giantdb/dist/iomanager.js

Large object database in native JavaScript, with encryption support

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.IOManager = void 0;
/**
 * Helper class for I/O operations.
 */
class IOManager {
    _adapter;
    _middlewareManager;
    /**
     * Construct a new IOManager.
     *
     * @param adapter The IO adapter.
     * @param middlewareManager The middleware manager.
     */
    constructor(adapter, middlewareManager) {
        this._adapter = adapter;
        this._middlewareManager = middlewareManager;
    }
    /**
     * Create a read stream for the item with the given id. Since this step may
     * modify item metadata, the result is an object with the following properties:
     * 'stream' (the readable stream), 'metadata' (the new metadata), and
     * 'metadataChanged' (a boolean indicating whether the metadata was modified).
     *
     * @param id The item id.
     * @param meta The item metadata.
     * @param options Middleware options.
     * @returns A Promise resolving to a result object.
     */
    async createReadStream(id, meta, options) {
        const stream = this._adapter.createReadStream(id);
        const result = await this._middlewareManager.transformReadable(stream, meta, options);
        if (result.metadataChanged) {
            await this.writeMetadata(id, result.metadata);
        }
        return result;
    }
    /**
     * Create a write stream for the item with the given id. Since this step may
     * modify item metadata, the result is an object with the following properties:
     * 'stream' (the writable stream), 'metadata' (the new metadata), and
     * 'metadataChanged' (a boolean indicating whether the metadata was modified).
     *
     * @param id The item id.
     * @param meta The item metadata.
     * @param options Middleware options.
     * @returns A Promise resolving to a result object.
     */
    async createWriteStream(id, meta, options) {
        const stream = this._adapter.createWriteStream(id);
        const result = await this._middlewareManager.transformWritable(stream, meta, options);
        if (result.metadataChanged) {
            await this.writeMetadata(id, result.metadata);
        }
        return result;
    }
    /**
     * Create a temporary write stream to an item that can be published later.
     *
     * @param id The item id.
     * @param options Middleware options.
     * @returns A Promise that resolves to a Writable Stream.
     */
    async createTemporary(id, options) {
        const stream = this._adapter.createWriteStream(id + '.tmp');
        const result = await this._middlewareManager.transformWritable(stream, {}, options);
        await this.writeMetadata(id, result.metadata);
        return result.stream;
    }
    /**
     * Mark the item with the given id as non-temporary as part of the commit
     * process.
     *
     * @param id The item id.
     * @returns A Promise that resolves when done.
     */
    async publish(id) {
        await this._adapter.rename(id + '.tmp', id);
    }
    /**
     * Delete all data for the item with the given id.
     *
     * @param id The item id.
     * @returns A Promise that resolves when done.
     */
    async delete(id) {
        await Promise.all([
            this._adapter.delete(id),
            this._adapter.delete(id + '.json')
        ]);
    }
    /**
     * Delete the temporary item with the given id.
     *
     * @param id The item id.
     * @returns A Promise that resolves when done.
     */
    async deleteTemporary(id) {
        await Promise.all([
            this._adapter.delete(id + '.tmp'),
            this._adapter.delete(id + '.json').catch((err) => {
                // ignore missing metadata file
                if (err.code !== 'ENOENT') {
                    throw err;
                }
            })
        ]);
    }
    /**
     * Read the metadata object for the item with the given id.
     *
     * @param id The item's id.
     * @returns A Promise that resolves to the metadata.
     */
    async readMetadata(id) {
        const json = await this._adapter.read(id + '.json', 'utf8');
        return JSON.parse(json);
    }
    /**
     * Write a metadata object for the item with the given id.
     *
     * @param id The item's id.
     * @param metadata The metadata to write.
     * @returns A Promise that resolves when done.
     */
    async writeMetadata(id, metadata) {
        const json = JSON.stringify(metadata);
        await this._adapter.write(id + '.json', json);
    }
}
exports.IOManager = IOManager;