14 Commits

• Update xmldoc
  Dean Herbert · 2021-02-25 16:22:40 +09:00
  5fa9bf61b6
• Allow determining a BeatmapDifficultyCache's bindable return's completion state via nullability
  Dean Herbert · 2021-02-25 16:19:01 +09:00
  03771ce8ec
• Fix deadlock scenario when calculating fallback difficulty

  The previous code would run a calcaulation for the beatmap's own ruleset
  if the current one failed. While this does make sense, with the current
  way we use this component (and the implementation flow) it is quite unsafe.
  
  The to the call on `.Result` in the `catch` block, this would 100%
  deadlock due to the thread concurrency of the `ThreadedTaskScheduler`
  being 1. Even if the nested run could be run inline (it should be), the
  task scheduler won't even get to the point of checking whether this is
  feasible due to it being saturated by the already running task.
  
  I'm not sure if we still need this fallback lookup logic. After removing
  it, it's feasible that 0 stars will be returned during the scenario that
  previously caused a deadlock, but I don't necessarily think this is
  incorrect. There may be another reason for this needing to exist which
  I'm not aware of (diffcalc?) but if that's the case we may want to move
  the try-catch handling to the point of usage.
  
  To reproduce the deadlock scenario with 100% success (the repro
  instructions in the linked issue aren't that simple and require some
  patience and good timing), the main portion of the lookup can be changed
  to randomly trigger a nested lookup:
  
  ```
  if (RNG.NextSingle() > 0.5f)
      return GetAsync(new
  DifficultyCacheLookup(key.Beatmap, key.Beatmap.Ruleset,
  key.OrderedMods)).Result;
  else
      return new StarDifficulty(attributes);
  ```
  
  After switching beatmap once or twice, pausing debug and viewing the
  state of threads should show exactly what is going on.

  Dean Herbert · 2021-01-14 18:25:34 +09:00
  8a0b975d71
• Add explicit lock object and some xmldoc for clarity
  Dean Herbert · 2020-11-10 14:31:52 +09:00
  6cc0bf17a9
• Fix unsafe list manipulation in BeatmapDifficultyCache
  smoogipoo · 2020-11-10 01:10:00 +09:00
  66ea1572c7
• Fix difficulty retrieval for online-sourced beatmaps
  Bartłomiej Dach · 2020-11-08 00:12:25 +01:00
  6d4bb4316c
• Remove non-null assert
  Dean Herbert · 2020-11-06 17:24:28 +09:00
  c1c3d37720
• Add ruleset fallback logic into cache lookup class
  Dean Herbert · 2020-11-06 16:58:53 +09:00
  f51cb0dd14
• Remove synchronous lookup path from BeatmapDifficultyCache
  Dean Herbert · 2020-11-06 14:53:15 +09:00
  c5b172d0dd
• Update BeatmapDifficultyCache to use base implementation logic
  Dean Herbert · 2020-11-06 14:31:21 +09:00
  b69ada64e8
• Move StarDifficulty to own file
  Dean Herbert · 2020-11-06 13:51:25 +09:00
  517a656899
• Remove unused using
  Dean Herbert · 2020-11-06 13:48:06 +09:00
  74ca2faa31
• Add basic base class to begin to standardise function across caching components
  Dean Herbert · 2020-11-06 13:26:39 +09:00
  0103b12575
• Rename BeatmapDifficultyManager to BeatmapDifficultyCache
  Dean Herbert · 2020-11-06 13:14:29 +09:00
  5113d4af8f