Complete const ledger state refactor

[SirTyson]

Description

Resolves #5073

This is the 2nd PR in the ledger state factor. Specifically, this PR covers steps 2-4.

The change is a bit larger than I would have liked, but it was difficult to break this down into smaller chunks that were still safe for master. While the diff is large, I've tried to make the commits easy to follow along. The commits are as follows:

• 3476e384c Remove LedgerHeader from BucketListSnapshotData

This reduces the duplication of LedgerHeader by removing it from the immutable BucketListSnapshotData struct. The header is moved to a centralized location in BucketSnapshotManager to prepare for a future commit, which will centralize the header to just CompleteConstLedgerState

• 9bec0791f Consolidated state access to LedgerStateSnapshot

This introduces LedgerStateSnapshot as the unified, searchable ledger state snapshot struct. This is a lightweight wrapper over a centralized CompleteConstLedgerState, which provides BucketList search functionality via local file streams. BucketSnapshotManager has not yet been removed yet, but basically is just a wrapper around the LedgerManager to serve LedgerStateSnapshot.

• 2b1957028 Make LedgerStateSnapshot threadsafe

Implements copy semantics for LedgerStateSnapshot and makes the default interface a value type. This removes footguns where two threads would have a pointer to the same snapshot, resulting in race conditions.

• b77fb68fe Remove BucketSnapshotManager and manage snapshot from LedgerManager

BucketSnapshotManager is removed entirely, and the LedgerManager maintains the canonical lcl ledger state snapshot, as well as provides getters for that snapshot. This hardens the distinction between the "apply state" snapshot (used only during ledger apply) and the ledger snapshot published and maintained by the main thread. The apply state, and all apply time functions, must use the 'apply state" snapshot, since this may be ahead of the main thread's snapshot. The main thread snapshot is what is copied by other non-apply threads, such as the query server and overlay thread.

• d143cc7f3 Fix minor race condition in invariant check

This has various small cleanups. It fixes a few dangling reference issues (that I introduced by removing a couple asserts) and adds a check back to a unit test I forgot I removed during development. Finally, this launches the snapshot invariant thread from the apply thread, not the main thread. This ensures that we always have consistent state between the in-memory state and the ledger state snapshot used for the invariant.

There are still some outstanding cleanups. For example, I still want to get rid of the weird mutable header copy in BucketSnapshotState (and maybe get rid of that class entirely). I also want to move historical snapshots outside of CompleteConstLedgerState and have the query server manage those directly, since it's the only subsystem that cares about it.

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[Copilot]

Pull request overview

This PR completes the ledger state refactoring by removing BucketSnapshotManager and centralizing state management in LedgerManager. The refactor introduces LedgerStateSnapshot as a unified, thread-safe snapshot type with copy semantics, preventing accidental sharing across threads.

Changes:

• Removed BucketSnapshotManager and moved snapshot management to LedgerManager
• Introduced LedgerStateSnapshot (copyable value type) and ApplyLedgerStateSnapshot (strong typedef for apply-time snapshots)
• Implemented copy semantics with fresh file stream caches per copy for thread safety
• Fixed snapshot invariant race condition by launching it from apply thread instead of main thread

Reviewed changes

Copilot reviewed 62 out of 62 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/ledger/LedgerStateSnapshot.h/cpp	New unified snapshot types with copy semantics
src/ledger/LedgerManagerImpl.h/cpp	Centralized snapshot management with thread-safe access
src/bucket/BucketSnapshotManager.h/cpp	Removed entirely
src/bucket/BucketListSnapshot.h/cpp	Added copy constructors for thread-safe copying
src/transactions/ParallelApplyUtils.h/cpp	Updated to use ApplyLedgerStateSnapshot
src/invariant/*	Updated invariant interfaces to use new snapshot types
src/main/QueryServer.h/cpp	Updated to use LedgerManager instead of BucketSnapshotManager
src/overlay/OverlayManagerImpl.h/cpp	Updated to use LedgerStateSnapshot value type
Test files	Updated to use new snapshot APIs