## Summary
- **Add a self-referencing `InterpolationHandler` to `ValueStringBuilder`** that writes directly into the builder's buffer — zero intermediate allocation, works with `stackalloc`-backed builders
- **Replace all `System.Text.StringBuilder` usage** across the codebase with `ValueStringBuilder`
- **Convert `ValueStringBuilder.Create()` to `stackalloc`** at 10 sites where output length is provably bounded
- **Convert manual `Dispose()` to `using var`** where possible, and hoist loop-scoped builders outside loops with `Reset()`
- **Convert verbose `Append()` chains to `Append($"...")`** interpolation for readability
- **Add comprehensive documentation** for string handling patterns
## InterpolationHandler Design
`ValueStringBuilder` is a `ref struct`, which creates challenges for C#'s interpolated string handler pattern:
- **`ref` fields to ref structs are not allowed** (CS9050)
- **`[InterpolatedStringHandlerArgument("")]` passes struct receivers by value**, not by ref
- **`ISelfInterpolatedStringHandler` requires boxing** ref structs into interface fields
**Solution: Copy-and-reconcile pattern.** The handler receives a value copy of the builder. The copy shares the same underlying `char` buffer (`Span` points to the same `stackalloc`/pooled memory), so writes go to the original buffer. `Append()` reconciles by `this = handler._builder`, updating `_length` and any buffer references changed by `Grow()`.
This is safe because:
- The game loop is single-threaded — no concurrent access between handler construction and reconciliation
- If `Grow()` occurs in the copy, the original's stale buffer isn't accessed until `Append()` replaces it
- `Dispose()` correctly returns the reconciled buffer to the pool
## Changes by Category
### ValueStringBuilder (`Projects/Server/Buffers/ValueStringBuilder.cs`)
- Added nested `InterpolationHandler` ref struct with copy-and-reconcile pattern
- Added `Append([InterpolatedStringHandlerArgument("")] scoped ref InterpolationHandler)` method
- Removed `RawInterpolatedStringHandler` overloads (new handler replaces them)
- All `AppendFormatted` overloads delegate to existing `Append` methods (no code duplication)
- Alignment support via direct private field access (nested type privilege)
### StringBuilder → ValueStringBuilder (15 files)
Replaced all `new StringBuilder()` with `ValueStringBuilder.Create()` or `stackalloc`:
- ConPVP games: KingOfTheHill, DoubleDom, CTF, BombingRun, TourneyMatch
- ConPVP infrastructure: Tournament, Participant, TourneyParticipant
- ConPVP gumps: ArenaGump, TournamentBracketGump, AcceptTeamGump, ConfirmSignupGump
- Commands: Handlers, Logging, Add
- Other: TownCrier, SpeechLogGump, TestCenter
Key patterns:
- `sb = new StringBuilder()` reassignment → `sb.Reset()`
- `sb.AppendFormat("{0:N0}", value)` → `sb.Append($"{value:N0}")`
- `sb.Append(x).Append(y)` chains → separate statements (VSB returns void)
### Create() → stackalloc (10 files)
Converted heap-allocated builders to stackalloc where output is bounded:
- ClientVersion (32), MapSelection (160), HouseRaffleStone (48)
- HolySense (96), UnholySense (96), ClientVerification (192)
- AcceptTeamGump (64), ConfirmSignupGump (64)
- BaseWeapon (160), BaseArmor (128)
### Loop optimizations (2 files)
Hoisted `ValueStringBuilder` creation outside loops with `Reset()` per iteration:
- TourneyMatch.cs: `using var` inside for loop → stackalloc before loop
- ArenaGump.cs: `Create()` + `Dispose()` per iteration → stackalloc before loop
### Append chain → interpolation (5 files)
Converted multi-line `Append()` chains to `Append($"...")`:
- BountyMessage.cs: title switch (6 cases), paragraph (15→1 Append), description lines, closing
- AcceptTeamGump, ConfirmSignupGump, TournamentBracketGump: tournament type strings
- AdminGump: comment/tag formatting in loops
### Documentation
- `dev-docs/string-handling.md`: Full reference — construction, interpolation, disposal, decision guide
- `dev-docs/claude-skills/modernuo-string-handling.md`: Claude skill with quick reference
- `CLAUDE.md`: Added rule 17 (no StringBuilder), dev-docs table entry, skills table entry
- `dev-docs/code-standards.md`: Updated memory management section
## Test Plan
- [x] `dotnet build` — 0 errors, 0 warnings
- [x] `dotnet test` — 940/940 tests pass
- [x] 28 ValueStringBuilder tests covering all reconciliation scenarios:
- Stackalloc no-grow, stackalloc with grow (→pool transition)
- Heap no-grow, heap with grow, heap double grow
- Pre-existing content with and without grow
- Sequential multiple `Append($"...")` calls
- Mixed plain + interpolated Append
- Empty interpolation, literal-only, format specifiers
- Null string holes, ISpanFormattable types
- Dispose after stackalloc→pool grow
* Fixes an issue with moving directories across volumes
* Removes usages of WebClient
* Removes usages of Cryptographic Providers
Note: Even though .NET 6 introduces Xoshiro RNG, there is no way to control the seed. I'll do some reconciliation of Xoshiro so it functions closer to the built in one. For the most part, it has parity though.
Benchmarks show there is nothing odd about the implementations, they are within 1ns of each other.
* Makes EnsureDirectory properly work for relative and absolute paths
* Adds a `PathUtility.GetFullPath` which returns full paths for relative paths to `Core.BaseDirectory`. If the path is absolute, it will return as-is.
* Moves EnsureDirectory to `PathUtility`. So `ScriptsHandler.EnsureDirectory` and `AssemblyHandler.EnsureDirectory` are now `PathUtility.EnsureDirectory`
* Fixes crash guard so that it copies accounts properly.
* Changes world save and auto archive to use a random folder name inside of the temp folder.
* Adds `BeforeSerialized` for entities to handle cleanup.
* Adds `Created` and `LastSerialized` fields to all entities. While this is a big bloat, this will be necessary for identifying dangling references to other invalid entities.
* Changes formula for determining a valid reference to be _not null, not deleted, and reference's created date must be at or before the entities last serialized date_.
* Adds versioning to idx file and serializes `Created` and `LastSerialized`.
* Fixes Save Stats and also disables it by default.
## Adds Auto Archiving
Backups are archived once an hour, day, and month. Archives older than 60 days are pruned automatically.
_Note: Automatic pruning is off by default_
### Archive compression format
The following formats are supported:
* Zstd (The fastest with best compression ratio)
* GZip
* Zip
* None (Tar)
_Note: By default archives use [zstandard](http://facebook.github.io/zstd/) format.
The archive format can be changed in modernuo.json `autoArchive.compressionFormat`_
### Restoring world from archive
Move the archive to the Saves folder (tar.zst file). On startup the server will extract the file and restore the latest save. See pictures below.
### Manually extracting an archives
#### Windows
* Use the latest version of [7-zip w/ ZStandard](https://github.com/mcmilk/7-Zip-zstd/releases/latest)
1. Extract the `.tar.zst` file.
2. Extract the `.tar` file. (Yes you have to do it in two steps)
* On Windows 10 you can use the command line. `zstd.exe` is in the Assemblies folder after building ModernUO.
1. `tar --use-compress-program "Distribution\Assemblies\zstd.exe -d" -xvf "Archives\Hourly\archivefile.tar.zst" -C "path to where you want to extract it"`
#### Mac
* Install [Keka](https://www.keka.io)
1. Drop the .tar.zst onto the keka interface.
#### Linux
1. Install zstd from a package manager
2. Run `tar -I zstd -xvf "Archives\Hourly\archivefile.tar.zst" -C "path to where you want to extract it"`
### Other changes
* Changes Autosave to occur at the same time no matter when the server is booted.
* Adds `[SaveFrequency <delay> [warning]`command to set save frequency and warning frequency in-game.
* Adds support for time zones that are configurable. The system timezone can also be manually configured. Check `TimeZoneHandler.cs` for details.
<img width="257" alt="Screen Shot 2021-09-22 at 11 23 18 PM" src="https://user-images.githubusercontent.com/3953314/134464929-a5bf3cd8-2ef0-4476-a9ad-71d0816a19ac.png">
<img width="241" alt="Screen Shot 2021-09-22 at 11 23 39 PM" src="https://user-images.githubusercontent.com/3953314/134464945-5f6f96dc-3d1e-434d-8256-5c6b3705e786.png">
<img width="836" alt="Screen Shot 2021-09-22 at 11 34 39 PM" src="https://user-images.githubusercontent.com/3953314/134464957-625e57f2-ef47-4ca1-a0a7-cd40c9b6539c.png">
<img width="631" alt="Screen Shot 2021-09-22 at 11 34 50 PM" src="https://user-images.githubusercontent.com/3953314/134464969-b2d65c0d-f8f5-497a-a832-5d805e8e0b22.png">
