## Summary
The save-stability infrastructure consumed by generator v3's `[AnchoredDateTime]`: anchored timestamps are written as **absolute values** and re-based once at load by the elapsed time since the save started — so downtime doesn't age them, and an unchanged entity serializes to identical bytes (the prerequisite for replacing delta-time encodings, which rewrite every entity on every save).
## Design
- **`WriteAnchoredTime` / `ReadAnchoredTime`** on `IGenericWriter`/`IGenericReader`. The read side applies the reader's `AnchoredTimeShift`; `Min/MaxValue` sentinels pass through unshifted, and shifts saturate instead of overflowing.
- **`World.SaveStartTime`** is stamped the moment the world freezes for a snapshot — one anchor for the entire save, no per-persistence skew.
- **idx v5**: the anchor ticks sit in the header right after the version. The anchor travels with the file it re-anchors, so a single idx+bin pair restored from a backup is self-describing, and anchor presence is guaranteed by the same version gate as the record format — there is no separate anchor file to lose.
- **The shift rides the reader instance** (`BufferReader`, `UnmanagedDataReader`, `BinaryFileReader` delegating), not a static — parallel per-persistence loads and ad-hoc restores each see their own file's anchor. idx v4 and older read with a zero shift.
## Scope
Behavior-neutral: nothing serializes anchored values yet (`Item.DecayResetTime` and the `[DeltaDateTime]` field migrations come separately, with their own version bumps). Saves written from this branch are idx v5; loading v4/v3 saves is unchanged and remains pinned by the existing hand-written-header tests.
## Testing
- Unit round-trips: exact with zero shift, shifted read, sentinel passthrough, saturation, Local→UTC normalization.
- End-to-end through the real worker/segment-log pipeline: an anchored timestamp re-bases across a simulated two-hour downtime via the idx v5 header.
- Full suites green: Server.Tests 835/835, UOContent.Tests 708/708 (including the existing v4/v3 idx loading tests).
### Summary
- `GenericEntityPersistence` is now a type of `GenericPersistence`. This allows developers to serialize both entities and non-entities in the same system. 🎉
- Each `SerializationThreadWorker` now allocates 1MB of heap for serialization _permanently_. If more memory is needed, that thread will double it's memory, not to exceed increments of 64MB.
- Several bugs with serialization introduced with the pure MMF implementation have been fixed.
- `BinaryFileReader` has been added back. 🎉
- Adds `world.useMultithreadedSaves` to allow disabling threaded saves.
> [!IMPORTANT]
> **Developer Note**
> The split file serialization has been deprecated and is no longer used. We have effectively gone back to the same file writing we had before the pure MMF implementation.
### Summary
Updates the serialization strategy to use `MemoryMappedFile` instead of thick buffers. This has the benefit of being on-par with the current implementation (based on hardware/OS), however won't incur the double-memory issue.
> [!Important]
> **Developer Note**
> The `BinaryFileWriter` and `BinaryFileReader` has been removed in favor of `MemoryMapFileWriter` and `UnmanagedDataReader`
### Summary
The BitArray class will be optimized over the next several years for various platforms/hardware and maintaining a duplicate for serialization is not practical. Removing the custom implementation. Recommend against using BitArray for serialization unless it is absolutely necessary.
## Changes
* Improves type hashing by introducing xxHash3 (64bit)
* Removes individual `tdb` files in favor of a single `SerializedTypes.db` file. This file is only used to identify a type that is being deserialized, which doesn't exist.
* Adds duplicate type alias detection
* Adds `AssemblyHandler.FindTypeByHash`
View changed files whitespaces: https://github.com/modernuo/ModernUO/pull/1172/files?diff=split&w=1
## SerializedTypes.db
The serialized types file is used to get back the original name of a type in case it no longer exists in code. This can easily be necessary if a class is renamed in code and no `TypeAlias` is provided.
### Format
byte[4] - version
byte[4] - count
--array--
byte[8] - xxHash
byte[1] - flag, 0 - null, 1 - not null
byte[n] - Full class name in UTF8
### Example
<img width="472" alt="SerializedTypes_Example" src="https://user-images.githubusercontent.com/3953314/195255429-31d24293-6bd1-419e-811b-07874dd0f78d.png">
## Benchmarks
Serialized 500 Type fields. The 8192bytes comes from the _ConcurrentQueue_ that would later be used for SerializedTypes.
Note that the queue is never cleared, so it's size grew considerably.
```cs
| Method | Mean | Error | StdDev | Allocated |
|--------------------- |---------:|---------:|---------:|----------:|
| BenchmarkXXHash | 18.44 us | 0.278 us | 0.260 us | 8192 B |
| BenchmarkTypeStrings | 25.09 us | 0.292 us | 0.259 us | - |
```
TODO:
* Add support in the Serialization Generator for `ReadType()` and `Write(Type)`
* Remove `SetTypeRef` from Serialization Generator
**Only one functional change**
* Fixes a bug in LogFactory where `Warning` is being logged as `Information`
Non-functional changes:
* Updates/Fixes copyright headers
* Removes namespace scopes for core files.
View with [whitespace off](https://github.com/modernuo/ModernUO/pull/1187/files?w=1).
* Adds a custom BitArray class with the following added features:
* ctor for creating BitArray against read only span
* ctor for creating BitArray against BinaryReader
* CopyTo to copy a BitArray to a Span
* Adds BitArray to UO Primitive serialization so it can be codegenned.
* 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.
- [X] Adds `AdhocPersistence` which replaces RunUO `Persistence`
- [X] Fixes a few minor bugs with EntityPersistence deserialization
- [X] Reverts/updates some serialization changes
- [X] Speeds up world loading
- [X] Removes PeekChar cause it wasn't used
- [X] Adds a BufferReader
- [X] Removes BinaryFileReader
- [X] Removes reading/writing `char` since it is not consistent and will cause a deserialize issue if used.
Bumps version release
- [X] Fixes bugs in the buffer writer
- [X] Removes background save commands
- [X] Avoids calling Serialize() on deserialization
- In a future optimization I will copy the entire object to a buffer, deserialize using a SpanReader, then use that buffer for the SaveBuffer
- [X] Fixes issue with decay queue.
Bumps release version
- [X] Removes all save strategies
- [X] Removes duplicate file writer that won't be used
- [X] Removes persistence (it will become a duplicate system)
- [X] Add a save position variable to skip serializing a clean item/mobile
- [X] Update Guilds/Accounts to be IEntity types
- Because guilds are abstract, this may make serialization tricky.
- [X] Update the generalized IEntity writing
- [X] Update the load/save to write to buffers then to files in background
Bumps release version
