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本文主要研究一下canal的EventTransactionBuffer
EventTransactionBuffer
canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/EventTransactionBuffer.java
public class EventTransactionBuffer extends AbstractCanalLifeCycle {
private static final long INIT_SQEUENCE = -1;
private int bufferSize = 1024;
private int indexMask;
private CanalEntry.Entry[] entries;
private AtomicLong putSequence = new AtomicLong(INIT_SQEUENCE); // 代表当前put操作最后一次写操作发生的位置
private AtomicLong flushSequence = new AtomicLong(INIT_SQEUENCE); // 代表满足flush条件后最后一次数据flush的时间
private TransactionFlushCallback flushCallback;
public EventTransactionBuffer(){
}
public EventTransactionBuffer(TransactionFlushCallback flushCallback){
this.flushCallback = flushCallback;
}
public void start() throws CanalStoreException {
super.start();
if (Integer.bitCount(bufferSize) != 1) {
throw new IllegalArgumentException("bufferSize must be a power of 2");
}
Assert.notNull(flushCallback, "flush callback is null!");
indexMask = bufferSize - 1;
entries = new CanalEntry.Entry[bufferSize];
}
public void stop() throws CanalStoreException {
putSequence.set(INIT_SQEUENCE);
flushSequence.set(INIT_SQEUENCE);
entries = null;
super.stop();
}
public void add(List<CanalEntry.Entry> entrys) throws InterruptedException {
for (CanalEntry.Entry entry : entrys) {
add(entry);
}
}
public void add(CanalEntry.Entry entry) throws InterruptedException {
switch (entry.getEntryType()) {
case TRANSACTIONBEGIN:
flush();// 刷新上一次的数据
put(entry);
break;
case TRANSACTIONEND:
put(entry);
flush();
break;
case ROWDATA:
put(entry);
// 针对非DML的数据，直接输出，不进行buffer控制
EventType eventType = entry.getHeader().getEventType();
if (eventType != null && !isDml(eventType)) {
flush();
}
break;
case HEARTBEAT:
// master过来的heartbeat，说明binlog已经读完了，是idle状态
put(entry);
flush();
break;
default:
break;
}
}
public void reset() {
putSequence.set(INIT_SQEUENCE);
flushSequence.set(INIT_SQEUENCE);
}
private void put(CanalEntry.Entry data) throws InterruptedException {
// 首先检查是否有空位
if (checkFreeSlotAt(putSequence.get() + 1)) {
long current = putSequence.get();
long next = current + 1;
// 先写数据，再更新对应的cursor,并发度高的情况，putSequence会被get请求可见，拿出了ringbuffer中的老的Entry值
entries[getIndex(next)] = data;
putSequence.set(next);
} else {
flush();// buffer区满了，刷新一下
put(data);// 继续加一下新数据
}
}
private void flush() throws InterruptedException {
long start = this.flushSequence.get() + 1;
long end = this.putSequence.get();
if (start <= end) {
List<CanalEntry.Entry> transaction = new ArrayList<CanalEntry.Entry>();
for (long next = start; next <= end; next++) {
transaction.add(this.entries[getIndex(next)]);
}
flushCallback.flush(transaction);
flushSequence.set(end);// flush成功后，更新flush位置
}
}
//......
}
- EventTransactionBuffer继承了AbstractCanalLifeCycle，其start方法创建bufferSize大小的CanalEntry.Entry数组；其stop方法设置putSequence及flushSequence为INIT_SQEUENCE，设置entries为null；其add方法根据entry.getEntryType()的不同类型做不同的处理，基本是执行put及flush方法；其reset方法设置putSequence及flushSequence为INIT_SQEUENCE；put方法给entries复制的同时更新putSequence，如果buffer满了则执行flush在重新put；flush方法则执行flushCallback.flush(transaction)，并更新flushSequence
TransactionFlushCallback
canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/EventTransactionBuffer.java
public static interface TransactionFlushCallback {
public void flush(List<CanalEntry.Entry> transaction) throws InterruptedException;
}
- TransactionFlushCallback接口定义了flush方法，它接收CanalEntry.Entry类型的List
EntryProtocol.proto
canal-1.1.4/protocol/src/main/java/com/alibaba/otter/canal/protocol/EntryProtocol.proto
syntax = "proto3";
package com.alibaba.otter.canal.protocol;
option java_package = "com.alibaba.otter.canal.protocol";
option java_outer_classname = "CanalEntry";
option optimize_for = SPEED;
/****************************************************************
* message model
*如果要在Enum中新增类型，确保以前的类型的下标值不变.
****************************************************************/
message Entry {
/**协议头部信息**/
Header header = 1;
///**打散后的事件类型**/ [default = ROWDATA]
oneof entryType_present{
EntryType entryType = 2;
}
/**传输的二进制数组**/
bytes storeValue = 3;
}
/**message Header**/
message Header {
/**协议的版本号**/ //[default = 1]
oneof version_present {
int32 version = 1;
}
/**binlog/redolog 文件名**/
string logfileName = 2;
/**binlog/redolog 文件的偏移位置**/
int64 logfileOffset = 3;
/**服务端serverId**/
int64 serverId = 4;
/** 变更数据的编码 **/
string serverenCode = 5;
/**变更数据的执行时间 **/
int64 executeTime = 6;
/** 变更数据的来源**/ //[default = MYSQL]
oneof sourceType_present {
Type sourceType = 7;
}
/** 变更数据的schemaname**/
string schemaName = 8;
/**变更数据的tablename**/
string tableName = 9;
/**每个event的长度**/
int64 eventLength = 10;
/**数据变更类型**/ // [default = UPDATE]
oneof eventType_present {
EventType eventType = 11;
}
/**预留扩展**/
repeated Pair props = 12;
/**当前事务的gitd**/
string gtid = 13;
}
/**每个字段的数据结构**/
message Column {
/**字段下标**/
int32 index = 1;
/**字段java中类型**/
int32 sqlType = 2;
/**字段名称(忽略大小写)，在mysql中是没有的**/
string name = 3;
/**是否是主键**/
bool isKey = 4;
/**如果EventType=UPDATE,用于标识这个字段值是否有修改**/
bool updated = 5;
/** 标识是否为空 **/ //[default = false]
oneof isNull_present {
bool isNull = 6;
}
/**预留扩展**/
repeated Pair props = 7;
/** 字段值,timestamp,Datetime是一个时间格式的文本 **/
string value = 8;
/** 对应数据对象原始长度 **/
int32 length = 9;
/**字段mysql类型**/
string mysqlType = 10;
}
message RowData {
/** 字段信息，增量数据(修改前,删除前) **/
repeated Column beforeColumns = 1;
/** 字段信息，增量数据(修改后,新增后) **/
repeated Column afterColumns = 2;
/**预留扩展**/
repeated Pair props = 3;
}
/**message row 每行变更数据的数据结构**/
message RowChange {
/**tableId,由数据库产生**/
int64 tableId = 1;
/**数据变更类型**/ //[default = UPDATE]
oneof eventType_present {
EventType eventType = 2;
}
/** 标识是否是ddl语句 **/ // [default = false]
oneof isDdl_present {
bool isDdl = 10;
}
/** ddl/query的sql语句 **/
string sql = 11;
/** 一次数据库变更可能存在多行 **/
repeated RowData rowDatas = 12;
/**预留扩展**/
repeated Pair props = 13;
/** ddl/query的schemaName，会存在跨库ddl，需要保留执行ddl的当前schemaName **/
string ddlSchemaName = 14;
}
/**开始事务的一些信息**/
message TransactionBegin{
/**已废弃，请使用header里的executeTime**/
int64 executeTime = 1;
/**已废弃，Begin里不提供事务id**/
string transactionId = 2;
/**预留扩展**/
repeated Pair props = 3;
/**执行的thread Id**/
int64 threadId = 4;
}
/**结束事务的一些信息**/
message TransactionEnd{
/**已废弃，请使用header里的executeTime**/
int64 executeTime = 1;
/**事务号**/
string transactionId = 2;
/**预留扩展**/
repeated Pair props = 3;
}
/**预留扩展**/
message Pair{
string key = 1;
string value = 2;
}
/**打散后的事件类型，主要用于标识事务的开始，变更数据，结束**/
enum EntryType{
ENTRYTYPECOMPATIBLEPROTO2 = 0;
TRANSACTIONBEGIN = 1;
ROWDATA = 2;
TRANSACTIONEND = 3;
/** 心跳类型，内部使用，外部暂不可见，可忽略 **/
HEARTBEAT = 4;
GTIDLOG = 5;
}
/** 事件类型 **/
enum EventType {
EVENTTYPECOMPATIBLEPROTO2 = 0;
INSERT = 1;
UPDATE = 2;
DELETE = 3;
CREATE = 4;
ALTER = 5;
ERASE = 6;
QUERY = 7;
TRUNCATE = 8;
RENAME = 9;
/**CREATE INDEX**/
CINDEX = 10;
DINDEX = 11;
GTID = 12;
/** XA **/
XACOMMIT = 13;
XAROLLBACK = 14;
/** MASTER HEARTBEAT **/
MHEARTBEAT = 15;
}
/**数据库类型**/
enum Type {
TYPECOMPATIBLEPROTO2 = 0;
ORACLE = 1;
MYSQL = 2;
PGSQL = 3;
}
- EntryProtocol.proto定义了CanalEntry.Entry，它包含header及entryType
AbstractEventParser.transactionBuffer
canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/AbstractEventParser.java
public abstract class AbstractEventParser<EVENT> extends AbstractCanalLifeCycle implements CanalEventParser<EVENT> {
//......
public AbstractEventParser(){
// 初始化一下
transactionBuffer = new EventTransactionBuffer(new TransactionFlushCallback() {
public void flush(List<CanalEntry.Entry> transaction) throws InterruptedException {
boolean successed = consumeTheEventAndProfilingIfNecessary(transaction);
if (!running) {
return;
}
if (!successed) {
throw new CanalParseException("consume failed!");
}
LogPosition position = buildLastTransactionPosition(transaction);
if (position != null) { // 可能position为空
logPositionManager.persistLogPosition(AbstractEventParser.this.destination, position);
}
}
});
}
protected boolean consumeTheEventAndProfilingIfNecessary(List<CanalEntry.Entry> entrys) throws CanalSinkException,
InterruptedException {
long startTs = -1;
boolean enabled = getProfilingEnabled();
if (enabled) {
startTs = System.currentTimeMillis();
}
boolean result = eventSink.sink(entrys, (runningInfo == null) ? null : runningInfo.getAddress(), destination);
if (enabled) {
this.processingInterval = System.currentTimeMillis() - startTs;
}
if (consumedEventCount.incrementAndGet() < 0) {
consumedEventCount.set(0);
}
return result;
}
//......
}
- AbstractEventParser的构造器使用匿名TransactionFlushCallback创建了EventTransactionBuffer；该TransactionFlushCallback会执行consumeTheEventAndProfilingIfNecessary，如果不成功则抛出CanalParseException，成功则构建position并执行ogPositionManager.persistLogPosition；consumeTheEventAndProfilingIfNecessary方法则执行eventSink.sink
小结
EventTransactionBuffer继承了AbstractCanalLifeCycle，其start方法创建bufferSize大小的CanalEntry.Entry数组；其stop方法设置putSequence及flushSequence为INIT_SQEUENCE，设置entries为null；其add方法根据entry.getEntryType()的不同类型做不同的处理，基本是执行put及flush方法；其reset方法设置putSequence及flushSequence为INIT_SQEUENCE；put方法给entries复制的同时更新putSequence，如果buffer满了则执行flush在重新put；flush方法则执行flushCallback.flush(transaction)，并更新flushSequence
