Support multi-raft

[TheR1sing3un]

Multi-DLedger

Structure

overall structure

Details

For the above several components, do the following detailed explanation.

DLedgerProxy

We previously used DLedgerServer directly as a vehicle for receiving and processing requests in DLedger.

If we want to upgrade to a Multi-Raft architecture, we need to decouple the parts that receive and send requests from the parts that process them. we use a layer proxy to proxy the underlying Raft node, we can use multiple DLedgerServers to share a RpcService for request processing. This DLedgerProxy is a wrapper around previously implemented methods such as handle requests, and can be routed according to the configuration.

That is we ip:port can not uniquely identify a Raft node, because ip:port can also be represented as a multi-Raft structure external services, then at this time, we need a selfID to differentiate the different Raft in this Multi-Raft. All of our DLedger communications will need to be located with selfID at this time. And we added several modules in DLedgerProxy, namely ConfigManager and DLedgerManager. The two modules manage the Raft-Group configuration and the native DLedgerServer instance configuration and processing logic, respectively.

Why use ip:port+selfID to identify a raft

We used to be able to locate a Raft instance with an ip:port, but now the process we locate with ip:port is a multi-Raft, so we need to locate in process according to selfID.

ConfigManager

ConfigManager is the configuration management module for DLedger. Subsequently, using a solution such as a configuration center, online changes can be made dynamically in the Region for which the Raft-Group is responsible. At this point, ConfigManager can make the appropriate requests and responses. Because of course we can have multiple DLedgerServers share a same RegionConfig, because RegionConfig is the same for all Raft in the cluster.

Can also manage and configure the configuration of the local DLedgerServer instance, and can instantiate the DLedgerServer according to the startup parameters at startup time, you can also manage the local DLedgerServer instance by changing the local DLedgerServer instance's configuration file in real time based on the network request.

DLedgerManager

DLedgerManager is the management module for DLedgerServer, which includes the ability to route to a DLedgerServer based on configuration for network requests to DLedgerServer, and for subsequent optimizations such as the request merge mentioned above, can be unified in this module processing.

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How to start with Multi-DLedger

If you need to start with Multi-DLedger, you need to start with a configuration file

Simple configurations include:

configs:
  - group: g0
    selfId: n0
    peers: n0-127.0.0.1:10000;n1-127.0.0.1:10001;n2-127.0.0.1:10002
    preferredLeaderIds: n0
  - group: g1
    selfId: a0
    peers: a0-127.0.0.1:10000;a1-127.0.0.1:10001;a2-127.0.0.1:10002
    preferredLeaderIds: a1
  - group: g2
    selfId: b0
    peers: b0-127.0.0.1:10000;b1-127.0.0.1:10001;b2-127.0.0.1:10002
    preferredLeaderIds: b2

Start in the command line:

java -jar ./DLedger.jar serverc -c ./config.yaml

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Request receiving and response process

Previous request response process

Because there is only one Dledgerserver, it can directly call the handle methods of Dledgerserver.

Current request response process

Now that we have multiple DLedgerServer instances, then we need to specifically route to a DLedgerServer according to the selftID in the request. Therefore, we need to let the DledgerManager in DLedgerProxy find the specific DLedgerServer to process the request based on Selfid-> DledgerServer.

[TheR1sing3un]

@yuz10 PING！Please check

[yuz10]

getDLedgerServer twice, the first dLedgerServer no use

[TheR1sing3un]

@yuz10 @RongtongJin Hi~ I have refactored some code about multi-raft structure! Please check! Thanks~

[yuz10]

@yuz10 @RongtongJin Hi~ I have refactored some code about multi-raft structure! Please check! Thanks~

Hi TheR1sing3un, please fix the merge conflicts.

[TheR1sing3un]

@yuz10 @RongtongJin Hi~ I have refactored some code about multi-raft structure! Please check! Thanks~

Hi TheR1sing3un, please fix the merge conflicts.

done~