change: use sysinfo's swap value for Windows (#1436)

* some consts

* change: use sysinfo's swap calculation for windows

I'll add an additional field for committed in a separate PR which shows
the previous value.

src/data_collection.rs

@@ -412,10 +412,7 @@ impl DataCollector {
                 self.data.cache = memory::get_cache_usage(&self.sys.system);
             }
 
-            self.data.swap = memory::get_swap_usage(
-                #[cfg(not(target_os = "windows"))]
-                &self.sys.system,
-            );
+            self.data.swap = memory::get_swap_usage(&self.sys.system);
 
             #[cfg(feature = "zfs")]
             {

src/data_collection/memory.rs

@@ -2,18 +2,15 @@
 
 #[cfg(not(target_os = "windows"))]
 pub(crate) use self::sysinfo::get_cache_usage;
-pub(crate) use self::sysinfo::get_ram_usage;
+pub(crate) use self::sysinfo::{get_ram_usage, get_swap_usage};
 
 pub mod sysinfo;
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "windows")] {
-        pub mod windows;
-        pub(crate) use self::windows::get_swap_usage;
-    } else {
-        pub(crate) use self::sysinfo::get_swap_usage;
-
-    }
-}
+// cfg_if::cfg_if! {
+//     if #[cfg(target_os = "windows")] {
+//         mod windows;
+//         pub(crate) use self::windows::get_committed_usage;
+//     }
+// }
 
 #[cfg(feature = "zfs")]
 pub mod arc;

src/data_collection/memory/sysinfo.rs

@@ -21,7 +21,6 @@ pub(crate) fn get_ram_usage(sys: &System) -> Option<MemHarvest> {
 }
 
 /// Returns SWAP usage.
-#[cfg(not(target_os = "windows"))]
 pub(crate) fn get_swap_usage(sys: &System) -> Option<MemHarvest> {
     let mem_used = sys.used_swap();
     let mem_total = sys.total_swap();

src/data_collection/memory/windows.rs

@@ -4,24 +4,26 @@ use windows::Win32::System::ProcessStatus::{GetPerformanceInfo, PERFORMANCE_INFO
 
 use crate::data_collection::memory::MemHarvest;
 
-// TODO: Note this actually calculates the total *committed* usage. Rename and change label for accuracy!
+const PERFORMANCE_INFORMATION_SIZE: u32 = size_of::<PERFORMANCE_INFORMATION>() as _;
+
 /// Get the committed memory usage.
 ///
 /// Code based on [sysinfo's](https://github.com/GuillaumeGomez/sysinfo/blob/6f8178495adcf3ca4696a9ec548586cf6a621bc8/src/windows/system.rs#L169).
-pub(crate) fn get_swap_usage() -> Option<MemHarvest> {
+pub(crate) fn get_committed_usage() -> Option<MemHarvest> {
     // SAFETY: The safety invariant is that we only touch what's in `perf_info` if it succeeds, and that
     // the bindings are "safe" to use with how we call them.
     unsafe {
         let mut perf_info: PERFORMANCE_INFORMATION = zeroed();
-        if GetPerformanceInfo(&mut perf_info, size_of::<PERFORMANCE_INFORMATION>() as u32).is_ok() {
-            // Saturating sub by perf_info.PhysicalTotal for what sysinfo does.
-            let swap_total = perf_info.PageSize.saturating_mul(perf_info.CommitLimit) as u64;
-            let swap_used = perf_info.PageSize.saturating_mul(perf_info.CommitTotal) as u64;
+        if GetPerformanceInfo(&mut perf_info, PERFORMANCE_INFORMATION_SIZE).is_ok() {
+            let page_size = perf_info.PageSize;
+
+            let committed_total = page_size.saturating_mul(perf_info.CommitLimit) as u64;
+            let committed_used = page_size.saturating_mul(perf_info.CommitTotal) as u64;
 
             Some(MemHarvest {
-                used_bytes: swap_used,
-                total_bytes: swap_total,
-                use_percent: Some(swap_used as f64 / swap_total as f64 * 100.0),
+                used_bytes: committed_used,
+                total_bytes: committed_total,
+                use_percent: Some(committed_used as f64 / committed_total as f64 * 100.0),
             })
         } else {
             None