Merge branch 'release-6.3'

# Conflicts:
#	CMakeLists.txt
#	fdbclient/Knobs.cpp
#	fdbclient/MasterProxyInterface.h
#	fdbrpc/simulator.h
#	fdbserver/MasterProxyServer.actor.cpp
#	tests/fast/CycleAndLock.txt
#	tests/fast/TxnStateStoreCycleTest.txt
#	tests/fast/VersionStamp.txt
#	tests/slow/ParallelRestoreOldBackupApiCorrectnessAtomicRestore.txt
#	tests/slow/ParallelRestoreOldBackupCorrectnessCycle.txt
#	versions.target

Author: etschannen

bindings/java/CMakeLists.txt

@@ -22,6 +22,8 @@ set(JAVA_BINDING_SRCS
   src/main/com/apple/foundationdb/directory/NoSuchDirectoryException.java
   src/main/com/apple/foundationdb/directory/package-info.java
   src/main/com/apple/foundationdb/directory/PathUtil.java
+  src/main/com/apple/foundationdb/DirectBufferIterator.java
+  src/main/com/apple/foundationdb/DirectBufferPool.java
   src/main/com/apple/foundationdb/FDB.java
   src/main/com/apple/foundationdb/FDBDatabase.java
   src/main/com/apple/foundationdb/FDBTransaction.java

bindings/java/fdbJNI.cpp

@@ -305,42 +305,6 @@ JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureStrings_FutureString
 	return arr;
 }
 
-JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureResults_FutureResults_1getSummary(JNIEnv *jenv, jobject, jlong future) {
-	if( !future ) {
-		throwParamNotNull(jenv);
-		return JNI_NULL;
-	}
- 
-	FDBFuture *f = (FDBFuture *)future;
-
-	const FDBKeyValue *kvs;
-	int count;
-	fdb_bool_t more;
-	fdb_error_t err = fdb_future_get_keyvalue_array( f, &kvs, &count, &more );
-	if( err ) {
-		safeThrow( jenv, getThrowable( jenv, err ) );
-		return JNI_NULL;
-	}
-
-	jbyteArray lastKey = JNI_NULL;
-	if(count) {
-		lastKey = jenv->NewByteArray(kvs[count - 1].key_length);
-		if( !lastKey ) {
-			if( !jenv->ExceptionOccurred() )
-				throwOutOfMem(jenv);
-			return JNI_NULL;
-		}
-
-		jenv->SetByteArrayRegion(lastKey, 0, kvs[count - 1].key_length, (jbyte *)kvs[count - 1].key);
-	}
-
-	jobject result = jenv->NewObject(range_result_summary_class, range_result_summary_init, lastKey, count, (jboolean)more);
-	if( jenv->ExceptionOccurred() )
-		return JNI_NULL;
-
-	return result;
-}
-
 // SOMEDAY: explore doing this more efficiently with Direct ByteBuffers
 JNIEXPORT jobject JNICALL Java_com_apple_foundationdb_FutureResults_FutureResults_1get(JNIEnv *jenv, jobject, jlong future) {
 	if( !future ) {
@@ -640,6 +604,68 @@ JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1
 	return (jlong)f;
 }
 
+JNIEXPORT void JNICALL Java_com_apple_foundationdb_FutureResults_FutureResults_1getDirect(
+    JNIEnv* jenv, jobject, jlong future, jobject jbuffer, jint bufferCapacity) {
+
+	if( !future ) {
+		throwParamNotNull(jenv);
+		return;
+	}
+
+	uint8_t* buffer = (uint8_t*)jenv->GetDirectBufferAddress(jbuffer);
+	if (!buffer) {
+		if (!jenv->ExceptionOccurred())
+			throwRuntimeEx(jenv, "Error getting handle to native resources");
+		return;
+	}
+
+	FDBFuture* f = (FDBFuture*)future;
+	const FDBKeyValue *kvs;
+	int count;
+	fdb_bool_t more;
+	fdb_error_t err = fdb_future_get_keyvalue_array( f, &kvs, &count, &more );
+	if( err ) {
+		safeThrow( jenv, getThrowable( jenv, err ) );
+		return;
+	}
+
+	// Capacity for Metadata+Keys+Values
+	//  => sizeof(jint) for total key/value pairs
+	//  => sizeof(jint) to store more flag
+	//  => sizeof(jint) to store key length per KV pair
+	//  => sizeof(jint) to store value length per KV pair
+	int totalCapacityNeeded = 2 * sizeof(jint);
+	for(int i = 0; i < count; i++) {
+		totalCapacityNeeded += kvs[i].key_length + kvs[i].value_length + 2*sizeof(jint);
+		if (bufferCapacity < totalCapacityNeeded) {
+			count = i; /* Only fit first `i` K/V pairs */
+			more = true;
+			break;
+		}
+	}
+
+	int offset = 0;
+
+	// First copy RangeResultSummary, i.e. [keyCount, more]
+	memcpy(buffer + offset, &count, sizeof(jint));
+	offset += sizeof(jint);
+
+	memcpy(buffer + offset, &more, sizeof(jint));
+	offset += sizeof(jint);
+
+	for (int i = 0; i < count; i++) {
+		memcpy(buffer + offset, &kvs[i].key_length, sizeof(jint));
+		memcpy(buffer + offset + sizeof(jint), &kvs[i].value_length, sizeof(jint));
+		offset += 2 * sizeof(jint);
+
+		memcpy(buffer + offset, kvs[i].key, kvs[i].key_length);
+		offset += kvs[i].key_length;
+
+		memcpy(buffer + offset, kvs[i].value, kvs[i].value_length);
+		offset += kvs[i].value_length;
+	}
+}
+
 JNIEXPORT jlong JNICALL Java_com_apple_foundationdb_FDBTransaction_Transaction_1getEstimatedRangeSizeBytes(JNIEnv *jenv, jobject, jlong tPtr, 
 		jbyteArray beginKeyBytes, jbyteArray endKeyBytes) {
 	if( !tPtr || !beginKeyBytes || !endKeyBytes) {

bindings/java/src/main/com/apple/foundationdb/DirectBufferIterator.java

@@ -0,0 +1,108 @@
+/*
+ * DirectBufferIterator.java
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2015-2020 Apple Inc. and the FoundationDB project authors
+ *
+ * Licensed 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 com.apple.foundationdb;
+
+import java.io.Closeable;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * Holds the direct buffer that is shared with JNI wrapper. A typical usage is as follows:
+ * 
+ * The serialization format of result is =>
+ *     [int keyCount, boolean more, ListOf<(int keyLen, int valueLen, byte[] key, byte[] value)>]
+ */
+class DirectBufferIterator implements Iterator<KeyValue>, AutoCloseable {
+	private ByteBuffer byteBuffer;
+	private int current = 0;
+	private int keyCount = -1;
+	private boolean more = false;
+
+	public DirectBufferIterator(ByteBuffer buffer) {
+		byteBuffer = buffer;
+		byteBuffer.order(ByteOrder.nativeOrder());
+	}
+
+	@Override
+	public void close() {
+		if (byteBuffer != null) {
+			DirectBufferPool.getInstance().add(byteBuffer);
+			byteBuffer = null;
+		}
+	}
+
+	public boolean hasResultReady() {
+		return keyCount > -1;
+	}
+
+	@Override
+	public boolean hasNext() {
+		assert (hasResultReady());
+		return current < keyCount;
+	}
+
+	@Override
+	public KeyValue next() {
+		assert (hasResultReady()); // Must be called once its ready.
+		if (!hasNext()) {
+			throw new NoSuchElementException();
+		}
+
+		final int keyLen = byteBuffer.getInt();
+		final int valueLen = byteBuffer.getInt();
+		byte[] key = new byte[keyLen];
+		byteBuffer.get(key);
+
+		byte[] value = new byte[valueLen];
+		byteBuffer.get(value);
+
+		current += 1;
+		return new KeyValue(key, value);
+	}
+
+	public ByteBuffer getBuffer() {
+		return byteBuffer;
+	}
+
+	public int count() {
+		assert (hasResultReady());
+		return keyCount;
+	}
+
+	public boolean hasMore() {
+		assert (hasResultReady());
+		return more;
+	}
+
+	public int currentIndex() {
+		return current;
+	}
+
+	public void readResultsSummary() {
+		byteBuffer.rewind();
+		byteBuffer.position(0);
+
+		keyCount = byteBuffer.getInt();
+		more = byteBuffer.getInt() > 0;
+	}
+}

bindings/java/src/main/com/apple/foundationdb/DirectBufferPool.java

@@ -0,0 +1,89 @@
+/*
+ * DirectBufferPool.java
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2015-2020 Apple Inc. and the FoundationDB project authors
+ *
+ * Licensed 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 com.apple.foundationdb;
+
+import java.nio.ByteBuffer;
+import java.util.concurrent.ArrayBlockingQueue;
+
+/**
+ * A singleton that manages a pool of {@link DirectByteBuffer}, that will be
+ * shared by the {@link DirectBufferIterator} instances. It is responsibilty of
+ * user to return the borrowed buffers.
+ */
+class DirectBufferPool {
+	static final DirectBufferPool __instance = new DirectBufferPool();
+
+	// When tuning this, make sure that the size of the buffer,
+	// is always greater than the maximum size KV allowed by FDB.
+	// Current limits is :
+	//     10kB for key + 100kB for value + 1 int for count + 1 int for more + 2 int for KV size
+	static public final int MIN_BUFFER_SIZE = (10 + 100) * 1000 + Integer.BYTES * 4;
+
+	static private final int DEFAULT_NUM_BUFFERS = 128;
+	static private final int DEFAULT_BUFFER_SIZE = 1024 * 512;
+
+	private ArrayBlockingQueue<ByteBuffer> buffers;
+	private int currentBufferCapacity;
+
+	public DirectBufferPool() {
+		resize(DEFAULT_NUM_BUFFERS, DEFAULT_BUFFER_SIZE);
+	}
+
+	public static DirectBufferPool getInstance() {
+		return __instance;
+	}
+
+	/**
+	 * Resizes buffer pool with given capacity and buffer size. Throws OutOfMemory exception
+	 * if unable to allocate as asked.
+	 */
+	public synchronized void resize(int newPoolSize, int bufferSize) {
+		if (bufferSize < MIN_BUFFER_SIZE) {
+			throw new IllegalArgumentException("'bufferSize' must be at-least: " + MIN_BUFFER_SIZE + " bytes");
+		}
+		buffers = new ArrayBlockingQueue<>(newPoolSize);
+		currentBufferCapacity = bufferSize;
+		while (buffers.size() < newPoolSize) {
+			ByteBuffer buffer = ByteBuffer.allocateDirect(bufferSize);
+			buffers.add(buffer);
+		}
+	}
+
+	/**
+	 * Requests a {@link DirectByteBuffer} from our pool. Returns null if pool is empty.
+	 */
+	public synchronized ByteBuffer poll() {
+		return buffers.poll();
+	}
+
+	/**
+	 * Returns the {@link DirectByteBuffer} that was borrowed from our pool.
+	 */
+	public synchronized void add(ByteBuffer buffer) {
+		if (buffer.capacity() != currentBufferCapacity) {
+			// This can happen when a resize is called while there are outstanding requests,
+			// older buffers will be returned eventually.
+			return;
+		}
+
+		buffers.offer(buffer);
+	}
+}

bindings/java/src/main/com/apple/foundationdb/FDB.java

@@ -85,6 +85,8 @@ public Thread newThread(Runnable r) {
 	private volatile boolean netStarted = false;
 	private volatile boolean netStopped = false;
 	volatile boolean warnOnUnclosed = true;
+	private boolean enableDirectBufferQueries = false;
+
 	private boolean useShutdownHook = true;
 	private Thread shutdownHook;
 	private final Semaphore netRunning = new Semaphore(1);
@@ -229,6 +231,35 @@ public int getAPIVersion() {
 		return apiVersion;
 	}
 
+	/**
+	 * Enables or disables use of DirectByteBuffers for getRange() queries.
+	 *
+	 *	@param enabled Whether DirectByteBuffer should be used for getRange() queries.
+	 */
+	public void enableDirectBufferQuery(boolean enabled) {
+		enableDirectBufferQueries = enabled;
+	}
+
+	/**
+	 * Determines whether {@code getRange()} queries can use {@code DirectByteBuffer} from
+	 * {@link DirectBufferPool} to copy results.
+	 *
+	 * @return {@code true} if direct buffer queries have been enabled and {@code false} otherwise
+	 */
+	public boolean isDirectBufferQueriesEnabled() {
+		return enableDirectBufferQueries;
+	}
+
+	/**
+	 * Resizes the DirectBufferPool with given parameters, which is used by getRange() requests.
+	 *
+	 * @param poolSize Number of buffers in pool
+	 * @param bufferSize Size of each buffer in bytes
+	 */
+	public void resizeDirectBufferPool(int poolSize, int bufferSize) {
+		DirectBufferPool.getInstance().resize(poolSize, bufferSize);
+	}
+
 	/**
 	 * Connects to the cluster specified by the
 	 *  <a href="/foundationdb/administration.html#default-cluster-file" target="_blank">default fdb.cluster file</a>.
@@ -507,4 +538,4 @@ protected static boolean evalErrorPredicate(int predicate, int code) {
 	private native boolean Error_predicate(int predicate, int code);
 
 	private native long Database_create(String clusterFilePath) throws FDBException;
-}
+}