/// <summary>
/// Merge some number of blocks, how many is decided by mergeFactor, into a single sorted block. This is done by opening <seealso cref="BlockEntryReader"/> on each
/// block that we want to merge and give them to a <seealso cref="MergingBlockEntryReader"/>. The <seealso cref="BlockEntryReader"/>s are pulled from a <seealso cref="BlockReader"/>
/// that iterate over Blocks in file in sequential order.
///
/// <seealso cref="MergingBlockEntryReader"/> pull head from each <seealso cref="BlockEntryReader"/> and hand them out in sorted order, making the multiple entry readers look
/// like a single large and sorted entry reader.
///
/// The large block resulting from the merge is written down to targetChannel by calling
/// <seealso cref="writeBlock(StoreChannel, BlockEntryCursor, long, long, Cancellation, IntConsumer, ByteBuffer)"/>.
/// </summary>
/// <param name="mergeFactor"> How many blocks to merge at the same time. Influence how much memory will be used because each merge block will have it's own
/// <seealso cref="ByteBuffer"/> that they read from. </param>
/// <param name="reader"> The <seealso cref="BlockReader"/> to pull blocks / <seealso cref="BlockEntryReader"/>s from. </param>
/// <param name="targetChannel"> The <seealso cref="StoreChannel"/> to write the merge result to. Result will be appended to current position. </param>
/// <param name="cancellation"> Injected so that this merge can be cancelled, if an external request to do that comes in. </param>
/// <param name="readBuffers"> buffers for all block readers. </param>
/// <param name="writeBuffer"> buffer for writing merged blocks. </param>
/// <returns> The number of blocks that where merged, most often this will be equal to mergeFactor but can be less if there are fewer blocks left in source. </returns>
/// <exception cref="IOException"> If something goes wrong when reading from file. </exception>
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: private int performSingleMerge(int mergeFactor, BlockReader<KEY,VALUE> reader, org.neo4j.io.fs.StoreChannel targetChannel, Cancellation cancellation, ByteBuffer[] readBuffers, ByteBuffer writeBuffer) throws java.io.IOException
private int PerformSingleMerge(int mergeFactor, BlockReader <KEY, VALUE> reader, StoreChannel targetChannel, Cancellation cancellation, ByteBuffer[] readBuffers, ByteBuffer writeBuffer)
{
using (MergingBlockEntryReader <KEY, VALUE> merger = new MergingBlockEntryReader <KEY, VALUE>(_layout))
{
long blockSize = 0;
long entryCount = 0;
int blocksMerged = 0;
for (int i = 0; i < mergeFactor; i++)
{
readBuffers[i].clear();
BlockEntryReader <KEY, VALUE> source = reader.NextBlock(readBuffers[i]);
if (source != null)
{
blockSize += source.BlockSize();
entryCount += source.EntryCount();
blocksMerged++;
merger.AddSource(source);
}
else
{
break;
}
}
writeBuffer.clear();
WriteBlock(targetChannel, merger, blockSize, entryCount, cancellation, _monitor.entriesMerged, writeBuffer);
_monitor.mergedBlocks(blockSize, entryCount, blocksMerged);
return(blocksMerged);
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: private void writeScanUpdatesToTree(RecordingConflictDetector<KEY,VALUE> recordingConflictDetector, org.neo4j.kernel.impl.index.schema.ByteBufferFactory.Allocator allocator, int bufferSize) throws java.io.IOException, org.neo4j.kernel.api.exceptions.index.IndexEntryConflictException
private void WriteScanUpdatesToTree(RecordingConflictDetector <KEY, VALUE> recordingConflictDetector, Allocator allocator, int bufferSize)
{
using (MergingBlockEntryReader <KEY, VALUE> allEntries = new MergingBlockEntryReader <KEY, VALUE>(layout))
{
ByteBuffer singleBlockAssertionBuffer = allocator.Allocate(( int )kibiBytes(8));
foreach (ThreadLocalBlockStorage part in _allScanUpdates)
{
using (BlockReader <KEY, VALUE> reader = part.BlockStorage.reader())
{
BlockEntryReader <KEY, VALUE> singleMergedBlock = reader.NextBlock(allocator.Allocate(bufferSize));
if (singleMergedBlock != null)
{
allEntries.AddSource(singleMergedBlock);
// Pass in some sort of ByteBuffer here. The point is that there should be no more data to read,
// if there is then it's due to a bug in the code and must be fixed.
if (reader.NextBlock(singleBlockAssertionBuffer) != null)
{
throw new System.InvalidOperationException("Final BlockStorage had multiple blocks");
}
}
}
}
int asMuchAsPossibleToTheLeft = 1;
using (Writer <KEY, VALUE> writer = tree.writer(asMuchAsPossibleToTheLeft))
{
while (allEntries.Next() && !_cancellation.cancelled())
{
WriteToTree(writer, recordingConflictDetector, allEntries.Key(), allEntries.Value());
_numberOfAppliedScanUpdates++;
}
}
}
}
/// <summary>
/// There are two files: sourceFile and targetFile. Blocks are merged, mergeFactor at the time, from source to target. When all blocks from source have
/// been merged into a larger block one merge iteration is done and source and target are flipped. As long as source contain more than a single block more
/// merge iterations are needed and we start over again.
/// When source only contain a single block we are finished and the extra file is deleted and <seealso cref="blockFile"/> contains the result with a single sorted
/// block.
///
/// See <seealso cref="performSingleMerge(int, BlockReader, StoreChannel, Cancellation, ByteBuffer[], ByteBuffer)"/> for further details.
/// </summary>
/// <param name="mergeFactor"> See <seealso cref="performSingleMerge(int, BlockReader, StoreChannel, Cancellation, ByteBuffer[], ByteBuffer)"/>. </param>
/// <param name="cancellation"> Injected so that this merge can be cancelled, if an external request to do that comes in.
/// A cancelled merge will leave the same end state file/channel-wise, just not quite completed, which is fine because the merge
/// was cancelled meaning that the result will not be used for anything other than deletion. </param>
/// <exception cref="IOException"> If something goes wrong when reading from file. </exception>
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: public void merge(int mergeFactor, Cancellation cancellation) throws java.io.IOException
public virtual void Merge(int mergeFactor, Cancellation cancellation)
{
_monitor.mergeStarted(_entryCount, CalculateNumberOfEntriesWrittenDuringMerges(_entryCount, _numberOfBlocksInCurrentFile, mergeFactor));
File sourceFile = _blockFile;
File tempFile = new File(_blockFile.Parent, _blockFile.Name + ".b");
try
{
using (Allocator mergeBufferAllocator = _bufferFactory.newLocalAllocator())
{
File targetFile = tempFile;
// Allocate all buffers that will be used and reused for all merge iterations
ByteBuffer writeBuffer = mergeBufferAllocator.Allocate(_bufferFactory.bufferSize());
ByteBuffer[] readBuffers = new ByteBuffer[mergeFactor];
for (int i = 0; i < readBuffers.Length; i++)
{
readBuffers[i] = mergeBufferAllocator.Allocate(_bufferFactory.bufferSize());
}
while (_numberOfBlocksInCurrentFile > 1)
{
// Perform one complete merge iteration, merging all blocks from source into target.
// After this step, target will contain fewer blocks than source, but may need another merge iteration.
using (BlockReader <KEY, VALUE> reader = reader(sourceFile), StoreChannel targetChannel = _fs.open(targetFile, OpenMode.READ_WRITE))
{
long blocksMergedSoFar = 0;
long blocksInMergedFile = 0;
while (!cancellation.Cancelled() && blocksMergedSoFar < _numberOfBlocksInCurrentFile)
{
blocksMergedSoFar += PerformSingleMerge(mergeFactor, reader, targetChannel, cancellation, readBuffers, writeBuffer);
blocksInMergedFile++;
}
_numberOfBlocksInCurrentFile = blocksInMergedFile;
_monitor.mergeIterationFinished(blocksMergedSoFar, blocksInMergedFile);
}
// Flip and restore the channels
File tmpSourceFile = sourceFile;
sourceFile = targetFile;
targetFile = tmpSourceFile;
}
}
}
finally
{
if (sourceFile == _blockFile)
{
_fs.deleteFile(tempFile);
}
else
{
_fs.deleteFile(_blockFile);
_fs.renameFile(tempFile, _blockFile);
}
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: private void assertContents(org.neo4j.index.internal.gbptree.SimpleLongLayout layout, BlockStorage<org.apache.commons.lang3.mutable.MutableLong,org.apache.commons.lang3.mutable.MutableLong> storage, Iterable<java.util.List<BlockEntry<org.apache.commons.lang3.mutable.MutableLong,org.apache.commons.lang3.mutable.MutableLong>>> expectedBlocks) throws java.io.IOException
private void AssertContents(SimpleLongLayout layout, BlockStorage <MutableLong, MutableLong> storage, IEnumerable <IList <BlockEntry <MutableLong, MutableLong> > > expectedBlocks)
{
using (BlockReader <MutableLong, MutableLong> reader = storage.Reader())
{
foreach (IList <BlockEntry <MutableLong, MutableLong> > expectedBlock in expectedBlocks)
{
using (BlockEntryReader <MutableLong, MutableLong> block = reader.NextBlock(HEAP_ALLOCATOR.allocate(1024)))
{
assertNotNull(block);
assertEquals(expectedBlock.Count, block.EntryCount());
foreach (BlockEntry <MutableLong, MutableLong> expectedEntry in expectedBlock)
{
assertTrue(block.Next());
assertEquals(0, layout.Compare(expectedEntry.Key(), block.Key()));
assertEquals(expectedEntry.Value(), block.Value());
}
}
}
}
}
