{* ../../docs_src/extending_openapi/tutorial001.py hl[22:24] *}

### Cache the OpenAPI schema

You can use the property `.openapi_schema` as a "cache", to store your generated schema.

That way, your application won't have to generate the schema every time a user opens your API docs.

It will be generated only once, and then the same cached schema will be used for the next requests.

		return nil
	})
	if err != nil {
		return cache, toStorageErr(err)
	}
	if final == nil {
		return cache, errors.New("no final cache")
	}
	return *final, nil
}

func (client *storageRESTClient) GetDiskID() (string, error) {
	if !client.IsOnlineWS() {
		// make sure to check if the disk is offline, since the underlying
		// value is cached we should attempt to invalidate it if such calls

        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }

        // Lifecycles cannot be cached as extensions might add custom lifecycles later in the execution.
        try {
            return registry != null

     *
     * @see Function
     * @see Optional
     * @see HashMap#computeIfAbsent(Object, Function)
     */
    static Function<String, String> memoize(Function<String, String> callback) {
        Map<String, Optional<String>> cache = new HashMap<>();
        return s -> cache.computeIfAbsent(s, v -> Optional.ofNullable(callback.apply(v)))

    firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

    firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

)

// metricsCache - cache for metrics.
//
// When serving metrics, this cache is passed to the MetricsLoaderFn.
//
// This cache is used for metrics that would result in network/storage calls.
type metricsCache struct {
	dataUsageInfo       *cachevalue.Cache[DataUsageInfo]
	esetHealthResult    *cachevalue.Cache[HealthResult]
	driveMetrics        *cachevalue.Cache[storageMetrics]

		if len(dui.BucketsUsage) > 0 {
			internalLogOnceIf(GlobalContext, fmt.Errorf("unable to retrieve usage information for bucket: %s, relying on older value cached in-memory: err(%v)", bucket, err), "bucket-usage-cache-"+bucket)
		} else {

	b.Run("uncached", func(b *testing.B) {
		fn := authenticateNode
		b.ResetTimer()
		b.ReportAllocs()
		for i := 0; i < b.N; i++ {
			fn(creds.AccessKey, creds.SecretKey)
		}
	})
	b.Run("cached", func(b *testing.B) {
		fn := newCachedAuthToken()
		b.ResetTimer()
		b.ReportAllocs()
		for i := 0; i < b.N; i++ {
			fn()
		}
	})

/**
 * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>