On Fri, 3 Feb 2017 09:33:32 +0000, Jun Wu wrote:
> 1) What does the worker talk to the master via IPC?
>
> Current: worker sends "possible_dirty_repo: $REPO_PATH" after runcommand
>
> It's coupled with the (pseudo) repo object. But the master could preload
> things in correct order - first changelog, then phase, obsstore, etc.
>
> What if: worker sends "possible_dirty_index: $INDEX_PATH",
> "possible_dirty_obsstore $OBSSTORE_PATH" etc.
>
> It looks more flexible at first sight. However the dependency issue
> could be tricky to solve - for example, the obsstore requires changelog
> (and revset). It's much harder to preload obsstore without a pseudo
> repo object with repo.changelog, repo.revs available.
>
> Therefore, probably just send the repo path.
Given this, I think pipes would be simpler than using shared memory. The master
IO can be multiplexed by select().
(But I don't have strong opinion to disagree with using shm.)
> 2) Preload function signature (used by master's background thread).
>
> This function is to hash and load things. It runs in the master, and is
> basically a generator (so the "loading" part could be skipped on cache
> hit, and it's easier to make content and hash_with_content consistent, if
> they share states):
>
> @preloadregistar(something)
> def preloadfunc(...):
> yield quick_hash
> yield content, hash_with_content
Isn't it simpler if preloadfunc() returns quick_hash and a delayed function
to build content? I feel this generator is kinda abuse and makes it less clear
where the costly part starts.
> Problem: What's "..." ? It could be "repopath" as that's exactly what the
> worker sends to us. But that will make the preload function more
> complicated to be correct - repo has "requirements", etc and the index is
> not always simply path.join(repo_path, 'store', '00changelog.i').
>
> Similar to 1, if we decouple from the repo object, index preloading would
> be fine:
>
> @preload('index')
> def preloadindex(indexpath):
> ....
>
> But things with dependency will have trouble:
>
> @preload('obsstore')
> def preloadobsstore(obsstorepath):
> # how to access repo.revs('....') ?
>
> Therefore, the preload function needs a repo (even it's "pseudo") to be
> convenient to implement.
For the "...", I agree repopath isn't enough.
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