fix(log): replace unit metadata with index for unit-* event

Reduce log size by using an integer index instead of full metadata.
The index is assigned deterministically at initialization.

Author: weihanglo

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

@@ -17,6 +17,7 @@ use crate::util::{CargoResult, GlobalContext};
 
 use cargo_util::paths;
 use indexmap::IndexMap;
+use itertools::Itertools as _;
 use std::collections::HashMap;
 use std::io::BufWriter;
 use std::time::{Duration, Instant};
@@ -51,6 +52,11 @@ pub struct Timings<'gctx> {
     total_fresh: u32,
     /// Total number of dirty units.
     total_dirty: u32,
+    /// A map from unit to index.
+    ///
+    /// This for saving log size.
+    /// Only the unit-started event needs to hold the entire unit information.
+    unit_to_index: HashMap<Unit, u64>,
     /// Time tracking for each individual unit.
     unit_times: Vec<UnitTime>,
     /// Units that are in the process of being built.
@@ -152,6 +158,7 @@ impl<'gctx> Timings<'gctx> {
                 profile: String::new(),
                 total_fresh: 0,
                 total_dirty: 0,
+                unit_to_index: HashMap::new(),
                 unit_times: Vec::new(),
                 active: HashMap::new(),
                 concurrency: Vec::new(),
@@ -185,6 +192,13 @@ impl<'gctx> Timings<'gctx> {
                 None
             }
         };
+        let unit_to_index = bcx
+            .unit_graph
+            .keys()
+            .sorted()
+            .enumerate()
+            .map(|(i, unit)| (unit.clone(), i as u64))
+            .collect();
 
         Timings {
             gctx: bcx.gctx,
@@ -197,6 +211,7 @@ impl<'gctx> Timings<'gctx> {
             profile,
             total_fresh: 0,
             total_dirty: 0,
+            unit_to_index,
             unit_times: Vec::new(),
             active: HashMap::new(),
             concurrency: Vec::new(),
@@ -244,6 +259,7 @@ impl<'gctx> Timings<'gctx> {
                 package_id: unit_time.unit.pkg.package_id().to_spec(),
                 target: (&unit_time.unit.target).into(),
                 mode: unit_time.unit.mode,
+                index: self.unit_to_index[&unit_time.unit],
                 elapsed: start,
             });
         }
@@ -303,9 +319,7 @@ impl<'gctx> Timings<'gctx> {
         }
         if let Some(logger) = build_runner.bcx.logger {
             logger.log(LogMessage::UnitFinished {
-                package_id: unit_time.unit.pkg.package_id().to_spec(),
-                target: (&unit_time.unit.target).into(),
-                mode: unit_time.unit.mode,
+                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(),

src/cargo/util/log_message.rs

@@ -33,13 +33,12 @@ pub enum LogMessage {
         package_id: PackageIdSpec,
         target: Target,
         mode: CompileMode,
+        index: u64,
         elapsed: f64,
     },
     /// Emitted when a compilation unit finishes.
     UnitFinished {
-        package_id: PackageIdSpec,
-        target: Target,
-        mode: CompileMode,
+        index: u64,
         duration: f64,
         #[serde(skip_serializing_if = "Option::is_none")]
         rmeta_time: Option<f64>,

tests/testsuite/build_analysis.rs

@@ -132,6 +132,7 @@ fn log_msg_timing_info() {
   },
   {
     "elapsed": "{...}",
+    "index": 0,
     "mode": "check",
     "package_id": "path+[ROOTURL]/foo/bar#0.0.0",
     "reason": "unit-started",
@@ -144,19 +145,15 @@ fn log_msg_timing_info() {
   },
   {
     "duration": "{...}",
-    "mode": "check",
-    "package_id": "path+[ROOTURL]/foo/bar#0.0.0",
+    "index": 0,
     "reason": "unit-finished",
     "rmeta_time": "{...}",
     "run_id": "[..]T[..]Z-[..]",
-    "target": {
-      "kind": "lib",
-      "name": "bar"
-    },
     "timestamp": "[..]T[..]Z"
   },
   {
     "elapsed": "{...}",
+    "index": 1,
     "mode": "check",
     "package_id": "path+[ROOTURL]/foo#0.0.0",
     "reason": "unit-started",
@@ -169,15 +166,10 @@ fn log_msg_timing_info() {
   },
   {
     "duration": "{...}",
-    "mode": "check",
-    "package_id": "path+[ROOTURL]/foo#0.0.0",
+    "index": 1,
     "reason": "unit-finished",
     "rmeta_time": "{...}",
     "run_id": "[..]T[..]Z-[..]",
-    "target": {
-      "kind": "lib",
-      "name": "foo"
-    },
     "timestamp": "[..]T[..]Z"
   }
 ]