synchronized HttpException createUpstreamUnavailableException()

in server/src/main/java/com/epam/aidial/core/server/upstream/TieredBalancer.java [74:107]

30 lines of code
9 McCabe index (conditional complexity)


    synchronized HttpException createUpstreamUnavailableException() {
        int busyUpstreamsCount = 0;
        for (UpstreamState upstreamState : upstreamStates) {
            if (upstreamState.getStatus() == HttpStatus.TOO_MANY_REQUESTS) {
                busyUpstreamsCount++;
            }
        }
        if (busyUpstreamsCount == upstreamStates.size()) {
            long replyAfter = -1;
            for (UpstreamState upstreamState : upstreamStates) {
                if (upstreamState.getStatus() == HttpStatus.TOO_MANY_REQUESTS
                        && upstreamState.getSource() == UpstreamState.RetryAfterSource.UPSTREAM) {
                    if (replyAfter == -1) {
                        replyAfter = upstreamState.getRetryAfter();
                    } else {
                        replyAfter = Math.min(replyAfter, upstreamState.getRetryAfter());
                    }
                }
            }
            String errorMessage = "Service is not available";
            if (replyAfter == -1) {
                // no upstreams with the requested source
                // we don't provide reply-after header
                return new HttpException(HttpStatus.SERVICE_UNAVAILABLE, errorMessage);
            } else {
                // according to the spec: A non-negative decimal integer indicating the seconds to delay after the response is received.
                long replyAfterInSeconds = Math.max(0, TimeUnit.MILLISECONDS.toSeconds(replyAfter - System.currentTimeMillis()));
                return new HttpException(HttpStatus.SERVICE_UNAVAILABLE, errorMessage,
                        Map.of(HttpHeaders.RETRY_AFTER.toString(), Long.toString(replyAfterInSeconds)));
            }
        }
        // default error - no route
        return new HttpException(HttpStatus.BAD_GATEWAY, "No route");
    }