void waitForRead(WriteEntry e) {
    boolean interrupted = false;
    int count = 0;
    synchronized (readWaiters) {
      while (readPoint.get() < e.getWriteNumber()) {
        if (count % 100 == 0 && count > 0) {
          long totalWaitTillNow = READPOINT_ADVANCE_WAIT_TIME * count;
          LOG.warn("STUCK for : " + totalWaitTillNow + " millis. " + this);
        }
        count++;
        try {
          readWaiters.wait(READPOINT_ADVANCE_WAIT_TIME);
        } catch (InterruptedException ie) {
          // We were interrupted... finish the loop -- i.e. cleanup --and then
          // on our way out, reset the interrupt flag.
          interrupted = true;
        }
      }
    }
    if (interrupted) {
      Thread.currentThread().interrupt();
    }
  }
Wait for the global readPoint to advance up to the passed in write entry number.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MultiVersionConcurrencyControl.java