< Context >
Since `HttpAysncClient` is non-blocking, but it's operation to memcached at `MemcachedHttpCacheStorage` layer still using blocking I/O manner. Even `spymemcached` client which has non-blocking I/O in nature, but `MemcachedHttpCacheStorage` is using `spymemcached` blocking API.
< Benefit >
If all the way in flow of `HttpAsyncClient` is non-blocking, then it can truely do high concurrency with just a few threads, otherwise, performance will be largely impact by blocking calls since there's only a few threads for serving http requests.
< Code Flow for Blocking manner >
- `org.apache.http.impl.client.cache.memcached.MemcachedHttpCacheStorage#getEntry` -> `final MemcachedCacheEntry mce = reconstituteEntry(client.get(key));`
Should use `net.spy.memcached.MemcachedClient#asyncGet(java.lang.String)`, but then whole API calling structure require big changes.