AegisMap: Flat Open-Addressing Hash Table

AegisMap<T> is a high-speed, zero-allocation flat hash table using open addressing with linear probing and 32-bit FNV-1a hashing.

---

Why Standard Map Causes Latency Spikes

JavaScript's native new Map() allocates node wrappers, hash buckets, and linked list entries on the V8 heap. As keys are inserted and deleted, hash buckets undergo rehashing and trigger garbage collection churn.

AegisMap eliminates this by storing all keys and record values in a single contiguous binary buffer.

---

Creation

Specify the struct schema and choose which field acts as the primary key:

import { Aegis, uint32, float64, fixedString } from '@aventine/aegis-js';

const UserSession = Aegis.struct({
  userId: uint32,
  token: fixedString(16),
  lastPing: float64,
});

// Create map keyed by userId with capacity for 50,000 sessions
const sessionMap = Aegis.map(UserSession, { 
  capacity: 50_000, 
  keyField: 'userId' 
});

---

Operations

Setting Entries

sessionMap.set(1001, {
  userId: 1001,
  token: 'AUTH-TOKEN-A1B2',
  lastPing: Date.now(),
});

Retrieving with Flyweight Cursor

get() returns an AegisCursor<T> mounted directly to the record's slot in the hash table, enabling sub-nanosecond lookups and in-place updates:

const session = sessionMap.get(1001);
if (session) {
  console.log(`User 1001 Token: ${session.token}`);
  
  // Mutate in place with zero allocation
  session.lastPing = Date.now();
}

Checking Existence & Deleting

if (sessionMap.has(1001)) {
  sessionMap.delete(1001);
}

console.log(`Active sessions: ${sessionMap.size}`);

Iterating Over Keys & Values

Iterate over all active entries without creating temporary key/value tuples:

sessionMap.forEach((session, key) => {
  console.log(`Active session for user ${key}: ${session.token}`);
});