private boolean isInExcess() {
        return inflight.get() - delayedCount.get() > throttler.targetInflight();
    }
Controls request execution and retries.

This class has all control flow for throttling and dispatching HTTP requests to an injected
HTTP {@link Cluster}, including error handling and retries through a {@link RetryStrategy},
a {@link CircuitBreaker} mechanism, and a {@link Throttler} for optimal load.

Dispatch to the provided {@link Cluster} is done by a single dispatch thread. If dispatch ever throws,
or the circuit breaker ever opens completely, the dispatch thread stops and all execution shuts down.
This is done through {@link #destroy()}, which when called also ensures all enqueued operations are
promptly completed, in addition to releasing any resources (threads, and in the provided cluster}.

@author jonmv
vespa-feed-client/src/main/java/ai/vespa/feed/client/impl/HttpRequestStrategy.java