core: update NameSpaceProvider#getParentOf to include name of target …

…in parent

Motivation:

The getParentOf method in NameSpaceProvider suffers from two limitations:
  1. lack of support for hard links,
  2. fails to include the name of the target file or directory.

Modification:

Update the method to return both the parent directory ID and the name of
the target.  The return is also updated to support multiple responses.

Chimera implementation of NameSpaceProvider is updated, following a
similar development to support this query.

The RemoteNameSpaceProvider is updated by updating PnfsManager, the cell
message that queries PnfsManager, and PnfsManager itself.

Result:

No admin- or user observable changes, but the NameSpaceProvider
interface is more powerful.

Target: master
Require-notes: no
Require-book: no
Patch: https://rb.dcache.org/r/10929/
Acked-by: Tigran Mkrtchyan

modules/dcache-chimera/src/main/java/org/dcache/chimera/PerformanceTest.java

@@ -32,7 +32,6 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.Objects;
@@ -44,10 +43,8 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
-import diskCacheV111.util.AccessLatency;
 import diskCacheV111.util.CacheException;
 import diskCacheV111.util.PnfsId;
-import diskCacheV111.util.RetentionPolicy;
 import diskCacheV111.vehicles.StorageInfo;
 
 import org.dcache.auth.Subjects;
@@ -85,7 +82,7 @@ private enum Operation
         CREATE_ENTRY("createentry", "Create a new file entry in the pool"),
         DELETE_ENTRY("deleteentry", "Removes file entry from the pool"),
         PNFS_ID_TO_PATH("pnfsidtopath", "Reads path of the file"),
-        GET_PARENT("getparent", "Reads the parent pnfsid of the file"),
+        FIND("find", "Locates the file in the namespace"),
         ADD_CHECKSUM("addchecksum", "Adds the given checksum to the file"),
         GET_CHECKSUMS("getchecksums", "Reads all the checksums of the file"),
         SET_FILE_ATTR("setfileattr", "Updates the file attributes"),
@@ -285,8 +282,8 @@ private void processOperation(Operation aOp, String path)
             case PNFS_ID_TO_PATH:
                 provider.pnfsidToPath(Subjects.ROOT, getPnfsid(path));
                 break;
-            case GET_PARENT:
-                provider.getParentOf(Subjects.ROOT, getPnfsid(path));
+            case FIND:
+                provider.find(Subjects.ROOT, getPnfsid(path));
                 break;
             case ADD_CHECKSUM:
                 provider.setFileAttributes(Subjects.ROOT, getPnfsid(path),

modules/dcache-chimera/src/main/java/org/dcache/chimera/namespace/ChimeraNameSpaceProvider.java

@@ -33,6 +33,8 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import diskCacheV111.namespace.NameSpaceProvider;
 import diskCacheV111.util.AccessLatency;
@@ -829,14 +831,27 @@ public void getInfo(PrintWriter pw)
     }
 
     @Override
-    public PnfsId getParentOf(Subject subject, PnfsId pnfsId) throws CacheException {
+    public Collection<Link> find(Subject subject, PnfsId pnfsId) throws CacheException {
         try {
-            ExtendedInode inodeOfResource = new ExtendedInode(_fs, pnfsId, NO_STAT);
-            ExtendedInode inodeParent = inodeOfResource.getParent();
-            if (inodeParent == null) {
+            ExtendedInode target = new ExtendedInode(_fs, pnfsId, NO_STAT);
+
+            Collection<Link> locations = _fs.find(target).stream()
+                    .flatMap(l -> {
+                                try {
+                                    ExtendedInode parent = new ExtendedInode(_fs, l.getParent());
+                                    PnfsId parentId = parent.getPnfsId();
+                                    return Stream.of(new Link(parentId, l.getName()));
+                                } catch (ChimeraFsException e) {
+                                    _log.error("Failed to find PnfsId of parent {}: {}",
+                                            l.getParent(), e.toString());
+                                    return Stream.of();
+                                }
+                            })
+                    .collect(Collectors.toList());
+            if (locations.isEmpty()) {
                 throw new FileNotFoundCacheException("No such file or directory: " + pnfsId);
             }
-            return inodeParent.getPnfsId();
+            return locations;
         } catch (FileNotFoundHimeraFsException e) {
             throw new FileNotFoundCacheException("No such file or directory: " + pnfsId);
         } catch (IOException e) {

modules/dcache-vehicles/src/main/java/diskCacheV111/vehicles/PnfsGetParentMessage.java

@@ -1,28 +1,54 @@
 package diskCacheV111.vehicles;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
 import diskCacheV111.util.PnfsId;
 
 public class PnfsGetParentMessage extends PnfsMessage
 {
     private static final long serialVersionUID = 7665073616113975562L;
     private PnfsId _parent;
+    private List<PnfsId> parents;
+    private List<String> names;
 
     public PnfsGetParentMessage(PnfsId pnfsId)
     {
         super(pnfsId);
         setReplyRequired(true);
     }
 
-    public void setParent(PnfsId parent)
+    public void addLocation(PnfsId parent, String name)
     {
-        _parent = parent;
+        if (parents == null) {
+            parents = new ArrayList<>();
+        }
+        if (names == null) {
+            names = new ArrayList<>();
+        }
+        if (_parent == null) {
+            _parent = parent;
+        }
+        parents.add(parent);
+        names.add(name);
     }
 
     public PnfsId getParent()
     {
         return _parent;
     }
 
+    public List<PnfsId> getParents()
+    {
+        return parents == null ? Collections.emptyList() : parents;
+    }
+
+    public List<String> getNames()
+    {
+        return names == null ? Collections.emptyList() : names;
+    }
+
     @Override
     public boolean invalidates(Message message)
     {

modules/dcache/src/main/java/diskCacheV111/namespace/NameSpaceProvider.java

@@ -31,6 +31,33 @@
  */
 public interface NameSpaceProvider
 {
+    /**
+     * A Link represents the appearance of a file or directory within the
+     * namespace.  The parent is always a directory.  Listing that directory
+     * will yield the target with the given name.
+     */
+    public class Link
+    {
+        private final PnfsId parent;
+        private final String name;
+
+        public Link(PnfsId parent, String name)
+        {
+            this.parent = parent;
+            this.name = name;
+        }
+
+        public PnfsId getParent()
+        {
+            return parent;
+        }
+
+        public String getName()
+        {
+            return name;
+        }
+    }
+
     /**
      * When the mode field is not specified in createEntry, the mode
      * is inherited from the parent directory. When creating new
@@ -141,7 +168,17 @@ void rename(Subject subject, @Nullable PnfsId pnfsId, String sourcePath, String
     String pnfsidToPath(Subject subject, PnfsId pnfsId) throws CacheException;
     PnfsId pathToPnfsid(Subject subject, String path, boolean followLinks) throws CacheException;
 
-    PnfsId getParentOf(Subject subject, PnfsId pnfsId) throws CacheException;
+    /**
+     * Find the locations of the target file or directory within the namespace.
+     * If the target is a directory then there is (at most) one location.  If
+     * the target is a file then more than one location is returned if the file
+     * has hard links.
+     * @param subject Subject of the user who invoked this method
+     * @param pnfsId the target to locate
+     * @return The locations where the target may be found.
+     * @throws CacheException
+     */
+    Collection<Link> find(Subject subject, PnfsId pnfsId) throws CacheException;
 
     void removeFileAttribute(Subject subject, PnfsId pnfsId, String attribute) throws CacheException;
 

modules/dcache/src/main/java/diskCacheV111/namespace/PnfsManagerV3.java

@@ -37,6 +37,7 @@
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
 
+import diskCacheV111.namespace.NameSpaceProvider.Link;
 import diskCacheV111.util.CacheException;
 import diskCacheV111.util.FileNotFoundCacheException;
 import diskCacheV111.util.FsPath;
@@ -1431,7 +1432,8 @@ private void getParent(PnfsGetParentMessage msg)
         try {
             PnfsId pnfsId = populatePnfsId(msg);
             checkMask(msg);
-            msg.setParent(_nameSpaceProvider.getParentOf(msg.getSubject(), pnfsId));
+            _nameSpaceProvider.find(msg.getSubject(), pnfsId)
+                    .forEach(l -> msg.addLocation(l.getParent(), l.getName()));
         } catch (CacheException e) {
             _log.warn(e.toString());
             msg.setFailed(e.getRc(), e.getMessage());

modules/dcache/src/main/java/diskCacheV111/util/PnfsHandler.java

@@ -6,12 +6,15 @@
 
 import javax.security.auth.Subject;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
+import diskCacheV111.namespace.NameSpaceProvider.Link;
 import diskCacheV111.vehicles.PnfsAddCacheLocationMessage;
 import diskCacheV111.vehicles.PnfsClearCacheLocationMessage;
 import diskCacheV111.vehicles.PnfsCreateEntryMessage;
@@ -362,10 +365,17 @@ public PnfsCreateEntryMessage createPnfsEntry(String path,
        return request(new PnfsCreateEntryMessage(path, attributes));
     }
 
-    public PnfsId getParentOf(PnfsId pnfsId)
-        throws CacheException
+    public Collection<Link> find(PnfsId pnfsId) throws CacheException
     {
-            return request(new PnfsGetParentMessage(pnfsId)).getParent();
+        PnfsGetParentMessage response = request(new PnfsGetParentMessage(pnfsId));
+        List<PnfsId> parents = response.getParents();
+        List<String> names = response.getNames();
+        int count = Math.min(parents.size(), names.size());
+        List<Link> locations = new ArrayList<>(count);
+        for (int i = 0; i < count; i++) {
+            locations.add(new Link(parents.get(i), names.get(i)));
+        }
+        return locations;
     }
 
     public PnfsId deletePnfsEntry(String path) throws CacheException

modules/dcache/src/main/java/org/dcache/auth/RemoteNameSpaceProvider.java

@@ -141,10 +141,9 @@ public PnfsId pathToPnfsid(Subject subject, String path,
     }
 
     @Override
-    public PnfsId getParentOf(Subject subject, PnfsId id) throws CacheException
+    public Collection<Link> find(Subject subject, PnfsId id) throws CacheException
     {
-        PnfsHandler pnfs = new PnfsHandler(_pnfs, subject, Restrictions.none());
-        return pnfs.getParentOf(id);
+        return new PnfsHandler(_pnfs, subject, Restrictions.none()).find(id);
     }
 
     @Override

modules/dcache/src/test/java/org/dcache/auth/RemoteNameSpaceProviderTests.java

@@ -18,6 +18,7 @@
 import java.util.Map;
 import java.util.concurrent.Executor;
 
+import diskCacheV111.namespace.NameSpaceProvider.Link;
 import diskCacheV111.util.CacheException;
 import diskCacheV111.util.FileExistsCacheException;
 import diskCacheV111.util.FileNotFoundCacheException;
@@ -422,29 +423,32 @@ public void shouldFaileWhenGetFileAttributesForMissingEntry()
 
 
     @Test
-    public void shouldSucceedForGetParentOfExistingEntry() throws Exception
+    public void shouldSucceedForFindExistingEntry() throws Exception
     {
         givenSuccessfulResponse((Modifier<PnfsGetParentMessage>)
-                (r) -> r.setParent(ANOTHER_PNFSID));
+                (r) -> r.addLocation(ANOTHER_PNFSID, "file"));
 
-        PnfsId parent = _namespace.getParentOf(ROOT, A_PNFSID);
+        Collection<Link> locations = _namespace.find(ROOT, A_PNFSID);
 
         PnfsGetParentMessage sent =
                 getSingleSendAndWaitMessage(PnfsGetParentMessage.class);
         assertThat(sent.getReplyRequired(), is(true));
         assertThat(sent.getSubject(), is(ROOT));
         assertThat(sent.getPnfsId(), is(A_PNFSID));
 
-        assertThat(parent, is(ANOTHER_PNFSID));
+        assertThat(locations.size(), is(1));
+        Link location = locations.iterator().next();
+        assertThat(location.getParent(), is(ANOTHER_PNFSID));
+        assertThat(location.getName(), is("file"));
     }
 
 
     @Test(expected=FileNotFoundCacheException.class)
-    public void shouldFailForGetParentOfMissingEntry() throws Exception
+    public void shouldFailForFindMissingEntry() throws Exception
     {
         givenFailureResponse(FILE_NOT_FOUND);
 
-        _namespace.getParentOf(ROOT, A_PNFSID);
+        _namespace.find(ROOT, A_PNFSID);
     }