/*
* Roll back to old snapshot at the block pool level
* If previous directory exists:
* <ol>
* <li>Rename <SD>/current/<bpid>/current to removed.tmp</li>
* <li>Rename * <SD>/current/<bpid>/previous to current</li>
* <li>Remove removed.tmp</li>
* </ol>
*
* Do nothing if previous directory does not exist.
* @param bpSd Block pool storage directory at <SD>/current/<bpid>
*/
/// <exception cref="System.IO.IOException"/>
internal virtual void DoRollback(Storage.StorageDirectory bpSd, NamespaceInfo nsInfo
)
{
FilePath prevDir = bpSd.GetPreviousDir();
// regular startup if previous dir does not exist
if (!prevDir.Exists())
{
return;
}
// read attributes out of the VERSION file of previous directory
Org.Apache.Hadoop.Hdfs.Server.Datanode.BlockPoolSliceStorage prevInfo = new Org.Apache.Hadoop.Hdfs.Server.Datanode.BlockPoolSliceStorage
();
prevInfo.ReadPreviousVersionProperties(bpSd);
// We allow rollback to a state, which is either consistent with
// the namespace state or can be further upgraded to it.
// In another word, we can only roll back when ( storedLV >= software LV)
// && ( DN.previousCTime <= NN.ctime)
if (!(prevInfo.GetLayoutVersion() >= HdfsConstants.DatanodeLayoutVersion && prevInfo
.GetCTime() <= nsInfo.GetCTime()))
{
// cannot rollback
throw new InconsistentFSStateException(bpSd.GetRoot(), "Cannot rollback to a newer state.\nDatanode previous state: LV = "
+ prevInfo.GetLayoutVersion() + " CTime = " + prevInfo.GetCTime() + " is newer than the namespace state: LV = "
+ HdfsConstants.DatanodeLayoutVersion + " CTime = " + nsInfo.GetCTime());
}
Log.Info("Rolling back storage directory " + bpSd.GetRoot() + ".\n target LV = "
+ nsInfo.GetLayoutVersion() + "; target CTime = " + nsInfo.GetCTime());
FilePath tmpDir = bpSd.GetRemovedTmp();
System.Diagnostics.Debug.Assert(!tmpDir.Exists(), "removed.tmp directory must not exist."
);
// 1. rename current to tmp
FilePath curDir = bpSd.GetCurrentDir();
System.Diagnostics.Debug.Assert(curDir.Exists(), "Current directory must exist.");
Rename(curDir, tmpDir);
// 2. rename previous to current
Rename(prevDir, curDir);
// 3. delete removed.tmp dir
DeleteDir(tmpDir);
Log.Info("Rollback of " + bpSd.GetRoot() + " is complete");
}
/// <summary>Perform rollback of the storage dir to the previous state.</summary>
/// <remarks>
/// Perform rollback of the storage dir to the previous state. The existing
/// current dir is removed, and the previous dir is renamed to current.
/// </remarks>
/// <param name="sd">the storage directory to roll back.</param>
/// <exception cref="System.IO.IOException">in the event of error</exception>
internal static void DoRollBack(Storage.StorageDirectory sd)
{
FilePath prevDir = sd.GetPreviousDir();
if (!prevDir.Exists())
{
return;
}
FilePath tmpDir = sd.GetRemovedTmp();
Preconditions.CheckState(!tmpDir.Exists(), "removed.tmp directory must not exist for rollback."
+ "Consider restarting for recovery.");
// rename current to tmp
FilePath curDir = sd.GetCurrentDir();
Preconditions.CheckState(curDir.Exists(), "Current directory must exist for rollback."
);
NNStorage.Rename(curDir, tmpDir);
// rename previous to current
NNStorage.Rename(prevDir, curDir);
// delete tmp dir
NNStorage.DeleteDir(tmpDir);
Log.Info("Rollback of " + sd.GetRoot() + " is complete.");
}
