Stop rewriting same PlayStore RPC data to cache #22
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Previously the code would load from cache and then rewrite the same data to cache. This is a problem for concurrency because reading/writing from a file will break when another process is doing the same thing. This adds a new class, DiscoveryAPI, to coordinate access to the cache file and it reduces collisions by only writing to the cache when there isn't a file.
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@ricky-crichq I think this is a step forward into the correct direction. Especially the extraction into an own class. Do we need further improvements? Especially in multi-process scenarios (e.g. using Unicorn) I expect to have the same problems!? |
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@jnbt you are right, there is still the possibility for something to go wrong here but the likelihood is now drastically reduced. Before this change we were writing to the file upon every call to We are using Puma with multiple workers and multiple threads and will be testing our own fork on our Staging servers. Will let you know how we get on. A proper solution for this would probably involve something like a Read/Write Lock: http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/ReentrantReadWriteLock.html In saying that, there are probably other considerations, I am not sure why Google recommends caching the discovery data but I suppose that this should only be cached for a certain length of time. 1 day, 1 week, 1 month, 1 year? I am not sure but as things stand now the gem will keep reading from cache as long as the server/container is alive and the file is present. This may not actually be the best thing to be doing. Do you know anymore about this? |
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The whole cache is not needed anymore with the rewrite of the Google API part in #35. See the Migration Guide for more information. |
Previously the code would load from the cache and then rewrite the same data
to cache. This is a problem for concurrency because reading/writing from
a file will break when another process is doing the same thing.
This adds a new class, DiscoveryAPI, to coordinate access to the cache
file and it reduces collisions by only writing to the cache when there
isn't a file.
CandyCheck issue: #17