocument =
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this.getLatestDocumentByRelativePath(newRelativePath);
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if (newDocument?.isDeleted === false) {
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throw new Error(
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`Document already exists at new location: ${newRelativePath}`
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);
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const saved = await this.loadData();
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if (saved) {
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this.state = structuredClone(saved);
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}
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oldDocument.relativePath = newRelativePath;
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// We're in a strange state where the target of the move has just got deleted,
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// however, its metadata might already have a bunch of updates queued up for
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// the document at the new location. We need to keep these updates.
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oldDocument.parallelVersion =
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newDocument !== undefined ? newDocument.parallelVersion + 1 : 0;
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this.saveInTheBackground();
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this.needsReload = false;
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}
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public delete(relativePath: RelativePath): void {
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const candidate = this.getLatestDocumentByRelativePath(relativePath);
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if (candidate === undefined) {
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throw new Error(
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`Document not found by relative path: ${relativePath}`
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);
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}
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candidate.isDeleted = true;
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}
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public getHasInitialSyncCompleted(): boolean {
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return this.hasInitialSyncCompleted;
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}
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public setHasInitialSyncCompleted(value: boolean): void {
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this.hasInitialSyncCompleted = value;
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this.saveInTheBackground();
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}
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public getLastSeenUpdateId(): VaultUpdateId {
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return this.lastSeenUpdateIds.min;
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}
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public addSeenUpdateId(value: number): void {
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const previousMin = this.lastSeenUpdateIds.min;
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this.lastSeenUpdateIds.add(value);
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if (previousMin !== this.lastSeenUpdateIds.min) {
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this.saveInTheBackground();
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}
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}
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public setLastSeenUpdateId(value: number): void {
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this.lastSeenUpdateIds.min = value;
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this.saveInTheBackground();
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}
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public reset(): void {
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this.documents = [];
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this.lastSeenUpdateIds = new CoveredValues(
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0 // the first updateId will be 1 which is the first integer after -1
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);
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this.hasInitialSyncCompleted = false;
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this.saveInTheBackground();
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public cloneState(): StoredDatabase {
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return structuredClone(this.state);
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}
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public async save(): Promise<void> {
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return this.saveData({
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documents: this.resolvedDocuments.map(
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({ relativePath, documentId, metadata }) => ({
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documentId,
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relativePath,
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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...metadata! // `resolvedDocuments` only returns docs with metadata set
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})
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),
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lastSeenUpdateId: this.lastSeenUpdateIds.min,
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hasInitialSyncCompleted: this.hasInitialSyncCompleted
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});
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await this.commit(this.state);
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}
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private ensureConsistency(): void {
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const idToPath = new Map<string, string[]>();
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this.resolvedDocuments.forEach(({ relativePath, documentId }) => {
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idToPath.set(documentId, [
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...(idToPath.get(documentId) ?? []),
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relativePath
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]);
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});
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const duplicates = Array.from(idToPath.entries())
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.filter(([_, paths]) => paths.length > 1)
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.map(([id, paths]) => `${id} (${paths.join(", ")})`);
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if (duplicates.length > 0) {
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throw new Error(
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"Document IDs are not unique, found duplicates: " +
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duplicates.join("; ")
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);
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}
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}
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private saveInTheBackground(): void {
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this.ensureConsistency();
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void this.save().catch((error: unknown) => {
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this.logger.error(`Error saving data: ${error}`);
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});
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}
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}
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