handle-resource-timeouts

description: Always set timeouts on resource acquisition to prevent indefinite waits. globs: "**/*.ts" alwaysApply: true

Handle Resource Timeouts

Rule: Always set timeouts on resource acquisition to prevent indefinite waits.

Example

import { Effect, Duration, Scope } from "effect"

// ============================================
// 1. Define a resource with slow acquisition
// ============================================

interface Connection {
  readonly id: string
  readonly query: (sql: string) => Effect.Effect<unknown>
}

const acquireConnection = Effect.gen(function* () {
  yield* Effect.log("Attempting to connect...")
  
  // Simulate slow connection
  yield* Effect.sleep("2 seconds")
  
  const connection: Connection = {
    id: crypto.randomUUID(),
    query: (sql) => Effect.succeed({ rows: [] }),
  }
  
  yield* Effect.log(`Connected: ${connection.id}`)
  return connection
})

const releaseConnection = (conn: Connection) =>
  Effect.log(`Released: ${conn.id}`)

// ============================================
// 2. Timeout on acquisition
// ============================================

const acquireWithTimeout = acquireConnection.pipe(
  Effect.timeout("1 second"),
  Effect.catchTag("TimeoutException", () =>
    Effect.fail(new Error("Connection timeout - database unreachable"))
  )
)

// ============================================
// 3. Timeout on usage
// ============================================

const queryWithTimeout = (conn: Connection, sql: string) =>
  conn.query(sql).pipe(
    Effect.timeout("5 seconds"),
    Effect.catchTag("TimeoutException", () =>
      Effect.fail(new Error(`Query timeout: ${sql}`))
    )
  )

// ============================================
// 4. Full resource lifecycle with timeouts
// ============================================

const useConnectionWithTimeouts = Effect.acquireRelease(
  acquireWithTimeout,
  releaseConnection
).pipe(
  Effect.flatMap((conn) =>
    Effect.gen(function* () {
      yield* Effect.log("Running queries...")
      
      // Each query has its own timeout
      const result1 = yield* queryWithTimeout(conn, "SELECT 1")
      const result2 = yield* queryWithTimeout(conn, "SELECT 2")
      
      return [result1, result2]
    })
  ),
  Effect.scoped
)

// ============================================
// 5. Timeout on entire operation
// ============================================

const entireOperationWithTimeout = useConnectionWithTimeouts.pipe(
  Effect.timeout("10 seconds"),
  Effect.catchTag("TimeoutException", () =>
    Effect.fail(new Error("Entire operation timed out"))
  )
)

// ============================================
// 6. Run with different scenarios
// ============================================

const program = Effect.gen(function* () {
  yield* Effect.log("=== Testing timeouts ===")
  
  const result = yield* entireOperationWithTimeout.pipe(
    Effect.catchAll((error) =>
      Effect.gen(function* () {
        yield* Effect.logError(`Failed: ${error.message}`)
        return []
      })
    )
  )
  
  yield* Effect.log(`Result: ${JSON.stringify(result)}`)
})

Effect.runPromise(program)