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feat: update lassie to sync Retriever (before provider rewrite revert) #167

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@rvagg rvagg commented Jan 24, 2023

  • Retriever#Retrieve() calls are now synchronous, so we get to wait for the direct return value and error synchronously
  • Change the AwaitGet call order and make it cancellable
  • Make the provider context-cancel aware for cleaner shutdown
  • Other minor fixes and adaptions to the new Lassie code

DRAFT for now because it's using filecoin-project/lassie#41

@elijaharita I'd like your eyes on this for the synchronous call in the provider, provider.retriever.Retrieve() now blocks, holding up one of the goroutines while a retrieval attempt happens. Most of them still fail from indexer lookup fails but the ones that attempt may cause a backlog.

Is there any mechanism in here to prevent an excessive backlog of tasks on the retrievalQueue that we can't process fast enough to keep up with incoming? I don't see it but I might be missing something. I'm also not experiencing a huge queue while running this locally but that might change when on a faster open network.

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codecov-commenter commented Jan 25, 2023

Codecov Report

Base: 4.87% // Head: 5.24% // Increases project coverage by +0.36% 🎉

Coverage data is based on head (ebf5c4e) compared to base (4b4dcae).
Patch coverage: 12.14% of modified lines in pull request are covered.

Additional details and impacted files
@@            Coverage Diff            @@
##           master    #167      +/-   ##
=========================================
+ Coverage    4.87%   5.24%   +0.36%     
=========================================
  Files          15      14       -1     
  Lines        1723    1697      -26     
=========================================
+ Hits           84      89       +5     
+ Misses       1634    1603      -31     
  Partials        5       5              
Impacted Files Coverage Δ
autoretrieve.go 0.00% <0.00%> (ø)
bitswap/provider.go 0.00% <0.00%> (ø)
endpoint/estuary.go 0.00% <0.00%> (ø)
blocks/manager.go 78.50% <92.85%> (+1.05%) ⬆️

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* Retriever#Retrieve() calls are now synchronous, so we get to wait for the
  direct return value and error synchronously
* Change the AwaitGet call order and make it cancellable
* Make the provider context-cancel aware for cleaner shutdown
* Other minor fixes and adaptions to the new Lassie code
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These are just some possibilities. I don't know whether they fix underlying issues though

blockManager: blockManager,
retriever: retriever,
requestQueue: peertaskqueue.New(peertaskqueue.TaskMerger(&overwriteTaskMerger{}), peertaskqueue.IgnoreFreezing(true)),
requestQueueSignalChan: make(chan struct{}, 10),
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so here's my recommendation for these signals:

  1. make them buffer 1
  2. when writing, call:
select {
   case provider.requestQueueSignalChan <- struct{}{}:
   default:
}

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oh, nice, so if it blocks then bail, I didn't think of that!

select {
case <-ctx.Done():
case <-time.After(time.Millisecond * 250):
case <-provider.responseQueueSignalChan:
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when len(tasks) != 0, you had better still optionally drain the signal chan, i.e

if len(tasks == 0) {
   ///...
   continue
}

select {
case <-provider.responseQueueSignalChan:
default:
}
///...

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I wouldn't be surprised if you're getting stuck cause of this.

@@ -325,13 +339,15 @@ func (provider *Provider) handleResponses() {
}
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why are we calling TasksDone twice when an error occurs sending a message?

case <-ctx.Done():
case <-time.After(time.Millisecond * 250):
case <-provider.retrievalQueueSignalChan:
}
continue
}

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same, better drain the signal queue


for {
func (provider *Provider) handleRetrievals(ctx context.Context) {
for ctx.Err() == nil {
peerID, tasks, _ := provider.retrievalQueue.PopTasks(1)
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now that retreival is synchronous, this appears to limit things to one retrieval per worker queue, no?

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yes, default is 8 workers, but I hadn't seen a reason to increase this (yet) because it appears the pipe of incoming requests is so small; but maybe I'm not seeing it right

@rvagg rvagg changed the title feat: update lassie to sync Retriever feat: update lassie to sync Retriever (before provider rewrite revert) Jan 31, 2023
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3 participants