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EBPrimitives is a framework that includes various generally-useful primitive classes, described below.

EBConcurrentQueue

EBConcurrentQueue is a lightweight operation queue implementation that supports both concurrency limits and queue priorities. EBConcurrentQueue is implemented as a thin layer atop plain libdispatch queues, eliminating much of the overhead of NSOperationQueue.

EBConditionLock

EBConditionLock is a locking primitive (similar to NSConditionLock) that allows clients to lock on any one of multiple conditions, specified using a bit field. An EBConditionLock is always in a single condition -- that is, its condition property is always an integer with exactly one bit set.

An EBConditionLock's condition is set upon initialization via -initWithCondition: (its designated initializer), and when unlocking the lock via -unlockWithCondition:.

EBConditionLock is locked by supplying one or more conditions to -lockOnConditions:. When more than one condition is supplied, they're combined using a bitwise-OR operation. Calling -lockOnConditions: with a value of 0 would result in a deadlock (since no conditions are specified), and therefore raises an exception.

EBDiskCache

EBDiskCache is a thread-safe, key-value cache implementation that stores and retrieves data to and from disk. Some noteworthy features of EBDiskCache include:

  • supports reading and writing data simultaneously from multiple threads
  • deletes data from disk when the adjustable size limit is reached
  • allows clients to use their own file-reading APIs via the -startAccessForKey: method, which returns the URL at which data is stored on disk
  • allows clients to safely delete the entire cache from disk

An EBDiskCache instance is created via its designated initializer -initWithStoreURL:sizeLimit:, where the on-disk URL for the cache is supplied, along with a maximum size to which the cache is allowed to grow until data is evicted. (The current data-eviction algorithm assumes that entries in the cache are of similar size; if a wide variation exists between the sizes of cache entries, the cache will grow beyond the limit in proportion to the variation. The size limit should therefore be considered a guideline rather than a hard limit.)

EBDiskCache can be destroyed (with all files being removed from disk) via the -destroy method. This method safely deletes the cache from disk once there are no outstanding clients reading the cache via -startAccessForKey:. Once the cache has been destroyed, -dataForKey: and -startAccessForKey: return nil for all keys, and other methods (such as -setData:forKey: and -sync) do nothing.

EBReadWriteLock

EBReadWriteLock is a simple Objective-C read-write lock, wrapping pthread's rwlock implementation.

EBUseTracker

EBUseTracker is an Objective-C least-recently-used (LRU) and most-recently-used (MRU) implementation that supports both forward and reverse enumeration.

Requirements

  • Mac OS 10.8 or iOS 6. (Earlier platforms have not been tested.)

Integration

  1. Integrate EBFoundation into your project.
  2. Drag EBPrimitives.xcodeproj into your project's file hierarchy.
  3. In your target's "Build Phases" tab:
    • Add EBPrimitives as a dependency ("Target Dependencies" section)
    • Link against libEBPrimitives.a ("Link Binary With Libraries" section)
  4. Add #import <EBPrimitives/EBPrimitives.h> to your source files.

Credits

EBPrimitives was created for Lasso.

License

EBPrimitives is available under the MIT license; see the LICENSE file for more information.