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From Jørgen Løland (JIRA) <j...@apache.org>
Subject [jira] Updated: (DERBY-2977) Replication: Add a ReplicationMaster controller that will manage replication on the master side
Date Thu, 27 Sep 2007 11:09:51 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Jørgen Løland updated DERBY-2977:

    Attachment: repli_logbuffer_v2.diff

Version 2 of the proof of concept code showed a problem with the way log is appended to the
repliation buffer. Currently, LogToFile#appendLogRecord is used to write log to the replication
master log buffer. However, the LogAccessFile class that wraps write operations to log file
also write checksums. We need these checksums at the slave because without them, the log instants
on the slave and master will differ, in turn making recovery impossible (undo operations refer
to a specific instant, which will not be correct).

The attached patch, repli_logbuffer_v2.*, changes this erroneous behavior. With this patch,
log is appended to the repliation log buffer in LogAccessFile, not LogToFile like now. The
patch modifies the following files:

M      java/engine/org/apache/derby/impl/services/replication/buffer/LogBufferElement.java
M      java/engine/org/apache/derby/impl/services/replication/buffer/ReplicationLogBuffer.java

The buffer now accepts chunks of log records from LogAccessFile#writeToLog (i.e., appended
to replication buffer in the same method that writes the log to disk) instead of single log
records from LogToFile#appendLogRecord

M      java/engine/org/apache/derby/impl/services/replication/slave/ReplicationLogScan.java

Modified the slave-side log parser to read the new chunk of log record format

M      java/engine/org/apache/derby/impl/services/replication/master/MasterController.java
M      java/engine/org/apache/derby/iapi/services/replication/master/MasterFactory.java

Modified appendLog signature to accept log from LogAccessFile instead of from LogToFile

M      java/engine/org/apache/derby/impl/store/raw/log/LogAccessFile.java

Can be set inReplicationMasterMode, in which log is appended to MasterFactory 

M      java/engine/org/apache/derby/impl/store/raw/log/LogToFile.java

Removed the code that appends log to replication log buffer, and tells LogAccessFile to go
into replication master mode when needed.

Allsuites and derbyall completed without error

> Replication: Add a ReplicationMaster controller that will manage replication on the master
> -----------------------------------------------------------------------------------------------
>                 Key: DERBY-2977
>                 URL: https://issues.apache.org/jira/browse/DERBY-2977
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Services
>    Affects Versions:
>            Reporter: Jørgen Løland
>            Assignee: Jørgen Løland
>         Attachments: derby_2977_1.diff, derby_2977_1.stat, derby_2977_1b.diff, derby_2977_1b.stat,
derby_2977_1c.diff, derby_2977_1c.stat, repli_logbuffer_v2.diff, repli_logbuffer_v2.stat
> The replication master role includes many tasks:
> * set up a network connection to the slave
> * sending the database to the slave before starting replication
> * make sure that log records are appended to the network buffer, and that the log is
later sent to the slave
> * etc
> This issue is for adding a controller that will start/stop/initiate all services needed
for the replication master role.

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