IndexedDB 内容寻址存储与去重实践

概述内容寻址以数据哈希作为键，能够实现去重与快速引用。本文展示哈希计算与存储模型。哈希与存储async function digest(bytes) { const buf = await crypto.subtle.digest('SHA-256', bytes); return Array.from(new Uint8Array(buf)).map(x => x.toString(16).padStart(2,'0')).join(''); } function openDB(name) { return new Promise((resolve, reject) => { const r = indexedDB.open(name, 1); r.onupgradeneeded = () => { const db = r.result; if (!db.objectStoreNames.contains('blobs')) db.createObjectStore('blobs', { keyPath: 'hash' }); }; r.onsuccess = () => resolve(r.result); r.onerror = () => reject(r.error); }); } async function putBytes(bytes) { const hash = await digest(bytes); const db = await openDB('cas'); const tx = db.transaction('blobs', 'readwrite'); tx.objectStore('blobs').put({ hash, bytes }); await new Promise((resolve, reject) => { tx.oncomplete = resolve; tx.onerror = () => reject(tx.error); }); db.close(); return hash; } async function getBytes(hash) { const db = await openDB('cas'); const tx = db.transaction('blobs', 'readonly'); const req = tx.objectStore('blobs').get(hash); const rec = await new Promise((resolve, reject) => { req.onsuccess = () => resolve(req.result); req.onerror = () => reject(req.error); }); db.close(); return rec ? rec.bytes : null; }