pool: Reduce number of stat calls in Bekeley DB backend

Motivation:

Java 7 introduced a new API for querying file attributes as a bulk
operation.

Modification:

Use Files.getFileAttributes to read all file attributes in a single
stat system call.

Restructure replica creation and replica loading to reduce duplicated
or unnecessary stat calls further.

Result:

No user visible changes.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Albert Rossi <arossi@fnal.gov>
Acked-by: Dmitry Litvintsev <litvinse@fnal.gov>

Reviewed at https://rb.dcache.org/r/9426/

modules/dcache/src/main/java/org/dcache/pool/repository/meta/db/BerkeleyDBMetaDataRepository.java

@@ -14,6 +14,9 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.attribute.BasicFileAttributeView;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -181,18 +184,23 @@ public MetaDataRecord get(PnfsId id) throws CacheException
     {
         try {
             File file = _fileStore.get(id);
-            if (!file.isFile()) {
-                return null;
+            BasicFileAttributes attributes =
+                    Files.getFileAttributeView(file.toPath(), BasicFileAttributeView.class).readAttributes();
+            if (!attributes.isRegularFile()) {
+                throw new DiskErrorCacheException("Not a regular file: " + file);
             }
-
-            return CacheRepositoryEntryImpl.load(this, id);
+            return CacheRepositoryEntryImpl.load(this, id, attributes);
         } catch (EnvironmentFailureException e) {
             if (!isValid()) {
-                throw new DiskErrorCacheException("Meta data update failed and a pool restart is required: " + e.getMessage(), e);
+                throw new DiskErrorCacheException("Meta data lookup failed and a pool restart is required: " + e.getMessage(), e);
             }
-            throw new CacheException("Meta data update failed: " + e.getMessage(), e);
+            throw new CacheException("Meta data lookup failed: " + e.getMessage(), e);
         } catch (OperationFailureException e) {
-            throw new CacheException("Meta data update failed: " + e.getMessage(), e);
+            throw new CacheException("Meta data lookup failed: " + e.getMessage(), e);
+        } catch (NoSuchFileException | FileNotFoundException e) {
+            return null;
+        } catch (IOException e) {
+            throw new CacheException("Failed to read " + id + ": " + e.getMessage(), e);
         }
     }
 

modules/dcache/src/main/java/org/dcache/pool/repository/meta/db/CacheRepositoryEntryImpl.java

@@ -11,9 +11,10 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.File;
+import java.io.IOException;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.util.Collection;
 import java.util.List;
-import java.util.concurrent.Callable;
 import java.util.function.Predicate;
 
 import diskCacheV111.util.CacheException;
@@ -61,35 +62,24 @@ public class CacheRepositoryEntryImpl implements MetaDataRecord
 
     private long _size;
 
-    public CacheRepositoryEntryImpl(BerkeleyDBMetaDataRepository repository,
-                                    PnfsId pnfsId)
+    public CacheRepositoryEntryImpl(BerkeleyDBMetaDataRepository repository, PnfsId pnfsId)
     {
         _repository = repository;
         _pnfsId = pnfsId;
-        _sticky = ImmutableList.of();
         _state = EntryState.NEW;
-        File file = getDataFile();
-        _lastAccess = file.lastModified();
-        _size = file.length();
-        if (_lastAccess == 0) {
-            _lastAccess = _creationTime;
-        }
+        _sticky = ImmutableList.of();
+        _lastAccess = _creationTime;
     }
 
-    private CacheRepositoryEntryImpl(BerkeleyDBMetaDataRepository repository,
-                                     PnfsId pnfsId,
-                                     CacheRepositoryEntryState state)
+    public CacheRepositoryEntryImpl(BerkeleyDBMetaDataRepository repository, PnfsId pnfsId, EntryState state,
+                                    Collection<StickyRecord> sticky, BasicFileAttributes attributes)
     {
         _repository = repository;
         _pnfsId = pnfsId;
-        _state = state.getState();
-        setStickyRecords(state.stickyRecords());
-        File file = getDataFile();
-        _lastAccess = file.lastModified();
-        _size = file.length();
-        if (_lastAccess == 0) {
-            _lastAccess = _creationTime;
-        }
+        _state = state;
+        setStickyRecords(sticky);
+        _lastAccess = attributes.lastModifiedTime().toMillis();
+        _size = attributes.size();
     }
 
     private void setStickyRecords(Iterable<StickyRecord> records)
@@ -305,13 +295,14 @@ private synchronized void storeState() throws CacheException
         }
     }
 
-    static CacheRepositoryEntryImpl load(BerkeleyDBMetaDataRepository repository, PnfsId pnfsId)
+    static CacheRepositoryEntryImpl load(BerkeleyDBMetaDataRepository repository, PnfsId pnfsId,
+                                         BasicFileAttributes attributes) throws IOException
     {
         try {
             String id = pnfsId.toString();
             CacheRepositoryEntryState state = repository.getStateMap().get(id);
             if (state != null) {
-                return new CacheRepositoryEntryImpl(repository, pnfsId, state);
+                return new CacheRepositoryEntryImpl(repository, pnfsId, state.getState(), state.stickyRecords(), attributes);
             }
         } catch (ClassCastException e) {
             _log.warn(e.toString());
@@ -326,8 +317,7 @@ static CacheRepositoryEntryImpl load(BerkeleyDBMetaDataRepository repository, Pn
             }
             _log.warn(e.toString());
         }
-
-        return new CacheRepositoryEntryImpl(repository, pnfsId);
+        return new CacheRepositoryEntryImpl(repository, pnfsId, EntryState.BROKEN, ImmutableList.of(), attributes);
     }
 
     private class UpdatableRecordImpl implements UpdatableRecord