LWDR SAOC Milestone 1, Weekly Report for 6th OCT to 15th OCT

[Dylan Graham]

[Source Code](https://github.com/hmmdyl/LWDR)
[Plan](https://github.com/hmmdyl/SAoC2021/blob/main/plan.md)
[Proposal](https://github.com/hmmdyl/SAoC2021/blob/main/proposal.md)
[SAOC 
Projects](https://dlang.org/blog/2021/08/30/saoc-2021-projects/)

[Report for week 1 of milestone 
1](https://forum.dlang.org/thread/vodbtqqwvdmapnjzlzaq@forum.dlang.org)
[Report for week 2 of milestone 
1](https://forum.dlang.org/thread/sqounqxhveqhbcxcmxbw@forum.dlang.org)
[Report for week 3 of milestone 
1](https://forum.dlang.org/post/mwymjwilsleoilaijiiz@forum.dlang.org)

Light Weight D Runtime.
15th October, 2021.
Symmetry Autumn of Code, Week 4 of Milestone 1.

Hi all,
Apologies for the delay on this update. On Wednesday night (13th 
OCT), I was rushed to hospital for difficulty breathing and chest 
pains (started on Monday 11th OCT), which has impacted me a bit. 
Fortunately, as of the 15th of October, LWDR has [fulfilled 
milestone 
1](https://github.com/hmmdyl/SAoC2021/blob/main/plan.md#milestone-1) of my plan.

Between the 6th of October and the 15th, when possible, work was 
completed on task 2 of milestone 1 - implementation of object 
monitors and support for `synchronized`. The work was 
straight-forward. DRuntime's 
[`monitor_.d`](https://github.com/dlang/druntime/blob/master/src/rt/monitor_.d) was [ported to LWDR](https://github.com/hmmdyl/LWDR/blob/67c8a849a5405e17a0593dea10d67934482b3ffb/source/rt/monitor_.d). It was almost 1:1, except for stuff involving the global mutex (used for allocating monitors), which relied on LWDR-specified hooks.

A [series of hooks in 
`rtoslink.d`](https://github.com/hmmdyl/LWDR/blob/67c8a849a5405e17a0593dea10d67934482b3ffb/source/rtoslink.d#L38) have been added. They forward operations involving mutexes to the underlying platform. Ie, creating, destroying, locking and unlocking mutexes (using `synchronized` or `core.sync.mutex.Mutex`) are all forwarded through these functions.

An LWDR-specific [implementation of 
`core.sync.mutex.Mutex`](https://github.com/hmmdyl/LWDR/blob/67c8a849a5405e17a0593dea10d67934482b3ffb/source/core/sync/mutex.d#L16) has been completed. It attempts to replicate the functionality of [DRuntime's `Mutex` class](https://dlang.org/phobos/core_sync_mutex.html).

[`object.Monitor`](https://github.com/hmmdyl/LWDR/blob/67c8a849a5405e17a0593dea10d67934482b3ffb/source/object.d#L65) was implemented - it's just an interface with two functions. For a while I considered perhaps changing the interface to make manual memory management easier, but I prioritise compatibility with DRuntime more. I don't want potential users to have to learn the ins and outs of a new runtime, it should be as compatible as possible.

I'm sorry there isn't much at all this week. Hopefully the next 
will be better.

All the best,
Dylan Graham.