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fix(cache): prevent bloom filter from rejecting reads on existing caches #20

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Merged
indexzero merged 1 commit into from
Feb 1, 2026
Merged

fix(cache): prevent bloom filter from rejecting reads on existing caches #20

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23 changes: 13 additions & 10 deletions src/cache/cache.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,10 @@ export class Cache {
this.bloomSize = options.bloomSize || 10000;
this.bloomFalsePositiveRate = options.bloomFalsePositiveRate || 0.01;
this._bloomInitialized = false;
this._bloomPopulated = false; // True only when bloom filter is populated from existing data
this._inflightRequests = new Map();
this._driverInitialized = false;

if (!this.driver) {
throw new Error('Storage driver is required');
}
Expand Down Expand Up @@ -61,12 +62,13 @@ export class Cache {
async _doFetch(key, options = {}) {
const driver = await this._ensureDriver();
await this._initBloomFilter();

// Check bloom filter first for non-existence
if (this.bloomFilter && !this.bloomFilter.has(key)) {

// Only use bloom filter if it was pre-populated (e.g., loaded from disk)
// An empty bloom filter would incorrectly reject all keys from existing caches
if (this.bloomFilter && this._bloomPopulated && !this.bloomFilter.has(key)) {
return null; // Definitely not in cache
}

try {
const value = await driver.get(key);
// Handle cache validation, ETags, etc.
Expand All @@ -82,20 +84,21 @@ export class Cache {
async set(key, value, options = {}) {
const driver = await this._ensureDriver();
await this._initBloomFilter();
// Add to bloom filter

// Add to bloom filter and mark as populated
if (this.bloomFilter) {
this.bloomFilter.add(key);
this._bloomPopulated = true;
}
return driver.put(key, value, options);
}

async has(key) {
const driver = await this._ensureDriver();
await this._initBloomFilter();
// Check bloom filter first
if (this.bloomFilter && !this.bloomFilter.has(key)) {

// Only use bloom filter if it was pre-populated
if (this.bloomFilter && this._bloomPopulated && !this.bloomFilter.has(key)) {
return false; // Definitely not in cache
}
return driver.has(key);
Expand Down