text: // Copyright 2014 Cloudera, Inc.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #include "kudu/fs/block_manager.h"
  #include "kudu/util/flag_tags.h"
  #include "kudu/util/metrics.h"
  
  // The default value is optimized for the case where:
  // 1. the cfile blocks are colocated with the WALs.
  // 2. The underlying hardware is a spinning disk.
  // 3. The underlying filesystem is either XFS or EXT4.
  // 4. cfile_do_on_finish is 'close' (see cfile/cfile_writer.cc).
  //
  // When all conditions hold, this value ensures low latency for WAL writes.
  DEFINE_bool(block_coalesce_close, false,
              "Coalesce synchronization of data during CloseBlocks()");
  TAG_FLAG(block_coalesce_close, experimental);
  
  DEFINE_bool(block_manager_lock_dirs, true,
              "Lock the data block directories to prevent concurrent usage. "
              "Note that read-only concurrent usage is still allowed.");
  TAG_FLAG(block_manager_lock_dirs, unsafe);
  
  namespace kudu {
  namespace fs {
  
  const char* BlockManager::kInstanceMetadataFileName = "block_manager_instance";
  
  BlockManagerOptions::BlockManagerOptions()
    : read_only(false) {
  }
  
  BlockManagerOptions::~BlockManagerOptions() {
  }
  
  } // namespace fs
  } // namespace kudu
  