Signals
Generic Cross Platform Signal Handler.
Prerequisites
Swift
- Swift Open Source
swift-4.0.0-RELEASEtoolchain (Minimum REQUIRED for latest release) - Swift Open Source
swift-4.2-RELEASEtoolchain (Recommended) - Swift toolchain included in Xcode Version 10.0 (10A255) or higher.
macOS
- macOS 10.11.6 (El Capitan) or higher.
- Xcode Version 9.0 or higher using one of the above toolchains.
- Xcode Version 10.0 (10A255) or higher using the included toolchain (Recommended).
iOS
- iOS 10.0 or higher
- Xcode Version 9.0 or higher using one of the above toolchains.
- Xcode Version 10.0 (10A255) or higher using the included toolchain (Recommended).
Linux
- Ubuntu 16.04 (or 16.10 but only tested on 16.04).
- One of the Swift Open Source toolchain listed above.
Build
To build Signals from the command line:
% cd <path-to-clone>
% swift build
Using Signals
Including in your project
Swift Package Manager
To include BlueSignals into a Swift Package Manager package, add it to the dependencies attribute defined in your Package.swift file. You can select the version using the majorVersion and minor parameters. For example:
dependencies: [
.Package(url: "https://github.com/IBM-Swift/BlueSignals.git", majorVersion: <majorVersion>, minor: <minor>)
]
Carthage
To include BlueSignals in a project using Carthage, add a line to your Cartfile with the GitHub organization and project names and version. For example:
github "IBM-Swift/BlueSignals" ~> <majorVersion>.<minor>
CocoaPods
To include BlueSignals in a project using CocoaPods, you just add BlueSignals to your Podfile, for example:
platform :ios, '10.0'
target 'MyApp' do
use_frameworks!
pod 'BlueSignals'
end
Before starting
The first thing you need to do is import the Signals framework. This is done by the following:
import Signals
Provided APIs
Signals provides four (4) class level APIs. Three (3) are used for trapping and handling operating system signals. The other function allows for the raising of a signal.
Trapping a signal
trap(signal signal: Signal, action: SigActionHandler)- This basic API allows you to set and specific handler for a specific signal.
The example below shows how to add a trap handler to a server in order to perform and orderly shutdown in the event that user press ^C which sends the process a SIGINT.
import Signals
...
let server: SomeServer = ...
Signals.trap(signal: .int) { signal in
server.shutdownServer()
}
server.run()
Additionally, convenience API's that build on the basic API specified above are provided that will allow for trapping multiple signals, each to a separate handler or to a single handler.
trap(signals signals: [(signal: Signal, action: SigActionHandler)])- This lets you trap multiple signals to separate handlers in a single function call.trap(signals signals: [Signal], action: SigActionHandler)- This API lets you trap multiple signals to a common handler.
Raising a signal
raise(signal signal: Signal)- This API is used to send an operating system signal to your application.
This example illustrates how to use Signals to raise a signal with the OS, in this case SIGABRT.
import Signals
...
Signals.raise(signal: .abrt)
Ignoring a signal
func ignore(signal: Signal)- This API is used to ignore an operating system signal.
This example illustrates how to use Signals to ignore a signal with the OS, in this case SIGPIPE.
import Signals
...
Signals.ignore(signal: .pipe)
Restoring a signals default handler
func restore(signal: Signal)- This API is used to restore an operating system signals default handler.
This example illustrates how to use Signals to restore a signals default handler, in this case SIGPIPE.
import Signals
...
Signals.restore(signal: .pipe)
Adding a USER-DEFINED signal
This example shows how to add a user defined signal, add a trap handler for it and then raise the signal.
import Signals
let mySignal = Signals.Signal.user(20)
Signals.trap(signal: mySignal) { signal in
print("Received signal \(signal)")
}
Signals.raise(signal: mySignal)
The output of the above snippet is:
Received signal 20
Community
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License
This library is licensed under Apache 2.0. Full license text is available in LICENSE.
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