[Internal] ThinProxy Integration: Adds New HttpTimeoutPolicy and Fix Cross Regional Retry Logic

[kundadebdatta]

Pull Request Template

Description

This PR adds the support for the below:

• Adds new HttpTimeoutPolicy: Primarily create a new http timeout policy to retry the proxy requests faster than the regular Gateway requests. We need an aggressive timeout policy to meet the SLA bar.

• Adds/ Fixes Cross Regional Retry Logic: Currently the cross regional retry logic for thin client has a gap and it does not resolve the thin proxy endpoints correctly. This PR is fixing that behavior.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Closing issues

To automatically close an issue: closes #5275

[github-actions]

All good!

[Copilot]

Pull Request Overview

This PR introduces an aggressive HTTP timeout policy for thin clients and corrects cross-regional retry routing by resolving thin proxy endpoints.

• Adds HttpTimeoutPolicyForThinClient and plugs it into HttpTimeoutPolicy.GetTimeoutPolicy
• Extends routing (LocationCache, ClientRetryPolicy, IGlobalEndpointManager, GlobalEndpointManager) to use thin client endpoints
• Adds a new integration test covering read-item retries across regions in thin client mode

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/.../RegionFailoverTests.cs	New test for read‐item retry logic under thin client mode
tests/.../MockSetupsHelper.cs	Extends account mock setup to include thin client locations
src/ThinClientStoreClient.cs	Enables thin‐client flag in HTTP invocations
src/Routing/LocationCache.cs	Adds thin‐client endpoint getters and static IsMetaData helper
src/Routing/IGlobalEndpointManager.cs	Exposes thin‐client endpoint collections on the interface
src/Routing/GlobalEndpointManager.cs	Implements thin‐client endpoint properties
src/HttpClient/HttpTimeoutPolicyForThinClient.cs	New timeout policy class for thin client
src/HttpClient/HttpTimeoutPolicy.cs	Updates policy selection logic for thin client
src/ClientRetryPolicy.cs	Routes requests to thin‐client endpoints when enabled

Comments suppressed due to low confidence (3)

Microsoft.Azure.Cosmos/src/HttpClient/HttpTimeoutPolicyForThinClient.cs:42

• [nitpick] The comment seems contradictory: retrieving metadata is idempotent, so it should indicate 'is idempotent' rather than 'is not idempotent'. Consider correcting the comment to reflect the correct idempotency assumptions.

        // The hot path should always be safe to retires since it should be retrieving meta data 

Microsoft.Azure.Cosmos/src/HttpClient/HttpTimeoutPolicyForThinClient.cs:12

• [nitpick] Public field names should follow PascalCase naming conventions (e.g. 'ShouldRetry') or be made private with public properties to align with .NET naming guidelines.

        public bool shouldRetry;

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/PartitionKeyRangeFailoverTests/RegionFailoverTests.cs:214

• [nitpick] Consider adding a similar test for write scenarios to ensure the HttpTimeoutPolicyForThinClient write path behaves as expected (no retries and correct 503 behavior).

        [TestMethod]

[FabianMeiswinkel]

LGTM

[FabianMeiswinkel]

LGTM - Thanks