Implement GET API of ip2geo datasource

[heemin32]

Description

Implement GET API of ip2geo datasource

Issues Resolved

N/A

Check List

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[jmazanec15]

@heemin32 Why does this PR need to change PUT action?

[heemin32]

@heemin32 Why does this PR need to change PUT action?

No. Thought it is small change so I mixed them in the PR. Let me break them..

[heemin32]

@jmazanec15 @junqiu-lei Could you take a look?

[VijayanB]

1. Will this name be unique?
2. Do we support regex?

[heemin32]

We don't support regex.
What do you mean by saying unique?

[VijayanB]

you are changing from id to name in get. I assume you are validating that data source name should be unique

[heemin32]

This naming is just for labeling. Still it is used as doc id internally.

[VijayanB]

shall we add instance and length check?

[heemin32]

what do you mean by saying "add instance"?
Also, length check is done in PutDatasourceRequest.

[VijayanB]

you are casting args[0] to String without checking is it string or not. It is safe to check array length wherever you are unpacking

[heemin32]

Value type and array length is defined in below code already. No need to validate again.

static {
        PARSER.declareString(ConstructingObjectParser.constructorArg(), NAME_FIELD);
        PARSER.declareLong(ConstructingObjectParser.constructorArg(), LAST_UPDATE_TIME_FIELD);
        PARSER.declareLong(ConstructingObjectParser.optionalConstructorArg(), ENABLED_TIME_FIELD);
        PARSER.declareBoolean(ConstructingObjectParser.constructorArg(), ENABLED_FIELD);
        PARSER.declareObject(ConstructingObjectParser.constructorArg(), (p, c) -> ScheduleParser.parse(p), SCHEDULE_FIELD);
        PARSER.declareString(ConstructingObjectParser.constructorArg(), ENDPOINT_FIELD);
        PARSER.declareString(ConstructingObjectParser.constructorArg(), STATE_FIELD);
        PARSER.declareStringArray(ConstructingObjectParser.constructorArg(), INDICES_FIELD);
        PARSER.declareObject(ConstructingObjectParser.constructorArg(), Database.PARSER, DATABASE_FIELD);
        PARSER.declareObject(ConstructingObjectParser.constructorArg(), UpdateStats.PARSER, UPDATE_STATS_FIELD);
    }

[VijayanB]

what is the data type for args here?

[heemin32]

Array of object I believe.

[heemin32]

This is not a new pattern that I invented. This is how we parse XContent in OpenSearch generally.

[VijayanB]

Don't want to block you from merging PR. My point is whenever we do casting, it is always safe to do instance check before casting it.

[heemin32]

In this case, we know what the instance type it is because the instance is not coming somewhere else but we provide it in our own code right below it.

[VijayanB]

nit: i don't think you need comments since it is very obvious from implementation/method name and it is private method.

[VijayanB]

Can you use private method in child class? Do you mean in inner class?

[heemin32]

You can use private method in inner class