From a4c98e347215528d20e4891e4f0e54b2d8523c89 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Sun, 15 Jan 2023 04:56:30 -0800
Subject: fix(runtime/os): use GetPerformanceInfo for swap info on Windows
 (#17433)

Fixes https://github.com/denoland/deno/issues/17417

According to
https://learn.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-memorystatusex
, `stat.ullTotalPageFile` value is reliable only from
GetPerformanceInfo()

Also see https://github.com/GuillaumeGomez/sysinfo/issues/534

Co-authored-by: Nightly <dhairysrivastava5@gmail.com>
---
 runtime/ops/os/sys_info.rs | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

(limited to 'runtime/ops/os')

diff --git a/runtime/ops/os/sys_info.rs b/runtime/ops/os/sys_info.rs
index 366864f46..1a9358dc0 100644
--- a/runtime/ops/os/sys_info.rs
+++ b/runtime/ops/os/sys_info.rs
@@ -274,6 +274,8 @@ pub fn mem_info() -> Option<MemInfo> {
   unsafe {
     use std::mem;
     use winapi::shared::minwindef;
+    use winapi::um::psapi::GetPerformanceInfo;
+    use winapi::um::psapi::PERFORMANCE_INFORMATION;
     use winapi::um::sysinfoapi;
 
     let mut mem_status =
@@ -290,10 +292,30 @@ pub fn mem_info() -> Option<MemInfo> {
       mem_info.free = stat.ullAvailPhys / 1024;
       mem_info.cached = 0;
       mem_info.buffers = 0;
-      mem_info.swap_total = (stat.ullTotalPageFile - stat.ullTotalPhys) / 1024;
-      mem_info.swap_free = (stat.ullAvailPageFile - stat.ullAvailPhys) / 1024;
-      if mem_info.swap_free > mem_info.swap_total {
-        mem_info.swap_free = mem_info.swap_total;
+
+      // `stat.ullTotalPageFile` is reliable only from GetPerformanceInfo()
+      //
+      // See https://learn.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-memorystatusex
+      // and https://github.com/GuillaumeGomez/sysinfo/issues/534
+
+      let mut perf_info = mem::MaybeUninit::<PERFORMANCE_INFORMATION>::uninit();
+      let result = GetPerformanceInfo(
+        perf_info.as_mut_ptr(),
+        mem::size_of::<PERFORMANCE_INFORMATION>() as minwindef::DWORD,
+      );
+      if result == minwindef::TRUE {
+        let perf_info = perf_info.assume_init();
+        let swap_total = perf_info.PageSize
+          * perf_info
+            .CommitLimit
+            .saturating_sub(perf_info.PhysicalTotal);
+        let swap_free = perf_info.PageSize
+          * perf_info
+            .CommitLimit
+            .saturating_sub(perf_info.PhysicalTotal)
+            .saturating_sub(perf_info.PhysicalAvailable);
+        mem_info.swap_total = (swap_total / 1000) as u64;
+        mem_info.swap_free = (swap_free / 1000) as u64;
       }
     }
   }
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