packfs-core/dist/esm/compression/BrotliStrategy.js

Semantic filesystem operations for LLM agent frameworks with natural language understanding. See LLM_AGENT_GUIDE.md for copy-paste examples.

import * as zlib from 'zlib';
import { promisify } from 'util';
import { CompressionStrategy } from './CompressionStrategy';
const brotliCompress = promisify(zlib.brotliCompress);
const brotliDecompress = promisify(zlib.brotliDecompress);
/**
 * Brotli compression strategy - excellent for text-based files like JavaScript
 */
export class BrotliStrategy extends CompressionStrategy {
    constructor(dictionary) {
        super();
        this.name = 'brotli';
        this.priority = 'size';
        this.supportsStreaming = true;
        this.dictionary = dictionary;
    }
    async compress(data, hints) {
        const startTime = performance.now();
        const options = {
            params: {
                [zlib.constants.BROTLI_PARAM_QUALITY]: this.getQualityLevel(hints),
                [zlib.constants.BROTLI_PARAM_SIZE_HINT]: data.length,
            }
        };
        // Use dictionary for JavaScript files
        if (this.dictionary && this.isJavaScript(hints.mimeType)) {
            options.params[zlib.constants.BROTLI_PARAM_LARGE_WINDOW] = 1;
        }
        const compressed = await brotliCompress(data, options);
        const compressionTime = performance.now() - startTime;
        return {
            data: compressed,
            algorithm: this.name,
            originalSize: data.length,
            compressedSize: compressed.length,
            dictionary: this.dictionary ? 'js-patterns' : undefined,
            metadata: {
                compressionTime,
                quality: options.params[zlib.constants.BROTLI_PARAM_QUALITY],
                mimeType: hints.mimeType
            }
        };
    }
    async decompress(chunk) {
        const startTime = performance.now();
        const result = await brotliDecompress(chunk.data);
        const decompressionTime = performance.now() - startTime;
        // Update metadata with decompression time
        chunk.metadata.decompressionTime = decompressionTime;
        return result;
    }
    createDecompressor(chunk) {
        const { Readable } = require('stream');
        const decompressor = zlib.createBrotliDecompress();
        // Create a readable stream from the compressed data
        const inputStream = new Readable({
            read() { }
        });
        // Push the compressed data and signal end
        inputStream.push(chunk.data);
        inputStream.push(null);
        // Pipe through the decompressor
        return inputStream.pipe(decompressor);
    }
    estimateRatio(_data, hints) {
        // Brotli performs exceptionally well on text data
        if (this.isTextFile(hints.mimeType)) {
            return this.dictionary ? 0.15 : 0.25; // 85% or 75% compression
        }
        // Less effective on binary data
        return 0.6; // 40% compression
    }
    shouldUse(data, hints) {
        // Perfect for JavaScript, CSS, HTML, JSON
        if (this.isTextFile(hints.mimeType)) {
            return true;
        }
        // Good for large files where compression ratio matters more than speed
        if (data.length > 100 * 1024 && !hints.isHot) {
            return true;
        }
        return false;
    }
    getQualityLevel(hints) {
        if (hints.isHot) {
            return 4; // Fast compression for frequently accessed files
        }
        if (hints.accessFrequency > 0.8) {
            return 6; // Balanced for moderately accessed files
        }
        return 11; // Maximum compression for rarely accessed files
    }
    isJavaScript(mimeType) {
        return mimeType.includes('javascript') ||
            mimeType.includes('typescript') ||
            mimeType.endsWith('.js') ||
            mimeType.endsWith('.ts') ||
            mimeType.endsWith('.jsx') ||
            mimeType.endsWith('.tsx');
    }
    isTextFile(mimeType) {
        return mimeType.startsWith('text/') ||
            mimeType.includes('javascript') ||
            mimeType.includes('json') ||
            mimeType.includes('css') ||
            mimeType.includes('html') ||
            mimeType.includes('xml');
    }
}
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