/// <summary>
/// Compute the difference between two snapshots (or a snapshot and the current
/// directory) of the directory.
/// </summary>
/// <param name="from">
/// The name of the start point of the comparison. Null indicating
/// the current tree.
/// </param>
/// <param name="to">The name of the end point. Null indicating the current tree.</param>
/// <returns>The difference between the start/end points.</returns>
/// <exception cref="Org.Apache.Hadoop.Hdfs.Protocol.SnapshotException">
/// If there is no snapshot matching the starting
/// point, or if endSnapshotName is not null but cannot be identified
/// as a previous snapshot.
/// </exception>
internal virtual SnapshotDiffInfo ComputeDiff(INodeDirectory snapshotRoot, string
from, string to)
{
Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot fromSnapshot = GetSnapshotByName
(snapshotRoot, from);
Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot toSnapshot = GetSnapshotByName
(snapshotRoot, to);
// if the start point is equal to the end point, return null
if (from.Equals(to))
{
return(null);
}
SnapshotDiffInfo diffs = new SnapshotDiffInfo(snapshotRoot, fromSnapshot, toSnapshot
);
ComputeDiffRecursively(snapshotRoot, snapshotRoot, new AList <byte[]>(), diffs);
return(diffs);
}
/// <summary>
/// Compute the difference between two snapshots of a directory, or between a
/// snapshot of the directory and its current tree.
/// </summary>
/// <exception cref="System.IO.IOException"/>
public virtual SnapshotDiffReport Diff(INodesInPath iip, string snapshotRootPath,
string from, string to)
{
// Find the source root directory path where the snapshots were taken.
// All the check for path has been included in the valueOf method.
INodeDirectory snapshotRoot = GetSnapshottableRoot(iip);
if ((from == null || from.IsEmpty()) && (to == null || to.IsEmpty()))
{
// both fromSnapshot and toSnapshot indicate the current tree
return(new SnapshotDiffReport(snapshotRootPath, from, to, Sharpen.Collections.EmptyList
<SnapshotDiffReport.DiffReportEntry>()));
}
SnapshotDiffInfo diffs = snapshotRoot.GetDirectorySnapshottableFeature().ComputeDiff
(snapshotRoot, from, to);
return(diffs != null?diffs.GenerateReport() : new SnapshotDiffReport(snapshotRootPath
, from, to, Sharpen.Collections.EmptyList <SnapshotDiffReport.DiffReportEntry>()));
}
/// <summary>
/// Recursively compute the difference between snapshots under a given
/// directory/file.
/// </summary>
/// <param name="snapshotRoot">The directory where snapshots were taken.</param>
/// <param name="node">The directory/file under which the diff is computed.</param>
/// <param name="parentPath">
/// Relative path (corresponding to the snapshot root) of
/// the node's parent.
/// </param>
/// <param name="diffReport">data structure used to store the diff.</param>
private void ComputeDiffRecursively(INodeDirectory snapshotRoot, INode node, IList
<byte[]> parentPath, SnapshotDiffInfo diffReport)
{
Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot earlierSnapshot = diffReport
.IsFromEarlier() ? diffReport.GetFrom() : diffReport.GetTo();
Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot laterSnapshot = diffReport
.IsFromEarlier() ? diffReport.GetTo() : diffReport.GetFrom();
byte[][] relativePath = Sharpen.Collections.ToArray(parentPath, new byte[parentPath
.Count][]);
if (node.IsDirectory())
{
DirectoryWithSnapshotFeature.ChildrenDiff diff = new DirectoryWithSnapshotFeature.ChildrenDiff
();
INodeDirectory dir = node.AsDirectory();
DirectoryWithSnapshotFeature sf = dir.GetDirectoryWithSnapshotFeature();
if (sf != null)
{
bool change = sf.ComputeDiffBetweenSnapshots(earlierSnapshot, laterSnapshot, diff
, dir);
if (change)
{
diffReport.AddDirDiff(dir, relativePath, diff);
}
}
ReadOnlyList <INode> children = dir.GetChildrenList(earlierSnapshot.GetId());
foreach (INode child in children)
{
byte[] name = child.GetLocalNameBytes();
bool toProcess = diff.SearchIndex(Diff.ListType.Deleted, name) < 0;
if (!toProcess && child is INodeReference.WithName)
{
byte[][] renameTargetPath = FindRenameTargetPath(snapshotRoot, (INodeReference.WithName
)child, laterSnapshot == null ? Org.Apache.Hadoop.Hdfs.Server.Namenode.Snapshot.Snapshot
.CurrentStateId : laterSnapshot.GetId());
if (renameTargetPath != null)
{
toProcess = true;
diffReport.SetRenameTarget(child.GetId(), renameTargetPath);
}
}
if (toProcess)
{
parentPath.AddItem(name);
ComputeDiffRecursively(snapshotRoot, child, parentPath, diffReport);
parentPath.Remove(parentPath.Count - 1);
}
}
}
else
{
if (node.IsFile() && node.AsFile().IsWithSnapshot())
{
INodeFile file = node.AsFile();
bool change = file.GetFileWithSnapshotFeature().ChangedBetweenSnapshots(file, earlierSnapshot
, laterSnapshot);
if (change)
{
diffReport.AddFileDiff(file, relativePath);
}
}
}
}