From 3268f3a6affd6a904bb5e4ac1266a5ea57c71afe Mon Sep 17 00:00:00 2001
From: adisbladis <adisbladis@gmail.com>
Date: Thu, 6 Jan 2022 13:19:15 +1300
Subject: [PATCH] Add flag to enable meta

I removed meta from the output in https://github.com/nix-community/nix-eval-jobs/commit/434376f8e1ef653e79b4c2b5a38cba45109152e4 with the intention of adding it back gated by a flag, but that never happened.

Adding meta is quite a substantial increase in output size and has some non-trivial performance impact at scale, so it's best to leave it as opt-in.
---
 src/nix-eval-jobs.cc | 36 +++++++++++++++++++++++-------------
 tests/test_eval.py   |  5 +++--
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/nix-eval-jobs.cc b/src/nix-eval-jobs.cc
index 996d5f2..47f202b 100644
--- a/src/nix-eval-jobs.cc
+++ b/src/nix-eval-jobs.cc
@@ -34,6 +34,7 @@ struct MyArgs : MixEvalArgs, MixCommonArgs
     Path releaseExpr;
     Path gcRootsDir;
     bool flake = false;
+    bool meta = false;
     size_t nrWorkers = 1;
     size_t maxMemorySize = 4096;
     pureEval evalMode = evalAuto;
@@ -94,6 +95,12 @@ struct MyArgs : MixEvalArgs, MixCommonArgs
             .handler = {&flake, true}
         });
 
+        addFlag({
+            .longName = "meta",
+            .description = "include derivation meta field in output",
+            .handler = {&meta, true}
+        });
+
         expectArg("expr", &releaseExpr);
     }
 };
@@ -182,21 +189,24 @@ static void worker(
                     reply["outputs"][out.first] = out.second;
                 }
 
-                nlohmann::json meta;
-                for (auto & name : drv->queryMetaNames()) {
-                  PathSet context;
-                  std::stringstream ss;
+                if (myArgs.meta) {
+                    nlohmann::json meta;
+                    for (auto & name : drv->queryMetaNames()) {
+                      PathSet context;
+                      std::stringstream ss;
 
-                  auto metaValue = drv->queryMeta(name);
-                  // Skip non-serialisable types
-                  // TODO: Fix serialisation of derivations to store paths
-                  if (metaValue == 0) {
-                    continue;
-                  }
+                      auto metaValue = drv->queryMeta(name);
+                      // Skip non-serialisable types
+                      // TODO: Fix serialisation of derivations to store paths
+                      if (metaValue == 0) {
+                        continue;
+                      }
 
-                  printValueAsJSON(state, true, *metaValue, noPos, ss, context);
-                  nlohmann::json field = nlohmann::json::parse(ss.str());
-                  meta[name] = field;
+                      printValueAsJSON(state, true, *metaValue, noPos, ss, context);
+                      nlohmann::json field = nlohmann::json::parse(ss.str());
+                      meta[name] = field;
+                    }
+                    reply["meta"] = meta;
                 }
 
                 /* Register the derivation as a GC root.  !!! This
diff --git a/tests/test_eval.py b/tests/test_eval.py
index 7df722a..db93f97 100644
--- a/tests/test_eval.py
+++ b/tests/test_eval.py
@@ -13,7 +13,7 @@ BIN = PROJECT_ROOT.joinpath("build", "src", "nix-eval-jobs")
 
 def common_test(extra_args: List[str]) -> None:
     with TemporaryDirectory() as tempdir:
-        cmd = [str(BIN), "--gc-roots-dir", tempdir] + extra_args
+        cmd = [str(BIN), "--gc-roots-dir", tempdir, "--meta"] + extra_args
         res = subprocess.run(
             cmd,
             cwd=TEST_ROOT.joinpath("assets"),
@@ -30,11 +30,12 @@ def common_test(extra_args: List[str]) -> None:
         assert built_job["name"] == "job1"
         assert built_job["outputs"]["out"].startswith("/nix/store")
         assert built_job["drvPath"].endswith(".drv")
-
+        assert built_job["meta"]['broken'] is False
 
         substituted_job = results[1]
         assert substituted_job["attr"] == "substitutedJob"
         assert substituted_job["name"].startswith("hello-")
+        assert substituted_job["meta"]['broken'] is False
 
 
 def test_flake() -> None: