AuroraRuntime/README.md

## IN DEVELOPMENT

## AuroraRuntime

The Aurora Runtime is a low level platform abstraction layer for cross-platform C++ development
targeting embedded and PC systems. Simply fetch a binary package for your toolchain or integrate
the buildscripts into your applications build pipeline to get started. 

![console](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/raw/branch/master/Media/wxHello.png)
![picture](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/raw/branch/master/Media/Hello%20Aurora.png)
![picture](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/raw/branch/master/Media/Hello%20Linux.png)

## Features

- Reduced C++ standard template library dependence (^1)
- High performance threading and synchronization primitives (os userland sched optimized)
- Async threading primitives with WaitMultipleObjects/RegisterWaitForSingleObject,RunLoop style interfaces (local IPC)
- Asynchronous and synchronous IO (network, character, file, buffered, process, and io watcher)
- Optional event driven async programming paradigm
- Consoles; graphical and standard, file archives
- Logging; UTF-8 logger, common sink backends
- Debug and Telementry; asserts, exception logging, fio, nio backends
- Crypto ECC/[25519, P-384, P-256], [AES, RSA, X509], [common digests]
- Basic cmdline parsing from any module
- Exit and fatal save condition callbacks
- IPC [WIP]
- Network [WIP]
- Random; secure and fast
- Hardware Info; memory and cpu info (including features, topology, e-core, and cache info)
- Software Stack Info (kernel, version, brand, build string, etc)
- FIO settings registry
- Compression
- Locale and encoding
- C++ utility templates and macros
- Follows all strings are UTF-8 convention

^1 bring your own types [auROXTL](https://git.reece.sx/AuroraSupport/auROXTL)

## Links

API:
* [Runtime](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/src/branch/master/Include/Aurora)
* [auROXTL](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/src/branch/master/Include/auROXTL)

Examples: [Hello Aurora](https://gitea.reece.sx/AuroraSupport/HelloAurora) \
Doxygen: \
Tests: [Hello Aurora](https://gitea.reece.sx/AuroraSupport/HelloAurora) \
Cmake-stable: \
Build Pipeline: https://git.reece.sx/AuroraPipeline/Build

## Performance

Performance should be that of native performance, ideally that of the best implementation on the
platform, and no worse than the STL. Due to heavyweight requirements and spiral model defined
objectives, a handful of portable C libraries have been brought into achieve compression, crypto,
alloc, and str formatting objectives using known good industry standard libraries. Footprint is 
expected to be on the heavier side with optimal performance (incl toll for C++ pluses tradeoffs).


Runtime as of 2022-02-01 *without the wxWidgets toolkit, with all compression libraries* on Windows LTSC 2019: 

 DLL Disk: 4.2MB \
 Size Of Image: 0x50B000 (5MB) \
 Real Commit Charge of a Console App: 9.7MB \
 ...the task manager lie: 3,168K (3.1MB -> less than our DLL) \
 ...HWInfo reports
 
[13:07:38] [Info]   | RamInfo Private Allocation: 10215424/71987290112 (^1) \
[13:07:38] [Info]   | RamInfo Address Space: 11669504/71987290112
 
 ^1 ...on LTSC 2019. Modern Windows 10 and 11 will return the exact task manager value of 3,168K (3.1MB).


Defer to benchmarks

## Utilities

Aurora Sugar:                          https://git.reece.sx/AuroraSupport/auROXTL/src/branch/master/Include/auROXTLUtils.hpp <br>
Aurora Macro Sugar:                    https://git.reece.sx/AuroraSupport/auROXTL/src/branch/master/Include/auROXTL/AU_MACROS.hpp <br>
Aurora Overloadable Type Declerations: https://git.reece.sx/AuroraSupport/auROXTL/src/branch/master/Include/auROXTLTypedefs.hpp


## Logging

Logging is implemented through 2 subsystems, console and logging. Console provides IO abstraction
to logger subsystem sinks. Sinks are user implementable interfaces that can be either synchronous
or asynchronous. Loggers are defined as an internal object the takes logger messages and dumps
them to the relevant subscriber.

Flushing occurs at a fixed rate on a low prio secondary thread without any configuration requirement.
The resources spent on the thread is shared with the telemetry and debug subsystems to reduce
the thread overhead of the runtime. Flushes also occur during panic events and other relevant
problematic points. 

Asynchronous logger sinks may double buffer log lines between the asynchronous callback and
on flush, where the latter call is guaranteed after one or more delegated dispatch. The Windows
Event Log backend takes advantage of this to multi-line group messages by approx time and log
level.

Additionally, in the console subsystem, consoles that provide an input stream can be used in
conjunction with the parse subsystem to provide basic command-based deserialization, tokenization,
and dispatch of UTF-8 translated strings regardless of the system locale. Command processing
comes under the namespace of consoles, not logging.

## Exceptions

![ICanHasStackTraces](https://gitea.reece.sx/AuroraSupport/AuroraRuntime/raw/branch/master/Media/ICanHasStackTraces.png)

Through the use of compiler internal overloads, ELF hooking, and Win32 
`AddVectoredExceptionHandler`, Aurora Runtime hooks exceptions at the time of throw, including 
*some* out of ecosystem exceptions, providing detailed telemetry of the object type, object 
string, and backtrace. In addition, the `AuDebug` namespace provides TLS based last-error and 
last-backtrace methods. <br>

EXCEPTIONS ARE NOT CONTROL FLOW...<br>
- Aurora Runtime WILL attempt to mitigate exceptions in internal logic
- Aurora Runtime WILL NOT abuse exceptions to communicate failure
- Aurora Runtime WILL try to decouple internal exceptions from the API
- Aurora Runtime WILL NOT use anything that automatically crashes on exception catch (no-noexcept)
- Aurora Runtime WILL provide extended exception information to telemetry backends and through 
   the `AuDebug` namespace
- Aurora Runtime WILL NOT make any guarantees of being globally-noexcept; however, it should be a 
   safe assumption in non-critical environments 

`SysPanic` can be used to format a `std::terminate`-like exit condition, complete with telemetry 
data and safe cleanup.

## Debug

### Error Markers

SysPushError[EFailureCategory shorthand] can be used to include additional side-channel telemetry
information about the execution of a program. SysPushError_(...) takes a string format sequence and
a variadic sequence of substitute values - or no arguments whatsoever.

#### Example:
```cpp
IBufferedCharacterConsumer *BufferConsumerFromProviderNew(const AuSPtr<ICharacterProvider> &provider)
{
    if (!provider)
    {
        SysPushErrorArg("Missing ICharacterProvider");
        return {};
    }

    return _new BufferedCharacterConsumer(provider);
}
```

### Asserts

[TODO]

#### Example: 
Debug, Release, and Ship (all) assertions:
```cpp
SysAssert(AuFunction{}, "unexpected default function")
```

Debug and Release (debug and optimized ship-with-debug) assertions:
```cpp
SysAssertDbg(AuFunction{}, "unexpected default function")
```

### Something went wrong                                                                                                      

You should ensure AuDebug::CheckErrors() or a SysPushError-like function is called to ensure enchanced TLS-state telemetry is
captured. AuDebug::PrintErrors() will print the the errors gathered by the debug subsystem for telemetry purposes. These may 
include the crts errno, the last reported posix return value, the last Win32 error code, and/or last reported microkernel error.

#### Example
Try/Catch:
```
try
{
    
}
catch (...)
{
    SysPushErrorCatch(); // THIS IS NOT REQUIRED FOR EXCEPTION TELEMETRY
}
```


Windows System Error Messages: \
CRT:
```cpp

```


POSIX:
```cpp

```


## Loop

The Aurora Runtime implements a kernel-scheduler optimized IO subsystem for managing Window, Network, File, IPC, and thread
synchronization objects through loop the loop subsystem.

Loop sources are an interface defined by the loop subsystem for objects with a signalable state. Attached to a LoopQueue, the
LoopQueue will provide a Wait-on related functions and subscription notifications of signal state change - allowing for optimized
loop source removal or reinsert hints from the return values of the subscription interface. In addition, the ILoopSource interface
permits arbitrary is-signaled-and-latch (TryLock) queries. 



## Thread Primitives

The Aurora Runtime provides platform optimized threading primitives inheriting from a featureful IWaitable interface.
Each method is guaranteed. Each primitive is user-land scheduler optimized.

```
struct IWaitable
{
   virtual bool TryLock()                            = 0;
   virtual void Lock(relativeTimeoutInMilliseconds)  = 0;
   virtual void Lock()                               = 0;
   virtual void Unlock()                             = 0;
}
```

Included high performance primitives
- arbitrary condition variable ^1
- condition mutex 
- condition variable
- critical section ^2
- event
- mutex
- semaphore 
- rwlock ^3
- spinlocks

^1 Accepts __any__ IWaitable as the mutex \
^2 Reentrant Mutex \
^3 Includes extended read to write upgrades and permits write-entrant read-routines to prevent writer deadlocks.

### Fixing problems in other scheduler apis

Problem one (1): \
    Most STL implementations have generally awful to unnecessarily inefficient abstraction.
    Defer to libc++'s abuse of spin while (cond) yield loops and msvc/stl's painfully slow
    std::mutex and semaphore primitives. 

Problem Two (2): \
    Moving to or from linux, macos, bsd, and win32 under varous kernels, there is no one
    standard (even in posix land) for the key thread primitives. 

Bonus point NT (3): \
    The userland CriticalSection/CV set of APIs suck, lacking timeouts and try lock 

Bonus point UNIX (4): \
    No wait multiple mechanism
    

1, 2, 3: Use the high performance AuThreadPrimitives objects

4: Consider using loop sources, perhaps with the async subsystem, in your async application. Performance of loop sources will
vary wildly between platforms, always being generally worse than the high performance primitives. They should be used to observe
kernel-level signalable resources.

4 ex: Windows developers could use loop sources as a replacement to WaitMultipleObjects with more overhead 

## Strings

The Aurora Runtime defines an `AuString` type as an `std::string`; however, it should be assumed this type represents a
binary blob of UTF-8. Looking to switch to `tiny-utf8` for UTF-8 safety. 

## Memory

### Allocator 

Objects are allocated across API/Module boundaries; and so long as the high level API design isn't horribly inefficient, the 
cache invalidation and indirect lookups should be minimalized. On modern hardware, indirect branching versus short jumps aren't
so expensive, and in combination with a fast enough allocator, it's a model that could provide reasonable OOP performance
through a C-with-classes-like API.

As for allocation, we generally expect a dependence on Microsoft's mimalloc. Linking against the Aurora Runtime in the Aurora
Ecosystem will automatically replace global allocators with `Aurora::Memory`, which in turn, proxies any other suitable allocator
with extended re[zero]allocate[aligned] with uniform deallocate APIs.

### Memory Heap

Aurora provides a heap allocator for dividing up a large preallocated region of memory

### Shared Pointers

By default, AuSPtr is backed by `std::shared_ptr`, extended by `#include <Aurora/Memory/ExtendStlLikeSharedPtr>`. Using this 
class, undefined behaviour on dereference and operator pointer is altered to guarantee an AU_THROW_STRING. Such hacks without
support for native behaviour from the language drivers themselves can be rather expensive; however, it's an experiment worth 
trying now that modern hardware can make up for software and microcode flaws; and architecture translation. Null exception
experiments can be easily disabled or configured from within your AuroraConfiguration.h file globally.


```
Types: 
    AuSPtr<Type_t>
    AuWPtr<Type_t>
    AuUPtr<Type_t, Deleter_t>
	
Functions:
    AuSPtr<T> AuMakeShared<T>(Args&& ...)
    AuSPtr<T> AuUnsafeRaiiToShared<T>(T *)
    AuSPtr<T> AuUnsafeRaiiToShared<T>(AuUPtr<T>) 

Macros:
    _new (pseudo no-throw new operator)
    AuSPtr<This_T> AuSharedFromThis()
    AuWPtr<This_T> AuWeakFromThis()
    AuFunction<...> AuBindThis(This_t *::?, ...)
```


### Note
Aurora provides a bring your own container and shared pointer model overloadable in your configuration header.<br>
User-overloadable type declerations and generic access utilities are defined under [auROXTL](https://git.reece.sx/AuroraSupport/auROXTL)


## Binding

Aurora Runtime provides C++ APIs; however, it should be noted that two libraries are used to extend interfaces and enums
to help with porting and internal utility access. One, AuroraEnums, wraps basic enumerations and provides value vectors;
value strings; look up; iteration; and more. The other, AuroraInterfaces, provides *TWO* class types for each virtual interface.
Each interface can be backed by a; C++ class method overriding a superclass's `virtual ...(...) = 0;` method, or a `AuFunctional`
-based structure.

It should be noted that most language bindings and generator libraries (^swig, v8pp, nbind, luabind) work with shared pointers.
Other user code may wish to stuff pointers into a machineword-sized space, whether its a C library, a FFI, or a size constraint.
One handle or abstraction layer will be required to integrate the C++ API into the destination platform, and assuming we have a
C++ language frontend parsing our API, we can use `AuSPtr` for all caller-to-method constant reference scanerios.
Furthermore, `AuSPtrs` can be created, without a deletor, using `AuUnsafeRaiiToShared(unique/raw pointer)`. To solve the raw
pointer issue, `AuSPtrs` are created in the public headers with the help of exported/default visibility interface create and
destroy functions. These APIs provide raw pointers to public C++ interfaces, and as such, can be binded using virtually any
shim generator. Method and API mapping will likely involve manual work from the library developer to reimplement AU concepts
under their language runtime instead of using the C++ platform, or at least require manual effort to shim or map each runtime
prototype into something more sane across the language barrier.

Memory is generally viewed through a `std::span` like concept called MemoryViews. `MemoryViewRead` and `MemoryViewWrite`
provide windows into a defined address range. `MemoryViewStreamRead` and `MemoryViewStreamWrite` expand upon this concept by
accepting an additional offset (`AuUInt &: reference`) that is used by internal APIs to indicate how many bytes were written
or read from a given input region. Such requirement came about from so many APIs, networking, compression, encoding, doing the
exact same thing in different not-so-portable ways. Unifying memory access to 4 class types should aid with SWIG prototyping. 

Unrelated note, structure interfacing with questionable C++ ABI reimplementations is somewhat sketchy in FFI projects (^ CppSharp)
can lead to some memory leaks.


## IO

[TODO] Summary

An important note about texting encoding. Stdin, file encoding, text decoders, and other IO resources work with codepage UTF-8
as the internal encoding scheme. String overloads and dedicated string APIs in the IO subsystem will always write BOM prefixed
UTF-8 and attempt to read a BOM to translate any other input to UTF-8.

### FIO

[TODO] async, fio abstraction, utf8 read/write, blob read/write, stat, dir recursion, stream abstraction

### Paths

We assume all paths are messy. Incorrect splitters, double splitters, relative paths, and keywords are resolved internally.
No URL or path builder, data structure to hold a tokenized URI expression, or similar concept exists in the codebase.
All string 'paths' are simply expanded, similar to MSCRT's `fullpath` or UNIX's `realpath`, at time of usage.


| Expression       | Meaning                             |
|------------------|-------------------------------------|
| `Path[0] == '.'` | Current Working Directory           |
| `Path[0] == '^'` | Executable module's Directory       |
| `Path[0] == '~'` | User Profile Storage + SDK brand    |
| `Path[0] == '!'` | All User Shared Storage + SDK brand |
| `..`             | Go up a directory                   |
| `/`              | Agnostic Directory Splitter         |
| `\`              | Agnostic Directory Splitter         |
| `.` [SPLITTER]   | Nothing                             |


[TODO] Aurora Branding <br>

### Resources
[TODO] Aurora IO Resources <br>


### NIO

- Worker thread delegated resolve using system resolver
- Callback with fence-id based asynchronous write abstraction
- Loop Source support

### CIO


### BIO


## Aurora Async

The Aurora Runtime offers an optional asynchronous task driven model under the AuAsync namespace. Featuring promises,
thread group pooling, functional-to-task wrapping, and task-completion callback-task-dispatch idioms built around 3
concepts. 

Example:

## Proccesses

The Aurora Runtime provides worker process monitoring, worker stdin/out stream redirection process spawning, file 
opening, and url opening functionality.

## Locale

Encoding and decoding UTF-8, UTF-16, UTF-32, GBK, GB-2312, and SJIS is supported through platform provided decoders.
Fetch system language and country backed by environment variables, the OS system configuration, the unix locale env
variable, and/or the provided overload mechanism.

## Dependencies

Aurora
- [AuroraPipeline Include](https://git.reece.sx/AuroraPipeline/Include) ^2
- [auROXTL](https://git.reece.sx/AuroraSupport/auROXTL) ^2
- [AuroraEnum](https://git.reece.sx/AuroraSupport/AuroraEnum) ^1
- [AuroraInterfaces](https://git.reece.sx/AuroraSupport/AuroraInterfaces) ^1
- [AuroraForEach](https://git.reece.sx/AuroraSupport/AuroraForEach) ^1

Crypto (third party)
- [LibTomCrypt](https://git.reece.sx/AuroraMiddleware/libtomcrypt) / [LibTomMath](https://git.reece.sx/AuroraMiddleware/libtommath) ^5
- [mbedTLS](https://git.reece.sx/AuroraMiddleware/mbedtls)

Compression (third party)
- [zstd](https://git.reece.sx/AuroraMiddleware/zstd)
- [zlib](https://git.reece.sx/AuroraMiddleware/zlib)
- [bzip2](https://git.reece.sx/AuroraMiddleware/bzip2)

Utility (third party)
- [stduuid](https://git.reece.sx/AuroraMiddleware/stduuid)  ^6
- [fmtlib](https://git.reece.sx/AuroraMiddleware/fmt) ^4 ^6
- [nl. json](https://git.reece.sx/AuroraMiddleware/nlohmannjson) ^6


^1 Include-only macro library \
^2 Provides core utilities and stl decoupling \
^3 Provides platform information, included by default by the Aurora build pipeline \
^4 C++ 20 saw another pathetic adoption attempt of an open source library, this one actually passed, but hardly \
   anyone implements std::format. Not to mention such is only a subset of the original library.  \
^5 Public Domain \
^6 Potentially STL heavy, still potentially portable w/ a modern-ish toolchain


## Philosophies

- Assume C++17 language support in the language driver

- Use AuXXX type bindings for std types, allow customers to overload the std namespace \
   We assume *some* containers and utility APIs exist, but where they come from is up to you

- Keep the code and build chain simple such that any C++ developer could maintain 
  their own software stack built around aurora components.

- Dependencies and concepts should be cross-platform, cross-architecture, cross-ring friendly
  
  It is recommended to fork and replace any legacy OS specific code with equivalent
   AuroraRuntime concepts, introducing a circular dependency with the Aurora Runtime
  
  APIs shouldn't be designed around userland, mobile computing, or desktop computing;
   AuroraRuntime must provide a common backbone for all applications. 
   
  Locale and user-info APIs will be limited due to the assumption userland is not a 
   concept

- Dependencies, excluding core reference algorithms (eg compression), must be rewritten
   and phased out over time.

- Dependencies should not be added if most platforms provide some degree of native support<br>
  Examples:<br>
            -> Don't depend on a pthread shim for windows; implement the best thread <br>
               primitives that lie on the best possible api for them <br>
            -> Don't depend on ICU when POSIX's iconv and Win32's multibyte apis cover<br>
               everything a conservative developer cares about; chinese, utf-16, utf-8,<br>
               utf-32 conversion, on top of all the ancient windows codepages

- Dependencies should only be added conservatively when it saves development time and 
  provides production hardening <br>
  Examples:<br>
            -> Use embedded crypto libraries; libtomcrypt, libtommath<br>
                ->> While there are some bugs in libtomcrypt and others, none appear to <br>
                   cryptographically cripple the library. Could you do better?<br>
            -> Use portable libraries like mbedtls, O(1) heap, mimalloc<br>
                ->> Writing a [D]TLS/allocator stack would take too much time<br>
                ->> Linking against external allocators, small cross-platform utilities, and <br>
                   so on is probably fine <br>
            -> Shim libcurl instead of inventing yet another http stack <br>