feat(log): track unblocked units in unit-started event

Author: weihanglo

src/cargo/core/compiler/timings/mod.rs

@@ -318,11 +318,13 @@ impl<'gctx> Timings<'gctx> {
             crate::drop_println!(self.gctx, "{}", msg);
         }
         if let Some(logger) = build_runner.bcx.logger {
+            let unblocked = unblocked.iter().map(|u| self.unit_to_index[u]).collect();
             logger.log(LogMessage::UnitFinished {
                 index: self.unit_to_index[&unit_time.unit],
                 duration: unit_time.duration,
                 rmeta_time: unit_time.rmeta_time,
                 sections: unit_time.sections.clone().into_iter().collect(),
+                unblocked,
             });
         }
         self.unit_times.push(unit_time);

src/cargo/util/log_message.rs

@@ -44,6 +44,8 @@ pub enum LogMessage {
         rmeta_time: Option<f64>,
         #[serde(skip_serializing_if = "Vec::is_empty")]
         sections: Vec<(String, CompilationSection)>,
+        #[serde(skip_serializing_if = "Vec::is_empty")]
+        unblocked: Vec<u64>,
     },
     /// Emitted when a unit needs to be rebuilt.
     Rebuild {

tests/testsuite/build_analysis.rs

@@ -149,7 +149,10 @@ fn log_msg_timing_info() {
     "reason": "unit-finished",
     "rmeta_time": "{...}",
     "run_id": "[..]T[..]Z-[..]",
-    "timestamp": "[..]T[..]Z"
+    "timestamp": "[..]T[..]Z",
+    "unblocked": [
+      1
+    ]
   },
   {
     "elapsed": "{...}",