RSCBC-136: Rework kv client stack

[chvck]

No description provided.

[Copilot]

Pull Request Overview

This PR implements a comprehensive rework of the KV client connection management stack, replacing the previous KvClientManager architecture with a new KvEndpointClientManager that uses a "babysitter" pattern for managing client lifecycle and health.

Key changes include:

• Introduction of KvClientBabysitter to handle individual client lifecycle, automatic reconnection, and health monitoring
• Replacement of KvClientManager with KvEndpointClientManager for per-endpoint client pool management
• Simplified client pool implementation focusing on client distribution rather than complex state management
• Error map support enabled by default in KV configuration
• Addition of fetch timeout configuration for config polling operations

Reviewed Changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
cluster_options.rs	Enables error map by default in KV configuration
vbucketrouter.rs	Removes unused KvClientManager import
searchcomponent.rs	Changes authenticator from Arc-wrapped to direct value
querycomponent.rs	Changes authenticator from Arc-wrapped to direct value
agent.rs	Major refactoring to use new KvEndpointClientManager and babysitter pattern
options/agent.rs	Adds error map and fetch timeout configuration options
mgmtcomponent.rs	Changes authenticator from Arc-wrapped to direct value
memdx/dispatcher.rs	Renames connection close handler to read loop close handler
memdx/client.rs	Updates to use renamed read loop close handler and improves error handling
lib.rs	Reorganizes module structure, adds new modules for refactored architecture
kvendpointclientmanager.rs	New file implementing endpoint-based client management
kvclientpool.rs	Complete rewrite simplifying pool to focus on client distribution
kvclientmanager.rs	File removed, functionality replaced by kvendpointclientmanager
kvclient_ops.rs	Updates dispatch error handling to mark clients as closed
kvclient_babysitter.rs	New file implementing automatic client lifecycle management
kvclient.rs	Major refactoring removing reconfigure logic, simplifying client creation
kv_orchestration.rs	New file providing orchestration helpers for KV operations
httpcomponent.rs	Changes authenticator from Arc-wrapped to direct value
diagnosticscomponent.rs	Updates to work with new endpoint client manager interface
crudcomponent.rs	Updates orchestration function calls for new architecture
configwatcher.rs	Updates to use KvEndpointClientManager interface
configmanager.rs	Adds endpoint_id parameter for out-of-band config fetching
configfetcher.rs	Adds timeout support for config fetch operations
componentconfigs.rs	New file centralizing component configuration generation
collection_resolver_memd.rs	Updates to use new orchestration functions

Comments suppressed due to low confidence (2)

sdk/couchbase-core/src/memdx/client.rs:1

• The compare_exchange logic is inverted. It should return early if the value was already true (i.e., already closed), but currently returns when compare_exchange succeeds. The condition should be == Ok(true) or the comparison should be checking for Ok(false).

/*

sdk/couchbase-core/src/diagnosticscomponent.rs:1

• Changed log message from 'Out-of-band fetch from {endpoint} failed' to use {endpoint_id}. The variable name in the message should match the actual variable being referenced.

/*

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[Matt-Woz]

LGTM, assuming FIT/FIT-SIT is happy, though you may want another pair of eyes as it's quite a significant change

[Matt-Woz]

Would it make sense for this to be a method of AgentState?

[chvck]

I don't think it can be, as it updates all of the components that are a part of AgentInner too.