extract cpu service from system stats, add --types filter to nova-stats

stats-daemon/src/main.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::io::{self, Write};
 use std::thread;
 use std::time::{Duration, Instant};
@@ -21,36 +22,69 @@ fn parse_interval_ms() -> u64 {
     1000
 }
 
+fn parse_types() -> HashSet<String> {
+    let args: Vec<String> = std::env::args().collect();
+    let mut i = 1;
+    while i < args.len() {
+        if args[i] == "--types" {
+            if let Some(list) = args.get(i + 1) {
+                return list.split(',').map(|s| s.trim().to_string()).collect();
+            }
+        }
+        i += 1;
+    }
+    HashSet::new() // empty = all types
+}
+
 fn main() {
     let interval = Duration::from_millis(parse_interval_ms());
+    let types = parse_types();
     let stdout = io::stdout();
     let mut out = io::BufWriter::new(stdout.lock());
     let mut prev: Vec<cpu::Sample> = vec![];
     let mut freqs: Vec<f64> = vec![];
-    let mut gpu = gpu::detect_gpu();
     let mut tick = 0u64;
 
+    let emit_cpu = types.is_empty() || types.contains("cpu");
+    let emit_mem = types.is_empty() || types.contains("mem");
+    let emit_temp = types.is_empty() || types.contains("temp");
+    let emit_graphics = types.is_empty() || types.contains("gpu");
+
+    let mut gpu = if emit_graphics {
+        gpu::detect_gpu()
+    } else {
+        gpu::GpuBackend::None
+    };
+
     loop {
         let t0 = Instant::now();
 
-        let curr = cpu::read_stat();
-        if tick.is_multiple_of(2) {
-            freqs = cpu::read_core_freqs();
+        if emit_cpu {
+            let curr = cpu::read_stat();
+            if tick.is_multiple_of(2) {
+                freqs = cpu::read_core_freqs();
+            }
+            cpu::emit_cpu(&mut out, &prev, &curr, &freqs);
+            prev = curr;
+        }
+
+        if emit_mem && tick.is_multiple_of(2) {
             mem::emit_mem(&mut out);
         }
-        cpu::emit_cpu(&mut out, &prev, &curr, &freqs);
-        prev = curr;
 
         if tick.is_multiple_of(4) {
-            temp::emit_temp(&mut out);
-            // AMD/Intel read sysfs (instant); NVIDIA shells out so runs less often
-            let emit = match &gpu {
-                gpu::GpuBackend::Amd { .. } | gpu::GpuBackend::Intel { .. } => true,
-                gpu::GpuBackend::Nvidia => tick.is_multiple_of(8),
-                gpu::GpuBackend::None => false,
-            };
-            if emit {
-                gpu::emit_gpu(&mut out, &mut gpu);
+            if emit_temp {
+                temp::emit_temp(&mut out);
+            }
+            if emit_graphics {
+                let emit = match &gpu {
+                    gpu::GpuBackend::Amd { .. } | gpu::GpuBackend::Intel { .. } => true,
+                    gpu::GpuBackend::Nvidia => tick.is_multiple_of(8),
+                    gpu::GpuBackend::None => false,
+                };
+                if emit {
+                    gpu::emit_gpu(&mut out, &mut gpu);
+                }
             }
         }