class_docstr: A rendezvous class for different actor/task processes to meet.
  
  To initialize an NCCL collective communication group, different
  actors/tasks spawned in Ray in a collective group needs to meet
  each other to synchronize the NCCLUniqueID. This class guarantees
  they meet via the NCCLUniqueIDStore, initialized on the rank=0
  process.
  
  Args:
      store_key: the unique store key, usually as a concatanation
          of group_name and communicator key. See `get_nccl_communicator`
          for more details.
docstr: Get the NCCLUniqueID from the store through Ray.
  
  Args:
      timeout_s: timeout in seconds.
  
  Return:
      uid: the NCCLUniqueID if successful.
docstr_tok: ["Get","the","NCCLUniqueID","from","the","store","through","Ray",".","Args",":","timeout_s",":","timeout","in","seconds",".","Return",":","uid",":","the","NCCLUniqueID","if","successful","."]
code: def get_nccl_id(self, timeout_s=180):
      """Get the NCCLUniqueID from the store through Ray.
  
      Args:
          timeout_s: timeout in seconds.
  
      Return:
          uid: the NCCLUniqueID if successful.
      """
      if not self._store:
          raise ValueError("Rendezvous store is not setup.")
      uid = None
      timeout_delta = datetime.timedelta(seconds=timeout_s)
      elapsed = datetime.timedelta(seconds=0)
      start_time = datetime.datetime.now()
      while elapsed < timeout_delta:
          uid = ray.get(self._store.get_id.remote())
          if not uid:
              time.sleep(1)
              elapsed = datetime.datetime.now() - start_time
              continue
          break
      if not uid:
          raise RuntimeError(
              "Unable to get the NCCLUniqueID from the store."
          )
      return uid
  
imports: import logging
  import datetime
  import time
  import ray
  import cupy
  from ray.util.collective.const import ENV
  from ray.util.collective.collective_group import nccl_util
  from ray.util.collective.collective_group.base_collective_group import BaseGroup
  from ray.util.collective.const import get_store_name
  from ray.util.collective.types import AllReduceOptions, BarrierOptions, Backend, ReduceOptions, BroadcastOptions, AllGatherOptions, ReduceScatterOptions, SendOptions, RecvOptions
  from ray.util.collective.collective_group.cuda_stream import get_stream_pool
label_desc: Use image node_id 4 for calling the Rendezvous obj's underlying member method code with example usage: obj.get_nccl_id(timeout_s) and returns: uid