SAMZA-1423: Implement time series storage for joins and windows

build.gradle

@@ -167,6 +167,7 @@ project(":samza-core_$scalaVersion") {
     compile "org.scala-lang:scala-library:$scalaLibVersion"
     compile "org.slf4j:slf4j-api:$slf4jVersion"
     testCompile project(":samza-api").sourceSets.test.output
+    testCompile project(":samza-kv-rocksdb_$scalaVersion")
     testCompile "junit:junit:$junitVersion"
     testCompile "org.mockito:mockito-all:$mockitoVersion"
     testCompile "org.powermock:powermock-api-mockito:$powerMockVersion"

samza-api/src/main/java/org/apache/samza/storage/kv/ClosableIterator.java

@@ -0,0 +1,39 @@
+/*
+ * 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.samza.storage.kv;
+
+import java.util.Iterator;
+
+/**
+ * An iterator that can be closed.
+ *
+ * <p> Implement close to free resources assigned to the iterator such as open file handles, persistent state etc.
+ *
+ * @param <V> the type of value returned by this iterator
+ */
+public interface ClosableIterator<V> extends Iterator<V> {
+
+  /**
+   * Closes this iterator and frees resources assigned to it.
+   *
+   * It is illegal to invoke {@link #next()} and {@link #hasNext()} after an iterator has been closed.
+   */
+  public void close();
+}

samza-core/src/main/java/org/apache/samza/operators/impl/store/TimeSeriesKey.java

@@ -0,0 +1,79 @@
+/*
+ * 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.samza.operators.impl.store;
+
+/**
+ * The store key used in the {@link TimeSeriesStore} to uniquely identify a row.
+ */
+public class TimeSeriesKey<K> {
+
+  private final K key;
+  private final long timestamp;
+
+  // allows a maximum of 2 Billion entries per window per key. maybe, long?
+  private final int seqNum;
+
+  public TimeSeriesKey(K k, long time, int seq) {
+    key = k;
+    timestamp = time;
+    seqNum = seq;
+  }
+
+  public K getKey() {
+    return key;
+  }
+
+  public long getTimestamp() {
+    return timestamp;
+  }
+
+  public int getSeqNum() {
+    return seqNum;
+  }
+
+  @Override
+  public int hashCode() {
+    int result = key != null ? key.hashCode() : 0;
+    result = 31 * result + (int) (timestamp ^ (timestamp >>> 32));
+    result = 31 * result + seqNum;
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || !getClass().equals(o.getClass())) return false;
+
+    TimeSeriesKey<?> that = (TimeSeriesKey<?>) o;
+
+    if (timestamp != that.timestamp) return false;
+    if (seqNum != that.seqNum) return false;
+    return key != null ? key.equals(that.key) : that.key == null;
+  }
+
+  @Override
+  public String toString() {
+    return "TimeSeriesKey{" +
+            "key=" + key +
+            ", timestamp=" + timestamp +
+            ", seqNum=" + seqNum +
+            '}';
+  }
+}

samza-core/src/main/java/org/apache/samza/operators/impl/store/TimeSeriesKeySerde.java

@@ -0,0 +1,88 @@
+/*
+ * 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.samza.operators.impl.store;
+
+import org.apache.samza.serializers.Serde;
+import java.nio.ByteBuffer;
+
+/**
+ * A {@link Serde} for {@link TimeSeriesKey}s.
+ *
+ * <p> This wraps the actual key's serde with serializers for timestamp and sequence number.
+ *
+ *  A {@link TimeSeriesKeySerde} serializes a key as follows:
+ *    +-------------------------+------------------+------------+
+ *    |  serialized-key bytes   |  timestamp       | seq num    |
+ *    |(serialized by keySerde) |                  |            |
+ *    +-------------------------+------------------+------------+
+ *    +---serialized key len----+-------8 bytes----+---4 bytes--+
+ *
+ * @param <K> the type of the wrapped key
+ */
+public class TimeSeriesKeySerde<K> implements Serde<TimeSeriesKey<K>> {
+
+  private static final int TIMESTAMP_SIZE = 8;
+  private static final int SEQNUM_SIZE = 4;
+
+  private final Serde<K> keySerde;
+
+  public TimeSeriesKeySerde(Serde<K> keySerde) {
+    this.keySerde = keySerde;
+  }
+
+  @Override
+  public byte[] toBytes(TimeSeriesKey<K> timeSeriesKey) {
+    K key = timeSeriesKey.getKey();
+    long timestamp = timeSeriesKey.getTimestamp();
+    int seqNum = timeSeriesKey.getSeqNum();
+
+    byte[] serializedKey = keySerde.toBytes(key);
+    int keySize = serializedKey == null ? 0 : serializedKey.length;
+
+    // append the timestamp and sequence number to the serialized key bytes
+    ByteBuffer buf = ByteBuffer.allocate(keySize + TIMESTAMP_SIZE + SEQNUM_SIZE);
+    if (serializedKey != null) {
+      buf.put(serializedKey);
+    }
+    buf.putLong(timestamp);
+    buf.putInt(seqNum);
+
+    return buf.array();
+  }
+
+  @Override
+  public TimeSeriesKey<K> fromBytes(byte[] timeSeriesKeyBytes) {
+    // First obtain the key bytes, and deserialize them. Later de-serialize the timestamp and sequence number
+    ByteBuffer buf = ByteBuffer.wrap(timeSeriesKeyBytes);
+    int keySize =  timeSeriesKeyBytes.length - TIMESTAMP_SIZE - SEQNUM_SIZE;
+    K key = null;
+
+    if (keySize != 0) {
+      byte[] keyBytes = new byte[keySize];
+      buf.get(keyBytes);
+      key = keySerde.fromBytes(keyBytes);
+    }
+
+    long timeStamp = buf.getLong();
+    int seqNum = buf.getInt();
+
+    return new TimeSeriesKey(key, timeStamp, seqNum);
+  }
+}

samza-core/src/main/java/org/apache/samza/operators/impl/store/TimeSeriesStore.java

@@ -0,0 +1,74 @@
+/*
+ * 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.samza.operators.impl.store;
+
+import org.apache.samza.storage.kv.ClosableIterator;
+
+/**
+ * A key-value store that allows entries to be queried and stored based on time ranges.
+ *
+ * Operations on the store can be invoked from multiple threads. Hence, implementations are expected to be thread-safe.
+ *
+ * @param <K> the type of key in the store
+ * @param <V> the type of value in the store
+ */
+
+public interface TimeSeriesStore<K, V> {
+
+  /**
+   * Insert a key and the value to the store with the provided timestamp.
+   *
+   * @param key the key to insert
+   * @param val the value to insert
+   * @param timeStamp the timestamp in milliseconds
+   */
+  void put(K key, V val, Long timeStamp);
+
+  /**
+   * Returns an iterator over values for the given key in the provided time-range - [{@code startTimestamp}, {@code endTimestamp})
+   *
+   * Values returned by the iterator are ordered by their timestamp. Values with the same timestamp are
+   * returned in their order of insertion.
+   *
+   * @param key the key to look up in the store
+   * @param startTimestamp the start timestamp of the range, inclusive
+   * @param endTimeStamp the end timestamp of the range, exclusive
+   * @throws IllegalArgumentException when startTimeStamp &gt; endTimeStamp, or when either of them is negative
+   */
+  ClosableIterator<TimeSeriesValue<V>> get(K key, Long startTimestamp, Long endTimeStamp);
+
+  /**
+   * Removes all values for this key in the given time-range.
+   *
+   * @param key the key to look up in the store
+   * @param startTimestamp the start timestamp of the range, inclusive
+   * @param endTimeStamp the end timestamp of the range, exclusive
+   * @throws IllegalArgumentException when startTimeStamp &gt; endTimeStamp, or when either of them is negative
+   */
+  void remove(K key, Long startTimestamp, Long endTimeStamp);
+
+  /**
+   * Closes this store.
+   *
+   * Use this to perform final clean-ups, release acquired resources etc.
+   */
+  void close();
+}