isPresentObjectForKey

[guptakshi16]

A api to check if the object is present in the cache will be a great enhancement in this project.
I was thinking of adding a bloom filter to add this functionality. Need feedback if this is already present in some other way.

[Broich]

+1

[jstn]

EDIT: never mind, see below.

objectForKey: is functionally equivalent, treat any non-nil return value as "object present". In the end it's just an ordinary NSDictionary lookup (there's no difference between accessing an object and seeing if it exists).

http://stackoverflow.com/questions/2784648/how-to-check-if-an-nsdictionary-or-nsmutabledictionary-contains-a-key

https://github.com/tumblr/TMCache/blob/master/TMCache/TMCache.m#L67

[guptakshi16]

I do not agree on the above. Currently objectForKey returns the object also. The object may be in the file system which means an expensive disk read and unarchive just for the presence check.

Imagine a use case where we want to sync a local TMCache with a remote cache on the server.
Server publishes the current list of files. Client code iterates over the list sent by server and updates based on the server list. In this scenario a presence check is required for all files.

[jstn]

@guptakshi16 you're totally right and I agree, thank you. It should be its own method, and TMDiskCache for its part should just check the presence of the file on disk.

Until that's added I think you could use TMDiskCache::fileURLForKey:block: and pass a block that manually checks for the file with NSURL::checkResourceIsReachableAndReturnError: followed immediately by a call to TMMemoryCache::objectForKey:block:

[irace]

This pull request might add the functionality that @guptakshi16 is asking for: #29