Then APIStar stopped to exist as a server and Starlette was created, and was a new better foundation for such a system. That was the final inspiration to build **FastAPI**.

I consider **FastAPI** a "spiritual successor" to APIStar, while improving and increasing the features, typing system, and other parts, based on the learnings from all these previous tools.

///

## Used by **FastAPI** { #used-by-fastapi }

 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

(This is the first released version of the Lesser GPL.  It also counts
 as the successor of the GNU Library Public License, version 2, hence
 the version number 2.1.)

                            Preamble

  The licenses for most software are designed to take away your

/**
 * A builder of {@link LoadingCache} and {@link Cache} instances.
 *
 * <h2>Prefer <a href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a> over Guava's caching
 * API</h2>
 *
 * <p>The successor to Guava's caching API is <a
 * href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a>. Its API is designed to make it a
 * nearly drop-in replacement. Note that it is not available for Android or GWT/J2CL and that it may

/**
 * A builder of {@link LoadingCache} and {@link Cache} instances.
 *
 * <h2>Prefer <a href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a> over Guava's caching
 * API</h2>
 *
 * <p>The successor to Guava's caching API is <a
 * href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a>. Its API is designed to make it a
 * nearly drop-in replacement. Note that it is not available for Android or GWT/J2CL and that it may

### **Kubernetes API**
#### User Provided Extensions

        // Next call should transition to HALF_OPEN
        String result = circuitBreaker.call(() -> "success");
        assertEquals("success", result);
        assertEquals(SimpleCircuitBreaker.State.HALF_OPEN, circuitBreaker.getState());
    }

    @Test
    @DisplayName("Test circuit closes after success threshold in HALF_OPEN")
    void testCircuitClosesAfterSuccessThreshold() throws Exception {

        // First success should transition to HALF_OPEN
        String result = circuitBreaker.executeWithCircuitBreaker(() -> "success 0");
        assertEquals("success 0", result, "Should execute in HALF_OPEN");
        assertEquals(State.HALF_OPEN, circuitBreaker.getState(), "Should be in HALF_OPEN after first success");

        // Need successThreshold (2) consecutive successes to close the circuit

        if (current == State.HALF_OPEN) {
            int successes = halfOpenSuccesses.incrementAndGet();
            if (successes >= successThreshold) {
                if (state.compareAndSet(State.HALF_OPEN, State.CLOSED)) {
                    stateChangeTime.set(System.currentTimeMillis());
                    log.info("Circuit breaker {} closed after {} successful attempts", name, successes);
                }
            }
        }

        if (currentState == State.HALF_OPEN) {
            int successes = successCount.incrementAndGet();
            log.debug("[{}] Success in HALF_OPEN state ({}/{})", name, successes, successThreshold);

            if (successes >= successThreshold) {
                log.info("[{}] Circuit breaker closing after {} successful attempts", name, successes);
                transitionTo(State.CLOSED);
            }

 *       order)
 * </ul>
 *
 * <p>{@code ValueGraph}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external
 * documentation</a> for details.
 *
 * <p>Examples of use:
 *
 * {@snippet :
 * // Building a mutable value graph