From a5186a9d8b3cd236fb3535eb419f88436d264f42 Mon Sep 17 00:00:00 2001
From: Mark Leyva <maleyva1@users.noreply.github.com>
Date: Mon, 15 Jul 2024 05:10:31 -0700
Subject: [PATCH] Use monotonic timestamp to calculate timeouts refs #23826
 (#23834)

Related to #23826. This address issues raised
[here](https://github.com/nim-lang/Nim/pull/23826#issuecomment-2226877361)
by using a monotonic timestamp to calculate timeouts and increasing the
max sleep time to 50ms.
---
 lib/pure/osproc.nim | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/lib/pure/osproc.nim b/lib/pure/osproc.nim
index ee824db9beb9..2deb9fcaa130 100644
--- a/lib/pure/osproc.nim
+++ b/lib/pure/osproc.nim
@@ -1353,7 +1353,8 @@ elif not defined(useNimRtl):
       result = exitStatusLikeShell(p.exitStatus)
 
   else:
-    import std/times
+    import std/times except getTime
+    import std/monotimes
 
     proc waitForExit(p: Process, timeout: int = -1): int =
       if p.exitFlag:
@@ -1369,10 +1370,10 @@ elif not defined(useNimRtl):
         p.exitFlag = true
         p.exitStatus = status
       else:
-        # Max 1ms delay
-        const maxWait = initDuration(milliseconds = 1)
+        # Max 50ms delay
+        const maxWait = initDuration(milliseconds = 50)
         let wait = initDuration(milliseconds = timeout)
-        let deadline = getTime() + wait
+        let deadline = getMonoTime() + wait
         # starting 50μs delay
         var delay = initDuration(microseconds = 50)
         
@@ -1387,7 +1388,7 @@ elif not defined(useNimRtl):
             raiseOsError(osLastError())
           else:
             # Continue waiting if needed
-            if getTime() >= deadline:
+            if getMonoTime() >= deadline:
               # Previous version of `waitForExit`
               # foricibly killed the process.
               # We keep this so we don't break programs
@@ -1395,14 +1396,19 @@ elif not defined(useNimRtl):
               if posix.kill(p.id, SIGKILL) < 0:
                 raiseOSError(osLastError())
             else:
-              let newWait = getTime() + delay
+              const max = 1_000_000_000
+              let 
+                newWait = getMonoTime() + delay
+                ticks = newWait.ticks()
+                ns = ticks mod max
+                secs = ticks div max
               var 
                 waitSpec: TimeSpec
                 unused: Timespec
-              waitSpec.tv_sec = posix.Time(newWait.toUnix())
-              waitSpec.tv_nsec = newWait.nanosecond.clong
-              discard posix.clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, waitSpec, unused)
-              let remaining = deadline - getTime()
+              waitSpec.tv_sec = posix.Time(secs)
+              waitSpec.tv_nsec = ns 
+              discard posix.clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, waitSpec, unused)
+              let remaining = deadline - getMonoTime()
               delay = min([delay * 2, remaining, maxWait])
 
       result = exitStatusLikeShell(p.exitStatus)