Java CachedBlock.getMark方法代码示例

import org.apache.hadoop.hdfs.server.namenode.CachedBlock; //导入方法依赖的package包/类
private String findReasonForNotCaching(CachedBlock cblock, 
        BlockInfoContiguous blockInfo) {
  if (blockInfo == null) {
    // Somehow, a cache report with the block arrived, but the block
    // reports from the DataNode haven't (yet?) described such a block.
    // Alternately, the NameNode might have invalidated the block, but the
    // DataNode hasn't caught up.  In any case, we want to tell the DN
    // to uncache this.
    return "not tracked by the BlockManager";
  } else if (!blockInfo.isComplete()) {
    // When a cached block changes state from complete to some other state
    // on the DataNode (perhaps because of append), it will begin the
    // uncaching process.  However, the uncaching process is not
    // instantaneous, especially if clients have pinned the block.  So
    // there may be a period of time when incomplete blocks remain cached
    // on the DataNodes.
    return "not complete";
  } else if (cblock.getReplication() == 0) {
    // Since 0 is not a valid value for a cache directive's replication
    // field, seeing a replication of 0 on a CacheBlock means that it
    // has never been reached by any sweep.
    return "not needed by any directives";
  } else if (cblock.getMark() != mark) { 
    // Although the block was needed in the past, we didn't reach it during
    // the current sweep.  Therefore, it doesn't need to be cached any more.
    // Need to set the replication to 0 so it doesn't flip back to cached
    // when the mark flips on the next scan
    cblock.setReplicationAndMark((short)0, mark);
    return "no longer needed by any directives";
  }
  return null;
}
 

import org.apache.hadoop.hdfs.server.namenode.CachedBlock; //导入方法依赖的package包/类
private String findReasonForNotCaching(CachedBlock cblock,
    BlockInfo blockInfo) {
  if (blockInfo == null) {
    // Somehow, a cache report with the block arrived, but the block
    // reports from the DataNode haven't (yet?) described such a block.
    // Alternately, the NameNode might have invalidated the block, but the
    // DataNode hasn't caught up.  In any case, we want to tell the DN
    // to uncache this.
    return "not tracked by the BlockManager";
  } else if (!blockInfo.isComplete()) {
    // When a cached block changes state from complete to some other state
    // on the DataNode (perhaps because of append), it will begin the
    // uncaching process.  However, the uncaching process is not
    // instantaneous, especially if clients have pinned the block.  So
    // there may be a period of time when incomplete blocks remain cached
    // on the DataNodes.
    return "not complete";
  } else if (cblock.getReplication() == 0) {
    // Since 0 is not a valid value for a cache directive's replication
    // field, seeing a replication of 0 on a CacheBlock means that it
    // has never been reached by any sweep.
    return "not needed by any directives";
  } else if (cblock.getMark() != mark) { 
    // Although the block was needed in the past, we didn't reach it during
    // the current sweep.  Therefore, it doesn't need to be cached any more.
    // Need to set the replication to 0 so it doesn't flip back to cached
    // when the mark flips on the next scan
    cblock.setReplicationAndMark((short)0, mark);
    return "no longer needed by any directives";
  }
  return null;
}
 

import org.apache.hadoop.hdfs.server.namenode.CachedBlock; //导入方法依赖的package包/类
private String findReasonForNotCaching(CachedBlock cblock, 
        BlockInfo blockInfo) {
  if (blockInfo == null) {
    // Somehow, a cache report with the block arrived, but the block
    // reports from the DataNode haven't (yet?) described such a block.
    // Alternately, the NameNode might have invalidated the block, but the
    // DataNode hasn't caught up.  In any case, we want to tell the DN
    // to uncache this.
    return "not tracked by the BlockManager";
  } else if (!blockInfo.isComplete()) {
    // When a cached block changes state from complete to some other state
    // on the DataNode (perhaps because of append), it will begin the
    // uncaching process.  However, the uncaching process is not
    // instantaneous, especially if clients have pinned the block.  So
    // there may be a period of time when incomplete blocks remain cached
    // on the DataNodes.
    return "not complete";
  } else if (cblock.getReplication() == 0) {
    // Since 0 is not a valid value for a cache directive's replication
    // field, seeing a replication of 0 on a CacheBlock means that it
    // has never been reached by any sweep.
    return "not needed by any directives";
  } else if (cblock.getMark() != mark) { 
    // Although the block was needed in the past, we didn't reach it during
    // the current sweep.  Therefore, it doesn't need to be cached any more.
    // Need to set the replication to 0 so it doesn't flip back to cached
    // when the mark flips on the next scan
    cblock.setReplicationAndMark((short)0, mark);
    return "no longer needed by any directives";
  }
  return null;
}