Directory Layer

/**
 * Directory with automatically allocated prefix
 * Provides multi-tenant keyspace management and hierarchical organization
 */
class Directory<KeyIn = any, KeyOut = any, ValIn = any, ValOut = any> {
  /** The content subspace for this directory (where user data is stored) */
  readonly content: Subspace<KeyIn, KeyOut, ValIn, ValOut>;
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Create or open a directory
const userDir = await fdb.directory.createOrOpen(db, ["myapp", "users"]);

// Store data in the directory
const userDb = db.at(userDir);
await userDb.set("alice", "Alice's data");

// Directory has a short, allocated prefix
console.log("Prefix:", userDir.content.prefix);

/**
 * Default directory layer instance
 * Manages directory metadata and prefix allocation
 */
const directory: DirectoryLayer;

/**
 * DirectoryLayer class for managing directories
 */
class DirectoryLayer {
  /**
   * Create or open a directory
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path (array of strings or single string)
   * @param layer - Optional layer identifier for directory type checking
   * @returns Promise resolving to Directory instance
   */
  createOrOpen(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer
  ): Promise<Directory>;

  /**
   * Open an existing directory (throws if not found)
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path
   * @param layer - Optional expected layer for validation
   * @returns Promise resolving to Directory instance
   * @throws DirectoryError if directory doesn't exist or layer mismatch
   */
  open(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer
  ): Promise<Directory>;

  /**
   * Create a new directory (throws if exists)
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path
   * @param layer - Optional layer identifier
   * @param prefix - Optional manual prefix (advanced usage)
   * @returns Promise resolving to Directory instance
   * @throws DirectoryError if directory already exists
   */
  create(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer,
    prefix?: Buffer
  ): Promise<Directory>;

  /**
   * List subdirectories (async generator)
   * @param txn - Transaction
   * @param path - Parent directory path (optional, defaults to root)
   * @yields Subdirectory names
   */
  list(
    txn: Transaction,
    path?: string | string[]
  ): AsyncIterableIterator<string>;

  /**
   * List all subdirectories as an array
   * @param txnOrDb - Transaction or Database
   * @param path - Parent directory path (optional, defaults to root)
   * @returns Promise resolving to array of subdirectory names
   */
  listAll(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<string[]>;

  /**
   * Check if a directory exists
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path (optional, defaults to root)
   * @returns Promise resolving to true if exists, false otherwise
   */
  exists(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<boolean>;

  /**
   * Remove a directory and all its contents
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path (optional, defaults to current directory)
   * @returns Promise that resolves when removal completes
   */
  remove(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<void>;

  /**
   * Remove a directory if it exists (no error if missing)
   * @param txnOrDb - Transaction or Database
   * @param path - Directory path
   * @returns Promise that resolves when removal completes
   */
  removeIfExists(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<void>;

  /**
   * Move a directory to a new path
   * @param txnOrDb - Transaction or Database
   * @param oldPath - Current directory path
   * @param newPath - New directory path
   * @returns Promise resolving to Directory at new path
   */
  move(
    txnOrDb: Transaction | Database,
    oldPath: string | string[],
    newPath: string | string[]
  ): Promise<Directory>;

  /**
   * Get the directory layer's path
   * @returns Path array
   */
  getPath(): string[];
}

class DirectoryError extends Error {
  /** Error message describing the directory operation failure */
  message: string;
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Create or open directory
const appDir = await fdb.directory.createOrOpen(db, "myapp");
const userDir = await fdb.directory.createOrOpen(db, ["myapp", "users"]);

// Open existing directory (throws if not found)
try {
  const dir = await fdb.directory.open(db, ["myapp", "users"]);
} catch (error) {
  console.error("Directory not found:", error);
}

// Create new directory (throws if exists)
try {
  const newDir = await fdb.directory.create(db, ["myapp", "new"]);
} catch (error) {
  console.error("Directory already exists:", error);
}

// List subdirectories
const subdirs = await fdb.directory.listAll(db, "myapp");
console.log("Subdirectories:", subdirs);

// Check existence
const exists = await fdb.directory.exists(db, ["myapp", "users"]);
console.log("Exists:", exists);

// Remove directory
await fdb.directory.remove(db, ["myapp", "temp"]);

// Move directory
await fdb.directory.move(db, ["myapp", "old"], ["myapp", "new"]);

/**
 * Directory instance methods
 */
class Directory<KeyIn, KeyOut, ValIn, ValOut> {
  /** The content subspace for storing data */
  readonly content: Subspace<KeyIn, KeyOut, ValIn, ValOut>;

  /**
   * Create or open a subdirectory
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path (relative to this directory)
   * @param layer - Optional layer identifier
   * @returns Promise resolving to subdirectory
   */
  createOrOpen(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer
  ): Promise<Directory>;

  /**
   * Open a subdirectory
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path
   * @param layer - Optional expected layer
   * @returns Promise resolving to subdirectory
   */
  open(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer
  ): Promise<Directory>;

  /**
   * Create a subdirectory
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path
   * @param layer - Optional layer identifier
   * @param prefix - Optional manual prefix
   * @returns Promise resolving to subdirectory
   */
  create(
    txnOrDb: Transaction | Database,
    path: string | string[],
    layer?: string | Buffer,
    prefix?: Buffer
  ): Promise<Directory>;

  /**
   * List subdirectories (async generator)
   * @param txn - Transaction
   * @param path - Parent path (optional)
   * @yields Subdirectory names
   */
  list(
    txn: Transaction,
    path?: string | string[]
  ): AsyncIterableIterator<string>;

  /**
   * List all subdirectories
   * @param txnOrDb - Transaction or Database
   * @param path - Parent path (optional)
   * @returns Array of subdirectory names
   */
  listAll(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<string[]>;

  /**
   * Move this directory to a new path
   * @param txnOrDb - Transaction or Database
   * @param newAbsolutePath - New absolute path
   * @returns Promise resolving to Directory at new location
   */
  moveTo(
    txnOrDb: Transaction | Database,
    newAbsolutePath: string | string[]
  ): Promise<Directory>;

  /**
   * Remove this directory or a subdirectory
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path (optional)
   * @returns Promise that resolves when removal completes
   */
  remove(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<void>;

  /**
   * Remove if exists (no error if missing)
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path
   * @returns Promise that resolves when removal completes
   */
  removeIfExists(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<void>;

  /**
   * Check if subdirectory exists
   * @param txnOrDb - Transaction or Database
   * @param path - Subdirectory path
   * @returns Promise resolving to true if exists
   */
  exists(
    txnOrDb: Transaction | Database,
    path?: string | string[]
  ): Promise<boolean>;

  /**
   * Get the directory's full path
   * @returns Path array
   */
  getPath(): string[];

  /**
   * Get the directory's layer identifier
   * @returns Layer as string
   */
  getLayer(): string;

  /**
   * Get the directory's layer as raw Buffer
   * @returns Layer as Buffer
   */
  getLayerRaw(): Buffer;

  /**
   * Check if this is a directory partition
   * @returns True if this is a partition
   */
  isPartition(): boolean;

  /**
   * Get the content subspace
   * @returns The content subspace
   */
  getSubspace(): Subspace<KeyIn, KeyOut, ValIn, ValOut>;
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Get directory
const appDir = await fdb.directory.createOrOpen(db, "myapp");

// Create subdirectories
const usersDir = await appDir.createOrOpen(db, "users");
const ordersDir = await appDir.createOrOpen(db, "orders");

// Get metadata
console.log("Path:", usersDir.getPath()); // ["myapp", "users"]
console.log("Layer:", usersDir.getLayer());

// List subdirectories
const subdirs = await appDir.listAll(db);
console.log("Subdirectories:", subdirs);

// Move directory
const movedDir = await usersDir.moveTo(db, ["myapp", "accounts"]);

// Remove directory
await ordersDir.remove(db);

/**
 * Layer parameter for create/open operations
 * Identifies the purpose or type of the directory
 */
type Layer = string | Buffer;

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Create directories with layers
const userDir = await fdb.directory.createOrOpen(db, ["myapp", "users"], "user_data");
const indexDir = await fdb.directory.createOrOpen(db, ["myapp", "indexes"], "index");

// Layer validation on open
try {
  // This will throw if layer doesn't match
  const dir = await fdb.directory.open(db, ["myapp", "users"], "user_data");
} catch (error) {
  console.error("Layer mismatch:", error);
}

// Check layer
console.log("User dir layer:", userDir.getLayer()); // "user_data"
console.log("Index dir layer:", indexDir.getLayer()); // "index"

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Tenant manager
class TenantManager {
  constructor(private db: typeof db, private appName: string) {}

  async createTenant(tenantId: string): Promise<Directory> {
    const path = [this.appName, "tenants", tenantId];
    return await fdb.directory.create(this.db, path, "tenant");
  }

  async getTenant(tenantId: string): Promise<Directory | null> {
    const path = [this.appName, "tenants", tenantId];
    const exists = await fdb.directory.exists(this.db, path);
    if (!exists) return null;
    return await fdb.directory.open(this.db, path);
  }

  async listTenants(): Promise<string[]> {
    return await fdb.directory.listAll(this.db, [this.appName, "tenants"]);
  }

  async deleteTenant(tenantId: string): Promise<void> {
    const path = [this.appName, "tenants", tenantId];
    await fdb.directory.remove(this.db, path);
  }
}

// Usage
const manager = new TenantManager(db, "myapp");

// Create tenants
await manager.createTenant("acme");
await manager.createTenant("techcorp");

// Use tenant directory
const acmeDir = await manager.getTenant("acme");
if (acmeDir) {
  const acmeDb = db.at(acmeDir);
  await acmeDb.set("config", "Acme config");
}

// List all tenants
const tenants = await manager.listTenants();
console.log("Tenants:", tenants);

// Delete tenant (removes all data)
await manager.deleteTenant("acme");

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Create hierarchy
await fdb.directory.createOrOpen(db, ["myapp"]);
await fdb.directory.createOrOpen(db, ["myapp", "users"]);
await fdb.directory.createOrOpen(db, ["myapp", "users", "profiles"]);
await fdb.directory.createOrOpen(db, ["myapp", "users", "sessions"]);
await fdb.directory.createOrOpen(db, ["myapp", "orders"]);
await fdb.directory.createOrOpen(db, ["myapp", "products"]);

// Navigate hierarchy
const appDir = await fdb.directory.open(db, "myapp");
const subdirs = await appDir.listAll(db);
console.log("App subdirectories:", subdirs);
// ["users", "orders", "products"]

const usersDir = await appDir.open(db, "users");
const userSubdirs = await usersDir.listAll(db);
console.log("User subdirectories:", userSubdirs);
// ["profiles", "sessions"]

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Note: Directory partitions are an advanced feature
// They create a new directory layer with its own prefix allocation

// Check if directory is a partition
const dir = await fdb.directory.open(db, ["myapp"]);
console.log("Is partition:", dir.isPartition());

// Partitions prevent access to parent directories from within the partition
// Useful for strict tenant isolation

/**
 * High-contention allocator for prefix generation
 * Used internally by DirectoryLayer
 */
class HighContentionAllocator {
  /**
   * Allocate a unique prefix
   * @param txn - Transaction
   * @returns Promise resolving to allocated prefix Buffer
   */
  allocate(txn: Transaction): Promise<Buffer>;
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// The HCA is used internally - you don't typically interact with it directly
// But it's what enables thousands of concurrent directory creations

// Create many directories concurrently
const promises = [];
for (let i = 0; i < 100; i++) {
  promises.push(
    fdb.directory.createOrOpen(db, ["myapp", "users", `user-${i}`])
  );
}

// All get unique, short prefixes
await Promise.all(promises);

// Each directory has a compact prefix
const dir = await fdb.directory.open(db, ["myapp", "users", "user-0"]);
console.log("Prefix length:", dir.content.prefix.length);
// Usually just a few bytes, not the full path length

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Practice 1: Use createOrOpen for idempotent operations
async function initializeApp() {
  // Safe to call multiple times
  const appDir = await fdb.directory.createOrOpen(db, "myapp");
  const usersDir = await fdb.directory.createOrOpen(db, ["myapp", "users"]);
  return { appDir, usersDir };
}

// Practice 2: Check existence before operations
async function safeDelete(path: string[]) {
  if (await fdb.directory.exists(db, path)) {
    await fdb.directory.remove(db, path);
  }
}

// Practice 3: Use layers for type safety
async function getUserDirectory(userId: string): Promise<Directory> {
  const path = ["myapp", "users", userId];
  const dir = await fdb.directory.open(db, path, "user_data");
  // Layer validation ensures this is a user directory
  return dir;
}

// Practice 4: Cleanup on tenant deletion
async function deleteTenant(tenantId: string) {
  await db.doTransaction(async (tn) => {
    // Remove directory (deletes all keys with that prefix)
    await fdb.directory.remove(tn, ["myapp", "tenants", tenantId]);

    // Also cleanup any tenant-specific indexes
    await fdb.directory.removeIfExists(tn, ["myapp", "indexes", tenantId]);
  });
}

// Practice 5: Cache directory references
const directoryCache = new Map<string, Directory>();

async function getCachedDirectory(path: string[]): Promise<Directory> {
  const key = path.join("/");
  if (!directoryCache.has(key)) {
    const dir = await fdb.directory.open(db, path);
    directoryCache.set(key, dir);
  }
  return directoryCache.get(key)!;
}

/**
 * Directory operation error
 */
class DirectoryError extends Error {
  message: string;
}

import fdb, { DirectoryError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Handle directory errors
try {
  const dir = await fdb.directory.open(db, ["nonexistent"]);
} catch (error) {
  if (error instanceof DirectoryError) {
    console.error("Directory error:", error.message);
    // Handle directory-specific error
  } else {
    // Other error
    throw error;
  }
}

// Safe operations with error handling
async function safeCreateDirectory(
  path: string[],
  layer?: string
): Promise<Directory | null> {
  try {
    return await fdb.directory.create(db, path, layer);
  } catch (error) {
    if (error instanceof DirectoryError) {
      console.log("Directory exists, opening instead");
      return await fdb.directory.open(db, path, layer);
    }
    throw error;
  }
}

// Layer validation
async function openUserDirectory(userId: string): Promise<Directory> {
  try {
    return await fdb.directory.open(
      db,
      ["myapp", "users", userId],
      "user_data"
    );
  } catch (error) {
    if (error instanceof DirectoryError) {
      // Layer mismatch or directory not found
      throw new Error(`Invalid user directory: ${userId}`);
    }
    throw error;
  }
}

import fdb from "foundationdb";
import { describe, beforeAll, afterAll, beforeEach, test, expect } from "@jest/globals";

describe("FoundationDB Tests", () => {
  let db: ReturnType<typeof fdb.open>;

  beforeAll(() => {
    fdb.setAPIVersion(620);
    db = fdb.open();
  });

  afterAll(() => {
    db.close();
    fdb.stopNetworkSync();
  });

  beforeEach(async () => {
    // Clear test data
    await db.clearRangeStartsWith("test:");
  });

  test("should perform basic operations", async () => {
    await db.set("test:key", "value");
    const result = await db.get("test:key");
    expect(result?.toString()).toBe("value");
  });

  test("should handle transactions", async () => {
    const count = await db.doTransaction(async (tn) => {
      tn.set("test:counter", "5");
      const val = await tn.get("test:counter");
      return parseInt(val?.toString() || "0");
    });
    expect(count).toBe(5);
  });

  test("should handle errors gracefully", async () => {
    await expect(async () => {
      await db.doTransaction(async (tn) => {
        throw new Error("Test error");
      });
    }).rejects.toThrow("Test error");
  });
});

import fdb from "foundationdb";
import { describe, before, after, beforeEach, it } from "mocha";
import { expect } from "chai";

describe("FoundationDB Operations", function() {
  this.timeout(10000); // 10 second timeout
  
  let db: ReturnType<typeof fdb.open>;

  before(() => {
    fdb.setAPIVersion(620);
    db = fdb.open();
  });

  after(() => {
    db.close();
    fdb.stopNetworkSync();
  });

  beforeEach(async () => {
    await db.clearRangeStartsWith("test:");
  });

  it("should read and write data", async () => {
    await db.set("test:mocha", "data");
    const value = await db.get("test:mocha");
    expect(value?.toString()).to.equal("data");
  });

  it("should handle concurrent operations", async () => {
    const operations = Array.from({ length: 10 }, (_, i) => 
      db.set(`test:item:${i}`, `value${i}`)
    );
    await Promise.all(operations);
    
    const items = await db.getRangeAllStartsWith("test:item:");
    expect(items).to.have.lengthOf(10);
  });

  it("should support atomic operations", async () => {
    const delta = Buffer.allocUnsafe(8);
    delta.writeBigInt64LE(1n, 0);
    
    await Promise.all([
      db.add("test:atomic", delta),
      db.add("test:atomic", delta),
      db.add("test:atomic", delta)
    ]);
    
    const result = await db.get("test:atomic");
    expect(result?.readBigInt64LE(0)).to.equal(3n);
  });
});

import fdb from "foundationdb";
import { describe, beforeAll, afterAll, beforeEach, test, expect } from "vitest";

describe("FoundationDB with Vitest", () => {
  let db: ReturnType<typeof fdb.open>;

  beforeAll(() => {
    fdb.setAPIVersion(620);
    db = fdb.open();
  });

  afterAll(() => {
    db.close();
    fdb.stopNetworkSync();
  });

  beforeEach(async () => {
    await db.clearRangeStartsWith("test:");
  });

  test("concurrent writes with snapshot isolation", async () => {
    const writes = Array.from({ length: 100 }, (_, i) =>
      db.set(`test:concurrent:${i}`, `value${i}`)
    );
    
    await Promise.all(writes);
    
    const results = await db.getRangeAllStartsWith("test:concurrent:");
    expect(results).toHaveLength(100);
  });

  test("transaction retry logic", async () => {
    let attempts = 0;
    
    const result = await db.doTransaction(async (tn) => {
      attempts++;
      const value = await tn.get("test:retry");
      tn.set("test:retry", (parseInt(value?.toString() || "0") + 1).toString());
      return attempts;
    });
    
    expect(result).toBeGreaterThanOrEqual(1);
  });

  test("range queries with limits", async () => {
    for (let i = 0; i < 50; i++) {
      await db.set(`test:range:${i.toString().padStart(3, "0")}`, `value${i}`);
    }
    
    const page1 = await db.getRangeAll("test:range:", "test:range:~", { limit: 10 });
    const page2 = await db.getRangeAll("test:range:", "test:range:~", { 
      limit: 10,
      reverse: true  
    });
    
    expect(page1).toHaveLength(10);
    expect(page2).toHaveLength(10);
    expect(page1[0][0].toString()).not.toBe(page2[0][0].toString());
  });
});

import fdb, { FDBError } from "foundationdb";

export class FDBTestHelper {
  private db: ReturnType<typeof fdb.open>;
  private testPrefix: string;

  constructor(testPrefix = "test:") {
    fdb.setAPIVersion(620);
    this.db = fdb.open();
    this.testPrefix = testPrefix;
  }

  getDB() {
    return this.db;
  }

  async cleanup() {
    await this.db.clearRangeStartsWith(this.testPrefix);
  }

  async close() {
    this.db.close();
  }

  async withTransaction<T>(
    fn: (tn: any) => Promise<T>,
    opts?: any
  ): Promise<T> {
    return await this.db.doTransaction(fn, opts);
  }

  async expectError(
    fn: () => Promise<any>,
    errorCode?: number
  ): Promise<FDBError> {
    try {
      await fn();
      throw new Error("Expected operation to throw");
    } catch (error) {
      if (error instanceof FDBError) {
        if (errorCode !== undefined && error.code !== errorCode) {
          throw new Error(`Expected error code ${errorCode}, got ${error.code}`);
        }
        return error;
      }
      throw error;
    }
  }

  async populateTestData(count: number, prefix?: string) {
    const pfx = prefix || this.testPrefix;
    const operations = Array.from({ length: count }, (_, i) =>
      this.db.set(`${pfx}${i}`, `value${i}`)
    );
    await Promise.all(operations);
  }

  async assertKeyExists(key: string): Promise<Buffer> {
    const value = await this.db.get(key);
    if (value === undefined) {
      throw new Error(`Expected key "${key}" to exist`);
    }
    return value;
  }

  async assertKeyNotExists(key: string): Promise<void> {
    const value = await this.db.get(key);
    if (value !== undefined) {
      throw new Error(`Expected key "${key}" to not exist`);
    }
  }
}

// Usage in tests
import { describe, beforeAll, afterAll, beforeEach, test, expect } from "vitest";

describe("Using FDBTestHelper", () => {
  let helper: FDBTestHelper;

  beforeAll(() => {
    helper = new FDBTestHelper("test:helper:");
  });

  afterAll(async () => {
    await helper.cleanup();
    await helper.close();
  });

  beforeEach(async () => {
    await helper.cleanup();
  });

  test("populate and verify test data", async () => {
    await helper.populateTestData(10);
    await helper.assertKeyExists("test:helper:0");
    await helper.assertKeyExists("test:helper:9");
    await helper.assertKeyNotExists("test:helper:10");
  });

  test("transaction helper", async () => {
    const result = await helper.withTransaction(async (tn) => {
      tn.set("test:helper:tx", "value");
      return "success";
    });
    expect(result).toBe("success");
  });
});

import fdb from "foundationdb";

class FDBConnectionPool {
  private static instance: FDBConnectionPool;
  private db: ReturnType<typeof fdb.open> | null = null;
  private initialized = false;

  private constructor() {}

  static getInstance(): FDBConnectionPool {
    if (!FDBConnectionPool.instance) {
      FDBConnectionPool.instance = new FDBConnectionPool();
    }
    return FDBConnectionPool.instance;
  }

  async initialize(opts?: { clusterFile?: string; trace?: string }) {
    if (this.initialized) return;

    try {
      fdb.setAPIVersion(620);

      if (opts?.trace) {
        fdb.configNetwork({
          trace_enable: opts.trace,
          trace_format: "json",
        });
      }

      this.db = fdb.open(opts?.clusterFile);
      this.db.setNativeOptions({
        transaction_timeout: 10000,
        transaction_retry_limit: 100,
        max_watches: 20000,
      });

      this.initialized = true;
    } catch (error) {
      console.error("Failed to initialize FDB connection:", error);
      throw error;
    }
  }

  getDatabase(): ReturnType<typeof fdb.open> {
    if (!this.db) {
      throw new Error("Database not initialized. Call initialize() first.");
    }
    return this.db;
  }

  async shutdown() {
    if (this.db) {
      this.db.close();
      fdb.stopNetworkSync();
      this.db = null;
      this.initialized = false;
    }
  }

  isInitialized(): boolean {
    return this.initialized;
  }
}

// Usage across application
export const fdbPool = FDBConnectionPool.getInstance();

// In application startup
await fdbPool.initialize({ trace: "./fdb-traces" });

// In any module
import { fdbPool } from "./fdb-pool";

async function getData(key: string) {
  const db = fdbPool.getDatabase();
  return await db.get(key);
}

// Graceful shutdown
process.on("SIGTERM", async () => {
  await fdbPool.shutdown();
  process.exit(0);
});

import fdb, { FDBError } from "foundationdb";

async function withRetry<T>(
  operation: () => Promise<T>,
  maxRetries = 5,
  baseDelay = 100
): Promise<T> {
  let lastError: Error | undefined;

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await operation();
    } catch (error) {
      lastError = error as Error;

      // Don't retry on non-retryable errors
      if (error instanceof FDBError && error.code === 1007) {
        throw error; // Not retryable
      }

      if (attempt < maxRetries) {
        const delay = baseDelay * Math.pow(2, attempt);
        const jitter = Math.random() * delay * 0.1;
        await new Promise((resolve) => setTimeout(resolve, delay + jitter));
      }
    }
  }

  throw new Error(`Operation failed after ${maxRetries} retries: ${lastError?.message}`);
}

// Usage
fdb.setAPIVersion(620);
const db = fdb.open();

const result = await withRetry(async () => {
  return await db.doTransaction(async (tn) => {
    const value = await tn.get("critical:data");
    tn.set("critical:data", "updated");
    return value;
  });
});

import fdb, { FDBError } from "foundationdb";

class CircuitBreaker {
  private failures = 0;
  private lastFailureTime = 0;
  private state: "closed" | "open" | "half-open" = "closed";

  constructor(
    private threshold = 5,
    private timeout = 60000,
    private resetTimeout = 30000
  ) {}

  async execute<T>(operation: () => Promise<T>): Promise<T> {
    if (this.state === "open") {
      if (Date.now() - this.lastFailureTime > this.resetTimeout) {
        this.state = "half-open";
      } else {
        throw new Error("Circuit breaker is OPEN");
      }
    }

    try {
      const result = await operation();
      this.onSuccess();
      return result;
    } catch (error) {
      this.onFailure();
      throw error;
    }
  }

  private onSuccess() {
    this.failures = 0;
    this.state = "closed";
  }

  private onFailure() {
    this.failures++;
    this.lastFailureTime = Date.now();

    if (this.failures >= this.threshold) {
      this.state = "open";
    }
  }

  getState() {
    return this.state;
  }
}

// Usage
fdb.setAPIVersion(620);
const db = fdb.open();
const breaker = new CircuitBreaker(5, 60000, 30000);

async function safeQuery(key: string): Promise<Buffer | undefined> {
  return await breaker.execute(async () => {
    return await db.get(key);
  });
}

import fdb from "foundationdb";

async function processBatchInChunks<T>(
  db: ReturnType<typeof fdb.open>,
  prefix: string,
  processor: (batch: Array<[Buffer, Buffer]>) => Promise<T[]>,
  chunkSize = 100
): Promise<T[]> {
  const results: T[] = [];
  let startKey = prefix;

  while (true) {
    const chunk = await db.getRangeAll(
      startKey,
      prefix + "~",
      { limit: chunkSize }
    );

    if (chunk.length === 0) break;

    const chunkResults = await processor(chunk);
    results.push(...chunkResults);

    if (chunk.length < chunkSize) break;

    // Continue from after last key
    startKey = chunk[chunk.length - 1][0].toString() + "\x00";
  }

  return results;
}

// Usage
fdb.setAPIVersion(620);
const db = fdb.open();

const processed = await processBatchInChunks(
  db,
  "users:",
  async (batch) => {
    return batch.map(([key, value]) => ({
      key: key.toString(),
      parsed: JSON.parse(value.toString()),
    }));
  },
  50
);

import fdb from "foundationdb";

class FDBCache<T> {
  private cache = new Map<string, { value: T; watch: any }>();

  constructor(private db: ReturnType<typeof fdb.open>) {}

  async get(key: string, parser: (buf: Buffer) => T): Promise<T | undefined> {
    // Check cache first
    const cached = this.cache.get(key);
    if (cached) {
      return cached.value;
    }

    // Fetch and cache with watch
    const watch = await this.db.getAndWatch(key);
    
    if (watch.value === undefined) {
      return undefined;
    }

    const value = parser(watch.value);
    this.cache.set(key, { value, watch });

    // Invalidate on change
    watch.promise.then(() => {
      this.cache.delete(key);
    });

    return value;
  }

  async set(key: string, value: T, serializer: (val: T) => Buffer) {
    await this.db.set(key, serializer(value));
    this.cache.delete(key); // Invalidate cache
  }

  clear() {
    this.cache.forEach(({ watch }) => watch.cancel());
    this.cache.clear();
  }
}

// Usage
fdb.setAPIVersion(620);
const db = fdb.open();
const cache = new FDBCache(db);

const user = await cache.get(
  "user:123",
  (buf) => JSON.parse(buf.toString())
);

await cache.set(
  "user:123",
  { name: "Alice", email: "alice@example.com" },
  (val) => Buffer.from(JSON.stringify(val))
);

import fdb from "foundationdb";

class DistributedLock {
  private lockKey: string;
  private lockValue: string;

  constructor(
    private db: ReturnType<typeof fdb.open>,
    lockName: string,
    private ttl = 30000
  ) {
    this.lockKey = `locks:${lockName}`;
    this.lockValue = `${Date.now()}-${Math.random()}`;
  }

  async acquire(timeout = 10000): Promise<boolean> {
    const startTime = Date.now();

    while (Date.now() - startTime < timeout) {
      try {
        const acquired = await this.db.doTransaction(async (tn) => {
          const existing = await tn.get(this.lockKey);

          if (existing === undefined) {
            // Lock is free
            tn.set(this.lockKey, this.lockValue);
            return true;
          }

          // Check if lock expired
          const lockData = existing.toString();
          const lockTime = parseInt(lockData.split("-")[0]);

          if (Date.now() - lockTime > this.ttl) {
            // Lock expired, take it
            tn.set(this.lockKey, this.lockValue);
            return true;
          }

          return false;
        });

        if (acquired) return true;
      } catch (error) {
        // Transaction conflict, retry
      }

      // Wait before retry
      await new Promise((resolve) => setTimeout(resolve, 100));
    }

    return false;
  }

  async release(): Promise<void> {
    await this.db.doTransaction(async (tn) => {
      const existing = await tn.get(this.lockKey);

      if (existing?.toString() === this.lockValue) {
        tn.clear(this.lockKey);
      }
    });
  }

  async withLock<T>(fn: () => Promise<T>, timeout = 10000): Promise<T> {
    const acquired = await this.acquire(timeout);
    if (!acquired) {
      throw new Error(`Failed to acquire lock: ${this.lockKey}`);
    }

    try {
      return await fn();
    } finally {
      await this.release();
    }
  }
}

// Usage
fdb.setAPIVersion(620);
const db = fdb.open();

const lock = new DistributedLock(db, "resource:123", 30000);

await lock.withLock(async () => {
  // Critical section - only one process can execute this at a time
  const value = await db.get("shared:resource");
  await db.set("shared:resource", "updated");
});

import fdb, { tuple } from "foundationdb";

interface Event {
  type: string;
  data: any;
  timestamp: number;
  version?: Buffer;
}

class EventStore {
  private db: ReturnType<typeof fdb.open>;

  constructor() {
    fdb.setAPIVersion(620);
    this.db = fdb.open()
      .withKeyEncoding(fdb.encoders.tuple)
      .withValueEncoding(fdb.encoders.json);
  }

  async appendEvent(
    streamId: string,
    eventType: string,
    data: any
  ): Promise<Buffer> {
    return await this.db.doTransaction(async (tn) => {
      const key = ["events", streamId, tuple.unboundVersionstamp()];
      
      const event: Event = {
        type: eventType,
        data,
        timestamp: Date.now(),
      };

      tn.setVersionstampedKey(key, event);
      
      const versionstamp = tn.getVersionstamp();
      return versionstamp.promise;
    });
  }

  async getEvents(
    streamId: string,
    fromVersion?: Buffer,
    limit?: number
  ): Promise<Event[]> {
    const start = fromVersion
      ? ["events", streamId, fromVersion]
      : ["events", streamId];

    const events = await this.db.getRangeAll(
      start,
      ["events", streamId, Buffer.from([0xff])],
      { limit }
    );

    return events.map(([key, value]) => ({
      ...(value as any),
      version: key[2] as Buffer,
    }));
  }

  async replay(
    streamId: string,
    handler: (event: Event) => void | Promise<void>
  ): Promise<void> {
    const events = await this.getEvents(streamId);
    
    for (const event of events) {
      await handler(event);
    }
  }

  async getSnapshot(streamId: string): Promise<any> {
    const events = await this.getEvents(streamId);
    
    // Rebuild state from events
    let state: any = {};
    
    for (const event of events) {
      state = this.applyEvent(state, event);
    }
    
    return state;
  }

  private applyEvent(state: any, event: Event): any {
    // Apply event to state based on event type
    switch (event.type) {
      case "created":
        return { ...event.data, created: true };
      case "updated":
        return { ...state, ...event.data };
      case "deleted":
        return { ...state, deleted: true };
      default:
        return state;
    }
  }
}

// Usage
const store = new EventStore();

// Append events
await store.appendEvent("order:123", "OrderCreated", {
  items: ["item1", "item2"],
  total: 100,
});

await store.appendEvent("order:123", "ItemAdded", {
  item: "item3",
});

await store.appendEvent("order:123", "OrderConfirmed", {
  confirmedAt: Date.now(),
});

// Replay events
await store.replay("order:123", (event) => {
  console.log(`Event: ${event.type}`, event.data);
});

// Get current snapshot
const currentState = await store.getSnapshot("order:123");
console.log("Current state:", currentState);

import fdb, { FDBError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function handleFDBErrors() {
  try {
    await db.doTransaction(async (tn) => {
      tn.set("key", "value");
    });
  } catch (error) {
    if (error instanceof FDBError) {
      switch (error.code) {
        case 1007: // Transaction too old
          console.error("Transaction took too long - increase timeout");
          break;
        
        case 1009: // Request for future version
          console.error("Clock skew detected - check system time");
          break;
        
        case 1020: // Not committed (transaction may have succeeded)
          console.error("Commit status unknown - check if data was written");
          break;
        
        case 1021: // Transaction cancelled
          console.error("Transaction was cancelled");
          break;
        
        case 1025: // Transaction timed out
          console.error("Operation exceeded timeout limit");
          break;
        
        case 2017: // Transaction too large
          console.error("Transaction size exceeds limit - split into smaller transactions");
          break;
        
        default:
          console.error(`FDB Error ${error.code}: ${error.message}`);
      }
    } else {
      console.error("Non-FDB error:", error);
    }
  }
}

import fdb, { FDBError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function handleConflicts() {
  let attempts = 0;
  const maxAttempts = 5;

  while (attempts < maxAttempts) {
    try {
      const result = await db.doTransaction(async (tn) => {
        attempts++;
        
        const value = await tn.get("counter");
        const count = parseInt(value?.toString() || "0");
        
        // Simulate some processing
        await new Promise(resolve => setTimeout(resolve, 10));
        
        tn.set("counter", (count + 1).toString());
        return count + 1;
      });
      
      console.log(`Success after ${attempts} attempts:`, result);
      return result;
    } catch (error) {
      if (error instanceof FDBError && error.code === 1007) {
        console.log(`Attempt ${attempts} failed with conflict, retrying...`);
        if (attempts >= maxAttempts) {
          throw new Error(`Failed after ${maxAttempts} attempts`);
        }
        // doTransaction handles retry automatically, but showing manual retry for illustration
      } else {
        throw error;
      }
    }
  }
}

import fdb, { FDBError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function handleTimeouts() {
  try {
    await db.doTransaction(async (tn) => {
      // Long-running operation
      for await (const batch of tn.getRangeBatch("data:", "data:~")) {
        // Process batch
        await processBatch(batch);
      }
    }, {
      timeout: 30000, // 30 second timeout
    });
  } catch (error) {
    if (error instanceof FDBError && error.code === 1025) {
      console.error("Transaction timed out");
      
      // Strategies to fix:
      // 1. Increase timeout
      // 2. Split into smaller transactions
      // 3. Use snapshot reads where possible
      // 4. Optimize query performance
    }
    throw error;
  }
}

async function processBatch(batch: any) {
  // Batch processing logic
}

import fdb, { FDBError } from "foundationdb";

async function handleNetworkErrors() {
  fdb.setAPIVersion(620);
  
  try {
    const db = fdb.open("/path/to/fdb.cluster");
    
    await db.doTransaction(async (tn) => {
      tn.set("key", "value");
    });
  } catch (error) {
    if (error instanceof FDBError) {
      if (error.code === 1031) {
        console.error("Cannot connect to cluster - check network and cluster file");
      } else if (error.code === 1032) {
        console.error("Cluster file invalid or corrupted");
      } else if (error.code === 2501) {
        console.error("No coordinators available - check FDB cluster health");
      }
    }
    throw error;
  }
}

import fdb, { directory, DirectoryError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function handleDirectoryErrors() {
  try {
    // Try to create existing directory
    const dir = await directory.create(db, ["myapp", "users"]);
  } catch (error) {
    if (error instanceof DirectoryError) {
      console.error("Directory operation failed:", error.message);
      
      // Check specific error messages
      if (error.message.includes("already exists")) {
        console.log("Directory exists, opening instead");
        const dir = await directory.open(db, ["myapp", "users"]);
      } else if (error.message.includes("does not exist")) {
        console.log("Directory missing, creating");
        const dir = await directory.create(db, ["myapp", "users"]);
      } else if (error.message.includes("layer mismatch")) {
        console.error("Directory layer type mismatch");
      }
    }
    throw error;
  }
}

import fdb, { FDBError } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function safeOperation<T>(
  operation: () => Promise<T>,
  fallback?: T
): Promise<T | undefined> {
  try {
    return await operation();
  } catch (error) {
    if (error instanceof FDBError) {
      console.error(`FDB Error ${error.code}:`, error.message);
      
      // Return fallback for specific errors
      if (error.code === 1025 || error.code === 1007) {
        console.log("Using fallback value due to transient error");
        return fallback;
      }
    }
    
    // Re-throw non-recoverable errors
    throw error;
  }
}

// Usage
const value = await safeOperation(
  async () => await db.get("config:setting"),
  Buffer.from("default-value")
);

// With retry wrapper
async function withGracefulRetry<T>(
  operation: () => Promise<T>,
  maxRetries = 3
): Promise<T> {
  let lastError: Error;
  
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await operation();
    } catch (error) {
      lastError = error as Error;
      
      if (error instanceof FDBError) {
        // Don't retry fatal errors
        if ([1031, 1032, 2501].includes(error.code)) {
          throw error;
        }
      }
      
      // Exponential backoff
      await new Promise(resolve => 
        setTimeout(resolve, Math.pow(2, i) * 100)
      );
    }
  }
  
  throw new Error(`Failed after ${maxRetries} retries: ${lastError!.message}`);
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Problem: Large transaction with many operations
async function slowTransaction() {
  await db.doTransaction(async (tn) => {
    // Thousands of operations in single transaction
    for (let i = 0; i < 10000; i++) {
      tn.set(`key:${i}`, `value:${i}`);
    }
  });
}

// Solution: Split into smaller transactions
async function fastTransactions() {
  const batchSize = 100;
  
  for (let i = 0; i < 10000; i += batchSize) {
    await db.doTransaction(async (tn) => {
      for (let j = i; j < i + batchSize && j < 10000; j++) {
        tn.set(`key:${j}`, `value:${j}`);
      }
    });
  }
}

// Solution: Use appropriate transaction options
await db.doTransaction(async (tn) => {
  // Process data
}, {
  timeout: 30000,
  size_limit: 50000000,
});

// Problem: Many transactions competing for same keys
async function highConflict() {
  await Promise.all(
    Array.from({ length: 100 }, () =>
      db.doTransaction(async (tn) => {
        const value = await tn.get("counter");
        const count = parseInt(value?.toString() || "0");
        tn.set("counter", (count + 1).toString());
      })
    )
  );
}

// Solution: Use atomic operations
async function lowConflict() {
  const delta = Buffer.allocUnsafe(8);
  delta.writeBigInt64LE(1n, 0);
  
  await Promise.all(
    Array.from({ length: 100 }, () =>
      db.add("counter", delta)
    )
  );
}

// Solution: Shard hot keys
class ShardedCounter {
  constructor(private db: typeof db, private shards = 10) {}
  
  async increment() {
    const shard = Math.floor(Math.random() * this.shards);
    const delta = Buffer.allocUnsafe(8);
    delta.writeBigInt64LE(1n, 0);
    await this.db.add(`counter:${shard}`, delta);
  }
  
  async getTotal(): Promise<number> {
    let total = 0;
    for (let i = 0; i < this.shards; i++) {
      const value = await this.db.get(`counter:${i}`);
      if (value) {
        total += Number(value.readBigInt64LE(0));
      }
    }
    return total;
  }
}

// Problem: Loading too much data at once
async function highMemory() {
  const allData = await db.getRangeAll("data:", "data:~");
  // Process huge dataset - may cause OOM
}

// Solution: Use streaming with batches
async function lowMemory() {
  for await (const batch of db.getRangeBatch("data:", "data:~")) {
    // Process one batch at a time
    await processBatch(batch);
  }
}

// Solution: Use appropriate streaming mode
import { StreamingMode } from "foundationdb";

async function optimizedStreaming() {
  for await (const batch of db.getRangeBatch("data:", "data:~", {
    streamingMode: StreamingMode.Small, // Smaller batches
  })) {
    await processBatch(batch);
  }
}

async function processBatch(batch: any) {
  // Process batch
}

import fdb from "foundationdb";

// Check 1: Verify cluster file
console.log("Checking cluster file...");
try {
  const clusterFile = "/etc/foundationdb/fdb.cluster";
  const fs = require("fs");
  const content = fs.readFileSync(clusterFile, "utf8");
  console.log("Cluster file content:", content);
} catch (error) {
  console.error("Cannot read cluster file:", error);
}

// Check 2: Test connection
fdb.setAPIVersion(620);
try {
  const db = fdb.open();
  await db.get("test");
  console.log("Connection successful");
} catch (error) {
  console.error("Connection failed:", error);
}

// Check 3: Verify network configuration
fdb.configNetwork({
  trace_enable: "./fdb-traces",
  trace_format: "json",
});

// Check traces for connection errors

// Diagnostic: Check transaction size
await db.doTransaction(async (tn) => {
  // Perform operations
  
  const size = tn.getApproximateSize();
  console.log("Transaction size:", size);
  
  if (size > 5000000) {
    console.warn("Transaction size large, may timeout");
  }
});

// Solution: Increase timeout or split transaction
db.setNativeOptions({
  transaction_timeout: 30000, // 30 seconds
});

// Or per-transaction
await db.doTransaction(async (tn) => {
  // Operations
}, {
  timeout: 60000, // 60 seconds
});

// Problem: Watch created outside transaction
// const watch = db.watch("key"); // ERROR

// Solution: Create watch in transaction
const watch = await db.doTransaction(async (tn) => {
  return tn.watch("key");
});

// Problem: Awaiting watch inside transaction
await db.doTransaction(async (tn) => {
  const watch = tn.watch("key");
  // await watch.promise; // DEADLOCK!
  return watch;
}).then(async (watch) => {
  await watch.promise; // Correct
});

// Problem: Too many watches
db.setNativeOptions({
  max_watches: 20000, // Increase limit
});

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Problem: Writing with one encoder, reading with another
await db.withValueEncoding(fdb.encoders.json)
  .set("key", { value: 123 });

const wrong = await db.withValueEncoding(fdb.encoders.string)
  .get("key"); // Wrong encoding!

// Solution: Consistent encoder usage
const jsonDb = db.withValueEncoding(fdb.encoders.json);

await jsonDb.set("key", { value: 123 });
const correct = await jsonDb.get("key"); // { value: 123 }

// Solution: Document encoding choices
class UserStore {
  private db: ReturnType<typeof fdb.open>;
  
  constructor(db: ReturnType<typeof fdb.open>) {
    this.db = db
      .at("users:")
      .withKeyEncoding(fdb.encoders.string)
      .withValueEncoding(fdb.encoders.json);
  }
  
  async save(id: string, user: any) {
    await this.db.set(id, user);
  }
  
  async load(id: string) {
    return await this.db.get(id);
  }
}

// Problem: Not using transactions properly
async function lostUpdate() {
  const value = await db.get("counter");
  const count = parseInt(value?.toString() || "0");
  // Another process might update here!
  await db.set("counter", (count + 1).toString());
}

// Solution: Use transactions
async function safeUpdate() {
  await db.doTransaction(async (tn) => {
    const value = await tn.get("counter");
    const count = parseInt(value?.toString() || "0");
    tn.set("counter", (count + 1).toString());
  });
}

// Better: Use atomic operations
const delta = Buffer.allocUnsafe(8);
delta.writeBigInt64LE(1n, 0);
await db.add("counter", delta);

import fdb, { directory } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Problem: Racing directory creation
async function racingCreation() {
  try {
    const dir = await directory.create(db, ["myapp", "tenant"]);
  } catch (error) {
    // Second process fails
  }
}

// Solution: Use createOrOpen
async function safeCreation() {
  const dir = await directory.createOrOpen(db, ["myapp", "tenant"]);
  // Works for all processes
}

// Solution: Handle errors gracefully
async function robustCreation() {
  try {
    const dir = await directory.create(db, ["myapp", "tenant"]);
  } catch (error) {
    if (error.message.includes("already exists")) {
      const dir = await directory.open(db, ["myapp", "tenant"]);
      return dir;
    }
    throw error;
  }
}

import fdb from "foundationdb";

// Enable detailed tracing
fdb.configNetwork({
  trace_enable: "./fdb-traces",
  trace_format: "json",
  trace_log_group: "myapp",
});

fdb.setAPIVersion(620);
const db = fdb.open();

// Check traces at ./fdb-traces/*.json
// Look for: errors, warnings, slow_task events

import fdb, { TransactionOptionCode } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

await db.doTransaction(async (tn) => {
  // Enable transaction logging
  tn.setOption(TransactionOptionCode.DebugTransactionIdentifier, "my-tx-123");
  tn.setOption(TransactionOptionCode.LogTransaction);
  
  // Perform operations
  tn.set("key", "value");
}, {
  debug_transaction_identifier: "test-transaction",
  log_transaction: true,
});

// Check traces for transaction details

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

async function profileOperation() {
  const start = Date.now();
  
  await db.doTransaction(async (tn) => {
    const opStart = Date.now();
    const value = await tn.get("key");
    console.log(`Get took ${Date.now() - opStart}ms`);
    
    const setStart = Date.now();
    tn.set("key", "value");
    console.log(`Set took ${Date.now() - setStart}ms`);
  });
  
  console.log(`Total transaction: ${Date.now() - start}ms`);
}

// Monitor transaction sizes
await db.doTransaction(async (tn) => {
  for (let i = 0; i < 1000; i++) {
    tn.set(`key:${i}`, `value:${i}`);
    
    if (i % 100 === 0) {
      console.log(`Size at ${i}:`, tn.getApproximateSize());
    }
  }
});

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Bad: Long-running computation in transaction
await db.doTransaction(async (tn) => {
  const data = await tn.get("data");
  
  // Expensive computation
  const result = await expensiveComputation(data);
  
  tn.set("result", result);
});

// Good: Compute outside transaction
const data = await db.get("data");
const result = await expensiveComputation(data);

await db.doTransaction(async (tn) => {
  tn.set("result", result);
});

// Bad: Read-modify-write
await db.doTransaction(async (tn) => {
  const value = await tn.get("counter");
  const count = parseInt(value?.toString() || "0");
  tn.set("counter", (count + 1).toString());
});

// Good: Atomic add
const delta = Buffer.allocUnsafe(8);
delta.writeBigInt64LE(1n, 0);
await db.add("counter", delta);

await db.doTransaction(async (tn) => {
  // Critical read (causes conflicts)
  const critical = await tn.get("critical:data");
  
  // Non-critical read (no conflicts)
  const metadata = await tn.snapshot().get("metadata");
  
  // Write based on critical data
  tn.set("result", processData(critical));
});

// Bad: Multiple transactions
await db.set("user:alice:name", "Alice");
await db.set("user:alice:email", "alice@example.com");
await db.set("user:alice:age", "30");

// Good: Single transaction
await db.doTransaction(async (tn) => {
  tn.set("user:alice:name", "Alice");
  tn.set("user:alice:email", "alice@example.com");
  tn.set("user:alice:age", "30");
});

async function processLargeDataset() {
  let startKey = "data:";
  const chunkSize = 1000;
  
  while (true) {
    const chunk = await db.getRangeAll(
      startKey,
      "data:~",
      { limit: chunkSize }
    );
    
    if (chunk.length === 0) break;
    
    await db.doTransaction(async (tn) => {
      for (const [key, value] of chunk) {
        // Process item
        tn.set(key.toString() + ":processed", "true");
      }
    });
    
    if (chunk.length < chunkSize) break;
    startKey = chunk[chunk.length - 1][0].toString() + "\x00";
  }
}

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Good: Hierarchical structure
await db.set("app:users:alice:profile", "...");
await db.set("app:users:alice:settings", "...");
await db.set("app:users:bob:profile", "...");
await db.set("app:orders:12345:items", "...");

// Query all user data
const aliceData = await db.getRangeAllStartsWith("app:users:alice:");

// Query all orders
const orders = await db.getRangeAllStartsWith("app:orders:");

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open().withKeyEncoding(fdb.encoders.tuple);

// Store with composite keys
await db.set(["user", "alice", "profile"], "data");
await db.set(["user", "alice", "settings"], "data");
await db.set(["order", 12345, "items"], "data");

// Query by prefix
const aliceData = await db.getRangeAllStartsWith(["user", "alice"]);
const orders = await db.getRangeAllStartsWith(["order"]);

import fdb, { directory } from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Create tenant directories
const tenant1 = await directory.createOrOpen(db, ["tenants", "acme"]);
const tenant2 = await directory.createOrOpen(db, ["tenants", "techcorp"]);

// Scoped databases
const acmeDb = db.at(tenant1);
const techcorpDb = db.at(tenant2);

// Isolated data
await acmeDb.set("data", "Acme data");
await techcorpDb.set("data", "Techcorp data");

async function withRetry<T>(
  operation: () => Promise<T>,
  maxRetries = 5,
  baseDelay = 100
): Promise<T> {
  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await operation();
    } catch (error) {
      if (attempt === maxRetries) throw error;
      
      const delay = baseDelay * Math.pow(2, attempt);
      await new Promise(resolve => setTimeout(resolve, delay));
    }
  }
  throw new Error("Should not reach here");
}

const result = await withRetry(() => db.get("key"));

class MetricsCollector {
  private metrics = {
    transactionCount: 0,
    errorCount: 0,
    avgDuration: 0,
  };

  async trackTransaction<T>(
    operation: () => Promise<T>
  ): Promise<T> {
    const start = Date.now();
    
    try {
      const result = await operation();
      this.metrics.transactionCount++;
      
      const duration = Date.now() - start;
      this.metrics.avgDuration = 
        (this.metrics.avgDuration * (this.metrics.transactionCount - 1) + duration) /
        this.metrics.transactionCount;
      
      return result;
    } catch (error) {
      this.metrics.errorCount++;
      throw error;
    }
  }

  getMetrics() {
    return { ...this.metrics };
  }
}

const metrics = new MetricsCollector();

await metrics.trackTransaction(() => 
  db.doTransaction(async (tn) => {
    tn.set("key", "value");
  })
);

console.log("Metrics:", metrics.getMetrics());

import fdb from "foundationdb";

fdb.setAPIVersion(620);
const db = fdb.open();

// Use try-finally for cleanup
try {
  await db.set("key", "value");
} finally {
  db.close();
  fdb.stopNetworkSync();
}

// Handle graceful shutdown
process.on("SIGTERM", () => {
  console.log("Shutting down...");
  db.close();
  fdb.stopNetworkSync();
  process.exit(0);
});

process.on("SIGINT", () => {
  console.log("Interrupted, cleaning up...");
  db.close();
  fdb.stopNetworkSync();
  process.exit(0);
});

class DatabasePool {
  private static db: ReturnType<typeof fdb.open> | null = null;

  static initialize() {
    if (!this.db) {
      fdb.setAPIVersion(620);
      this.db = fdb.open();
      this.db.setNativeOptions({
        transaction_timeout: 10000,
        max_watches: 20000,
      });
    }
  }

  static getDatabase() {
    if (!this.db) {
      throw new Error("Database not initialized");
    }
    return this.db;
  }

  static shutdown() {
    if (this.db) {
      this.db.close();
      fdb.stopNetworkSync();
      this.db = null;
    }
  }
}

// Initialize once at startup
DatabasePool.initialize();

// Use throughout application
const db = DatabasePool.getDatabase();
await db.set("key", "value");

// Shutdown on exit
process.on("exit", () => {
  DatabasePool.shutdown();
});