db: Import db/commmitlog/*

Signed-off-by: Calle Wilund <calle@cloudius-systems.com>

db/commitlog/ReplayPosition.java

@@ -0,0 +1,143 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.cassandra.db.commitlog;
+
+import java.io.DataInput;
+import java.io.IOException;
+import java.util.Comparator;
+
+import com.google.common.base.Function;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Ordering;
+
+import org.apache.cassandra.db.TypeSizes;
+import org.apache.cassandra.io.ISerializer;
+import org.apache.cassandra.io.sstable.format.SSTableReader;
+import org.apache.cassandra.io.util.DataOutputPlus;
+
+public class ReplayPosition implements Comparable<ReplayPosition>
+{
+    public static final ReplayPositionSerializer serializer = new ReplayPositionSerializer();
+
+    // NONE is used for SSTables that are streamed from other nodes and thus have no relationship
+    // with our local commitlog. The values satisfy the critera that
+    //  - no real commitlog segment will have the given id
+    //  - it will sort before any real replayposition, so it will be effectively ignored by getReplayPosition
+    public static final ReplayPosition NONE = new ReplayPosition(-1, 0);
+
+    /**
+     * Convenience method to compute the replay position for a group of SSTables.
+     * @param sstables
+     * @return the most recent (highest) replay position
+     */
+    public static ReplayPosition getReplayPosition(Iterable<? extends SSTableReader> sstables)
+    {
+        if (Iterables.isEmpty(sstables))
+            return NONE;
+
+        Function<SSTableReader, ReplayPosition> f = new Function<SSTableReader, ReplayPosition>()
+        {
+            public ReplayPosition apply(SSTableReader sstable)
+            {
+                return sstable.getReplayPosition();
+            }
+        };
+        Ordering<ReplayPosition> ordering = Ordering.from(ReplayPosition.comparator);
+        return ordering.max(Iterables.transform(sstables, f));
+    }
+
+
+    public final long segment;
+    public final int position;
+
+    public static final Comparator<ReplayPosition> comparator = new Comparator<ReplayPosition>()
+    {
+        public int compare(ReplayPosition o1, ReplayPosition o2)
+        {
+            if (o1.segment != o2.segment)
+                return Long.valueOf(o1.segment).compareTo(o2.segment);
+
+            return Integer.valueOf(o1.position).compareTo(o2.position);
+        }
+    };
+
+    public ReplayPosition(long segment, int position)
+    {
+        this.segment = segment;
+        assert position >= 0;
+        this.position = position;
+    }
+
+    public int compareTo(ReplayPosition other)
+    {
+        return comparator.compare(this, other);
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        ReplayPosition that = (ReplayPosition) o;
+
+        if (position != that.position) return false;
+        return segment == that.segment;
+    }
+
+    @Override
+    public int hashCode()
+    {
+        int result = (int) (segment ^ (segment >>> 32));
+        result = 31 * result + position;
+        return result;
+    }
+
+    @Override
+    public String toString()
+    {
+        return "ReplayPosition(" +
+               "segmentId=" + segment +
+               ", position=" + position +
+               ')';
+    }
+
+    public ReplayPosition clone()
+    {
+        return new ReplayPosition(segment, position);
+    }
+
+    public static class ReplayPositionSerializer implements ISerializer<ReplayPosition>
+    {
+        public void serialize(ReplayPosition rp, DataOutputPlus out) throws IOException
+        {
+            out.writeLong(rp.segment);
+            out.writeInt(rp.position);
+        }
+
+        public ReplayPosition deserialize(DataInput in) throws IOException
+        {
+            return new ReplayPosition(in.readLong(), in.readInt());
+        }
+
+        public long serializedSize(ReplayPosition rp, TypeSizes typeSizes)
+        {
+            return typeSizes.sizeof(rp.segment) + typeSizes.sizeof(rp.position);
+        }
+    }
+}