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import {catchError, filter, finalize, map, share, switchMap, takeUntil} from 'rxjs/operators';
import {Writer} from '@jsonjoy.com/buffers/lib/Writer';
import {CborJsonValueCodec} from '@jsonjoy.com/json-pack/lib/codecs/cbor';
import {Model, Patch} from 'json-joy/lib/json-crdt';
import {deepEqual} from '@jsonjoy.com/json-equal/lib/deepEqual';
import {RpcError} from '@jsonjoy.com/rpc-error';
import {SESSION} from 'json-joy/lib/json-crdt-patch/constants';
import {once} from 'thingies/lib/once';
import {timeout} from 'thingies/lib/timeout';
import {pubsub} from '../../pubsub';
import type {ServerBatch, ServerHistory, ServerPatch} from '../../remote/types';
import type {
BlockId,
LocalRepo,
LocalRepoEvent,
LocalRepoDeleteEvent,
LocalRepoMergeEvent,
LocalRepoRebaseEvent,
LocalRepoResetEvent,
LocalRepoSyncRequest,
LocalRepoSyncResponse,
LocalRepoGetResponse,
LocalRepoGetRequest,
LocalRepoCreateResponse,
LocalRepoCreateRequest,
LocalRepoGet0Response,
LocalRepoGetIfResponse,
LocalRepoGetIfRequest,
LocalRepoPullResponse,
} from '../types';
import type {
BinStrLevel,
BinStrLevelOperation,
BlockMeta,
LocalBatch,
SyncResult,
LevelLocalRepoPubSub,
LevelLocalRepoPubSubMessage,
LevelLocalRepoCursor,
BlockSyncRecord,
} from './types';
import type {CrudLocalRepoCipher} from './types';
import type {Locks} from 'thingies/lib/Locks';
import type {JsonValueCodec} from '@jsonjoy.com/json-pack/lib/codecs/types';
/**
* @todo
*
* 1. Implement pull loop, when WebSocket subscription cannot be established.
*/
enum Defaults {
/**
* The root of the block repository.
*
* ```
* b!<collection>!<id>!
* ```
*/
BlockRepoRoot = 'b',
/**
* The root of the key-space where items are marked as "dirty" and need sync.
*
* ```
* s!b!<collection>!<id>
* ```
*/
// eslint-disable-next-line
SyncRoot = 's',
/**
* The metadata of the block.
*
* ```
* b!<collection>!<id>!k!x
* ```
*/
Metadata = 'k!x',
/**
* The state of the latest known server-side model.
*
* ```
* b!<collection>!<id>!k!m
* ```
*/
Model = 'k!m',
/**
* List of frontier patches.
*
* ```
* b!<collection>!<id>!f!<time>
* ```
*/
Frontier = 'f',
/**
* List of batches verified by the server.
*
* ```
* b!<collection>!<id>!h!<seq>
* ```
*/
Batches = 'h',
/**
* List of snapshots.
*
* ```
* b!<collection>!<id>!s!<seq>
* ```
*/
// eslint-disable-next-line
Snapshots = 's',
/**
* The default length of the history, if `hist` metadata property not
* specified.
*/
HistoryLength = 100,
}
export interface LevelLocalRepoOpts {
/**
* Session ID of the user on this device. The same session ID is reused across
* all tabs.
*/
readonly sid: number;
/**
* Local persistance LevelDB API.
*/
readonly kv: BinStrLevel;
/**
* Optional content encryption/decryption API.
*/
readonly cipher?: CrudLocalRepoCipher;
/**
* Cross-tab locking API.
*/
readonly locks: Locks;
/**
* Optional observable that emits `true` when the device is connected to the
* server and `false` when it's not.
*/
readonly connected$?: BehaviorSubject<boolean>;
/**
* RPC API for communication with the server.
*/
readonly rpc: ServerHistory;
/**
* Event bus.
*/
readonly pubsub?: LevelLocalRepoPubSub;
/**
* Number of milliseconds after which remote calls are considered timed out.
*/
readonly remoteTimeout?: number;
/**
* Minimum backoff time in milliseconds for the sync loop.
*/
readonly syncLoopMinBackoff?: number;
/**
* Maximum backoff time in milliseconds for the sync loop.
*/
readonly syncLoopMaxBackoff?: number;
/**
* If specified, background sync errors will be emitted here.
*/
readonly onSyncError?: (error: Error | unknown) => void;
}
export class LevelLocalRepo implements LocalRepo {
readonly kv: BinStrLevel;
public readonly locks: Locks;
public readonly sid: number;
public readonly connected$: BehaviorSubject<boolean>;
protected readonly pubsub: LevelLocalRepoPubSub;
protected readonly cipher?: CrudLocalRepoCipher;
protected readonly codec: JsonValueCodec = new CborJsonValueCodec(new Writer(1024 * 16) as any);
constructor(protected readonly opts: LevelLocalRepoOpts) {
this.kv = opts.kv;
this.locks = opts.locks;
this.sid = opts.sid;
this.connected$ = opts.connected$ ?? new BehaviorSubject(true);
this.pubsub = opts.pubsub ?? pubsub('level-local-repo');
this.cipher = opts.cipher;
this._conSub = this.connected$.subscribe((connected) => {
if (connected && !this._remoteSyncLoopActive) this.runRemoteSyncLoop();
});
}
private _conSub: Subscription | undefined = undefined;
private _stopped = false;
private readonly _stop$ = new Subject<void>();
@once
public stop(): void {
this._remoteSyncLoopActive = false;
clearTimeout(this._remoteSyncDelayTimer as any);
this._stopped = true;
this._stop$.next();
this._stop$.complete();
this._conSub?.unsubscribe();
}
protected emitSyncError(error: Error | unknown): void {
Eif (this._stopped) return;
this.opts.onSyncError?.(error);
}
protected emitPubSub(message: LevelLocalRepoPubSubMessage): void {
if (this._stopped) return;
try {
this.pubsub.pub(message);
} catch (error) {
if (this._stopped) return;
this.emitSyncError(error);
}
}
// eslint-disable-next-line
protected async encrypt(blob: Uint8Array, zip: boolean): Promise<Uint8Array> {
// if (zip) blob = await gzip(blob);
// if (this.cipher) blob = await this.cipher.encrypt(blob);
return blob;
}
// eslint-disable-next-line
protected async decrypt(blob: Uint8Array, zip: boolean): Promise<Uint8Array> {
// if (this.cipher) blob = await this.cipher.decrypt(blob);
// if (zip) blob = await ungzip(blob);
return blob;
}
protected async encode(value: unknown, zip: boolean): Promise<Uint8Array> {
const encoded = this.codec.encoder.encode(value);
const encrypted = await this.encrypt(encoded, zip);
return encrypted;
}
protected async decode(blob: Uint8Array, zip: boolean): Promise<unknown> {
const decrypted = await this.decrypt(blob, zip);
const decoded = this.codec.decoder.decode(decrypted);
return decoded;
}
/** @todo Encrypt collection and key. */
public async blockKeyBase(id: BlockId): Promise<string> {
return Defaults.BlockRepoRoot + '!' + id.join('!') + '!';
}
public frontierKeyBase(blockKeyBase: string): string {
return blockKeyBase + Defaults.Frontier + '!';
}
public frontierKey(blockKeyBase: string, time: number): string {
const timeFormatted = time.toString(36).padStart(8, '0');
return this.frontierKeyBase(blockKeyBase) + timeFormatted;
}
public batchKeyBase(blockKeyBase: string): string {
return blockKeyBase + Defaults.Batches + '!';
}
public batchKey(blockKeyBase: string, seq: number): string {
const seqFormatted = seq.toString(36).padStart(8, '0');
return this.batchKeyBase(blockKeyBase) + seqFormatted;
}
public snapshotKeyBase(blockKeyBase: string): string {
return blockKeyBase + Defaults.Snapshots + '!';
}
public snapshotKey(blockKeyBase: string, seq: number): string {
const seqFormatted = seq.toString(36).padStart(8, '0');
return this.snapshotKeyBase(blockKeyBase) + seqFormatted;
}
protected syncKey(keyBase: string): string {
return Defaults.SyncRoot + '!' + keyBase;
}
protected async _exists(keyBase: string): Promise<boolean> {
const metaKey = keyBase + Defaults.Metadata;
const exists = (await this.kv.keys({gte: metaKey, lte: metaKey, limit: 1}).all()).length > 0;
return exists;
}
protected _modelWrOp(keyBase: string, model: Uint8Array): Promise<BinStrLevelOperation> {
return this.encode(model, true).then(
(value) =>
({
type: 'put',
key: keyBase + Defaults.Model,
value,
}) as BinStrLevelOperation,
);
}
protected _metaWrOp(keyBase: string, meta?: BlockMeta): Promise<BinStrLevelOperation> {
return this.encode(meta, false).then(
(value) =>
({
type: 'put',
key: keyBase + Defaults.Metadata,
value,
}) as BinStrLevelOperation,
);
}
protected async _modelWrOps(keyBase: string, model: Uint8Array, meta?: BlockMeta): Promise<BinStrLevelOperation[]> {
const ops: Promise<BinStrLevelOperation>[] = [this._modelWrOp(keyBase, model)];
Eif (meta) ops.push(this._metaWrOp(keyBase, meta));
return Promise.all(ops);
}
protected async _wrModel(keyBase: string, model: Uint8Array, meta?: BlockMeta): Promise<void> {
const ops = await this._modelWrOps(keyBase, model, meta);
await this.kv.batch(ops);
}
protected async load(id: BlockId): Promise<{model: Model; cursor: number}> {
const blockId = id.join('/');
const res = await this.opts.rpc.read(blockId);
const block = res.block;
const snapshot = block.snapshot;
const seq = snapshot.seq;
const sid = this.sid;
const model = Model.load(snapshot.blob, sid);
for (const batch of block.tip) for (const patch of batch.patches) model.applyPatch(Patch.fromBinary(patch.blob));
const keyBase = await this.blockKeyBase(id);
const metaKey = keyBase + Defaults.Metadata;
const meta: BlockMeta = {
time: 0,
seq,
};
const modelBlob = model.toBinary();
const [metaBlob, modelTupleBlob] = await Promise.all([this.encode(meta, false), this.encode(modelBlob, true)]);
const ops: BinStrLevelOperation[] = [
{
type: 'put',
key: metaKey,
value: metaBlob,
},
{
type: 'put',
key: keyBase + Defaults.Model,
value: modelTupleBlob,
},
];
await this.lockBlock(keyBase, async () => {
const exists = await this._exists(keyBase);
if (exists) throw new Error('EXISTS');
await this.kv.batch(ops);
});
// TODO: Emit something here...
// this.pubsub.pub(['pull', {id, batches: [], snapshot: {seq, blob: modelBlob}}])
return {model, cursor: seq};
}
protected async readMeta(keyBase: string): Promise<BlockMeta> {
const metaKey = keyBase + Defaults.Metadata;
const blob = await this.kv.get(metaKey);
const meta = (await this.decode(blob as any, false)) as BlockMeta;
return meta;
}
public async readModel0(keyBase: string): Promise<Uint8Array> {
const modelKey = keyBase + Defaults.Model;
const blob = await this.kv.get(modelKey);
const decoded = (await this.decode(blob as any, true)) as Uint8Array;
return decoded;
}
public async readModel(keyBase: string): Promise<Model> {
try {
const blob = await this.readModel0(keyBase);
const model = Model.load(blob, this.sid);
return model;
} catch (error) {
Eif (!!error && typeof error === 'object' && (error as any).code === 'LEVEL_NOT_FOUND')
throw new Error('NOT_FOUND');
throw error;
}
}
public async *readFrontierBlobs0(keyBase: string) {
const gt = this.frontierKeyBase(keyBase);
const lt = gt + '~';
for await (const [key, buf] of this.kv.iterator({gt, lt})) {
/** @todo Remove this conversion once json-pack supports Buffers. */
const uint8 = new Uint8Array(buf.buffer, buf.byteOffset, buf.byteLength);
yield [key, uint8] as const;
}
}
public async readFrontier0(keyBase: string): Promise<Patch[]> {
const patches: Patch[] = [];
for await (const [, blob] of this.readFrontierBlobs0(keyBase)) {
const patch = Patch.fromBinary(blob);
patches.push(patch);
}
return patches;
}
public async readFrontierTip(keyBase: string): Promise<Patch | undefined> {
const frontierBase = this.frontierKeyBase(keyBase);
const lte = frontierBase + '~';
for await (const blob of this.kv.values({lte, limit: 1, reverse: true}))
return Patch.fromBinary(await this.decrypt(blob, false));
return;
}
protected async lockBlock<T>(keyBase: string, fn: () => Promise<T>): Promise<T> {
return await this.locks.lock(keyBase, 500, 500)<T>(fn);
}
protected async lockBlockForSync<T>(keyBase: string, fn: () => Promise<T>): Promise<T> {
const key = 's!' + keyBase;
return await this.locks.lock(key, 2000, 3000)<T>(fn);
}
protected isBlockLockedForSync(keyBase: string): boolean {
const key = 's!' + keyBase;
return this.locks.isLocked(key);
}
// --------------------------------------------------- Remote synchronization
protected async markDirty(keyBase: string, id: BlockId): Promise<void> {
const key = this.syncKey(keyBase);
const record: BlockSyncRecord = [id, Date.now()];
const blob = await this.encode(record, false);
await this.kv.put(key, blob);
}
protected async markDirtyAndSync(keyBase: string, id: BlockId): Promise<boolean> {
if (this._stopped) return false;
this.markDirty(keyBase, id).catch((error) => {
if (this._stopped) return;
this.emitSyncError(error);
});
try {
return await this.push(keyBase, id, true);
} catch (error) {
Iif (typeof error === 'object' && error && (error as any).message === 'Not Found') return false;
else if (error instanceof Error && error.message === 'DISCONNECTED') return false;
throw error;
}
}
protected remoteTimeout(): number {
return this.opts.remoteTimeout ?? 5000;
}
/**
* Pushes to remote.
* @param id Block ID.
* @param pull Whether to pull if there are no patches to push.
*/
protected async push(keyBase: string, id: BlockId, doPull = false): Promise<boolean> {
Iif (this._stopped) return false;
if (!this.connected$.getValue()) throw new Error('DISCONNECTED');
const remote = this.opts.rpc;
const remoteId = id.join('/');
const patches: ServerPatch[] = [];
const ops: BinStrLevelOperation[] = [{type: 'del', key: this.syncKey(keyBase)}];
for await (const [key, blob] of this.readFrontierBlobs0(keyBase)) {
ops.push({type: 'del', key});
patches.push({blob});
}
if (!patches.length) {
const meta = await this.readMeta(keyBase);
if (meta.seq === -1) {
remote.create(remoteId).catch((error) => {
const code = !!error && typeof error === 'object' ? (error as any).code : undefined;
const message = error instanceof Error ? error.message : undefined;
Eif (code === 'CONFLICT' || message === 'CONFLICT') return;
this.emitSyncError(error);
});
}
Eif (doPull) {
await this.pull(id);
}
return false;
}
// TODO: handle case when this times out, but actually succeeds, so on re-sync it handles the case when the block is already synced.
return await this.lockBlock(keyBase, async () => {
const TIMEOUT = this.remoteTimeout();
const startTime = Date.now();
const assertTimeout = () => {
Iif (Date.now() - startTime > TIMEOUT) throw new Error('TIMEOUT');
if (this._stopped) throw new Error('STOPPED');
};
return await timeout(TIMEOUT, async () => {
const read = await Promise.all([this.readModel(keyBase), this.readMeta(keyBase)]);
assertTimeout();
let model = read[0];
const meta = read[1];
// TODO: Track some meta to avoid unnecessary syncs.
// if (Date.now() - meta.ts < 1000) return false;
const hist = !!meta.hist;
const lastKnownSeq = meta.seq;
try {
const response = await remote.update(remoteId, {patches}, lastKnownSeq);
assertTimeout();
// TODO: handle case when block is deleted on the server.
// Process pull
const merge: Uint8Array[] = []; // List of merge patches to emit over pubsub.
const pull = response.pull;
Eif (pull) {
const snapshot = pull.snapshot;
const batches = pull.batches;
Iif (snapshot) {
model = Model.load(snapshot.blob, this.sid);
if (hist) {
ops.push({
type: 'put',
key: this.snapshotKey(keyBase, snapshot.seq),
value: await this.encode(snapshot, true),
});
assertTimeout();
}
}
Eif (batches) {
for (const b of batches) {
const patches = b.patches;
for (const patch of patches) {
const blob = patch.blob;
merge.push(blob);
model.applyPatch(Patch.fromBinary(blob));
}
Iif (hist) {
ops.push({
type: 'put',
key: this.batchKey(keyBase, b.seq),
value: await this.encode(b, false),
});
assertTimeout();
}
}
}
}
// Process the latest batch
for (const patch of patches) {
const blob = patch.blob;
merge.push(blob);
model.applyPatch(Patch.fromBinary(blob));
}
const batch: LocalBatch = {...response.batch, patches};
const seq = batch.seq;
Iif (hist) {
ops.push({
type: 'put',
key: this.batchKey(keyBase, seq),
value: await this.encode(batch, false),
});
assertTimeout();
}
// Process the model and metadata
delete meta.syncFailures;
meta.syncTs = Date.now();
meta.time = model.clock.time - 1;
meta.seq = seq;
const modelOps = await this._modelWrOps(keyBase, model.toBinary(), meta);
assertTimeout();
ops.push(...modelOps);
await this.kv.batch(ops);
Eif (merge.length) {
this.emitPubSub({type: 'merge', id, patches: merge, seq: seq});
}
return true;
} catch (error) {
// Store fails and time.
meta.syncTs = Date.now();
meta.syncFailures = (meta.syncFailures ?? 0) + 1;
try {
const op = await this._metaWrOp(keyBase, meta);
await this.kv.batch([op]);
} catch (err) {
this.emitSyncError(err);
}
throw error;
}
});
});
}
/**
* Iterates over all blocks marked as dirty.
*/
protected async *listDirty(): AsyncIterableIterator<BlockSyncRecord> {
const gt: string = Defaults.SyncRoot;
const lt: string = Defaults.SyncRoot + '~';
for await (const blob of this.kv.values({gt, lt})) yield (await this.decode(blob, false)) as BlockSyncRecord;
}
protected async *listDirtyBatch(batchSize: number = 3): AsyncIterableIterator<BlockSyncRecord[]> {
let batch: BlockSyncRecord[] = [];
for await (const record of this.listDirty()) {
batch.push(record);
Iif (batch.length >= batchSize) {
yield batch;
batch = [];
}
}
if (batch.length) yield batch;
}
public async syncItem(keyBase: string, id: BlockId): Promise<SyncResult> {
try {
const meta = await this.readMeta(keyBase);
Iif (meta.syncFailures && meta.syncTs) {
const timeout = Math.min(1000 * Math.pow(2, meta.syncFailures), 30000);
const now = Date.now();
const shouldSkip = now - timeout < meta.syncTs;
if (shouldSkip) return [id, false];
}
return await this.lockBlockForSync(keyBase, async () => {
const success = await this.push(keyBase, id, true);
return [id, success];
});
} catch (error) {
return [id, false, error];
}
}
public async remoteSyncAll(): Promise<SyncResult[]> {
const resultList: SyncResult[] = [];
for await (const batch of this.listDirtyBatch()) {
Iif (this._stopped) return resultList;
Iif (!this._remoteSyncLoopActive) return resultList;
Iif (!this.connected$.getValue()) return resultList;
await Promise.all(
batch.map(async (record) => {
const [id] = record;
const keyBase = await this.blockKeyBase(id);
const isLocked = this.isBlockLockedForSync(keyBase);
Iif (isLocked) return;
const result = await this.syncItem(keyBase, id);
resultList.push(result);
}),
);
}
return resultList;
}
protected _remoteSyncLoopActive = false;
protected _remoteSyncDelayTimer: unknown;
protected runRemoteSyncLoop(): void {
this._remoteSyncLoopActive = true;
Iif (!this.connected$.getValue()) {
this._remoteSyncLoopActive = false;
return;
}
this.remoteSyncAll()
.catch((error) => {
this.emitSyncError(error);
})
.finally(() => {
if (!this._remoteSyncLoopActive) return;
Iif (!this.connected$.getValue()) {
this._remoteSyncLoopActive = false;
return;
}
const timer = setTimeout(() => {
Iif (!this._remoteSyncLoopActive) return;
this.runRemoteSyncLoop();
}, 2000);
(timer as {unref?: () => void}).unref?.();
this._remoteSyncDelayTimer = timer;
});
}
/** ----------------------------------------------------- {@link LocalRepo} */
public async create({id, patches}: LocalRepoCreateRequest): Promise<LocalRepoCreateResponse> {
const keyBase = await this.blockKeyBase(id);
const meta: BlockMeta = {
time: 0,
seq: -1,
};
const ops: BinStrLevelOperation[] = [];
const model = Model.create(void 0, this.sid);
if (patches && patches.length) {
for (const patch of patches) {
const patchId = patch.getId();
Iif (!patchId) throw new Error('PATCH_ID_MISSING');
model.applyPatch(patch);
const patchKey = this.frontierKey(keyBase, patchId.time);
const op: BinStrLevelOperation = {
type: 'put',
key: patchKey,
value: await this.encrypt(patch.toBinary(), false),
};
ops.push(op);
}
}
ops.push(...(await this._modelWrOps(keyBase, model.toBinary(), meta)));
await this.lockBlock(keyBase, async () => {
const exists = await this._exists(keyBase);
if (exists) throw new Error('EXISTS');
await this.kv.batch(ops);
});
const remote = this.markDirtyAndSync(keyBase, id)
.then(() => {})
.catch((error) => {
Eif (this._stopped) return;
this.emitSyncError(error);
});
remote.catch(() => {});
return {model, remote};
}
public async get0(id: BlockId): Promise<LocalRepoGet0Response> {
const keyBase = await this.blockKeyBase(id);
const [model, meta, frontier] = await Promise.all([
this.readModel(keyBase),
this.readMeta(keyBase),
this.readFrontier0(keyBase),
]);
return {
model,
frontier,
meta,
};
}
public async get({id, remote}: LocalRepoGetRequest): Promise<LocalRepoGetResponse> {
try {
const {model, cursor} = await this._syncRead(id);
Iif (!model) throw RpcError.notFound();
return {model, cursor};
} catch (error) {
const code = !!error && typeof error === 'object' ? (error as any).code : undefined;
const message = error instanceof Error ? error.message : undefined;
const notFound = code === 'NOT_FOUND' || message === 'NOT_FOUND' || message === 'Not Found';
Iif (remote && notFound) return await this.load(id);
Eif (notFound) {
Iif (RpcError.isRpcError(error)) throw error;
throw RpcError.notFound('Not Found', undefined, error);
}
throw error;
}
}
public async getIf(request: LocalRepoGetIfRequest): Promise<null | LocalRepoGetIfResponse> {
let get = false;
const keyBase = await this.blockKeyBase(request.id);
const meta = await this.readMeta(keyBase);
if (typeof request.cursor === 'number') {
if (request.cursor < meta.seq) get = true;
}
if (!get && typeof request.time === 'number') {
Iif (request.time < meta.time) get = true;
else {
const tip = await this.readFrontierTip(keyBase);
if (tip) {
const tipTime = tip.getId()?.time ?? 0;
Iif (request.time < tipTime + tip.span() - 1) get = true;
}
}
}
if (!get) return null;
const [model, frontier] = await Promise.all([this.readModel(keyBase), this.readFrontier0(keyBase)]);
model.applyBatch(frontier);
const cursor: LevelLocalRepoCursor = meta.seq;
return {model, cursor};
}
public async sync(req: LocalRepoSyncRequest): Promise<LocalRepoSyncResponse> {
const cursor = req.cursor as LevelLocalRepoCursor | undefined;
const {id, patches} = req;
const isNewSession = cursor === undefined;
const isCreate = !!patches;
const isWrite = !!patches && patches.length !== 0;
if (isNewSession) {
if (isWrite) {
try {
return await this._syncCreate(req);
} catch (error) {
Eif (error instanceof Error && error.message === 'EXISTS') {
return await this._syncMerge(req);
}
throw error;
}
} else if (isCreate) {
try {
return await this._syncCreate(req);
} catch (error) {
Eif (error instanceof Error && error.message === 'EXISTS')
// TODO: make sure reset does not happen, if models are the same.
// TODO: Check for `req.time` in `_syncRead`.
return await this._syncRead(id);
throw error;
}
} else {
return await this._syncRead(id);
}
} else return await this._syncMerge(req);
}
private async _syncCreate(req: LocalRepoSyncRequest): Promise<LocalRepoSyncResponse> {
const {remote} = await this.create(req);
const cursor: LevelLocalRepoCursor = -1;
return {cursor, remote};
}
private async _syncMerge(req: LocalRepoSyncRequest): Promise<LocalRepoSyncResponse> {
const {id, patches} = req;
let lastKnownTime = 0;
const reqTime = req.time;
if (typeof reqTime === 'number') {
lastKnownTime = reqTime;
const firstPatch = patches?.[0];
if (firstPatch?.getId()?.sid === SESSION.GLOBAL) lastKnownTime = firstPatch.getId()!.time + firstPatch.span() - 1;
} else Eif (patches?.length) {
const firstPatchTime = patches?.[0]?.getId()?.time;
Eif (typeof firstPatchTime === 'number') lastKnownTime = firstPatchTime - 1;
}
const keyBase = await this.blockKeyBase(id);
Iif (!patches || !patches.length) throw new Error('EMPTY_BATCH');
const writtenPatches: Uint8Array[] = [];
let cursor: LevelLocalRepoCursor = -1;
// TODO: Check if `patches` need rebasing, if not, just merge.
// TODO: Return correct response.
// TODO: Check that remote state is in sync, too.
let needsReset = false;
const didPush = await this.lockBlock(keyBase, async () => {
const [tip, meta] = await Promise.all([this.readFrontierTip(keyBase), this.readMeta(keyBase)]);
let nextTick = meta.time + 1;
if (lastKnownTime < meta.time) needsReset = true;
cursor = meta.seq;
if (tip) {
const tipTime = tip.getId()?.time ?? 0;
nextTick = tipTime + tip.span();
}
const ops: BinStrLevelOperation[] = [];
const sid = this.sid;
const length = patches.length;
for (let i = 0; i < length; i++) {
const patch = patches[i];
const patchId = patch.getId();
Iif (!patchId) throw new Error('PATCH_ID_MISSING');
const isSchemaPatch = patchId.sid === SESSION.GLOBAL && patchId.time === 1;
if (isSchemaPatch) {
const patchAheadOfTip = patchId.time >= nextTick;
if (!patchAheadOfTip) continue;
}
let rebased = patch;
if (patchId.sid === sid && nextTick > patchId.time) {
needsReset = true;
rebased = patch.rebase(nextTick);
nextTick = rebased.getId()!.time + rebased.span();
}
const id = rebased.getId()!;
const time = id.time;
const patchKey = this.frontierKey(keyBase, time);
const uint8 = await this.encrypt(rebased.toBinary(), false);
writtenPatches.push(uint8);
const op: BinStrLevelOperation = {type: 'put', key: patchKey, value: uint8};
ops.push(op);
}
if (writtenPatches.length) {
this.emitPubSub({type: 'rebase', id, patches: writtenPatches, session: req.session});
}
if (ops.length) {
await this.kv.batch(ops);
return true;
}
return false;
});
if (!didPush && !needsReset) {
const merge = await this.readFrontier0(keyBase);
return {cursor, merge};
}
const remote = this.markDirtyAndSync(keyBase, id)
.then(() => {})
.catch((error) => {
Eif (this._stopped) return;
this.emitSyncError(error);
});
if (needsReset) {
const {cursor, model} = await this._syncRead0(keyBase);
return {cursor, model, remote};
}
return {cursor, remote};
}
protected async readLocal0(keyBase: string): Promise<[model: Model, cursor: LevelLocalRepoCursor]> {
const [model, meta, frontier] = await Promise.all([
this.readModel(keyBase),
this.readMeta(keyBase),
this.readFrontier0(keyBase),
]);
model.applyBatch(frontier);
const cursor: LevelLocalRepoCursor = meta.seq;
return [model, cursor];
}
private async _syncRead0(keyBase: string): Promise<LocalRepoSyncResponse> {
const [model, cursor] = await this.readLocal0(keyBase);
return {
model,
cursor,
// TODO: `remote` should load the block from the server.
remote: Promise.resolve(),
};
}
private async _syncRead(id: BlockId): Promise<LocalRepoSyncResponse> {
const keyBase = await this.blockKeyBase(id);
return this._syncRead0(keyBase);
}
public async del(id: BlockId): Promise<void> {
const keyBase = await this.blockKeyBase(id);
const frontierKeyBase = this.frontierKeyBase(keyBase);
const batchKeyBase = this.batchKeyBase(keyBase);
const snapshotKeyBase = this.snapshotKeyBase(keyBase);
const kv = this.kv;
await this.lockBlock(keyBase, async () => {
await kv.batch([
{type: 'del', key: keyBase + Defaults.Metadata},
{type: 'del', key: keyBase + Defaults.Model},
]);
this.emitPubSub({id, type: 'del'});
await Promise.all([
kv.clear({
gt: frontierKeyBase,
lt: frontierKeyBase + '~',
}),
kv.clear({
gt: batchKeyBase,
lt: batchKeyBase + '~',
}),
kv.clear({
gt: snapshotKeyBase,
lt: snapshotKeyBase + '~',
}),
]);
});
await this.opts.rpc.delete?.(id.join('/'));
}
/**
* Pull from remote.
*/
public async pull(id: BlockId): Promise<LocalRepoPullResponse> {
const keyBase = await this.blockKeyBase(id);
try {
const {model, meta} = await this.pullExisting(id, keyBase);
return {model, cursor: meta.seq};
} catch (error) {
if (!!error && typeof error === 'object' && (error as any).code === 'LEVEL_NOT_FOUND') {
try {
const {model, meta} = await this.pullNew(id, keyBase);
return {model, cursor: meta.seq};
} catch (error) {
if (error instanceof Error && error.message === 'EXISTS') {
const {model, meta} = await this.pullExisting(id, keyBase);
return {model, cursor: meta.seq};
}
throw error;
}
} else Eif (error instanceof Error && error.message === 'CONCURRENCY') {
const [model, cursor] = await this.readLocal0(keyBase);
return {model, cursor};
}
throw error;
}
}
protected async pullNew(id: BlockId, keyBase: string): Promise<{model: Model; meta: BlockMeta}> {
const blockId = id.join('/');
const {block} = await this.opts.rpc.read(blockId);
const _pubsub = this.pubsub;
return this.lockBlock(keyBase, async () => {
const exists = await this._exists(keyBase);
if (exists) throw new Error('EXISTS');
const model = Model.load(block.snapshot.blob, this.sid);
let seq = block.snapshot.seq;
for (const batch of block.tip) {
if (batch.seq <= seq) continue;
seq = batch.seq;
for (const patch of batch.patches) model.applyPatch(Patch.fromBinary(patch.blob));
}
const meta: BlockMeta = {
time: 0,
seq,
};
const blob = model.toBinary();
await this._wrModel(keyBase, blob, meta);
this.emitPubSub({type: 'reset', id, model: blob});
return {model, meta};
});
}
protected async pullExisting(id: BlockId, keyBase: string): Promise<{model: Model; meta: BlockMeta}> {
// TODO: try catching up using batches, if not possible, reset
// TODO: load batches to catch up with remote
const blockId = id.join('/');
const meta = await this.readMeta(keyBase);
const {seq} = meta;
const pull = await this.opts.rpc.pull(blockId, seq);
const nextSeq = pull.batches.length ? pull.batches[pull.batches.length - 1].seq : (pull.snapshot?.seq ?? seq);
const _pubsub = this.pubsub;
if (nextSeq < seq) {
return this.lockBlock(keyBase, async () => {
const seq2 = (await this.readMeta(keyBase)).seq;
Iif (seq2 !== seq) throw new Error('CONCURRENCY');
Iif (!pull.snapshot) throw new Error('missing snapshot');
const model = Model.load(pull.snapshot.blob, this.sid);
for (const batch of pull.batches)
for (const patch of batch.patches) model.applyPatch(Patch.fromBinary(patch.blob));
const modelBlob = model.toBinary();
meta.time = model.clock.time - 1;
meta.seq = nextSeq;
meta.syncTs = Date.now();
delete meta.syncFailures;
await this._wrModel(keyBase, modelBlob, meta);
this.emitPubSub({type: 'reset', id, model: modelBlob});
return {model, meta};
});
}
return this.lockBlock(keyBase, async () => {
const [model, meta] = await Promise.all([this.readModel(keyBase), this.readMeta(keyBase)]);
const seq2 = meta.seq;
if (seq2 !== seq) throw new Error('CONCURRENCY');
if (pull.snapshot) {
Eif (nextSeq > seq2) {
const model = Model.load(pull.snapshot.blob, this.sid);
for (const batch of pull.batches)
for (const patch of batch.patches) model.applyPatch(Patch.fromBinary(patch.blob));
const modelBlob = model.toBinary();
meta.seq = nextSeq;
await this._wrModel(keyBase, modelBlob, meta);
this.emitPubSub({type: 'reset', id, model: modelBlob});
}
return {model, meta};
}
Iif (!model) throw new Error('NO_MODEL');
const patches: Uint8Array[] = [];
for (const batch of pull.batches)
for (const patch of batch.patches) {
model.applyPatch(Patch.fromBinary(patch.blob));
patches.push(patch.blob);
}
meta.seq = nextSeq;
await this._wrModel(keyBase, model.toBinary(), meta);
this.emitPubSub({type: 'merge', id, patches, seq: meta.seq});
return {model, meta};
});
}
public change$(id: BlockId): Observable<LocalRepoEvent> {
return defer(() => {
const remoteSubscription = this._subRemote(id).subscribe(() => {});
return this.pubsub.bus$.pipe(
takeUntil(this._stop$),
map((msg) => {
switch (msg.type) {
case 'rebase': {
if (!deepEqual(id, msg.id)) return;
const rebase: Patch[] = [];
for (const blob of msg.patches) rebase.push(Patch.fromBinary(blob));
const event: LocalRepoRebaseEvent = {rebase, session: msg.session};
return event;
}
case 'reset': {
Iif (!deepEqual(id, msg.id)) return;
const reset = Model.load(msg.model, this.sid);
const event: LocalRepoResetEvent = {reset};
return event;
}
case 'merge': {
if (!deepEqual(id, msg.id)) return;
const merge: Patch[] = [];
for (const blob of msg.patches) {
const patch = Patch.fromBinary(blob);
if (patch.getId()?.sid === SESSION.GLOBAL) continue;
merge.push(patch);
}
if (!merge.length) return;
const event: LocalRepoMergeEvent = {merge, cursor: msg.seq};
return event;
}
case 'del': {
Iif (!deepEqual(id, msg.id)) return;
const event: LocalRepoDeleteEvent = {del: true};
return event;
}
}
}),
filter((event): event is LocalRepoEvent => !!event),
finalize(() => {
remoteSubscription.unsubscribe();
}),
share(),
);
});
}
private _subs: Record<string, Observable<void>> = {};
protected _subRemote(id: BlockId): Observable<void> {
const blockId = id.join('/');
let sub = this._subs[blockId];
if (sub) return sub;
const source = defer(() =>
this.opts.rpc.listen(blockId).pipe(
takeUntil(this._stop$),
switchMap(async ({event}) => {
Iif (this._stopped) return;
switch (event[0]) {
case 'new':
await this.pull(id);
break;
case 'upd':
await this._onUpd(id, event[1].batch);
break;
case 'del':
await this.del(id);
break;
}
}),
),
);
sub = source.pipe(
catchError(() => source),
finalize<void>(() => {
delete this._subs[blockId];
}),
share(),
);
this._subs[blockId] = sub;
return sub;
}
protected async _onUpd(id: BlockId, batch: ServerBatch): Promise<void> {
try {
Iif (this._stopped) return;
const keyBase = await this.blockKeyBase(id);
const firstPatch = batch.patches[0];
Iif (!firstPatch) return;
const firstPatchSid = Patch.fromBinary(firstPatch.blob).getId()?.sid;
if (firstPatchSid === this.sid) return;
try {
const meta = await this.readMeta(keyBase);
const alreadySynced = meta.seq >= batch.seq;
if (alreadySynced) return;
const needsPull = meta.seq + 1 < batch.seq;
if (needsPull) {
await this.pull(id);
return;
}
} catch (error) {
Eif (!!error && typeof error === 'object' && (error as any).code === 'LEVEL_NOT_FOUND') {
Iif (this._stopped) return;
await this.pullNew(id, keyBase);
return;
}
throw error;
}
let needsPull = false;
await this.lockBlock(keyBase, async () => {
Iif (this._stopped) return;
const [model, meta] = await Promise.all([this.readModel(keyBase), this.readMeta(keyBase)]);
Iif (this._stopped) return;
Eif (meta.seq >= batch.seq) return;
if (meta.seq + 1 < batch.seq) {
needsPull = true;
return;
}
const patches: Uint8Array[] = [];
for (const serverPatch of batch.patches) {
const patch = Patch.fromBinary(serverPatch.blob);
model.applyPatch(patch);
patches.push(serverPatch.blob);
}
meta.seq = batch.seq;
await this._wrModel(keyBase, model.toBinary(), meta);
this.emitPubSub({type: 'merge', id, patches, seq: meta.seq});
});
Iif (needsPull && !this._stopped) await this.pull(id);
} catch (error) {
this.emitSyncError(error);
}
}
}
|