Extracted findAllKeys() query into a helper class, made it possible for Query

to request a read-write connection.

src/java/com/samskivert/depot/DepotRepository.java

@@ -309,68 +309,10 @@ public abstract class DepotRepository
      * the latest data.
      */
     protected <T extends PersistentRecord> List<Key<T>> findAllKeys (
-        final Class<T> type, boolean forUpdate, Collection<? extends QueryClause> clauses)
+        Class<T> type, boolean forUpdate, Collection<? extends QueryClause> clauses)
         throws DatabaseException
     {
-        final List<Key<T>> keys = Lists.newArrayList();
+        return _ctx.invoke(new FindAllKeysQuery<T>(_ctx, type, forUpdate, clauses));
-        final DepotMarshaller<T> marsh = _ctx.getMarshaller(type);
-        SelectClause<T> select = new SelectClause<T>(type, marsh.getPrimaryKeyFields(), clauses);
-        final SQLBuilder builder = _ctx.getSQLBuilder(DepotTypes.getDepotTypes(_ctx, select));
-        builder.newQuery(select);
-
-        if (forUpdate) {
-            _ctx.invoke(new Modifier(null) {
-                @Override
-                protected int invoke (Connection conn, DatabaseLiaison liaison) throws SQLException {
-                    PreparedStatement stmt = builder.prepare(conn);
-                    try {
-                        ResultSet rs = stmt.executeQuery();
-                        while (rs.next()) {
-                            keys.add(marsh.makePrimaryKey(rs));
-                        }
-                        // TODO: cache this result?
-                        if (PersistenceContext.CACHE_DEBUG) {
-                            log.info("Loaded " + StringUtil.shortClassName(type) + " keys",
-                                     "count", keys.size());
-                        }
-                        return 0;
-                    } finally {
-                        JDBCUtil.close(stmt);
-                    }
-                }
-                @Override public void updateStats (Stats stats) {
-                    stats.noteQuery(0, 1, 0, 0); // one uncached query
-                }
-            });
-
-        } else {
-            _ctx.invoke(new Query.Trivial<Void>() {
-                @Override
-                public Void invoke (PersistenceContext ctx, Connection conn,
-                                    DatabaseLiaison liaison) throws SQLException {
-                    PreparedStatement stmt = builder.prepare(conn);
-                    try {
-                        ResultSet rs = stmt.executeQuery();
-                        while (rs.next()) {
-                            keys.add(marsh.makePrimaryKey(rs));
-                        }
-                        // TODO: cache this result?
-                        if (PersistenceContext.CACHE_DEBUG) {
-                            log.info("Loaded " + StringUtil.shortClassName(type) + " keys",
-                                     "count", keys.size());
-                        }
-                        return null;
-                    } finally {
-                        JDBCUtil.close(stmt);
-                    }
-                }
-                public void updateStats (Stats stats) {
-                    stats.noteQuery(0, 1, 0, 0); // one uncached query
-                }
-            });
-        }
-
-        return keys;
     }
 
     /**

src/java/com/samskivert/depot/FindAllKeysQuery.java

@@ -0,0 +1,100 @@
+//
+// $Id$
+//
+// Depot library - a Java relational persistence library
+// Copyright (C) 2006-2008 Michael Bayne and Pär Winzell
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.depot;
+
+import java.util.Collection;
+import java.util.List;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+import com.google.common.collect.Lists;
+
+import com.samskivert.jdbc.DatabaseLiaison;
+import com.samskivert.jdbc.JDBCUtil;
+
+import com.samskivert.depot.clause.QueryClause;
+import com.samskivert.depot.clause.SelectClause;
+
+import static com.samskivert.depot.Log.log;
+
+/**
+ * Loads all primary keys for the records matching the supplied clause.
+ */
+public class FindAllKeysQuery<T extends PersistentRecord> extends Query<List<Key<T>>>
+{
+    public FindAllKeysQuery (PersistenceContext ctx, Class<T> type, boolean forUpdate,
+                             Collection<? extends QueryClause> clauses)
+        throws DatabaseException
+    {
+        _forUpdate = forUpdate;
+        _marsh = ctx.getMarshaller(type);
+        _select = new SelectClause<T>(type, _marsh.getPrimaryKeyFields(), clauses);
+        _builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
+        _builder.newQuery(_select);
+    }
+
+    @Override // from Query
+    public boolean isReadOnly ()
+    {
+        return !_forUpdate;
+    }
+
+    @Override // from Query
+    public List<Key<T>> getCachedResult (PersistenceContext ctx)
+    {
+        return null; // TODO
+    }
+
+    @Override // from Query
+    public List<Key<T>> invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
+        throws SQLException
+    {
+        List<Key<T>> keys = Lists.newArrayList();
+        PreparedStatement stmt = _builder.prepare(conn);
+        try {
+            ResultSet rs = stmt.executeQuery();
+            while (rs.next()) {
+                keys.add(_marsh.makePrimaryKey(rs));
+            }
+            // TODO: cache this result?
+            if (PersistenceContext.CACHE_DEBUG) {
+                log.info("Loaded " + _marsh.getTableName(), "count", keys.size());
+            }
+            return keys;
+        } finally {
+            JDBCUtil.close(stmt);
+        }
+    }
+
+    @Override // from Query
+    public void updateStats (Stats stats)
+    {
+        stats.noteQuery(0, 1, 0, 0); // one uncached query
+    }
+
+    protected boolean _forUpdate;
+    protected SQLBuilder _builder;
+    protected DepotMarshaller<T> _marsh;
+    protected SelectClause<T> _select;
+}

src/java/com/samskivert/depot/FindAllQuery.java

@@ -49,8 +49,7 @@ import static com.samskivert.depot.Log.log;
  * This class implements the functionality required by {@link DepotRepository#findAll}: fetch
  * a collection of persistent objects using one of two included strategies.
  */
-public abstract class FindAllQuery<T extends PersistentRecord>
+public abstract class FindAllQuery<T extends PersistentRecord> extends Query<List<T>>
-    implements Query<List<T>>
 {
     /**
      * The two-pass collection query implementation. See {@link DepotRepository#findAll} for 
@@ -76,7 +75,7 @@ public abstract class FindAllQuery<T extends PersistentRecord>
             }
 
             _select = new SelectClause<T>(_type, _marsh.getPrimaryKeyFields(), clauses);
-            _builder = _ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
+            _builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
             _builder.newQuery(_select);
         }
 
@@ -95,7 +94,7 @@ public abstract class FindAllQuery<T extends PersistentRecord>
                     Key<T> key = _marsh.makePrimaryKey(rs);
                     allKeys.add(key);
 
-                    T value = _ctx.<T>cacheLookup(key);
+                    T value = ctx.<T>cacheLookup(key);
                     if (value != null) {
                         @SuppressWarnings("unchecked") T newValue = (T) value.clone();
                         entities.put(key, newValue);
@@ -124,7 +123,6 @@ public abstract class FindAllQuery<T extends PersistentRecord>
             stats.noteQuery(0, 1, _cachedRecords, _uncachedRecords); // one uncached query
         }
 
-        protected SelectClause<T> _select;
         protected int _cachedRecords, _uncachedRecords;
     }
 
@@ -148,7 +146,7 @@ public abstract class FindAllQuery<T extends PersistentRecord>
             Map<Key<T>, T> entities = Maps.newHashMap();
             Set<Key<T>> fetchKeys = Sets.newHashSet();
             for (Key<T> key : _keys) {
-                T value = _ctx.<T>cacheLookup(key);
+                T value = ctx.<T>cacheLookup(key);
                 if (value != null) {
                     @SuppressWarnings("unchecked") T newValue = (T) value.clone();
                     entities.put(key, newValue);
@@ -213,49 +211,28 @@ public abstract class FindAllQuery<T extends PersistentRecord>
             stats.noteQuery(0, 1, 0, _uncachedRecords);
         }
 
-        protected SelectClause<T> _select;
         protected int _uncachedRecords;
     }
 
-    public FindAllQuery (PersistenceContext ctx, Class<T> type)
+    @Override // from Query
-        throws DatabaseException
-    {
-        _ctx = ctx;
-        _type = type;
-        _marsh = _ctx.getMarshaller(type);
-    }
-
-    // from interface Query
     public List<T> getCachedResult (PersistenceContext ctx)
     {
         return null; // TODO
     }
 
-//     // from interface Query
+    @Override // from Operation
-//     public List<T> transformCacheHit (CacheKey key, List<T> bits)
-//     {
-//         if (bits == null) {
-//             return bits;
-//         }
-
-//         List<T> result = Lists.newArrayList();
-//         for (T bit : bits) {
-//             if (bit != null) {
-//                 @SuppressWarnings("unchecked") T cbit = (T) bit.clone();
-//                 result.add(cbit);
-//             } else {
-//                 result.add(null);
-//             }
-//         }
-//         return result;
-//     }
-
-    // from interface Operation
     public void updateStats (Stats stats)
     {
         // TODO
     }
 
+    protected FindAllQuery (PersistenceContext ctx, Class<T> type)
+        throws DatabaseException
+    {
+        _type = type;
+        _marsh = ctx.getMarshaller(type);
+    }
+
     protected List<T> loadAndResolve (PersistenceContext ctx, Connection conn,
                                       Collection<Key<T>> allKeys, Set<Key<T>> fetchKeys,
                                       Map<Key<T>, T> entities, String origStmt)
@@ -346,8 +323,8 @@ public abstract class FindAllQuery<T extends PersistentRecord>
         return builder.append(")").toString();
     }
 
-    protected PersistenceContext _ctx;
     protected SQLBuilder _builder;
     protected DepotMarshaller<T> _marsh;
     protected Class<T> _type;
+    protected SelectClause<T> _select;
 }

src/java/com/samskivert/depot/FindOneQuery.java

@@ -37,8 +37,7 @@ import static com.samskivert.depot.Log.log;
 /**
  * The implementation of {@link DepotRepository#load} functionality.
  */
-public class FindOneQuery<T extends PersistentRecord>
+public class FindOneQuery<T extends PersistentRecord> extends Query<T>
-    implements Query<T>
 {
     public FindOneQuery (PersistenceContext ctx, Class<T> type, QueryClause[] clauses)
         throws DatabaseException
@@ -53,7 +52,7 @@ public class FindOneQuery<T extends PersistentRecord>
         _builder.newQuery(_select);
     }
 
-    // from interface Query
+    @Override // from Query
     public T getCachedResult (PersistenceContext ctx)
     {
         CacheKey key = getCacheKey();
@@ -70,7 +69,7 @@ public class FindOneQuery<T extends PersistentRecord>
         return cvalue;
     }
 
-    // from interface Query
+    @Override // from Query
     public T invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
         throws SQLException
     {
@@ -110,7 +109,7 @@ public class FindOneQuery<T extends PersistentRecord>
         }
     }
 
-    // from interface Operation
+    @Override // from Operation
     public void updateStats (Stats stats)
     {
         stats.noteQuery(0, 0, _cachedRecords, 1-_cachedRecords);

src/java/com/samskivert/depot/Modifier.java

@@ -117,6 +117,12 @@ public abstract class Modifier implements Operation<Integer>
         _invalidator = invalidator;
     }
 
+    // from interface Operation
+    public boolean isReadOnly ()
+    {
+        return false;
+    }
+
     // from interface Operation
     public Integer invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
         throws SQLException

src/java/com/samskivert/depot/Operation.java

@@ -30,6 +30,11 @@ import com.samskivert.jdbc.DatabaseLiaison;
  */
 public interface Operation<T>
 {
+    /**
+     * Indicates whether or not this operation is safe to invoke on a database mirror.
+     */
+    public boolean isReadOnly ();
+
     /**
      * Performs the actual JDBC interactions associated with this operation.
      */

src/java/com/samskivert/depot/PersistenceContext.java

@@ -523,7 +523,7 @@ public class PersistenceContext
     {
         checkAreInitialized(); // le check du sanity
 
-        boolean isReadOnly = !(op instanceof Modifier);
+        boolean isReadOnly = op.isReadOnly();
         Connection conn;
         long preConnect = System.nanoTime();
         try {

src/java/com/samskivert/depot/Query.java

@@ -29,21 +29,16 @@ import com.samskivert.depot.PersistenceContext.CacheListener;
 /**
  * The base of all read-only queries.
  */
-public interface Query<T> extends Operation<T>
+public abstract class Query<T>
+    implements Operation<T>
 {
     /** A simple base class for non-complex queries. */
-    public abstract class Trivial<T> implements Query<T>
+    public static abstract class Trivial<T> extends Query<T>
     {
-        public abstract T invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
+        @Override // from Query
-            throws SQLException;
-
         public T getCachedResult (PersistenceContext ctx) {
             return null;
         }
-
-        public T transformCacheHit (CacheKey key, T value) {
-            return value;
-        }
     }
 
     /**
@@ -51,5 +46,11 @@ public interface Query<T> extends Operation<T>
      * method. If null is returned, the query will be {@link #invoke}d to obtain its result from
      * persistent storage.
      */
-    public T getCachedResult (PersistenceContext ctx);
+    public abstract T getCachedResult (PersistenceContext ctx);
+
+    // from interface Operation
+    public boolean isReadOnly ()
+    {
+        return true;
+    }
 }