alluxio源码解析-rpc调用概述-client和worker之间的block模块的通信架构(netty版本)(3)

(1.8版本)client和worker之间的block模块的通信架构

block做为alluxio文件读取或者存储的最小基本单位,都是经过BlockOutStream和BlockInputtream实现的

其中具体的数据包传输有Short circuit和netty两种实现:

• Short circuit:经过本地的ramdisk传输和netty传输
• tcp传输:只经过netty传输

输入流代码中,关于两种实现的选择逻辑:

 1 public static BlockInStream create(FileSystemContext context, BlockInfo info,
 2  WorkerNetAddress dataSource, BlockInStreamSource dataSourceType, InStreamOptions options) 3 throws IOException { 4 URIStatus status = options.getStatus(); 5 OpenFileOptions readOptions = options.getOptions(); 6 7 boolean promote = readOptions.getReadType().isPromote(); 8 9 long blockId = info.getBlockId(); 10 long blockSize = info.getLength(); 11 12 // Construct the partial read request 13 Protocol.ReadRequest.Builder builder = 14  Protocol.ReadRequest.newBuilder().setBlockId(blockId).setPromote(promote); 15 // Add UFS fallback options 16  builder.setOpenUfsBlockOptions(options.getOpenUfsBlockOptions(blockId)); 17 18 boolean shortCircuit = Configuration.getBoolean(PropertyKey.USER_SHORT_CIRCUIT_ENABLED); 19 boolean sourceSupportsDomainSocket = NettyUtils.isDomainSocketSupported(dataSource); 20 boolean sourceIsLocal = dataSourceType == BlockInStreamSource.LOCAL; 21 22 // Short circuit 23 if (sourceIsLocal && shortCircuit && !sourceSupportsDomainSocket) { 24 LOG.debug("Creating short circuit input stream for block {} @ {}", blockId, dataSource); 25 try { 26 return createLocalBlockInStream(context, dataSource, blockId, blockSize, options); 27 } catch (NotFoundException e) { 28 // Failed to do short circuit read because the block is not available in Alluxio. 29 // We will try to read via netty. So this exception is ignored. 30 LOG.warn("Failed to create short circuit input stream for block {} @ {}. Falling back to " 31 + "network transfer", blockId, dataSource); 32  } 33  } 34 35 // Netty 36 LOG.debug("Creating netty input stream for block {} @ {} from client {} reading through {}", 37  blockId, dataSource, NetworkAddressUtils.getClientHostName(), dataSource); 38 return createNettyBlockInStream(context, dataSource, dataSourceType, builder.buildPartial(), 39  blockSize, options); 40 }

输出流代码中,关于两种实现的选择逻辑:

 1 /**
 2      * @param context the file system context
 3      * @param blockId the block ID
 4      * @param blockSize the block size in bytes
 5      * @param address the Alluxio worker address
 6      * @param options the out stream options
 7      * @return the {@link PacketWriter} instance
 8      */
 9     public static PacketWriter create(FileSystemContext context, long blockId, long blockSize,
10         WorkerNetAddress address, OutStreamOptions options) throws IOException { 11 if (CommonUtils.isLocalHost(address) && Configuration 12 .getBoolean(PropertyKey.USER_SHORT_CIRCUIT_ENABLED) && !NettyUtils 13  .isDomainSocketSupported(address)) { 14 LOG.debug("Creating short circuit output stream for block {} @ {}", blockId, address); 15 return LocalFilePacketWriter.create(context, address, blockId, options); 16 } else { 17 LOG.debug("Creating netty output stream for block {} @ {} from client {}", blockId, address, 18  NetworkAddressUtils.getClientHostName()); 19 return NettyPacketWriter 20  .create(context, address, blockId, blockSize, Protocol.RequestType.ALLUXIO_BLOCK, 21  options); 22  } 23 }

 

 

short-circuit策略

针对block的的建立/摧毁,经过netty进行网络通信

针对block的实际内容,直接经过ramdisk写到本地,避免了使用netty进行网络通信,

short-circuit通信-客户端:

 

下图是Netty版本的客户端+LocalFileBlockWriter+LocalFileBlockReader调用过程

 

short-circuit通信-服务端:

下图是Netty版本的服务端调用

非short-circuit

非short-circuit通信-客户端:

下图是Netty版本的客户端调用过程

 

非short-circuit通信-服务端:

下图是Netty版本的服务端调用

 

 

下一篇将介绍BlockWorker相关的功能