code: @Trivial
      protected synchronized int size(int bufferType) {
          if (bufferType == EXPLICIT_BUFFER) {
              return this.explicitBuffer.size();
          } else if (bufferType == SCAN_BUFFER) {
              return this.scanBuffer.size();
          } else if (bufferType == GC_BUFFER) {
              return this.garbageCollectorBuffer.size();
          }
          return 0;
      }
docs: Call this method to get the size from one of invalidation buffers.
  
  @param eventAlreadyFired
  - boolean to select which invalidation buffer is used to get the size.
  @return int - the size.