How to cache the response in google cloud endpoint?

Question

I'm making an android app which uses google cloud endpoints as the backend. So I'm making request from the app. I want to cache the response of these requests in memory as well as storage.

I want to cache the response on the phone, so that I don't have to make unnecessary repeated network requests.

I searched the internet for some inbuilt solution but couldn't find anything like that in the api provided by google.

There's a total of about 2MB data that I want to cache. This data is spread over 20 end point requests.

What are my best options to implement such a cache?

Answer 1

You can implement an amazing library called android-easy-cache

the sample implementation is shown in my answer here

Answer 2

I'm going to answer my own question so that it can help someone until there's a more clean solution available.

I'm using this library for caching responses: https://github.com/vincentbrison/android-easy-cache

1. GCE result is a GenericJson. Serialize the response using this SerializationUtil

2. Use this code to create DualCache library boilerplate. dualCacheByteArray for caching the response and dualCacheDate for keeping track of time_to_live_for_response

   public static final int APP_CACHE_VERSION = 1;
   public static final String CACHE_ID = "cache_id_string";
   public static final String CACHE_ID_DATE = "cache_id_date";
   public static final int RAM_CACHE_SIZE = 5 * 1024 * 1024; // 5 mb
   public static final int DISK_CACHE_SIZE = 15 * 1024 * 1024; //15 mb
   public static final int RAM_CACHE_SIZE_DATE = 1 * 1024 * 1024; // 5 mb
   public static final int DISK_CACHE_SIZE_DATE = 3 * 1024 * 1024; //15 mb
   
   
   private DualCache<byte[]> dualCacheByteArray;
   private DualCache<Date> dualCacheDate;
   
   public DualCache<byte[]> getDualCacheByteArray() {
   if (dualCacheByteArray == null) {
       dualCacheByteArray = new DualCacheBuilder<byte[]>(Constants.CACHE_ID, Constants.APP_CACHE_VERSION, byte[].class)
               .useReferenceInRam(Constants.RAM_CACHE_SIZE, new SizeOf<byte[]>() {
                   @Override
                   public int sizeOf(byte[] object) {
                       return object.length;
                   }
               })
               .useDefaultSerializerInDisk(Constants.DISK_CACHE_SIZE, true);
       }
       return dualCacheByteArray;
   }
   
   public DualCache<Date> getDualCacheDate() {
   if (dualCache == null) {
       dualCacheDate = new DualCacheBuilder<Date>(Constants.CACHE_ID_DATE, Constants.APP_CACHE_VERSION, Date.class)
               .useReferenceInRam(Constants.RAM_CACHE_SIZE_DATE, new SizeOf<Date>() {
                   @Override
                   public int sizeOf(Date date) {
                       byte[] b = new byte[0];
                       try {
                           ByteArrayOutputStream baos = new ByteArrayOutputStream();
                           ObjectOutputStream oos = new ObjectOutputStream(baos);
                           oos.writeObject(date);
                           oos.flush();
                           byte[] buf = baos.toByteArray();
                           return buf.length;
                       } catch (IOException e) {
                           Log.e("some prob", "error in calculating date size for caching", e);
                       }
                       return sizeOf(date);
                   }
               })
               .useDefaultSerializerInDisk(Constants.DISK_CACHE_SIZE_DATE, true);
       }
       return dualCacheDate;
   }
   

3. Now use the above DualCaches to cache your response.

   getDualCacheByteArray().put(YOUR_RESPONSE_CACHE_KEY, serializedProduct);
   getDualCacheDate().put(YOUR_RESPONSE_CACHE_KEY, new Date());
   

4. Before making a new request using google cloud endpoints, you should check in dual cache if the old response is already present in cache

   public byte[] getCachedGenericJsonByteArray(String key, int cacheExpireTimeInMinutes) {
       Date cachingDate = getDualCacheDate().get(key);
       if(cachingDate!=null) {
           long expirationTime = TimeUnit.MILLISECONDS.convert(cacheExpireTimeInMinutes, TimeUnit.MINUTES);
           long timeElapsedAfterCaching = new Date().getTime() - cachingDate.getTime();
           if (timeElapsedAfterCaching >= expirationTime) {
               //the cached data has expired
               return null;
           } else {
               byte[] cachedGenericJsonByteArray = getDualCacheByteArray().get(key);
               return cachedGenericJsonByteArray;
           }
       } else {
       //result for this key was never cached or is cleared
       return null;
       }
   }
   

if the cached byte array is not null, then deserialize it using SerializationUtil and use it as a cached response, else make a new request from google cloud endpoints

EDIT : Using serialization util may not be necessary in every case as pointed out by Sanket Berde in other answer