From 0fee8b6edbf95ab9838a363b87687abb985b8093 Mon Sep 17 00:00:00 2001
From: Davide Miola <davide.miola99@gmail.com>
Date: Fri, 21 Jul 2023 07:32:06 +0000
Subject: [PATCH] Move trace saving to optional feature

---
 main/Cargo.toml                   |  3 +++
 main/src/actors/trace_analyzer.rs |  7 ++++++-
 main/src/ksyms.rs                 | 26 ++++++++++++++++++++------
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/main/Cargo.toml b/main/Cargo.toml
index 01c8583..394afeb 100644
--- a/main/Cargo.toml
+++ b/main/Cargo.toml
@@ -21,3 +21,6 @@ metrics-common = { path = "../metrics-common" }
 [build-dependencies]
 libbpf-cargo = "0.20"
 bindgen = "0.64"
+
+[features]
+save-traces = []
diff --git a/main/src/actors/trace_analyzer.rs b/main/src/actors/trace_analyzer.rs
index bb14868..b89dbd4 100644
--- a/main/src/actors/trace_analyzer.rs
+++ b/main/src/actors/trace_analyzer.rs
@@ -1,4 +1,4 @@
-use std::{time::{Duration, Instant}, fs::File};
+use std::time::{Duration, Instant};
 use actix::{Actor, Context, AsyncContext, Addr};
 use anyhow::anyhow;
 use libbpf_rs::MapFlags;
@@ -7,6 +7,8 @@ use tokio::sync::mpsc::Sender;
 use crate::{ksyms::{Counts, KSyms}, common::{event_types_EVENT_MAX, self, event_types_EVENT_SOCK_SENDMSG, event_types_EVENT_NET_TX_SOFTIRQ, event_types_EVENT_NET_RX_SOFTIRQ}, bpf::ProgSkel};
 use libc::{mmap, PROT_READ, MAP_SHARED, sysconf, _SC_CLK_TCK};
 use super::{metrics_collector::MetricsCollector, MetricUpdate, SubmitUpdate};
+#[cfg(feature = "save-traces")]
+use std::fs::File;
 
 /// Actor responsible for interacting with BPF via shared maps,
 /// retrieve stack traces from the ring buffer, and analyze them
@@ -53,6 +55,7 @@ pub struct TraceAnalyzer {
     /// previous update cycle
     prev_total_energy: u64,
 
+    #[cfg(feature = "save-traces")]
     traces_output_file: File
 }
 
@@ -102,6 +105,7 @@ impl TraceAnalyzer {
             prev_update_ts: Instant::now(),
             prev_total_times: vec![vec![0;  event_types_EVENT_MAX as _]; num_possible_cpus],
             prev_total_energy: 0,
+            #[cfg(feature = "save-traces")]
             traces_output_file: File::create("traces")?
         })
     }
@@ -162,6 +166,7 @@ impl TraceAnalyzer {
                         &self.ksyms,
                         trace_ptr.add(1),
                         trace_size as _,
+                        #[cfg(feature = "save-traces")]
                         &mut self.traces_output_file
                     );
                 }
diff --git a/main/src/ksyms.rs b/main/src/ksyms.rs
index aba75c6..ffee601 100644
--- a/main/src/ksyms.rs
+++ b/main/src/ksyms.rs
@@ -1,4 +1,6 @@
-use std::{io::{self, BufReader, BufRead, Write}, fs::File, ops::{Add, AddAssign}, collections::BTreeMap, iter::Sum};
+use std::{io::{self, BufReader, BufRead}, fs::File, ops::{Add, AddAssign}, collections::BTreeMap, iter::Sum};
+#[cfg(feature = "save-traces")]
+use std::io::Write;
 
 /// Helper to load and manage application-defined kernel symbols
 #[derive(Default)]
@@ -174,15 +176,23 @@ impl KSyms {
 impl Counts {
     /// Iterate over the frames in the trace and accumulate the instances of the symbols in this Counts
     #[inline]
-    pub unsafe fn acc_trace(&mut self, ksyms: &KSyms, trace_ptr: *const u64, max_frames: usize, mut output: impl Write) {
+    pub unsafe fn acc_trace(
+        &mut self,
+        ksyms: &KSyms,
+        trace_ptr: *const u64,
+        max_frames: usize,
+        #[cfg(feature = "save-traces")]
+        mut output: impl Write
+    ) {
+        #[cfg(feature = "save-traces")]
+        let mut first_iter = true;
+        
         let mut c = Self::default();
         let mut frame_props = PerFrameProps {
             in_nf_hook: 0,
             ip_rcv_finish: 0
         };
 
-        let mut first_iter = true;
-        
         for frame_idx in 0..max_frames {
             // Load stack frame
             let ip = trace_ptr.add(frame_idx).read_volatile();
@@ -190,8 +200,11 @@ impl Counts {
                 break;
             }
 
-            let _ = write!(output, "{}{ip}", if first_iter { "" } else { "," });
-            first_iter = false;
+            #[cfg(feature = "save-traces")]
+            {
+                let _ = write!(output, "{}{ip}", if first_iter { "" } else { "," });
+                first_iter = false;
+            }
 
             // Check for known symbols
             if let Some((_, KSymsVal { range_end, fun })) = ksyms
@@ -206,6 +219,7 @@ impl Counts {
                 }
         }
 
+        #[cfg(feature = "save-traces")]
         let _ = writeln!(output);
 
         *self += c;