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@@ -22,19 +22,26 @@ import java.util.ArrayList;
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import java.util.List;
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import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
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+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
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+import org.apache.hadoop.hdfs.server.namenode.INode;
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import org.apache.hadoop.hdfs.server.namenode.INodeDirectory;
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-import org.apache.hadoop.hdfs.server.namenode.Namesystem;
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+import org.apache.hadoop.hdfs.server.namenode.INodeFile;
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+import org.apache.hadoop.hdfs.server.namenode.INodeFileUnderConstruction;
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+import org.apache.hadoop.hdfs.server.namenode.INodeSymlink;
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/** Manage snapshottable directories and their snapshots. */
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public class SnapshotManager {
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- private final Namesystem namesystem;
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+ private final FSNamesystem namesystem;
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+ private final FSDirectory fsdir;
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/** All snapshottable directories in the namesystem. */
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private final List<INodeDirectorySnapshottable> snapshottables
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= new ArrayList<INodeDirectorySnapshottable>();
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- public SnapshotManager(final Namesystem namesystem) {
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+ public SnapshotManager(final FSNamesystem namesystem,
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+ final FSDirectory fsdir) {
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this.namesystem = namesystem;
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+ this.fsdir = fsdir;
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}
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/**
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@@ -43,8 +50,8 @@ public class SnapshotManager {
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* Otherwise, the {@link INodeDirectory} of the path is replaced by an
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* {@link INodeDirectorySnapshottable}.
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*/
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- public void setSnapshottable(final String path, final int snapshotQuota,
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- final FSDirectory fsdir) throws IOException {
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+ public void setSnapshottable(final String path, final int snapshotQuota
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+ ) throws IOException {
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namesystem.writeLock();
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try {
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final INodeDirectory d = INodeDirectory.valueOf(fsdir.getINode(path), path);
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@@ -62,16 +69,108 @@ public class SnapshotManager {
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}
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}
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- /** Create a snapshot of given path. */
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- public void createSnapshot(final String snapshotName, final String path,
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- final FSDirectory fsdir) throws IOException {
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- final INodeDirectorySnapshottable d = INodeDirectorySnapshottable.valueOf(
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- fsdir.getINode(path), path);
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-
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- //TODO: check ns quota
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+ /**
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+ * Create a snapshot of the given path.
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+ *
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+ * @param snapshotName The name of the snapshot.
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+ * @param path The directory path where the snapshot will be taken.
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+ */
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+ public void createSnapshot(final String snapshotName, final String path
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+ ) throws IOException {
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+ new SnapshotCreation(path).run(snapshotName);
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+ }
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+
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+ /**
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+ * Create a snapshot of subtrees for recursively coping the directory
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+ * structure from the source directory to the snapshot destination directory.
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+ * This creation algorithm requires O(N) running time and O(N) memory,
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+ * where N = # files + # directories + # symlinks.
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+ */
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+ class SnapshotCreation {
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+ /** The source root directory path where the snapshot is taken. */
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+ final INodeDirectorySnapshottable srcRoot;
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+
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+ /**
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+ * Constructor.
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+ * @param path The path must be a snapshottable directory.
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+ */
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+ private SnapshotCreation(final String path) throws IOException {
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+ srcRoot = INodeDirectorySnapshottable.valueOf(fsdir.getINode(path), path);
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+ }
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- final INodeDirectorySnapshotRoot root = d.addSnapshotRoot(snapshotName);
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+ void run(final String name) throws IOException {
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+ final INodeDirectorySnapshotRoot root = srcRoot.addSnapshotRoot(name);
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+ processRecursively(srcRoot, root);
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+ }
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+
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+ /** Process snapshot creation recursively. */
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+ private void processRecursively(final INodeDirectory srcDir,
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+ final INodeDirectory dstDir) throws IOException {
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+ final List<INode> children = srcDir.getChildren();
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+ if (children != null) {
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+ final List<INode> inodes = new ArrayList<INode>(children.size());
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+ for(final INode c : children) {
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+ final INode i;
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+ if (c == null) {
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+ i = null;
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+ } else if (c instanceof INodeDirectory) {
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+ //also handle INodeDirectoryWithQuota
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+ i = processINodeDirectory((INodeDirectory)c);
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+ } else if (c instanceof INodeFileUnderConstruction) {
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+ //TODO: support INodeFileUnderConstruction
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+ throw new IOException("Not yet supported.");
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+ } else if (c instanceof INodeFile) {
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+ i = processINodeFile(srcDir, (INodeFile)c);
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+ } else if (c instanceof INodeSymlink) {
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+ i = new INodeSymlink((INodeSymlink)c);
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+ } else {
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+ throw new AssertionError("Unknow INode type: " + c.getClass()
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+ + ", inode = " + c);
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+ }
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+ inodes.add(i);
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+ }
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+ dstDir.setChildren(inodes);
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+ }
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+ }
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- //TODO: create the remaining subtree
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+ /**
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+ * Create destination INodeDirectory and make the recursive call.
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+ * @return destination INodeDirectory.
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+ */
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+ private INodeDirectory processINodeDirectory(final INodeDirectory srcChild
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+ ) throws IOException {
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+ final INodeDirectory dstChild = new INodeDirectory(srcChild);
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+ dstChild.setChildren(null);
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+ processRecursively(srcChild, dstChild);
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+ return dstChild;
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+ }
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+
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+ /**
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+ * Create destination INodeFileSnapshot and update source INode type.
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+ * @return destination INodeFileSnapshot.
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+ */
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+ private INodeFileSnapshot processINodeFile(final INodeDirectory parent,
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+ final INodeFile file) {
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+ final INodeFileSnapshot snapshot = new INodeFileSnapshot(
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+ file, file.computeFileSize(true));
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+
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+ final INodeFileWithLink srcWithLink;
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+ //check source INode type
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+ if (file instanceof INodeFileWithLink) {
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+ srcWithLink = (INodeFileWithLink)file;
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+ } else {
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+ //source is an INodeFile, replace the source.
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+ srcWithLink = new INodeFileWithLink(file);
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+ file.removeNode();
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+ parent.addChild(srcWithLink, false);
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+
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+ //update block map
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+ namesystem.getBlockManager().addBlockCollection(srcWithLink);
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+ }
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+
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+ //insert the snapshot to src's linked list.
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+ srcWithLink.insert(snapshot);
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+ return snapshot;
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+ }
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}
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}
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Suresh Srinivas