Fix spin_wait::spin_one() on Windows platforms

lewissbaker · web-flow · commit 7ac4be2c0eb8 · 2019-05-28T11:33:35.000-07:00
A conditional was accidentally inverted which meant that the spin-wait would first start yielding to the OS and then later start spinning with very large loopCount values, potentially leading to large pauses. Originally fixed by @loopunit in loopunit@242db2b
diff --git a/lib/spin_wait.cpp b/lib/spin_wait.cpp
@@ -44,8 +44,8 @@ namespace cppcoro
 	{
 #if CPPCORO_OS_WINNT
 		// Spin strategy taken from .NET System.SpinWait class.
-		// I assume the Microsoft guys knew what they're doing.
-		if (next_spin_will_yield())
+		// I assume the Microsoft developers knew what they're doing.
+		if (!next_spin_will_yield())
 		{
 			// CPU-level pause
 			// Allow other hyper-threads to run while we busy-wait.

Original file line number	Diff line number	Diff line change
`@@ -44,8 +44,8 @@ namespace cppcoro`
`44`	`44`	`{`
`45`	`45`	`#if CPPCORO_OS_WINNT`
`46`	`46`	`// Spin strategy taken from .NET System.SpinWait class.`
`47`		`- // I assume the Microsoft guys knew what they're doing.`
`48`		`- if (next_spin_will_yield())`
	`47`	`+ // I assume the Microsoft developers knew what they're doing.`
	`48`	`+ if (!next_spin_will_yield())`
`49`	`49`	`{`
`50`	`50`	`// CPU-level pause`
`51`	`51`	`// Allow other hyper-threads to run while we busy-wait.`