Support for service lifecycle on Windows

[xtremekforever]

I know that this is primarily a package for Swift on Server applications on Linux or macOS. But, I feel like Windows applications coded in Swift could also benefit from this package. Right now, of course it does not compile because it depends on UnixSignals:

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:34:32: error: cannot find 'DispatchQueue' in scope
 32 | /// for the same signal.
 33 | public struct UnixSignalsSequence: AsyncSequence, Sendable {
 34 |     private static let queue = DispatchQueue(label: "com.service-lifecycle.unix-signals")
    |                                `- error: cannot find 'DispatchQueue' in scope
 35 | 
 36 |     public typealias Element = UnixSignal

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:39:29: error: cannot find type 'DispatchSource' in scope
 37 | 
 38 |     fileprivate struct Source: Sendable {
 39 |         var dispatchSource: DispatchSource
    |                             `- error: cannot find type 'DispatchSource' in scope
 40 |         var signal: UnixSignal
 41 |     }

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:34:32: error: cannot find 'DispatchQueue' in scope
 32 | /// for the same signal.
 33 | public struct UnixSignalsSequence: AsyncSequence, Sendable {
 34 |     private static let queue = DispatchQueue(label: "com.service-lifecycle.unix-signals")
    |                                `- error: cannot find 'DispatchQueue' in scope
 35 |
 36 |     public typealias Element = UnixSignal


C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:39:29: error: cannot find type 'DispatchSource' in scope
 37 |
 38 |     fileprivate struct Source: Sendable {
 39 |         var dispatchSource: DispatchSource
    |                             `- error: cannot find type 'DispatchSource' in scope
 40 |         var signal: UnixSignal
 41 |     }


C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:88:37: error: cannot find 'DispatchSource' in scope
 86 |                 return .init(
 87 |                     // This force-unwrap is safe since Dispatch always returns a `DispatchSource`
 88 |                     dispatchSource: DispatchSource.makeSignalSource(
    |                                     `- error: cannot find 'DispatchSource' in scope
 89 |                         signal: sig.rawValue,
 90 |                         queue: UnixSignalsSequence.queue


C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignalsSequence.swift:91:27: error: cannot find type 'DispatchSource' in scope
 89 |                         signal: sig.rawValue,
 90 |                         queue: UnixSignalsSequence.queue
 91 |                     ) as! DispatchSource,
    |                           `- error: cannot find type 'DispatchSource' in scope
 92 |                     signal: sig
 93 |                 )

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:116:20: error: cannot find 'SIGABRT' in scope
114 |         switch self {
115 |         case .sigabrt:
116 |             return SIGABRT
    |                    `- error: cannot find 'SIGABRT' in scope
117 |         case .sighup:
118 |             return SIGHUP

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:118:20: error: cannot find 'SIGHUP' in scope
116 |             return SIGABRT
117 |         case .sighup:
118 |             return SIGHUP
    |                    `- error: cannot find 'SIGHUP' in scope
119 |         case .sigill:
120 |             return SIGILL

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:120:20: error: cannot find 'SIGILL' in scope
118 |             return SIGHUP
119 |         case .sigill:
120 |             return SIGILL
    |                    `- error: cannot find 'SIGILL' in scope
121 |         case .sigint:
122 |             return SIGINT

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:122:20: error: cannot find 'SIGINT' in scope
120 |             return SIGILL
121 |         case .sigint:
122 |             return SIGINT
    |                    `- error: cannot find 'SIGINT' in scope
123 |         case .sigquit:
124 |             return SIGQUIT

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:124:20: error: cannot find 'SIGQUIT' in scope
122 |             return SIGINT
123 |         case .sigquit:
124 |             return SIGQUIT
    |                    `- error: cannot find 'SIGQUIT' in scope
125 |         case .sigsegv:
126 |             return SIGSEGV

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:126:20: error: cannot find 'SIGSEGV' in scope
124 |             return SIGQUIT
125 |         case .sigsegv:
126 |             return SIGSEGV
    |                    `- error: cannot find 'SIGSEGV' in scope
127 |         case .sigterm:
128 |             return SIGTERM

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:128:20: error: cannot find 'SIGTERM' in scope
126 |             return SIGSEGV
127 |         case .sigterm:
128 |             return SIGTERM
    |                    `- error: cannot find 'SIGTERM' in scope
129 |         case .sigusr1:
130 |             return SIGUSR1

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:130:20: error: cannot find 'SIGUSR1' in scope
128 |             return SIGTERM
129 |         case .sigusr1:
130 |             return SIGUSR1
    |                    `- error: cannot find 'SIGUSR1' in scope
131 |         case .sigusr2:
132 |             return SIGUSR2

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:132:20: error: cannot find 'SIGUSR2' in scope
130 |             return SIGUSR1
131 |         case .sigusr2:
132 |             return SIGUSR2
    |                    `- error: cannot find 'SIGUSR2' in scope
133 |         case .sigalrm:
134 |             return SIGALRM

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:134:20: error: cannot find 'SIGALRM' in scope
132 |             return SIGUSR2
133 |         case .sigalrm:
134 |             return SIGALRM
    |                    `- error: cannot find 'SIGALRM' in scope
135 |         case .sigwinch:
136 |             return SIGWINCH

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:136:20: error: cannot find 'SIGWINCH' in scope
134 |             return SIGALRM
135 |         case .sigwinch:
136 |             return SIGWINCH
    |                    `- error: cannot find 'SIGWINCH' in scope
137 |         case .sigcont:
138 |             return SIGCONT

C:\tmp\swift-service-lifecycle\Sources\UnixSignals\UnixSignal.swift:138:20: error: cannot find 'SIGCONT' in scope
136 |             return SIGWINCH
137 |         case .sigcont:
138 |             return SIGCONT
    |                    `- error: cannot find 'SIGCONT' in scope
139 |         }
140 |     }

[4/40] Compiling UnixSignals UnixSignal.swift

I wonder if perhaps there could be a way provide compatibility for Windows, perhaps by using something like the TerminateProcess API, and map the unix signals to a similar equivalent. Or, provide a different termination event for Windows vs. Unix. But, it still feels like this could be very useful in the future!