flushing http cache (#332)

lib/source/cosmosV0-source.js

@@ -1,4 +1,5 @@
-const { RESTDataSource } = require('apollo-datasource-rest')
+const { RESTDataSource, HTTPCache } = require('apollo-datasource-rest')
+const { InMemoryLRUCache } = require('apollo-server-caching')
 const BigNumber = require('bignumber.js')
 const _ = require('lodash')
 const { encodeB32, decodeB32, pubkeyToAddress } = require('../tools')
@@ -17,11 +18,22 @@ class CosmosV0API extends RESTDataSource {
     this.setReducers()
   }
 
+  initialize(config) {
+    this.context = config.context
+    // manually set cache to checking it
+    this.cache = new InMemoryLRUCache()
+    this.httpCache = new HTTPCache(this.cache, this.httpFetch)
+  }
+
   setReducers() {
     this.reducers = require('../reducers/cosmosV0-reducers')
   }
 
   async getRetry(url, intent = 0) {
+    // check cache size, and flush it if it's bigger than something
+    if ((await this.cache.getTotalSize()) > 100000) {
+      await this.cache.flush()
+    }
     // cleareing memoizedResults
     this.memoizedResults.clear()
     try {