public TPushPipeMetaRespExceptionMessage handleDropPipe(final String pipeName) {
    acquireWriteLock();
    try {
      return handleDropPipeInternal(pipeName);
    } finally {
      releaseWriteLock();
    }
  }
State transition diagram of a pipe task:

<p><code>
|----------------|                     |---------| --> stop  pipe --> |---------|                   |---------|
| initial status | --> create pipe --> | RUNNING |                    | STOPPED | --> drop pipe --> | DROPPED |
|----------------|                     |---------| <-- start pipe <-- |---------|                   |---------|
                                            |                                                            |
                                            | ----------------------> drop pipe -----------------------> |
</code>

<p>Other transitions are not allowed, will be ignored when received in the {@link PipeTaskAgent}.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/agent/task/PipeTaskAgent.java