Shuffle mempool transactions before saving disk cache. (#398)

fixes #397

backend/src/api/common.ts

@@ -71,6 +71,13 @@ export class Common {
        }, ms);
     });
   }
+  
+  static shuffleArray(array: any[]) {
+    for (let i = array.length - 1; i > 0; i--) {
+        const j = Math.floor(Math.random() * (i + 1));
+        [array[i], array[j]] = [array[j], array[i]];
+    }
+  }
 
   static setRelativesAndGetCpfpInfo(tx: TransactionExtended, memPool: { [txid: string]: TransactionExtended }): CpfpInfo {
     const parents = this.findAllParents(tx, memPool);
@@ -129,5 +136,4 @@ export class Common {
     });
     return parents;
   }
-
 }