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⚡ Bolt: direct string HMAC update and single output allocation in PersistenceLayer.save #438

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⚡ Bolt: direct string HMAC update and single output allocation in PersistenceLayer.save #438

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22 changes: 6 additions & 16 deletions src/os/persistence/PersistenceLayer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,28 +8,18 @@ const SIGNATURE_LENGTH = 32;
export class PersistenceLayer {
/**
* Bolt Optimization: Explicitly typed as Buffer.
* Constructs output buffer using Buffer.allocUnsafe() with manual .set() and .write() copying,
* which is significantly faster (~15%) than Buffer.concat() and avoids multiple buffer allocations.
* Computes HMAC directly on string payload and writes directly to pre-allocated buffer
* using Buffer.alloc to eliminate uninitialized memory leak hazards while avoiding extra allocations.
*/
save(data: any, key: string): Buffer {
const payload = JSON.stringify(data);
const payloadBuf = Buffer.from(payload, 'utf8');

// Bolt Optimization: Allocate unsafe buffer for exact combined size to avoid Buffer.concat and intermediate payload allocations
const outBuf = Buffer.allocUnsafe(38 + payloadBuf.length);

// Copy pre-allocated header and payload
outBuf.set(HEADER_BUF, 0);
outBuf.set(payloadBuf, 38);
const payloadByteLength = Buffer.byteLength(payload, 'utf8');

// Compute and write HMAC signature directly
const hmac = crypto.createHmac('sha256',. key);
hmac.update(payloadBuf);
const hmac = crypto.createHmac('sha256', key);
hmac.update(payload, 'utf8');
const signature = hmac.digest();
outBuf.set(signature, 6);

const payloadByteLength = Buffer.byteLength(payload, 'utf8');
const out = Buffer.allocUnsafe(HEADER_LENGTH + SIGNATURE_LENGTH + payloadByteLength);
const out = Buffer.alloc(HEADER_LENGTH + SIGNATURE_LENGTH + payloadByteLength);

// Zero-copy set of pre-allocated header
out.set(HEADER_MAGIC, 0);
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