Detect competing access to DiskLruCache; explode

[kaciula]

I'm getting crash reports from users of my Android app with the following stacktrace:

java.lang.RuntimeException: java.io.IOException
       at com.squareup.okhttp.internal.DiskLruCache$1.run(DiskLruCache.java:175)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
       at java.lang.Thread.run(Thread.java:841)
Caused by: java.io.IOException
       at com.squareup.okhttp.internal.DiskLruCache.renameTo(DiskLruCache.java:390)
       at com.squareup.okhttp.internal.DiskLruCache.rebuildJournal(DiskLruCache.java:372)
       at com.squareup.okhttp.internal.DiskLruCache.access$300(DiskLruCache.java:86)
       at com.squareup.okhttp.internal.DiskLruCache$1.run(DiskLruCache.java:171)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
       at java.lang.Thread.run(Thread.java:841)

Right now, all affected users are on Android 4.3

All I am doing is using a OkHttpClient singleton with a HttpResponseCache attached.

[swankjesse]

Thanks for reporting this. It's unclear what we want to do if we can't rename files on the cache's host filesystem.

[kaciula]

Still, I think crashing the app is not an appropriate solution here.

I just realized that the problem may be due to the fact that I am really using multiple rest adapter - okhttpclient pairs and all okhttp instances use the same cache directory. Could it be that it can't rename cache files because another okhttp client instance is accessing it? Can I use one single okhttpclient with all my rest adapters?

[JakeWharton]

Can I use one single okhttpclient with all my rest adapters?

Yes.

I am really using multiple rest adapter - okhttpclient pairs

Why are you using multiple RestAdapter instances? Different serialization types?

[kaciula]

I am using multiple rest adapters because I am accessing multiple servers (which are known only at runtime) but the Api is identical.

Should I be using a singleton and then change the server used with setEndpoint() every time? I would need to cancel somehow the pending calls for the previous server. I do not know exactly what other issues might be so that's why I preferred to use multiple instances.

[JakeWharton]

Nope it's totally fine to use multiple. I was just curious as to the reason.

OkHttpClient is safe to use across all of them though. You can treat an instance of it as a singleton connection factory for all your HTTP needs.

[swankjesse]

@kaciula multiple instances of HttpResponseCache or a single instance? Multiple instances is definitely not a good idea.

[kaciula]

@swankjesse Indeed, I was using multiple instances of okHttp, each with its own instance of HttpResponseCache pointing to the same cache directory.

I moved to using a okhttp singleton (and one HttpResponseCache instance) with multiple rest adapters. Thanks for the help.