public boolean isFull() {
        // when free memory less than certain value, consider it's full
        return cache.estimatedSize() > 0 && MemoryLimitCalculator.maxAvailable() < maxFreeMemory;
    }
whether to full.

@return true if it's full
shenyu-common/src/main/java/org/apache/shenyu/common/cache/MemorySafeWindowTinyLFUMap.java