/// <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: BlockEntryReader<KEY,VALUE> nextBlock(ByteBuffer blockBuffer) throws java.io.IOException internal virtual BlockEntryReader <KEY, VALUE> NextBlock(ByteBuffer blockBuffer) { long position = _channel.position(); if (position >= _channel.size()) { return(null); } StoreChannel blockChannel = _fs.open(_file, OpenMode.READ); blockChannel.Position(position); PageCursor pageCursor = new ReadableChannelPageCursor(new ReadAheadChannel <>(blockChannel, blockBuffer)); BlockEntryReader <KEY, VALUE> blockEntryReader = new BlockEntryReader <KEY, VALUE>(pageCursor, _layout); long blockSize = blockEntryReader.BlockSize(); _channel.position(position + blockSize); return(blockEntryReader); }