/// <summary>Scan a block.</summary>
/// <param name="cblock">The block to scan.</param>
/// <param name="bytesPerSec">The bytes per second to scan at.</param>
/// <returns>
/// The length of the block that was scanned, or
/// -1 if the block could not be scanned.
/// </returns>
private long ScanBlock(ExtendedBlock cblock, long bytesPerSec)
{
// 'cblock' has a valid blockId and block pool id, but we don't yet know the
// genstamp the block is supposed to have. Ask the FsDatasetImpl for this
// information.
ExtendedBlock block = null;
try
{
Block b = volume.GetDataset().GetStoredBlock(cblock.GetBlockPoolId(), cblock.GetBlockId
());
if (b == null)
{
Log.Info("FileNotFound while finding block {} on volume {}", cblock, volume.GetBasePath
());
}
else
{
block = new ExtendedBlock(cblock.GetBlockPoolId(), b);
}
}
catch (FileNotFoundException)
{
Log.Info("FileNotFoundException while finding block {} on volume {}", cblock, volume
.GetBasePath());
}
catch (IOException)
{
Log.Warn("I/O error while finding block {} on volume {}", cblock, volume.GetBasePath
());
}
if (block == null)
{
return(-1);
}
// block not found.
BlockSender blockSender = null;
try
{
blockSender = new BlockSender(block, 0, -1, false, true, true, datanode, null, CachingStrategy
.NewDropBehind());
throttler.SetBandwidth(bytesPerSec);
long bytesRead = blockSender.SendBlock(nullStream, null, throttler);
resultHandler.Handle(block, null);
return(bytesRead);
}
catch (IOException e)
{
resultHandler.Handle(block, e);
}
finally
{
IOUtils.Cleanup(null, blockSender);
}
return(-1);
}
public virtual void Handle(ExtendedBlock block, IOException e)
{
FsVolumeSpi volume = scanner.volume;
if (e == null)
{
Log.Trace("Successfully scanned {} on {}", block, volume.GetBasePath());
return;
}
// If the block does not exist anymore, then it's not an error.
if (!volume.GetDataset().Contains(block))
{
Log.Debug("Volume {}: block {} is no longer in the dataset.", volume.GetBasePath(
), block);
return;
}
// If the block exists, the exception may due to a race with write:
// The BlockSender got an old block path in rbw. BlockReceiver removed
// the rbw block from rbw to finalized but BlockSender tried to open the
// file before BlockReceiver updated the VolumeMap. The state of the
// block can be changed again now, so ignore this error here. If there
// is a block really deleted by mistake, DirectoryScan should catch it.
if (e is FileNotFoundException)
{
Log.Info("Volume {}: verification failed for {} because of " + "FileNotFoundException. This may be due to a race with write."
, volume.GetBasePath(), block);
return;
}
Log.Warn("Reporting bad {} on {}", block, volume.GetBasePath());
try
{
scanner.datanode.ReportBadBlocks(block);
}
catch (IOException)
{
// This is bad, but not bad enough to shut down the scanner.
Log.Warn("Cannot report bad " + block.GetBlockId(), e);
}
}