Fix bug preventing running without threads

Threads were added in the sample step irrespective of the boolean flag.
This commit fixes it.
It also adjusts the interactive mode to take threads into account.

src/main.rs

@@ -60,6 +60,6 @@ fn interactive(args: Cli, user_hz: f64) -> Result<()> {
         print_proc_metrics(metrics, descriptions);
 
         sampler.sample(sample_duration)?;
-        clear_n_lines(args.pids.len() + 1);
+        clear_n_lines(sampler.buffers().count() + 1);
     }
 }

src/sample.rs

@@ -91,6 +91,7 @@ struct ProcSampler {
     pid: usize,
     proc_buf: Buffer,
     thread_bufs: BTreeMap<usize, Buffer>,
+    with_threads: bool,
 }
 
 impl ProcSampler {
@@ -111,37 +112,40 @@ impl ProcSampler {
             pid,
             proc_buf,
             thread_bufs,
+            with_threads,
         })
     }
 
     pub fn sample(&mut self, start: Instant) -> Result<()> {
         // Sample main process
         self.proc_buf.sample(start)?;
 
-        // Find potentially new threads
-        let tids = get_threads(self.pid);
-        for tid in tids {
-            if let Entry::Vacant(e) = self.thread_bufs.entry(tid) {
-                if let Ok(buffer) =
-                    Buffer::from_pid_tid(self.pid, tid, self.proc_buf.buf.capacity())
-                {
-                    e.insert(buffer);
+        if self.with_threads {
+            // Find potentially new threads
+            let tids = get_threads(self.pid);
+            for tid in tids {
+                if let Entry::Vacant(e) = self.thread_bufs.entry(tid) {
+                    if let Ok(buffer) =
+                        Buffer::from_pid_tid(self.pid, tid, self.proc_buf.buf.capacity())
+                    {
+                        e.insert(buffer);
+                    }
                 }
             }
-        }
 
-        let mut pids_to_remove = vec![];
+            let mut pids_to_remove = vec![];
 
-        // Sample all threads
-        for (pid, buffer) in self.thread_bufs.iter_mut() {
-            if buffer.sample(start).is_err() {
-                pids_to_remove.push(*pid);
+            // Sample all threads
+            for (pid, buffer) in self.thread_bufs.iter_mut() {
+                if buffer.sample(start).is_err() {
+                    pids_to_remove.push(*pid);
+                }
             }
-        }
 
-        // Remove unreadable threads
-        for pid in pids_to_remove {
-            self.thread_bufs.remove(&pid);
+            // Remove unreadable threads
+            for pid in pids_to_remove {
+                self.thread_bufs.remove(&pid);
+            }
         }
 
         Ok(())