fix the memory allocation of eth_newBlockFilter

Author: 317787106

framework/src/main/java/org/tron/core/services/jsonrpc/TronJsonRpcImpl.java

@@ -117,6 +117,11 @@ public enum RequestSource {
           .maximumSize(300_000L) // 300s * tps(1000) * 1 log/tx ≈ 300_000
           .expireAfterWrite(EXPIRE_SECONDS, TimeUnit.SECONDS)
           .recordStats().build(); //LRU cache
+  private static final Cache<String, String> blockHashCache =
+      CacheBuilder.newBuilder()
+          .maximumSize(60_000L) // 300s * 200 block/s when syncing
+          .expireAfterWrite(EXPIRE_SECONDS, TimeUnit.SECONDS)
+          .recordStats().build(); //LRU cache
   /**
    * for log filter in Full Json-RPC
    */
@@ -194,7 +199,16 @@ public static void handleBLockFilter(BlockFilterCapsule blockFilterCapsule) {
         it.remove();
         continue;
       }
-      entry.getValue().getResult().add(ByteArray.toJsonHex(blockFilterCapsule.getBlockHash()));
+      String blockHash = ByteArray.toJsonHex(blockFilterCapsule.getBlockHash());
+      String finalBlockHash = blockHash;
+      try {
+        // compare with hashcode() first, then with equals(). If not exist, put it.
+        blockHash = blockHashCache.get(blockHash, () -> finalBlockHash);
+      } catch (ExecutionException e) {
+        logger.error("Getting/loading blockHash from cache fails", e);// never happen
+        continue;
+      }
+      entry.getValue().getResult().add(blockHash);
     }
   }