Replace Endpoints with Regional Endpoints

[tvaron3]

Description

The service will now start returning two endpoints for a region. A GetDatabaseAccount call used to get the following uri for a region test-account-name-westus.cosmos.documents.com. Now, it will randomly send variations of this endpoint. Ex: test-account-name-westus-1.cosmos.documents.com, test-account-name-westus-2.cosmos.documents.com. This is to improve availability in scenarios when gateway goes down.

Implementation

Location cache will now have a new RegionalEndpoint object that will have a current and previous. The idea is the previous can be used in certain scenarios to retry.

Pseudocode of new current and previous logic

request in progress
on current:
    success:
        no op
    failure:
        use previous:
 
on previous:
    success:
        temp = current
        current = previous
        previous = temp 
    failure:
        refresh the cache:
            if (current != new value):
                previous = current:
            current = new value
 
on database account refresh - every 5 mins:
    initial:
        current = new value
        previous = None
    next:
        if current != new value
            previous = current
        current = new value

Testing

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

azure-cosmos

[FabianMeiswinkel]

just curious - why all small letters (patch) when the OpType is defined with capital letters here. Don't we have to do case-insensitive comaprison due to it everywehre -

azure-sdk-for-python/sdk/cosmos/azure-cosmos/azure/cosmos/documents.py

Lines 347 to 364 in f2f1e98

	class _OperationType:
	"""Represents the type of the operation"""
	Create: Literal["Create"] = "Create"
	Delete: Literal["Delete"] = "Delete"
	ExecuteJavaScript: Literal["ExecuteJavaScript"] = "ExecuteJavaScript"
	Head: Literal["Head"] = "Head"
	HeadFeed: Literal["HeadFeed"] = "HeadFeed"
	Patch: Literal["Patch"] = "Patch"
	Query: Literal["Query"] = "Query"
	QueryPlan: Literal["QueryPlan"] = "QueryPlan"
	Read: Literal["Read"] = "Read"
	ReadFeed: Literal["ReadFeed"] = "ReadFeed"
	Recreate: Literal["Recreate"] = "Recreate"
	Replace: Literal["Replace"] = "Replace"
	SqlQuery: Literal["SqlQuery"] = "SqlQuery"
	Update: Literal["Update"] = "Update"
	Upsert: Literal["Upsert"] = "Upsert"
	Batch: Literal["Batch"] = "Batch"

[azure-pipelines]

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[tvaron3]

Use get() instead of location[""]

[tvaron3]

for example, all of these connection errors should be handled properly and can be safely retried in my opinion (more research required) https://docs.aiohttp.org/en/stable/client_reference.html#connection-errors

Further client errors by aio http package -> https://docs.aiohttp.org/en/stable/client_reference.html#client-exceptions
Client Reference — aiohttp 3.11.11 documentation