New metric for empty coverage (#3610)

* add

* Adding coverage output to every iteration of coverage task.

* Adding metric for empty coverage.

* Fixing.

* Fixing.

src/agent/onefuzz-task/src/tasks/coverage/generic.rs

@@ -28,7 +28,9 @@ use onefuzz_file_format::coverage::{
 };
 use onefuzz_result::job_result::JobResultData;
 use onefuzz_result::job_result::{JobResultSender, TaskJobResultClient};
-use onefuzz_telemetry::{event, warn, Event::coverage_data, Event::coverage_failed, EventData};
+use onefuzz_telemetry::{
+    event, warn, Event::coverage_data, Event::coverage_empty, Event::coverage_failed, EventData,
+};
 use storage_queue::{Message, QueueClient};
 use tokio::fs;
 use tokio::sync::RwLock;
@@ -148,7 +150,6 @@ impl CoverageTask {
 
         info!("report initial coverage");
         context.report_coverage_stats().await;
-
         context.heartbeat.alive();
 
         for dir in &self.config.readonly_inputs {
@@ -174,7 +175,6 @@ impl CoverageTask {
             context.save_and_sync_coverage().await?;
         }
 
-        info!("report coverage");
         context.report_coverage_stats().await;
 
         context.heartbeat.alive();
@@ -308,6 +308,11 @@ impl<'a> TaskContext<'a> {
 
     async fn try_record_input(&mut self, input: &Path) -> Result<()> {
         let coverage = self.record_impl(input).await?;
+        let coverage_stats = CoverageStats::new(&coverage);
+        if coverage_stats.covered == 0 {
+            event!(coverage_empty; EventData::Path = input.display().to_string());
+            metric!(coverage_empty; 1.0; EventData::Path = input.display().to_string());
+        }
         let mut self_coverage = RwLock::write(&self.coverage).await;
         self_coverage.merge(&coverage);
         Ok(())

src/agent/onefuzz-telemetry/src/lib.rs

@@ -76,6 +76,7 @@ pub enum Event {
     task_start,
     coverage_data,
     coverage_failed,
+    coverage_empty,
     new_result,
     new_crashdump,
     new_coverage,
@@ -94,6 +95,7 @@ impl Event {
             Self::task_start => "task_start",
             Self::coverage_data => "coverage_data",
             Self::coverage_failed => "coverage_failed",
+            Self::coverage_empty => "coverage_empty",
             Self::new_coverage => "new_coverage",
             Self::new_crashdump => "new_crashdump",
             Self::new_result => "new_result",