Dynamo use gloabal worker

[joowon-byun]

Proposed changes

• non-single DynamoDB can be created
  • If you set table name as dynamo-table, tables such as dynamo-table-body, dynamo-table-header, dynamo-table-statetrie, and so on will be created.
• All DynamoDB tables will share a worker pool.
• Sharded DB is not enabled for dynamoDB.

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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• I have added tests that prove my fix is effective or that my feature works
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• Any dependent changes have been merged and published in downstream modules

Related issues

Further comments

[CLAassistant]

All committers have signed the CLA.

[aidan-kwon]

LGTM

[ehnuje]

Is there any possibility of panic if Close is called while processing Put operation?

[joowon-byun]

I've just tested.
A panic will not occur even though Close() is called on non-empty channel. (call Put() -> Close()) It will close after all of the items are processed.
However, a panic will occur when put is called in a closed channel (call Close() -> Put()).

[ehnuje]

Yes. To avoid the second case, we need to use switch & case. Do you have any other alternatives?

[joowon-byun]

If we use the original code, not all of the items in the channel will be processed. There might be some items we expect to be writen but actually no. Actually, in the original code, it will wait inifinitively in Write() because the workers will not process the input and wg.Done() is not called.
Is there other ways to handle both cases?

[KimKyungup]

I think we don't need to consider the 2nd case. It is misbehavior of users.

[ehnuje]

I think we don't need to consider the 2nd case. It is misbehavior of users.

I think this is the case which rarely happens.
However, I don't think it is misbehavior of users. Since the user does not know whether it will cause panic or not.

However, again, as Database.Close is called after Blockchain.Stop, there is no possibility that Database.Put is called after Database.Close.