Fale sobre a posição do canal

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Este artigo estuda principalmente a posição do canal

Posição

canal-1.1.4 / protocolo / src / principal / java / com / alibaba / lontra / canal / protocolo / posição / Position.java

public abstract class Position implements Serializable {

    private static final long serialVersionUID = 2332798099928474975L;

    public String toString() {
        return ToStringBuilder.reflectionToString(this, CanalToStringStyle.DEFAULT_STYLE);
    }

}
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• Position define o método toString, usando o método ToStringBuilder.reflectionToString para converter em CanalToStringStyle.DEFAULT_STYLE

TimePosition

canal-1.1.4 / protocolo / src / principal / java / com / alibaba / lontra / canal / protocolo / posição / TimePosition.java

public class TimePosition extends Position {

    private static final long serialVersionUID = 6185261261064226380L;
    protected Long            timestamp;

    public TimePosition(Long timestamp){
        this.timestamp = timestamp;
    }

    public Long getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(Long timestamp) {
        this.timestamp = timestamp;
    }

    //......
}
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• TimePosition herda Position, que define o atributo timestamp

EntryPosition

canal-1.1.4 / protocolo / src / principal / java / com / alibaba / lontra / canal / protocolo / posição / EntryPosition.java

public class EntryPosition extends TimePosition {

    private static final long serialVersionUID      = 81432665066427482L;
    public static final int   EVENTIDENTITY_SEGMENT = 3;
    public static final char  EVENTIDENTITY_SPLIT   = (char) 5;

    private boolean           included              = false;
    private String            journalName;
    private Long              position;
    // add by agapple at 2016-06-28
    private Long              serverId              = null;              // 记录一下位点对应的serverId
    private String            gtid                  = null;

    //......
}
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• EntryPosition herda TimePosition, que define os atributos incluídos, journalName, position, serverId e gtid

SlaveEntryPosition

canal-1.1.4 / parse / src / main / java / com / alibaba / lontra / canal / parse / de entrada / mysql / SlaveEntryPosition.java

public class SlaveEntryPosition extends EntryPosition {

    private static final long serialVersionUID = 5271424551446372093L;
    private final String      masterHost;
    private final String      masterPort;

    public SlaveEntryPosition(String fileName, long position, String masterHost, String masterPort){
        super(fileName, position);

        this.masterHost = masterHost;
        this.masterPort = masterPort;
    }

    public String getMasterHost() {
        return masterHost;
    }

    public String getMasterPort() {
        return masterPort;
    }
}
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• SlaveEntryPosition herda EntryPosition, que define os atributos de masterHost e masterPort

LogPosition

canal-1.1.4 / protocolo / src / principal / java / com / alibaba / lontra / canal / protocolo / posição / LogPosition.java

public class LogPosition extends Position {

    private static final long serialVersionUID = 3875012010277005819L;
    private LogIdentity       identity;
    private EntryPosition     postion;

    public LogIdentity getIdentity() {
        return identity;
    }

    public void setIdentity(LogIdentity identity) {
        this.identity = identity;
    }

    public EntryPosition getPostion() {
        return postion;
    }

    public void setPostion(EntryPosition postion) {
        this.postion = postion;
    }

    //......
}
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• LogPosition herda Position, que define dois atributos, identidade e posição

cursor

canal-1.1.4 / meta / src / principal / java / com / alibaba / lontra / canal / meta / CanalMetaManager.java

public interface CanalMetaManager extends CanalLifeCycle {
	
	//......

    /**
     * 获取 cursor 游标
     */
    Position getCursor(ClientIdentity clientIdentity) throws CanalMetaManagerException;

    /**
     * 更新 cursor 游标
     */
    void updateCursor(ClientIdentity clientIdentity, Position position) throws CanalMetaManagerException;

	//......

}
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• CanalMetaManager define os métodos getCursor e updateCursor; o método getCursor retorna Position de acordo com clientIdentity; o método updateCursor atualiza a posição do clientIdentity especificado

MemoryMetaManager

canal-1.1.4 / meta / src / principal / java / com / alibaba / lontra / canal / meta / MemoryMetaManager.java

public class MemoryMetaManager extends AbstractCanalLifeCycle implements CanalMetaManager {

    protected Map<String, List<ClientIdentity>>              destinations;
    protected Map<ClientIdentity, MemoryClientIdentityBatch> batches;
    protected Map<ClientIdentity, Position>                  cursors;

    //......

    public Position getCursor(ClientIdentity clientIdentity) throws CanalMetaManagerException {
        return cursors.get(clientIdentity);
    }

    public void updateCursor(ClientIdentity clientIdentity, Position position) throws CanalMetaManagerException {
        cursors.put(clientIdentity, position);
    }

    //......
}
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• MemoryMetaManager implementa a interface CanalMetaManager, que define os cursores da estrutura Map, a chave é ClientIdentity e o valor é Position; o método getCursor obtém a posição dos cursores de acordo com o clientIdentity; o método updateCursor atualiza o valor da chave nos cursores para o clientIdentity.

Sumário

Position define o método toString, usando o método ToStringBuilder.reflectionToString para converter em CanalToStringStyle.DEFAULT_STYLE; possui duas subclasses diretas, TimePosition e LogPosition; EntryPosition herda TimePosition; SlaveEntryPosition herda EntryPosition; LogPosition combina EntryPosition

doc

• Posição