HBase client总览
HBase Client总览
1. affects concurrent readers and writers of that same row ==> atomic on a per-row basis
2. RWCC : ReadWriteConsistencyControl
read without wait for writes
write wait for other writes
3. CRUD
Put (single/batch) :
rowlock, writeToWAL, timeStamp, client-side write buffer, atomic compare-and-set
Get(single/batch) :
rowlock, timeRage, filter, cacheBlocks
Scan:
Caching , Batching
4. Schema
Tables attributed Classes --> Hadoop Writalbe
Talbe Properities: name, column families, maximum file size, read-only, memstore flush size, deferred log flush
Column families: name, maximum versions, compression, block size, block cache, time-to-live, in-memory, bloom filter, replication scope
HBase Client源码
1. HConnection : HConnectionManager.HConnectionImplement
use by HTableInterface, HMasterInterface, RootRegionTracker, MasterrAddressTrakder, ZookeeperWatcher
pause, numberTrtries, maxRPCAttempts, rpcTimeout, configuration
cacheRegionLocations, cachedServer
2. HTableInterface : HTable
connection, tableName, configuration
operationTimeout, cleanPoolOnClose, cleanConnectionOnClose
writerBuffer, writeBufferSize, currentWriteBufferSize, DOPUT_WB_CHECK, scannerCaching, maxKeyValueSize
3. HConnectionManager
Map
4. HConnectionKey
properties : map
userrname: String
5. ClientScanner
6. ScannerCallable extends ServerCallable
7. ServerCallable extends VersionedProtocol
connection, table, row, hRegionLocation
HRegionInterface server; // java动态代理机制 入口
Result[] call()
openScanner
server.next(scannerid, caching)
8. Result
KeyValue [] kvsNavigableMap
byte [] row
ImmutableBytesWritable bytes
RPC机制
1. 通信
rpc角色： client/server
通信信道：socket
接口/协议： 对象序列化
控制： 传输，并发， 会话
保障： 出错重试
2. 工作流程
客户端获取通信接口实例
客户端通过调用实例方法， 向服务端传输请求
服务端被调用， 进行处理并返回结果
3. 序列化
Hbase: org.apache.hadoop.hbase.io.HbaseObjectWritable
1) 类code映射表->CLASS_TO_CODE
2）类实例code映射表->CODE_TO_CLASS : 要传输的类（实现Writable）, 原始类型， 其他（String, 数组）
Hadoop: org.apache.hadoop.io.WriteAble
1) write(DataOutput out)
2) readFile(DataInput in)