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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,133 @@ | ||
| //===----------------------------------------------------------------------===// | ||
| // | ||
| // This source file is part of the SwiftNIO open source project | ||
| // | ||
| // Copyright (c) 2023 Apple Inc. and the SwiftNIO project authors | ||
| // Licensed under Apache License v2.0 | ||
| // | ||
| // See LICENSE.txt for license information | ||
| // See CONTRIBUTORS.txt for the list of SwiftNIO project authors | ||
| // | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
|
||
| import Atomics | ||
| #if canImport(Darwin) | ||
| import Darwin | ||
| #elseif os(Windows) | ||
| import ucrt | ||
| import WinSDK | ||
| #elseif canImport(Glibc) | ||
| import Glibc | ||
| #elseif canImport(Musl) | ||
| import Musl | ||
| #else | ||
| #error("Unsupported C library") | ||
| #endif | ||
|
|
||
| /// SwiftNIO provided singleton resources for programs & libraries that don't need full control over all operating | ||
| /// system resources. This type holds sizing (how many loops/threads) suggestions. | ||
| public enum NIOGlobalSingletons { | ||
| } | ||
|
|
||
| extension NIOGlobalSingletons { | ||
| /// A suggestion of how many ``EventLoop``s the global singleton ``EventLoopGroup``s are supposed to consist of. | ||
| /// | ||
| /// The thread count is ``System/coreCount`` unless the environment variable `NIO_SINGLETON_GROUP_LOOP_COUNT` | ||
| /// is set or this value was set manually by the user. | ||
| /// | ||
| /// - note: You must not set this value more than once. | ||
| public static var suggestedGlobalSingletonGroupLoopCount: Int { | ||
| set { | ||
| Self.userSetSingletonThreadCount(rawStorage: globalRawSuggestedLoopCount, userValue: newValue) | ||
| } | ||
|
|
||
| get { | ||
| return Self.getTrustworthyThreadCount(rawStorage: globalRawSuggestedLoopCount, | ||
| environmentVariable: "NIO_SINGLETON_GROUP_LOOP_COUNT") | ||
| } | ||
| } | ||
|
|
||
| /// A suggestion of how many threads the global singleton thread pools that can be used for synchronous, blocking | ||
| /// functions (such as ``NIOThreadPool``) are supposed to consist of | ||
| /// | ||
| /// The thread count is ``System/coreCount`` unless the environment variable | ||
| /// `NIO_SINGLETON_BLOCKING_POOL_THREAD_COUNT` is set or this value was set manually by the user. | ||
| /// | ||
| /// - note: You must not set this value more than once. | ||
| public static var suggestedBlockingPoolThreadCount: Int { | ||
| set { | ||
| Self.userSetSingletonThreadCount(rawStorage: globalRawSuggestedBlockingThreadCount, userValue: newValue) | ||
| } | ||
|
|
||
| get { | ||
| return Self.getTrustworthyThreadCount(rawStorage: globalRawSuggestedBlockingThreadCount, | ||
| environmentVariable: "NIO_SINGLETON_BLOCKING_POOL_THREAD_COUNT") | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // DO NOT TOUCH THESE DIRECTLY, use `userSetSingletonThreadCount` and `getTrustworthyThreadCount`. | ||
| private let globalRawSuggestedLoopCount = ManagedAtomic(0) | ||
| private let globalRawSuggestedBlockingThreadCount = ManagedAtomic(0) | ||
|
|
||
| extension NIOGlobalSingletons { | ||
| private static func userSetSingletonThreadCount(rawStorage: ManagedAtomic<Int>, userValue: Int) { | ||
| precondition(userValue > 0, "illegal value: needs to be strictly positive") | ||
|
|
||
| // The user is trying to set it. We can only do this if the value is at 0 and we will set the | ||
| // negative value. So if the user wants `5`, we will set `-5`. Once it's used (set getter), it'll be upped | ||
| // to 5. | ||
| let (exchanged, _) = rawStorage.compareExchange(expected: 0, desired: -userValue, ordering: .relaxed) | ||
| guard exchanged else { | ||
| fatalError("singleton suggested loop/thread count has been set more than once by user") | ||
| } | ||
| } | ||
|
|
||
| private static func validateTrustedThreadCount(_ threadCount: Int) { | ||
| assert(threadCount > 0, | ||
| "BUG IN NIO, please report: negative suggested loop/thread count: \(threadCount)") | ||
| assert(threadCount <= 1024, | ||
| "BUG IN NIO, please report: overly big suggested loop/thread count: \(threadCount)") | ||
| } | ||
|
|
||
| private static func getTrustworthyThreadCount(rawStorage: ManagedAtomic<Int>, environmentVariable: String) -> Int { | ||
| let returnedValueUnchecked: Int | ||
|
|
||
| let rawSuggestion = rawStorage.load(ordering: .relaxed) | ||
| switch rawSuggestion { | ||
| case 0: // == 0 | ||
| // Not set by user, not yet finalised, let's try to get it from the env var and fall back to | ||
| // `System.coreCount`. | ||
| let envVarString = getenv(environmentVariable).map { String(cString: $0) } | ||
| returnedValueUnchecked = envVarString.flatMap(Int.init) ?? System.coreCount | ||
| case .min ..< 0: // < 0 | ||
| // Untrusted and unchecked user value. Let's invert and then sanitise/check. | ||
| returnedValueUnchecked = -rawSuggestion | ||
| case 1 ... .max: // > 0 | ||
| // Trustworthy value that has been evaluated and sanitised before. | ||
| let returnValue = rawSuggestion | ||
| Self.validateTrustedThreadCount(returnValue) | ||
| return returnValue | ||
| default: | ||
| // Unreachable | ||
| preconditionFailure() | ||
| } | ||
|
|
||
| // Can't have fewer than 1, don't want more than 1024. | ||
| let returnValue = max(1, min(1024, returnedValueUnchecked)) | ||
| Self.validateTrustedThreadCount(returnValue) | ||
|
|
||
| // Store it for next time. | ||
| let (exchanged, _) = rawStorage.compareExchange(expected: rawSuggestion, | ||
| desired: returnValue, | ||
| ordering: .relaxed) | ||
| if !exchanged { | ||
| // We lost the race, this must mean it has been concurrently set correctly so we can safely recurse | ||
| // and try again. | ||
| return Self.getTrustworthyThreadCount(rawStorage: rawStorage, environmentVariable: environmentVariable) | ||
| } | ||
| return returnValue | ||
| } | ||
| } |
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