text: /*************************************************************************
   * Copyright (c) 2015-2020, NVIDIA CORPORATION. All rights reserved.
   *
   * See LICENSE.txt for license information
   ************************************************************************/
  
  #include "channel.h"
  #include "param.h"
  
  ncclResult_t initChannel(struct ncclComm* comm, int channelid) {
    struct ncclChannel* channel = comm->channels+channelid;
    if (channel->id != -1) return ncclSuccess;
    channel->id = channelid;
  
    // Ring index to user rank table.
    NCCLCHECK(ncclCudaCalloc(&channel->ring.devUserRanks, comm->nRanks));
    NCCLCHECK(ncclCalloc(&channel->ring.userRanks, comm->nRanks));
  
    // Communication structures with peers.
    NCCLCHECK(ncclCudaCalloc(&channel->devPeers, comm->nRanks+1)); // The extra one rank is for collnet root (i.e. network)
    NCCLCHECK(ncclCalloc(&channel->peers, comm->nRanks+1));
    for (size_t i=0; i<comm->nRanks+1; ++i) {
      channel->peers[i].send.comm = comm;
      channel->peers[i].recv.comm = comm;
    }
  
    // Per-channel operation list.
    NCCLCHECK(ncclCudaHostCalloc(&channel->collectives, NCCL_MAX_OPS));
    return ncclSuccess;
  }
  
  ncclResult_t freeChannel(struct ncclChannel* channel, int nRanks) {
    if (channel->id == -1) return ncclSuccess;
    // Operation list
    NCCLCHECK(ncclCudaHostFree(channel->collectives));
  
    // Free Ring index to rank tables
    free(channel->ring.userRanks);
    CUDACHECK(cudaFree(channel->ring.devUserRanks));
  
    // Free transport proxy resources
    // Note: free all send resources first due to CollNet arrangement
    for (int r=0; r<nRanks+1; r++) {
      struct ncclPeer* peer = channel->peers+r;
      if (peer->send.transportResources) NCCLCHECK(peer->send.transportComm->free(peer->send.transportResources));
    }
    for (int r=0; r<nRanks+1; r++) {
      struct ncclPeer* peer = channel->peers+r;
      if (peer->recv.transportResources) NCCLCHECK(peer->recv.transportComm->free(peer->recv.transportResources));
    }
  
    // Free the peer structures.
    CUDACHECK(cudaFree(channel->devPeers));
    free(channel->peers);
  
    return ncclSuccess;
  }
  