feat(cluster): Implement Request and Response Policy Based Routing in Cluster Mode (#3422)

* Add search module builders and tests (#1)

* Add search module builders and tests

* Add tests

* Use builders and Actions in more clean way

* Update search_builders.go

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

* Update search_builders.go

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

* feat(routing): add internal request/response policy enums

* feat: load the policy table in cluster client (#4)

* feat: load the policy table in cluster client

* Remove comments

* modify Tips and command pplicy in commandInfo (#5)

* centralize cluster command routing in osscluster_router.go and refactor osscluster.go (#6)

* centralize cluster command routing in osscluster_router.go and refactor osscluster.go

* enalbe ci on all branches

* Add debug prints

* Add debug prints

* FIX: deal with nil policy

* FIX: fixing clusterClient process

* chore(osscluster): simplify switch case

* wip(command): ai generated clone method for commands

* feat: implement response aggregator for Redis cluster commands

* feat: implement response aggregator for Redis cluster commands

* fix: solve concurrency errors

* fix: solve concurrency errors

* return MaxRedirects settings

* remove locks from getCommandPolicy

* Handle MOVED errors more robustly, remove cluster reloading at exectutions, ennsure better routing

* Fix: supports Process hook test

* Fix: remove response aggregation for single shard commands

* Add more preformant type conversion for Cmd type

* Add router logic into processPipeline

---------

Co-authored-by: Nedyalko Dyakov <nedyalko.dyakov@gmail.com>

* remove thread debugging code

* remove thread debugging code && reject commands with policy that cannot be used in pipeline

* refactor processPipline and cmdType enum

* remove FDescribe from cluster tests

* Add tests

* fix aggregation test

* fix mget test

* fix mget test

* remove aggregateKeyedResponses

* added scaffolding for the req-resp manager

* added default policies for the search commands

* split command map into module->command

* cleanup, added logic to refresh the cache

* added reactive cache refresh

* revert cluster refresh

* fixed lint

* addresed first batch of comments

* rewrote aggregator implementations with atomic for native or nearnative primitives

* addressed more comments, fixed lint

* added batch aggregator operations

* fixed lint

* updated batch aggregator, fixed extractcommandvalue

* fixed lint

* added batching to aggregateResponses

* fixed deadlocks

* changed aggregator logic, added error params

* added preemptive return to the aggregators

* more work on the aggregators

* updated and and or aggregators

* fixed lint

* added configurable policy resolvers

* slight refactor

* removed the interface, slight refactor

* change func signature from cmdName to cmder

* added nil safety assertions

* few small refactors

* added read only policies

* removed leftover prints

* Rebased to master, resolved comnflicts

* fixed lint

* updated gha

* fixed tests, minor consistency refactor

* preallocated simple errors

* changed numeric aggregators to use float64

* speculative test fix

* Update command.go

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

* Update main_test.go

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

* Add static shard picker

* Fix nil value handling in command aggregation

* Modify the Clone method to return a shallow copy

* Add clone method to digest command

* Optimize keyless command routing to respect ShardPicker policy

* Remove MGET references

* Fix MGET aggregation to map individual values to keys across shards

* Add clone method to hybrid search commands

* Undo changes in route keyless test

* remove comments

* Add test for DisableRoutingPolicies option

* Add Routing Policies Comprehensive Test Suite and Fix multi keyed aggregation for different step

---------

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>
Co-authored-by: Nedyalko Dyakov <nedyalko.dyakov@gmail.com>
Co-authored-by: Hristo Temelski <hristo.temelski@redis.com>

internal/routing/shard_picker.go

@@ -0,0 +1,57 @@
+package routing
+
+import (
+	"math/rand"
+	"sync/atomic"
+)
+
+// ShardPicker chooses “one arbitrary shard” when the request_policy is
+// ReqDefault and the command has no keys.
+type ShardPicker interface {
+	Next(total int) int // returns an index in [0,total)
+}
+
+// StaticShardPicker always returns the same shard index.
+type StaticShardPicker struct {
+	index int
+}
+
+func NewStaticShardPicker(index int) *StaticShardPicker {
+	return &StaticShardPicker{index: index}
+}
+
+func (p *StaticShardPicker) Next(total int) int {
+	if total == 0 || p.index >= total {
+		return 0
+	}
+	return p.index
+}
+
+/*───────────────────────────────
+   Round-robin (default)
+────────────────────────────────*/
+
+type RoundRobinPicker struct {
+	cnt atomic.Uint32
+}
+
+func (p *RoundRobinPicker) Next(total int) int {
+	if total == 0 {
+		return 0
+	}
+	i := p.cnt.Add(1)
+	return int(i-1) % total
+}
+
+/*───────────────────────────────
+   Random
+────────────────────────────────*/
+
+type RandomPicker struct{}
+
+func (RandomPicker) Next(total int) int {
+	if total == 0 {
+		return 0
+	}
+	return rand.Intn(total)
+}