Implement Request and Response Policy Based Routing in Cluster Mode

[ofekshenawa]

This PR introduces support for Redis COMMAND-based request_policy and response_policy routing for Redis commands when used in OSS Cluster client.

Key Additions:

Command Policy Loader: Parses and caches COMMAND metadata with routing/aggregation tips on first use.
Routing Engine Enhancements:
Implements support for all request policies: default(keyless), default(hashslot), all_shards, all_nodes, multi_shard, and special.
Response Aggregator: Combines multi-shard replies based on response_policy:
all_succeeded, one_succeeded, agg_sum, special, etc.
Includes custom handling for special commands like FT.CURSOR.
Raw Command Support: Policies are enforced on Client.Do(ctx, args...).

[ndyakov]

Submitting partial review for the aggregators.

[ndyakov]

Submitting another partial review.

[ndyakov]

Final part of initial review

Overview:

• Let's use atomics when possible.
• Left questions related to the node selection and setting of values.

Overall the design of the solution looks good, would have to do an additional pass over the test files once this review is addressed.

Thank you both @ofekshenawa and @htemelski-redis!

[ndyakov]

left some comments related to aggregators

[ndyakov]

The aggregators look good, there are some prints left in the code as bunch of unanswered questions. Let's resolve them before merging this. cc @ofekshenawa , @htemelski-redis

[Copilot]

Pull Request Overview

This PR adds support for explicit routing policies in Redis Cluster operations by introducing a command policy resolver system. The changes enable commands to be routed to specific shards based on their requirements (all shards, multiple shards, single shard) and aggregate responses accordingly.

• Implements a comprehensive routing and aggregation framework for cluster commands
• Adds Clone() methods to various command types to support concurrent execution
• Introduces configurable shard picker strategies (round-robin, random, static)
• Adds extensive test coverage for routing policies and command aggregation

Reviewed Changes

Copilot reviewed 30 out of 46 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
osscluster_router.go	New file implementing command routing logic and response aggregation
osscluster.go	Integration of command policy resolver and routing infrastructure
command_policy_resolver.go	New resolver for determining command routing policies
internal/routing/*.go	Core routing policy types and aggregation implementations
internal/util/atomic_*.go	Atomic min/max utilities for response aggregation
*_commands.go	Added cmdType fields and Clone() methods to command structs
osscluster_test.go	Extensive test coverage for routing policies and aggregation

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[htemelski-oss]

Looks good

[ndyakov]

I do think we can merge this as experimental feature and release it in a bet next week. will have to sync with one other PR (#3560)

[Copilot]

Pull Request Overview

Copilot reviewed 30 out of 46 changed files in this pull request and generated no new comments.

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[ndyakov]

looks good, missing a README about this change, would you mind adding and marking it as Experimental in the options comment? Other than this, left one comment regarding the new dependency that we are going to have. I do think we can implement the atomic.Float64 functionality without the need to pull the whole package.

@ofekshenawa let me know what you think and if you would like to merge it as it is, we can release the beta as it is and resolve the dependency before the GA release.

[ndyakov]

i personally do not like that we are pulling the whole package just for the Float64 atomic type, since its implementation is ~150 lines (that we actually don't need and ca implement here with Uint64 and some math.