Re: [aether-users] Why does DefaultArtifactResolver.resolveArtifacts aqu

[Andreas Sewe <andreas.sewe@xxxxxxxxxxxxxx>]

Hi Igor,

> I haven't looked at the code recently, but what happens when two
> unrelated sessions resolve the same artifact? Even if one session is
> offline, the other maybe downloading the same artifact at the same time.

from what I understand, a shared SyncContext is a "read lock", an
exclusive SyncContext is a "write lock". I would imagine that the online
session downloading the artifact would have obtained an exclusive
SyncContext (whose implementation would then use, e.g., a FileLock under
the hood), which would prevent the offline session from obtaining its
shared SyncContext, blocking until the download is complete.

I am unsure, however, how SyncContexts are meant to used with multiple
sessions; the session's SyncContextFactories need to somehow produce
SyncContexts that can communicate, e.g., through FileLocks.

Anyway, the code calling SyncContext.acquire/close
(DefaultArtifactResolver.resolveArtifacts) needs to first state its
intention ("read access", "write access"). What a specific SyncContext
implementation makes of it is the second step.

Hope that clarifies things (or at least my understanding of said things ;-).

Andreas

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