BufferedLogger

BufferedLogger is a tiny but thread-safe logger with a buffering and retrying mechanism for iOS.

• Buffer log entries until it's time to output them.
• Batch multiple log entries to use them at the same time.
• Retry outputing log entries when some backoff time elapsed after some errors occurred.

You can use this framework...

• To send a group of log entries to your server.
• To resend them when some errors like a networking trouble were occured.

Runtime Requirements

• iOS 9.0 or later
• Swift5

Installation

Carthage

github "yoheimuta/BufferedLogger"

CocoaPods

pod "BufferedLogger"

Usage

For details, refer to a Demo project.

Define your own Writer

Posted log entries are buffered and emitted as a chunk on a routine schedule.

write method is ensured to call serially, which means it is run by a serial queue.

class MyWriter: Writer {
    func write(_ chunk: Chunk, completion: @escaping (Bool) -> Void) {
        // You can implement something useful like uploading logs to your server.
        print("chunk is \(chunk)")

        chunk.entries.forEach {
            print("entry is \($0)")
        }

        completion(true)
    }
}

Make the logger and post a log

You have to register your writer to the logger and can post your log with it from any thread.

A call to post method is no blocking.

import BufferedLogger

logger = BFLogger(writer: MyWriter())
logger.post("1".data(using: .utf8)!)
logger.post("2".data(using: .utf8)!)
logger.post("3".data(using: .utf8)!)

You can also create your configuration for buffering and emitting mechanism.

If you omit to define your configuration, default below is used. Each meaning is in a comment.

/// Config represents a configuration for buffering and writing logs.
public struct Config {
    /// flushEntryCount is the maximum number of entries per one chunk.
    /// When the number of entries of buffer reaches this count, it starts to write a chunk.
    public let flushEntryCount: Int

    /// flushInterval is a interval to write a chunk.
    public let flushInterval: TimeInterval

    /// retryRule is a rule of retry.
    public let retryRule: RetryRule

    /// maxEntryCountInStorage is a max count of entry to be saved in the storage.
    /// When the number of entries in the storage reaches this count, it starts to
    /// delete the older entries.
    public let maxEntryCountInStorage: Int

    /// storagePath is a path to the entries.
    /// When you uses multiple BFLogger, you must set an unique path.
    public let storagePath: String

    public init(flushEntryCount: Int = 5,
                flushInterval: TimeInterval = 10,
                retryRule: RetryRule = DefaultRetryRule(retryLimit: 3),
                maxEntryCountInStorage: Int = 1000,
                storagePath: String = defaultStoragePath) {
        self.flushEntryCount = flushEntryCount
        self.flushInterval = flushInterval
        self.retryRule = retryRule
        self.maxEntryCountInStorage = maxEntryCountInStorage
        self.storagePath = storagePath
    }

    /// default is a default configuration.
    public static let `default` = Config()
}

Persistence

BufferedLogger stores the unsent entries in the local storage when the application couldn't send log entries.

By default, it stores them in local files in the Library/Caches directory.

You can also define your own custom log entry storage backed by any storage system.

See the EntryStroage protocol for more details.

Contributing

• Fork it
• Create your feature branch: git checkout -b your-new-feature
• Commit changes: git commit -m 'Add your feature'
• Push to the branch: git push origin your-new-feature
• Submit a pull request

License

The MIT License (MIT)

Acknowledgement

Thank you to the Puree-Swift: https://github.com/cookpad/Puree-Swift

I inspired by this library for the elaborate design, interface and some implementation.