PSSRedisClient

A simple Swift-based interface to Redis, using CocoaAsyncSocket

Introduction

We had a project that required a modern implementation of either an ObjC or Swift-based redis client. After some research, it became clear that most objc or swift libraries either attempt to implement both the socket communication and the redis protocol, or use one-off socket communication libraries. For example, here is one such dual socket and redis protocol implementation, ObjCHiredis. Such libraries contain an excessive amount of network and pointer logic, and we found this one in particular prone to crashes. Additionally, experience suggests that pointer-heavy C/C++ code not actively maintained is almost certainly vulnerable to exploits.

In order to have maximum confidence in the robustness of our socket communication, we investigated iOS socket libraries. CocoaAsyncSocket was the choice we made, for these reasons:

First result in Google searches for iOS socket libraries
It is in the public domain
More than 8k stars and 2k forks, which is an order of magnitude more than the next most popular library
Actively and frequently maintained

Finally, as an additional consideration for our redis client, we wanted a library installable via Cocoapods.

Numerous Swift-based interfaces to redis exist, including:

RedBird - This library has a networking dependency on the Vaport Socks library, not the CocoaAsyncSocket library. It is not available on Cocoapods.
Zewo Redis - This library has a dependency on Zewo's own TCP socket library, again not CocoaAsyncSocket library. It is not available on Cocoapods.
Swidis - There doesn't seem to be any actual code in this library?. It is not available on Cocoapods.
SwiftRedis - This library appears to implement the networking functions itself, instead of using the CocoaAsyncSocket library. It is not available on Cocoapods.

Because none of these solutions were built atop CocoaAsyncSockets, and none were available on Cocoapods, we created our own simple class that is able to use CocoaAsyncSockets for the networking component, and that parses the redis protocol.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Requirements

iOS 9+

Installation

PSSRedisClient is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "PSSRedisClient"

Usage

override func viewDidLoad() {
    ... 

    self.redisManager = RedisClient(delegate: self)
    self.subscriptionManager = RedisClient(delegate: self)
    
    self.redisManager?.connect(host: "localhost",
                               port: 6379,
                               pwd: "password")
    self.subscriptionManager?.connect(host: "localhost",
                                      port: 6379,
                                      pwd: "password")
}

func socketDidConnect(client: RedisClient) {
    debugPrint("SOCKET: Connected")

    // Setup a subscription after we have connected
    if (redisManager == self.subscriptionManager) {
        self.subscriptionManager?.exec(args: ["subscribe", channel], completion: nil)
    }
}

func socketDidDisconnect(client: RedisClient, error: Error?) {
    debugPrint("Disconnected (Error: \(error?.localizedDescription))")
}

func subscriptionMessageReceived(results: NSArray) {
    if (results.count == 3 && results.firstObject as? String != nil) {
        let message = results.firstObject as! String

        if (message == "message") {
            debugPrint("SOCKET: Sending message of \(results[2])");

            self.results.text = "Subscription heard: \(results[2])"
        } else if (message == "subscribe") {
            debugPrint("SOCKET: Subscription successful");
        } else {
            debugPrint("SOCKET: Unknown message received");
        }
    }
}

func messageReceived(message: NSArray) {
    if (message.firstObject as? NSError != nil) {
        let error = message.firstObject as! NSError
        let userInfo = error.userInfo

        if let possibleMessage = userInfo["message"] {
            if let actualMessage = possibleMessage as? String {
                debugPrint("SOCKETS: Error: \(actualMessage)")
            }
        }
    } else {
        debugPrint("Results: \(message.componentsJoined(by: " "))")
    }
}

Author

Eric Silverberg, @esilverberg

License

PSSRedisClient is available under the MIT license. See the LICENSE file for more info.

petrpavlik / PSSRedisClient