feat: add server FDv2 data system orchestrator#529
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Potential test suggestions in Just validating the behavior of destruction mid-synchronization/initialization. |
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And another set of test suggestions in |
Adds two regression tests that exercise the destruction protocol contract documented on FDv2DataSystem: when the destructor runs while an initializer or synchronizer Future is unresolved, the orchestrator must close the active source, transition status to kOff, and tear down the captured-this continuation chain without firing it against the destroyed object. Existing Destructor_TransitionsStatusToOff only covers the offline-mode case (no factories, no orchestration ever started); the in-flight teardown paths were not exercised. Adds StalledInitializer / StalledSynchronizer mocks that return an unresolved Future to drive the orchestrator into the in-flight state, then destroy the data system before the future resolves.
Adds two regression tests for the Goodbye handling added in d154cbe: - GoodbyeEventTriggersAsyncRestart: verifies that on receiving a goodbye event, the synchronizer drives sse::Client::async_restart with the documented reason string. Without this, the server's "we're about to disconnect" signal would lead to a stalled connection rather than a controlled reconnect. Adds a MockSseClient that records calls and a SetSseClient test peer to inject it. - GoodbyeMidPayloadDiscardsAccumulatedAndAcceptsFreshChangeset: feeds a partial payload, then a goodbye, then a fresh full changeset, and asserts that the accumulated puts were discarded and only the fresh put is in the resulting ChangeSet. Locks in the spec-aligned property that Goodbye does not corrupt subsequent payloads.
Adds SynchronizerGoodbye_PreservesSelectorOnNextCall: drives the orchestrator through initializer-basis@v1 -> ChangeSet@v2 -> Goodbye -> Shutdown, and asserts the captured Next() selectors are v1, v2, v2 in order. The existing SynchronizerGoodbye_StaysOnSameSynchronizer test only checks that Goodbye does not rotate the synchronizer factory; it does not verify what selector the post-Goodbye Next() call receives. Without this preservation, the SDK would reconnect with stale or empty payload state on every Goodbye, forcing the server into expensive xfer-full responses instead of efficient xfer-changes. Verified load-bearing: temporarily clearing selector_ on Goodbye in fdv2_data_system.cpp makes only this test fail (the existing Goodbye test still passes).
kinyoklion
approved these changes
May 6, 2026
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Add FDv2DataSystem orchestrator
Orchestrates FDv2 initializers and synchronizers; applies changesets and reports data-source status.
What's implemented
FDv2DataSystem—IDataSystemimpl. Runs initializers, then a synchronizer; applies changesets; tracks the selector; emits status (kInitializing→kValidon first apply /kInterruptedon errors →kOffon destruction). Offline (no factories) goes straight tokValid.IFDv2InitializerFactory,IFDv2SynchronizerFactory— build a fresh source per call.ITransactionalDestination— extendsIDestinationwithApply(ChangeSet); implemented byMemoryStoreandChangeNotifier.ChangeNotifier::Apply— diffs against the current store, updates the dependency tracker, applies to the sink, emits change events. Full diffs per-kind and version-aware; Partial notifies unconditionally per item.Design decisions
shared_ptr<State>for orchestrator-level async safety. Other FDv2 components keep async state in ashared_ptr<State>so callbacks can outlive the public object. This one capturesthisdirectly — safe because~ClientImpldoesioc_.stop()andrun_thread_.join()before destroying the data system. This was done becauseClientImplis shared with FDv1.ITransactionalDestinationrather than addingApplytoIDestination. Leaves the FDv1 persistent-store path untouched.DataSourceStatusManageris non-owning.ClientImpl(shared with FDv1) is its sole owner; the data system only borrows it. Declaration order inClientImplguarantees the manager outlives the data system.Test plan
11 cases in
libs/server-sdk/tests/fdv2_data_system_test.cppcover lifecycle, initializer phase (basis received, basis-skips-remaining, Interrupted advances, ChangeSet without selector continues), and synchronizer phase (apply, Interrupted loops, Goodbye/TerminalError advances, selector forwarding). Mocks resolve futures synchronously; tests run the io_context to drain orchestration before assertions.Note
Medium Risk
Introduces new FDv2 orchestration and a transactional changeset apply path that affects how flags/segments are updated and how change notifications fire; bugs here could lead to stale/incorrect flag state or missed updates under concurrency.
Overview
Implements a new
FDv2DataSystemthat orchestrates FDv2 initializers and synchronizers on an executor, applies incoming changesets into an in-memory store, tracks the latest selector for incremental updates, and drivesDataSourceStatusManagertransitions.Adds
ITransactionalDestination(extendingIDestination) plusChangeNotifier::Applysupport so full/partial/none changesets can be applied atomically while updating dependency tracking and emitting change events;MemoryStoreandChangeNotifierare updated to implement this interface.Improves
FDv2StreamingSynchronizerhandling ofgoodbyeevents by resetting protocol state and restarting the underlying SSE connection; adds/extends unit tests for the new orchestrator, changeset apply semantics, and goodbye restart/reset behavior.Reviewed by Cursor Bugbot for commit 7a147d2. Bugbot is set up for automated code reviews on this repo. Configure here.