/**
* Cache implementation for Cloud Logging MCP server
*/
import type { LogCache } from "../domain/cache";
import type { RawLogEntry } from "../domain/api";
import type { LogId } from "../domain/log-id";
/**
* Cache configuration
*/
interface CacheConfig {
/** Time-to-live in milliseconds */
ttlMs: number;
/** Maximum number of entries to store */
maxEntries: number;
}
/**
* Interface for log cache entries
*/
interface LogCacheEntry {
entry: RawLogEntry;
timestamp: number;
}
/**
* Cache for log entries
*/
export class LogCacheImpl implements LogCache {
private cache: Map<LogId, LogCacheEntry> = new Map();
private readonly maxEntries: number;
private readonly ttlMs: number;
/**
* Creates a new LogCache instance
* @param config Cache configuration
*/
constructor(config?: Partial<CacheConfig>) {
this.maxEntries = config?.maxEntries ?? 1000; // Default: 1000 entries
this.ttlMs = config?.ttlMs ?? 30 * 60 * 1000; // Default: 30 minutes
}
/**
* Adds an entry to the cache
* @param id The log ID
* @param entry The log entry
*/
add(id: LogId, entry: RawLogEntry): void {
// If cache is full, remove oldest entries
if (this.cache.size >= this.maxEntries) {
this.evictOldestEntries();
}
// Add to cache
this.cache.set(id, {
entry,
timestamp: Date.now(),
});
}
/**
* Gets an entry from the cache
* @param id The log ID
* @returns The log entry or undefined if not found or expired
*/
get(id: LogId): RawLogEntry | undefined {
const cached = this.cache.get(id);
return !cached
? undefined
: (Date.now() - cached.timestamp > this.ttlMs)
? (this.cache.delete(id), undefined)
: cached.entry;
}
/**
* Evicts the oldest entries from the cache
*/
private evictOldestEntries(): void {
// Convert to array, sort by timestamp, and remove oldest
const entries = Array.from(this.cache.entries()).sort(
(a, b) => a[1].timestamp - b[1].timestamp,
);
// Remove oldest entries to make room
const toRemove = entries.slice(0, Math.max(1, Math.floor(this.maxEntries * 0.1))); // Remove at least 1 entry or 10% of max
for (const [key] of toRemove) {
this.cache.delete(key);
}
}
}
