[ISSUE #1070] DLedger Connector: first exploratory implementation

[LIU-WEI-git]

trafficstars

Hi, I'm the selected student of OSPP2022. This pr is about the DLedger Connector. Here is a rough design doc about this module.

Related issue #1070.

Documentation

• This pull request introduce a new feature.
• The detail doc will be added after all development done.

[LIU-WEI-git]

DLedger provides only two simple commitlog management operations: append and get. So I have to implement pub/sub mechanism by my self, which brings many design problems to current implementation.

• Implement a pub/sub mechanism which is against the separation of computing and storage for connector module.
• Just store cloudevent in DLedger while not store the metadata of pub/sub mechanism.
• Metadata of pub/sub could not synchronize among eventmesh cluster.
• Could not recover the pub/sub status from crash.

[mytang0]

Great! Excluding other commits will make it easier to review.

[Alonexc]

Welcome, you need to provide an issue for this pr.

[codecov[bot]]

Codecov Report

Merging #1061 (cff54f7) into dledger-connector (dab1086) will increase coverage by 0.27%. The diff coverage is 32.85%.

@@                  Coverage Diff                   @@
##             dledger-connector   #1061      +/-   ##
======================================================
+ Coverage                 8.42%   8.70%   +0.27%     
- Complexity                 534     565      +31     
======================================================
  Files                      362     374      +12     
  Lines                    23228   23508     +280     
  Branches                  2546    2559      +13     
======================================================
+ Hits                      1958    2047      +89     
- Misses                   21118   21300     +182     
- Partials                   152     161       +9     

Impacted Files	Coverage Δ
...e/eventmesh/connector/dledger/DLedgerConsumer.java	0.00% <0.00%> (ø)
...sh/connector/dledger/broker/CloudEventMessage.java	0.00% <0.00%> (ø)
...connector/dledger/broker/DLedgerMessageWriter.java	0.00% <0.00%> (ø)
...ntmesh/connector/dledger/broker/SubscribeTask.java	0.00% <0.00%> (ø)
...r/dledger/exception/DLedgerConnectorException.java	0.00% <0.00%> (ø)
...e/eventmesh/connector/dledger/DLedgerProducer.java	33.33% <33.33%> (ø)
...ector/dledger/broker/DLedgerTopicIndexesStore.java	33.33% <33.33%> (ø)
...onnector/dledger/clientpool/DLedgerClientPool.java	43.47% <43.47%> (ø)
...or/dledger/config/DLedgerConfigurationWrapper.java	52.63% <52.63%> (ø)
...ector/dledger/clientpool/DLedgerClientFactory.java	66.66% <66.66%> (ø)
... and 4 more

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