From f17aae686342aa893aa5bbf360331eccbebc03db Mon Sep 17 00:00:00 2001
From: Bruce Guenter <bruce.guenter@datadoghq.com>
Date: Tue, 15 Aug 2023 10:19:40 -0600
Subject: [PATCH] Implement Windows calculation

---
 src/windows/process.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/windows/process.rs b/src/windows/process.rs
index 9c1371fe0..8d3a4f7bc 100644
--- a/src/windows/process.rs
+++ b/src/windows/process.rs
@@ -205,6 +205,7 @@ pub struct Process {
     old_written_bytes: u64,
     read_bytes: u64,
     written_bytes: u64,
+    nb_cpus: u64,
 }
 
 struct CPUsageCalculationValues {
@@ -212,6 +213,7 @@ struct CPUsageCalculationValues {
     old_process_user_cpu: u64,
     old_system_sys_cpu: u64,
     old_system_user_cpu: u64,
+    nb_cpus: u64,
 }
 
 impl CPUsageCalculationValues {
@@ -221,8 +223,18 @@ impl CPUsageCalculationValues {
             old_process_user_cpu: 0,
             old_system_sys_cpu: 0,
             old_system_user_cpu: 0,
+            nb_cpus: 0,
         }
     }
+
+    const fn total_accumulated_cpu_usage(&self) -> f32 {
+        self.old_process_user_cpu
+            .saturating_add(self.old_process_sys_cpu) as f32
+            / self
+                .old_system_user_cpu
+                .saturating_add(self.old_system_sys_cpu) as f32
+            * self.nb_cpus as f32
+    }
 }
 static WINDOWS_8_1_OR_NEWER: Lazy<bool> = Lazy::new(|| unsafe {
     let mut version_info: RTL_OSVERSIONINFOEXW = MaybeUninit::zeroed().assume_init();
@@ -600,7 +612,7 @@ impl ProcessExt for Process {
     }
 
     fn total_accumulated_cpu_usage(&self) -> f32 {
-        FIXME
+        self.cpu_calc_values.total_accumulated_cpu_usage()
     }
 
     fn disk_usage(&self) -> DiskUsage {
@@ -1112,6 +1124,7 @@ pub(crate) fn compute_cpu_usage(p: &mut Process, nb_cpus: u64) {
         p.cpu_calc_values.old_process_sys_cpu = sys;
         p.cpu_calc_values.old_system_user_cpu = global_user_time;
         p.cpu_calc_values.old_system_sys_cpu = global_kernel_time;
+        p.cpu_calc_values.nb_cpus = nb_cpus;
 
         let denominator = delta_global_user_time.saturating_add(delta_global_kernel_time) as f32;