LogHeader (canal dbsync module for otter 1.1.4 1.1.4 API)

java.lang.Object
- com.taobao.tddl.dbsync.binlog.event.LogHeader

public final class LogHeader
extends java.lang.Object

The Common-Header, documented in the table @ref Table_common_header "below", always has the same form and length within one version of MySQL. Each event type specifies a format and length of the Post-Header. The length of the Common-Header is the same for all events of the same type. The Body may be of different format and length even for different events of the same type. The binary formats of Post-Header and Body are documented separately in each subclass. The binary format of Common-Header is as follows.

Common-Header
Name	Format	Description
timestamp	4 byte unsigned integer	The time when the query started, in seconds since 1970.
type	1 byte enumeration	See enum #Log_event_type.
server_id	4 byte unsigned integer	Server ID of the server that created the event.
total_size	4 byte unsigned integer	The total size of this event, in bytes. In other words, this is the sum of the sizes of Common-Header, Post-Header, and Body.
master_position	4 byte unsigned integer	The position of the next event in the master binary log, in bytes from the beginning of the file. In a binlog that is not a relay log, this is just the position of the next event, in bytes from the beginning of the file. In a relay log, this is the position of the next event in the master's binlog.
flags	2 byte bitfield	See Log_event::flags.

Summing up the numbers above, we see that the total size of the common header is 19 bytes.

版本:: 1.0
作者:: Changyuan.lh
另请参阅:: mysql-5.1.60/sql/log_event.cc

字段概要

字段
限定符和类型	字段和说明
`protected int`	`checksumAlg` The value is set by caller of FD constructor and Log_event::write_header() for the rest.
`protected long`	`crc` Placeholder for event checksum while writing to binlog.
`protected int`	`eventLen` Number of bytes written by write() function
`protected int`	`flags` Some 16 flags.
`protected java.util.Map<java.lang.String,java.lang.String>`	`gtidMap`
`protected java.lang.String`	`logFileName` binlog fileName
`protected long`	`logPos` The offset in the log where this event originally appeared (it is preserved in relay logs, making SHOW SLAVE STATUS able to print coordinates of the event in the master's binlog).
`protected long`	`serverId` The master's server id (is preserved in the relay log; used to prevent from infinite loops in circular replication).
`protected int`	`type`
`protected long`	`when` Timestamp on the master(for debugging and replication of NOW()/TIMESTAMP).

构造器概要

构造器
构造器和说明

LogHeader(int type)

LogHeader(LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent)

构造器
构造器和说明
`LogHeader(int type)`
`LogHeader(LogBuffer buffer, FormatDescriptionLogEvent descriptionEvent)`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`int`	`getChecksumAlg()`
`long`	`getCrc()`
`java.lang.String`	`getCurrentGtid()`
`java.lang.String`	`getCurrentGtidLastCommit()`
`java.lang.String`	`getCurrentGtidSn()`
`int`	`getEventLen()` The total size of this event, in bytes.
`int`	`getFlags()` Some 16 flags.
`java.lang.String`	`getGtidSetStr()`
`java.lang.String`	`getLogFileName()`
`long`	`getLogPos()` The position of the next event in the master binary log, in bytes from the beginning of the file.
`long`	`getServerId()` Server ID of the server that created the event.
`int`	`getType()` The different types of log events.
`long`	`getWhen()` The time when the query started, in seconds since 1970.
`void`	`putGtid(GTIDSet gtidSet, GtidLogEvent event)`
`void`	`setLogFileName(java.lang.String logFileName)`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - type
```
protected final int type
```
  - logPos
```
protected long logPos
```
    The offset in the log where this event originally appeared (it is preserved in relay logs, making SHOW SLAVE STATUS able to print coordinates of the event in the master's binlog). Note: when a transaction is written by the master to its binlog (wrapped in BEGIN/COMMIT) the log_pos of all the queries it contains is the one of the BEGIN (this way, when one does SHOW SLAVE STATUS it sees the offset of the BEGIN, which is logical as rollback may occur), except the COMMIT query which has its real offset.
  - when
```
protected long when
```
    Timestamp on the master(for debugging and replication of NOW()/TIMESTAMP). It is important for queries and LOAD DATA INFILE. This is set at the event's creation time, except for Query and Load (et al.) events where this is set at the query's execution time, which guarantees good replication (otherwise, we could have a query and its event with different timestamps).
  - eventLen
```
protected int eventLen
```
    Number of bytes written by write() function
  - serverId
```
protected long serverId
```
    The master's server id (is preserved in the relay log; used to prevent from infinite loops in circular replication).
  - flags
```
protected int flags
```
    Some 16 flags. See the definitions above for LOG_EVENT_TIME_F, LOG_EVENT_FORCED_ROTATE_F, LOG_EVENT_THREAD_SPECIFIC_F, and LOG_EVENT_SUPPRESS_USE_F for notes.
  - checksumAlg
```
protected int checksumAlg
```
    The value is set by caller of FD constructor and Log_event::write_header() for the rest. In the FD case it's propagated into the last byte of post_header_len[] at FD::write(). On the slave side the value is assigned from post_header_len[last] of the last seen FD event.
  - crc
```
protected long crc
```
    Placeholder for event checksum while writing to binlog.
  - logFileName
```
protected java.lang.String logFileName
```
    binlog fileName
  - gtidMap
```
protected java.util.Map<java.lang.String,java.lang.String> gtidMap
```
- 构造器详细资料
  - LogHeader
```
public LogHeader(int type)
```
  - LogHeader
```
public LogHeader(LogBuffer buffer,
                 FormatDescriptionLogEvent descriptionEvent)
```
- 方法详细资料
  - getType
```
public final int getType()
```
    The different types of log events.
  - getLogPos
```
public final long getLogPos()
```
    The position of the next event in the master binary log, in bytes from the beginning of the file. In a binlog that is not a relay log, this is just the position of the next event, in bytes from the beginning of the file. In a relay log, this is the position of the next event in the master's binlog.
  - getEventLen
```
public final int getEventLen()
```
    The total size of this event, in bytes. In other words, this is the sum of the sizes of Common-Header, Post-Header, and Body.
  - getWhen
```
public final long getWhen()
```
    The time when the query started, in seconds since 1970.
  - getServerId
```
public final long getServerId()
```
    Server ID of the server that created the event.
  - getFlags
```
public final int getFlags()
```
    Some 16 flags. See the definitions above for LOG_EVENT_TIME_F, LOG_EVENT_FORCED_ROTATE_F, LOG_EVENT_THREAD_SPECIFIC_F, and LOG_EVENT_SUPPRESS_USE_F for notes.
  - getCrc
```
public long getCrc()
```
  - getChecksumAlg
```
public int getChecksumAlg()
```
  - getLogFileName
```
public java.lang.String getLogFileName()
```
  - setLogFileName
```
public void setLogFileName(java.lang.String logFileName)
```
  - getGtidSetStr
```
public java.lang.String getGtidSetStr()
```
  - getCurrentGtid
```
public java.lang.String getCurrentGtid()
```
  - getCurrentGtidSn
```
public java.lang.String getCurrentGtidSn()
```
  - getCurrentGtidLastCommit
```
public java.lang.String getCurrentGtidLastCommit()
```
  - putGtid
```
public void putGtid(GTIDSet gtidSet,
                    GtidLogEvent event)
```

类 LogHeader

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

type

logPos

when

eventLen

serverId

flags

checksumAlg

crc

logFileName

gtidMap

构造器详细资料

LogHeader

LogHeader

方法详细资料

getType

getLogPos

getEventLen

getWhen

getServerId

getFlags

getCrc

getChecksumAlg

getLogFileName

setLogFileName

getGtidSetStr

getCurrentGtid

getCurrentGtidSn

getCurrentGtidLastCommit

putGtid