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Copy pathscan-iterator.ts
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184 lines (161 loc) · 4.95 KB
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import type {ScanItem} from './scan-item.js';
import type {Invoke, ScanRequest} from './repm-invoker.js';
import type {JSONValue} from './json.js';
import {throwIfClosed} from './transaction-closed-error.js';
interface IdCloser {
close(): void;
closed: boolean;
id: number;
}
type ScanIterableKind = 'key' | 'value' | 'entry';
/**
* An async iterator that is used with {@link ReadTransaction.scan}.
*/
class ScanIterator<V> implements AsyncIterableIterator<V> {
private readonly _scanItems: ScanItem[] = [];
private _current = 0;
private readonly _prefix: string;
private readonly _kind: ScanIterableKind;
private readonly _startKey?: string;
private readonly _startKeyExclusive?: boolean;
private readonly _limit?: number;
private readonly _indexName?: string;
private _loadPromise?: Promise<unknown> = undefined;
private readonly _getTransaction: () => Promise<IdCloser> | IdCloser;
private readonly _shouldCloseTransaction: boolean;
private _transaction?: IdCloser = undefined;
private readonly _invoke: Invoke;
constructor(
kind: ScanIterableKind,
prefix: string,
startKey: string | undefined,
startKeyExclusive: boolean | undefined,
limit: number | undefined,
indexName: string | undefined,
invoke: Invoke,
getTransaction: () => Promise<IdCloser> | IdCloser,
shouldCloseTranscation: boolean,
) {
this._kind = kind;
this._prefix = prefix;
this._startKey = startKey;
this._startKeyExclusive = startKeyExclusive;
this._limit = limit;
this._indexName = indexName;
this._invoke = invoke;
this._getTransaction = getTransaction;
this._shouldCloseTransaction = shouldCloseTranscation;
}
[Symbol.asyncIterator](): AsyncIterableIterator<V> {
return this;
}
private async _ensureTransaction(): Promise<IdCloser> {
if (!this._transaction) {
this._transaction = await this._getTransaction();
}
return this._transaction;
}
async next(): Promise<IteratorResult<V>> {
throwIfClosed(await this._ensureTransaction());
await this._load();
if (
this._current >= this._scanItems.length ||
(this._limit !== undefined && this._current >= this._limit)
) {
return this.return();
}
const entry = this._scanItems[this._current++];
if (this._kind === 'value') {
return {value: entry.value} as IteratorResult<V>;
}
const key =
this._indexName !== undefined
? [entry.secondaryKey, entry.primaryKey]
: entry.primaryKey;
switch (this._kind) {
case 'key':
return {value: key} as IteratorResult<V>;
case 'entry':
return {value: [key, entry.value]} as IteratorResult<V>;
}
}
async return(): Promise<IteratorResult<V>> {
if (this._transaction) {
throwIfClosed(this._transaction);
if (this._shouldCloseTransaction) {
this._transaction.close();
}
}
return {done: true, value: undefined};
}
private async _load(): Promise<void> {
if (this._loadPromise) {
await this._loadPromise;
return;
}
if (!this._transaction) {
this._transaction = await this._getTransaction();
}
const responseItems: ScanItem[] = [];
const decoder = new TextDecoder();
const receiver = (
primaryKey: string,
secondaryKey: string | null,
value: Uint8Array,
) => {
const text = decoder.decode(value);
responseItems.push({
primaryKey,
secondaryKey,
value: JSON.parse(text),
});
};
const args: ScanRequest = {
transactionId: this._transaction.id,
opts: {
prefix: this._prefix,
// eslint-disable-next-line @typescript-eslint/naming-convention
start_key: this._startKey,
// eslint-disable-next-line @typescript-eslint/naming-convention
start_key_exclusive: this._startKeyExclusive,
limit: this._limit,
indexName: this._indexName,
},
receiver,
};
this._loadPromise = this._invoke('scan', args);
await this._loadPromise;
this._scanItems.push(...responseItems);
}
}
type Args = [
prefix: string,
startKey: string | undefined,
startKeyExclusive: boolean | undefined,
limit: number | undefined,
indexName: string | undefined,
invoke: Invoke,
getTransaction: () => Promise<IdCloser> | IdCloser,
shouldCloseTranscation: boolean,
];
export class ScanResult<K> implements AsyncIterable<JSONValue> {
private readonly _args: Args;
constructor(...args: Args) {
this._args = args;
}
[Symbol.asyncIterator](): AsyncIterableIterator<JSONValue> {
return this.values();
}
values(): AsyncIterableIterator<JSONValue> {
return this._newIterator('value');
}
keys(): AsyncIterableIterator<K> {
return this._newIterator('key');
}
entries(): AsyncIterableIterator<[K, JSONValue]> {
return this._newIterator('entry');
}
private _newIterator<V>(kind: ScanIterableKind): AsyncIterableIterator<V> {
return new ScanIterator<V>(kind, ...this._args);
}
}