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import {deepEqual} from './json.js';
import type {JSONValue} from './json.js';
import type {
KeyTypeForScanOptions,
ScanOptions,
ScanOptionsRPC,
} from './scan-options.js';
import {REPMWasmInvoker, RPC} from './repm-invoker.js';
import type {
ChangedKeysMap,
InitInput,
Invoke,
Invoker,
OpenResponse,
OpenTransactionRequest,
} from './repm-invoker.js';
import {
CreateIndexDefinition,
SubscriptionTransactionWrapper,
} from './transactions.js';
import {IndexTransactionImpl} from './transactions.js';
import {ReadTransactionImpl, WriteTransactionImpl} from './transactions.js';
import {ScanResult} from './scan-iterator.js';
import type {ReadTransaction, WriteTransaction} from './transactions.js';
import {ConnectionLoop} from './connection-loop.js';
import {getLogger} from './logger.js';
import type {Logger, LogLevel} from './logger.js';
type BeginPullResult = {
requestID: string;
syncHead: string;
ok: boolean;
};
export const httpStatusUnauthorized = 401;
export type MaybePromise<T> = T | Promise<T>;
type ToPromise<P> = P extends Promise<unknown> ? P : Promise<P>;
/** The key name to use in localStorage when synchronizing changes. */
const storageKeyName = (name: string) => `/replicache/root/${name}`;
/** The maximum number of time to call out to getDataLayerAuth before giving up and throwing an error. */
const MAX_REAUTH_TRIES = 8;
/**
* This type describes the data we send on the BroadcastChannel when things change.
*/
type BroadcastData = {
root?: string;
changedKeys: ChangedKeysMap;
index?: string;
};
/**
* When using localStorage instead of BroadcastChannel we need to use a JSON string.
*/
type StorageBroadcastData = Omit<BroadcastData, 'changedKeys'> & {
changedKeys: [string, string[]][];
};
/**
* The type used to describe the mutator definitions passed into [[Replicache]]
* constructor as part of the [[ReplicacheOptions]].
*
* See [[ReplicacheOptions]] [[ReplicacheOptions.mutators|mutators]] for more info.
*/
export type MutatorDefs = {
[key: string]: (
tx: WriteTransaction,
// Not sure how to not use any here...
// eslint-disable-next-line @typescript-eslint/no-explicit-any
args?: any,
) => MaybePromise<JSONValue | void>;
};
/**
* The options passed to [[Replicache]].
*/
export interface ReplicacheOptions<MD extends MutatorDefs> {
/**
* This is the
* [authentication](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#authentication)
* token used when doing a [push
* ](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#step-4-upstream-sync).
*/
pushAuth?: string;
/**
* This is the URL to the server endpoint dealing with the push updates. See
* [Server Setup Upstream Sync](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#step-4-upstream-sync)
* for more details.
*/
pushURL?: string;
/**
* This is the
* [authentication](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#authentication)
* token used when doing a [pull
* ](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#step-4-upstream-sync).
*/
pullAuth?: string;
/**
* This is the URL to the server endpoint dealing with pull. See [Server Setup
* Downstream
* Sync](https://github.com/rocicorp/replicache/blob/main/SERVER_SETUP.md#step-1-downstream-sync)
* for more details.
*/
pullURL?: string;
/**
* The name of the Replicache database. This defaults to `"default"`.
*
* You can use multiple Replicache instances as long as the names are unique.
*
* Using different names for different users allows you to switch users even
* when you are offline.
*/
name?: string;
/**
* The schema version of the data understood by this application. This enables
* versioning of mutators (in the push direction) and the client view (in the
* pull direction).
*/
schemaVersion?: string;
/**
* The duration between each [[pull]]. Set this to `null` to prevent pulling
* in the background.
*/
pullInterval?: number | null;
/**
* The delay between when a change is made to Replicache and when Replicache
* attempts to push that change.
*/
pushDelay?: number;
/**
* By default we will load the Replicache wasm module relative to the
* Replicache js files but under some circumstances (like bundling with old
* versions of Webpack) it is useful to manually configure where the wasm
* module is located on the web server.
*
* If you provide your own path to the wasm module it probably makes sense to
* use a relative URL relative to your current file.
*
* ```js
* wasmModule: new URL('./relative/path/to/replicache.wasm', import.meta.url),
* ```
*
* You might also want to consider using an absolute URL so that we can find
* the wasm module no matter where your js file is loaded from:
*
* ```js
* wasmModule: '/static/replicache.wasm',
* ```
*/
wasmModule?: InitInput | undefined;
/**
* Allows using an in memory store instead of IndexedDB. This is useful for
* testing for example. Notice that when this is `true` no data is persisted
* in Replicache and all the data that has not yet been synced when Replicache
* is [[closed]] or the page is unloaded is lost.
*/
useMemstore?: boolean;
/**
* Determines how much logging to do. When this is set to `'debug'`,
* Replicache will also log `'info'` and `'error'` messages. When set to
* `'info'` we log `'info'` and `'error'` but not `'debug'`. When set to
* `'error'` we only log `'error'` messages.
*/
logLevel?: LogLevel;
/**
* An object used as a map to define the *mutators*. These gets registered at
* startup of [[Replicache]].
*
* *Mutators* are used to make changes to the data.
*
* ## Example
*
* The registered *mutations* are reflected on the
* [[Replicache.mutate|mutate]] property of the [[Replicache]] instance.
*
* ```ts
* const rep = new Replicache({
* mutators: {
* async createTodo(tx: WriteTransaction, args: JSONValue) {
* const key = `/todo/${args.id}`;
* if (await tx.has(key)) {
* throw new Error('Todo already exists');
* }
* await tx.put(key, args);
* },
* async deleteTodo(tx: WriteTransaction, id: number) {
* ...
* },
* },
* });
* ```
*
* This will create the function to later use:
*
* ```ts
* await rep.mutate.createTodo({
* id: 1234,
* title: 'Make things work offline',
* complete: true,
* });
* ```
*
* ## Replays
*
* *Mutators* run once when they are initially invoked, but they might also be
* *replayed* multiple times during sync. As such *mutators* should not modify
* application state directly. Also, it is important that the set of
* registered mutator names only grows over time. If Replicache syncs and
* needed *mutator* is not registered, it will substitute a no-op mutator, but
* this might be a poor user experience.
*
* ## Server application
*
* During push, a description of each mutation is sent to the server's [push
* endpoint](https://github.com/rocicorp/replicache/blob/stable/doc/setup.md#step-6-remote-mutations)
* where it is applied. Once the *mutation* has been applied successfully, as
* indicated by the [client
* view](https://github.com/rocicorp/replicache/blob/stable/doc/setup.md#step-1-design-your-client-view)'s
* `lastMutationId` field, the local version of the *mutation* is removed. See
* the [design
* doc](https://github.com/rocicorp/replicache/blob/stable/doc/design.md) for
* additional details on the sync protocol.
*
* ## Transactionality
*
* *Mutators* are atomic: all their changes are applied together, or none are.
* Throwing an exception aborts the transaction. Otherwise, it is committed.
* As with [[query]] and [[subscribe]] all reads will see a consistent view of
* the cache while they run.
*/
mutators?: MD;
}
const emptySet: ReadonlySet<string> = new Set();
// eslint-disable-next-line @typescript-eslint/ban-types
export class Replicache<MD extends MutatorDefs = {}>
implements ReadTransaction {
private _pullAuth: string;
private readonly _pullURL: string;
private _pushAuth: string;
private readonly _pushURL: string;
private readonly _name: string;
private readonly _repmInvoker: Invoker;
private readonly _useMemstore: boolean;
private readonly _schemaVersion: string = '';
private _closed = false;
private _online = true;
private readonly _logLevel: LogLevel;
private readonly _logger: Logger;
private _openResponse!: Promise<OpenResponse>;
private _root: Promise<string | undefined> = Promise.resolve(undefined);
private readonly _mutatorRegistry = new Map<
string,
(tx: WriteTransaction, args?: JSONValue) => MutatorReturn
>();
/**
* The mutators that was registered in the constructor.
*/
readonly mutate: MakeMutators<MD>;
// Number of pushes/pulls at the moment.
private _pushCounter = 0;
private _pullCounter = 0;
private _pullConnectionLoop: ConnectionLoop;
private _pushConnectionLoop: ConnectionLoop;
private _broadcastChannel?: BroadcastChannel = undefined;
private readonly _subscriptions = new Set<
Subscription<JSONValue | undefined, unknown>
>();
/**
* The duration between each periodic [[pull]]. Setting this to `null`
* disables periodic pull completely. Pull will still happen if you call
* [[pull]] manually.
*/
pullInterval: number | null;
/**
* The delay between when a change is made to Replicache and when Replicache
* attempts to push that change.
*/
pushDelay: number;
/**
* `onSync` is called when a sync begins, and again when the sync ends. The parameter `syncing`
* is set to `true` when `onSync` is called at the beginning of a sync, and `false` when it
* is called at the end of a sync.
*
* This can be used in a React like app by doing something like the following:
*
* ```js
* const [syncing, setSyncing] = useState(false);
* useEffect(() => {
* rep.>
* }, [rep]);
* ```
*/
onSync: ((syncing: boolean) => void) | null = null;
/**
* This gets called when we get an HTTP unauthorized (410) response from the
* pull endpoint. Set this to a function that will ask your user to
* reauthenticate.
*/
getPullAuth:
| (() => MaybePromise<string | null | undefined>)
| null
| undefined = null;
/**
* This gets called when we get an HTTP unauthorized (410) response from the push
* endpoint. Set this to a function that will ask your user to reauthenticate.
*/
getPushAuth:
| (() => MaybePromise<string | null | undefined>)
| null
| undefined = null;
constructor(options: ReplicacheOptions<MD> = {}) {
const {
name = 'default',
logLevel = 'info',
pullAuth = '',
pullURL = '',
pushAuth = '',
pushDelay = 10,
pushURL = '',
schemaVersion = '',
pullInterval = 60_000,
useMemstore = false,
wasmModule,
mutators = {} as MD,
} = options;
this._pullAuth = pullAuth;
this._pullURL = pullURL;
this._pushAuth = pushAuth;
this._pushURL = pushURL;
this._name = name;
this._repmInvoker = new REPMWasmInvoker(wasmModule);
this._schemaVersion = schemaVersion;
this.pullInterval = pullInterval;
this.pushDelay = pushDelay;
this._useMemstore = useMemstore;
this._pullConnectionLoop = new ConnectionLoop({
invokeSend: () => this._invokePull(),
watchdogTimer: () => this.pullInterval,
debounceDelay: () => 0,
maxConnections: 1,
...getLogger(['PULL'], logLevel),
});
this._pushConnectionLoop = new ConnectionLoop({
invokeSend: () => this._invokePush(MAX_REAUTH_TRIES),
debounceDelay: () => this.pushDelay,
maxConnections: 1,
...getLogger(['PUSH'], logLevel),
});
this._logLevel = logLevel;
this._logger = getLogger([], logLevel);
this.mutate = this._registerMutators(mutators);
this._open().then(async () => {
// TODO: Make log level an arg to open and scope the log level to a db
// connection.
await this._invoke(RPC.SetLogLevel, {level: this._logLevel});
this.pull();
this._push();
});
}
private async _open(): Promise<void> {
this._openResponse = this._repmInvoker.invoke(this._name, RPC.Open, {
useMemstore: this._useMemstore,
});
if (hasBroadcastChannel) {
this._broadcastChannel = new BroadcastChannel(storageKeyName(this._name));
this._broadcastChannel. MessageEvent<BroadcastData>) =>
this._onBroadcastMessage(e.data);
} else {
window.addEventListener('storage', this._onStorage);
}
this._root = this._getRoot();
await this._root;
}
/**
* The client ID for this instance of Replicache. Each web browser and
* instance of Replicache gets a unique client ID keyed by the
* {@link ReplicacheOptions.name | name}. This is persisted locally between
* sessions (unless [[useMemstore]] is true in which case it is reset every
* time a new Replicache instance is created).
*/
get clientID(): Promise<string> {
return this._openResponse;
}
/**
* A rough heuristic for whether the client is currently online. Note that there is no way to know
* for certain whether a client is online - the next request can always fail. This is true if the last
* sync attempt succeeded, and false otherwise.
*/
get online(): boolean {
return this._online;
}
/**
* Whether the Replicache database has been closed. Once Replicache has been
* closed it no longer syncs and you can no longer read or write data out of
* it. After it has been closed it is pretty much useless and should not be
* used any more.
*/
get closed(): boolean {
return this._closed;
}
/**
* Closes this Replicache instance.
*
* When closed all subscriptions end and no more read or writes are allowed.
*/
async close(): Promise<void> {
this._closed = true;
const p = this._invoke(RPC.Close);
this._pullConnectionLoop.close();
this._pushConnectionLoop.close();
if (this._broadcastChannel) {
this._broadcastChannel.close();
this._broadcastChannel = undefined;
} else {
window.removeEventListener('storage', this._onStorage);
}
// Clear subscriptions
for (const subscription of this._subscriptions) {
subscription.onDone?.();
}
this._subscriptions.clear();
await p;
}
private async _getRoot(): Promise<string | undefined> {
if (this._closed) {
return undefined;
}
const res = await this._invoke(RPC.GetRoot);
return res.root;
}
private _onStorage = (e: StorageEvent) => {
const {key, newValue} = e;
if (newValue && key === storageKeyName(this._name)) {
const {root, changedKeys, index} = JSON.parse(
newValue,
) as StorageBroadcastData;
this._onBroadcastMessage({
root,
changedKeys: new Map(changedKeys),
index,
});
}
};
// Callback for when a different tab changes the db.
private async _onBroadcastMessage(data: BroadcastData) {
// Cannot just use the root value from the other tab, because it can be behind us.
// Also, in the case of memstore, it will have a totally different, unrelated
// hash chain.
const {changedKeys, index} = data;
const changedKeysSubs = subscriptionsForChangedKeys(
this._subscriptions,
changedKeys,
);
const indexSubs = index
? subscriptionsForIndexDefinitionChanged(this._subscriptions, index)
: [];
const subscriptions: Set<
Subscription<JSONValue | undefined, unknown>
> = new Set();
for (const s of changedKeysSubs) {
subscriptions.add(s);
}
for (const s of indexSubs) {
subscriptions.add(s);
}
await this._fireSubscriptions(subscriptions);
}
private _broadcastChange(
root: string | undefined,
changedKeys: ChangedKeysMap,
index: string | undefined,
) {
if (this._broadcastChannel) {
const data = {root, changedKeys, index};
this._broadcastChannel.postMessage(data);
} else {
// local storage needs a string...
const data = {root, changedKeys: [...changedKeys.entries()], index};
localStorage[storageKeyName(this._name)] = JSON.stringify(data);
}
}
private async _checkChange(
root: string | undefined,
changedKeys: ChangedKeysMap,
): Promise<void> {
const currentRoot = await this._root; // instantaneous except maybe first time
if (root !== undefined && root !== currentRoot) {
this._root = Promise.resolve(root);
this._broadcastChange(root, changedKeys, undefined);
await this._fireOnChange(changedKeys);
}
}
private _invoke: Invoke = async (
rpc: RPC,
args?: JSONValue,
): Promise<JSONValue> => {
await this._openResponse;
return await this._repmInvoker.invoke(this._name, rpc, args);
};
/** Get a single value from the database. */
get(key: string): Promise<JSONValue | undefined> {
return this.query(tx => tx.get(key));
}
/** Determines if a single `key` is present in the database. */
has(key: string): Promise<boolean> {
return this.query(tx => tx.has(key));
}
/** Whether the database is empty. */
isEmpty(): Promise<boolean> {
return this.query(tx => tx.isEmpty());
}
/**
* Gets many values from the database. This returns a `ScanResult` which
* implements `AsyncIterable`. It also has methods to iterate over the `keys`
* and `entries`.
*
* If `options` has an `indexName`, then this does a scan over an index with
* that name. A scan over an index uses a tuple for the key consisting of
* `[secondary: string, primary: string]`.
*/
scan<O extends ScanOptions, K extends KeyTypeForScanOptions<O>>(
options?: O,
): ScanResult<K> {
let tx: ReadTransactionImpl;
return new ScanResult<K>(
options,
this._invoke,
async () => {
if (tx) {
return tx;
}
tx = new ReadTransactionImpl(this._invoke);
await tx.open({isSubscription: false});
return tx;
},
true,
);
}
/**
* Convenience form of `scan()` which returns all the entries as an array.
* @deprecated Use `scan().entries().toArray()` instead.
*/
async scanAll<O extends ScanOptions, K extends KeyTypeForScanOptions<O>>(
options?: O,
): Promise<[K, JSONValue][]> {
const tx = new ReadTransactionImpl(this._invoke);
try {
await tx.open({isSubscription: false});
return await tx.scanAll(options);
} finally {
closeIgnoreError(tx);
}
}
/**
* Creates a persistent secondary index in Replicache which can be used with scan.
*
* If the named index already exists with the same definition this returns success
* immediately. If the named index already exists, but with a different definition
* an error is thrown.
*/
async createIndex(def: CreateIndexDefinition): Promise<void> {
await this._indexOp(tx => tx.createIndex(def));
await this._indexDefinitionChanged(def.name);
}
/**
* Drops an index previously created with [[createIndex]].
*/
async dropIndex(name: string): Promise<void> {
await this._indexOp(tx => tx.dropIndex(name));
await this._indexDefinitionChanged(name);
}
private async _indexOp(
f: (tx: IndexTransactionImpl) => Promise<void>,
): Promise<void> {
const tx = new IndexTransactionImpl(this._invoke);
try {
await tx.open({isSubscription: false});
await f(tx);
} finally {
tx.commit();
}
}
protected async _maybeEndPull(
beginPullResult: BeginPullResult,
): Promise<void> {
if (this._closed) {
return;
}
let {syncHead} = beginPullResult;
const {replayMutations, changedKeys} = await this._invoke(
RPC.MaybeEndTryPull,
beginPullResult,
);
if (!replayMutations || replayMutations.length === 0) {
// All done.
await this._checkChange(syncHead, changedKeys);
return;
}
// Replay.
for (const mutation of replayMutations) {
syncHead = await this._replay(
syncHead,
mutation.original,
mutation.name,
JSON.parse(mutation.args),
);
}
await this._maybeEndPull({...beginPullResult, syncHead});
}
private async _replay<A extends JSONValue>(
basis: string,
original: string,
name: string,
args: A,
): Promise<string> {
let mutatorImpl = this._mutatorRegistry.get(name);
if (!mutatorImpl) {
// Developers must not remove mutator names from the set once registered,
// because Replicache needs to be able to replay mutations during sync.
//
// If we detect that this has happened, stub in a no-op mutator so that at
// least sync can move forward. Note that the server-side mutation will
// still get sent. This doesn't remove the queued local mutation, it just
// removes its visible effects.
this._logger.error?.(`Unknown mutator ${name}`);
mutatorImpl = async () => {
// no op
};
}
const res = await this._mutate(name, mutatorImpl, args, {
invokeArgs: {
rebaseOpts: {basis, original},
isSubscription: false,
},
isReplay: true,
});
return res.ref;
}
private async _invokePull(): Promise<boolean> {
return await this._wrapInOnlineCheck(async () => {
try {
this._changeSyncCounters(0, 1);
const beginPullResult = await this._beginPull(MAX_REAUTH_TRIES);
if (!beginPullResult.ok) {
return false;
}
if (beginPullResult.syncHead !== '') {
await this._maybeEndPull(beginPullResult);
}
} finally {
this._changeSyncCounters(0, -1);
}
return true;
}, 'Pull');
}
private async _wrapInOnlineCheck(
f: () => Promise<boolean>,
name: string,
): Promise<boolean> {
let >
try {
return await f();
} catch (e) {
// The error paths of beginPull and maybeEndPull need to be reworked.
//
// We want to distinguish between:
// a) network requests failed -- we're offline basically
// b) sync was aborted because one's already in progress
// c) oh noes - something unexpected happened
//
// Right now, all of these come out as errors. We distinguish (b) with a
// hacky string search. (a) and (c) are not distinguishable currently
// because repc doesn't provide sufficient information, so we treat all
// errors that aren't (b) as (a).
if (e.toString().includes('JSLogInfo')) {
>
}
this._logger.info?.(`${name} returned: ${e}`);
return false;
} finally {
this._online = online;
}
}
private async _invokePush(maxAuthTries: number): Promise<boolean> {
return await this._wrapInOnlineCheck(async () => {
let pushResponse;
try {
this._changeSyncCounters(1, 0);
pushResponse = await this._invoke(RPC.TryPush, {
pushURL: this._pushURL,
pushAuth: this._pushAuth,
schemaVersion: this._schemaVersion,
});
} finally {
this._changeSyncCounters(-1, 0);
}
const {httpRequestInfo} = pushResponse;
if (httpRequestInfo) {
const reauth = checkStatus(
httpRequestInfo,
'push',
this._pushURL,
this._logger,
);
// TODO: Add back support for mutationInfos? We used to log all the errors
// here.
if (reauth && this.getPushAuth) {
if (maxAuthTries === 0) {
this._logger.info?.('Tried to reauthenticate too many times');
return false;
}
const pushAuth = await this.getPushAuth();
if (pushAuth != null) {
this._pushAuth = pushAuth;
// Try again now instead of waiting for next push.
return await this._invokePush(maxAuthTries - 1);
}
}
return httpRequestInfo.httpStatusCode === 200;
}
// No httpRequestInfo means we didn't do a push because there were no
// pending mutations.
return true;
}, 'Push');
}
/**
* Push pushes pending changes to the [[pushURL]].
*
* You do not usually need to manually call push. If [[pushDelay]] is non-zero
* (which it is by default) pushes happen automatically shortly after
* mutations.
*/
private _push(): void {
this._pushConnectionLoop.send();
}
/**
* Pull pulls changes from the [[pullURL]]. If there are any changes
* local changes will get replayed on top of the new server state.
*/
pull(): void {
this._pullConnectionLoop.send();
}
protected async _beginPull(maxAuthTries: number): Promise<BeginPullResult> {
const beginPullResponse = await this._invoke(RPC.BeginTryPull, {
pullAuth: this._pullAuth,
pullURL: this._pullURL,
schemaVersion: this._schemaVersion,
});
const {httpRequestInfo, syncHead, requestID} = beginPullResponse;
const reauth = checkStatus(
httpRequestInfo,
'pull',
this._pullURL,
this._logger,
);
if (reauth && this.getPullAuth) {
if (maxAuthTries === 0) {
this._logger.info?.('Tried to reauthenticate too many times');
return {requestID, syncHead: '', ok: false};
}
let pullAuth;
try {
// Don't want to say we are syncing when we are waiting for auth
this._changeSyncCounters(0, -1);
pullAuth = await this.getPullAuth();
} finally {
this._changeSyncCounters(0, 1);
}
if (pullAuth != null) {
this._pullAuth = pullAuth;
// Try again now instead of waiting for next pull.
return await this._beginPull(maxAuthTries - 1);
}
}
return {requestID, syncHead, ok: httpRequestInfo.httpStatusCode === 200};
}
private _changeSyncCounters(pushDelta: 0, pullDelta: 1 | -1): void;
private _changeSyncCounters(pushDelta: 1 | -1, pullDelta: 0): void;
private _changeSyncCounters(pushDelta: number, pullDelta: number): void {
this._pushCounter += pushDelta;
this._pullCounter += pullDelta;
const delta = pushDelta + pullDelta;
const counter = this._pushCounter + this._pullCounter;
if ((delta === 1 && counter === 1) || counter === 0) {
const syncing = counter > 0;
Promise.resolve().then(() => this.onSync?.(syncing));
}
}
private async _fireOnChange(changedKeys: ChangedKeysMap): Promise<void> {
const subscriptions = subscriptionsForChangedKeys(
this._subscriptions,
changedKeys,
);
await this._fireSubscriptions(subscriptions);
}
private async _indexDefinitionChanged(name: string): Promise<void> {
// When an index definition changes we fire all subscriptions that uses
// index scans with that index.
const subscriptions = subscriptionsForIndexDefinitionChanged(
this._subscriptions,
name,
);
await this._fireSubscriptions(subscriptions);
this._broadcastChange(await this._root, new Map(), name);
}
private async _fireSubscriptions(
subscriptions: Iterable<Subscription<JSONValue | undefined, unknown>>,
) {
const subs = [...subscriptions];
type R =
| {ok: true; value: JSONValue | undefined}
| {ok: false; error: unknown};
const results = await this.query(async tx => {
const promises = subs.map(async s => {
// Tag the result so we can deal with success vs error below.
try {
const stx = new SubscriptionTransactionWrapper(tx);
const value = await s.body(stx);
s.keys = stx.keys;
s.scans = stx.scans;
return {ok: true, value} as R;
} catch (error) {
return {ok: false, error} as R;
}
});
return await Promise.all(promises);
});
for (let i = 0; i < subs.length; i++) {
const s = subs[i];
const result = results[i];
if (result.ok) {
const {value} = result;
if (!deepEqual(value, s.lastValue)) {
s.lastValue = value;
s.onData(value);
}
} else {
s.onError?.(result.error);
}
}
}
/**
* Subcribe to changes to the underlying data. Every time the underlying data
* changes `body` is called and if the result of `body` changes compared to
* last time `onData` is called. The function is also called once the first
* time the subscription is added.
*
* This returns a function that can be used to cancel the subscription.
*
* If an error occurs in the `body` the `onError` function is called if
* present. Otherwise, the error is thrown.
*/
subscribe<R extends JSONValue | undefined, E>(
body: (tx: ReadTransaction) => Promise<R>,
{
onData,
onError,
onDone,
}: {
onData: (result: R) => void;
onError?: (error: E) => void;
onDone?: () => void;
},
): () => void {
const s = {
body,
onData,
onError,
onDone,
lastValue: undefined,
keys: emptySet,
scans: [],
} as Subscription<R, E>;
this._subscriptions.add(
(s as unknown) as Subscription<JSONValue | undefined, unknown>,
);
(async () => {
try {
const {result, keys, scans} = await this._querySubscription(s.body);
s.keys = keys;
s.scans = scans;
s.lastValue = result;
s.onData(result);
} catch (ex) {
if (s.onError) {
s.onError(ex);
} else {
throw ex;
}
}
})();
return (): void => {
this._subscriptions.delete(
(s as unknown) as Subscription<JSONValue | undefined, unknown>,
);
};
}
/**
* Query is used for read transactions. It is recommended to use transactions
* to ensure you get a consistent view across multiple calls to `get`, `has`
* and `scan`.
*/
async query<R>(body: (tx: ReadTransaction) => Promise<R> | R): Promise<R> {
const tx = new ReadTransactionImpl(this._invoke);
await tx.open({isSubscription: false});
try {
return await body(tx);
} finally {
// No need to await the response.
closeIgnoreError(tx);
}
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