feat: inherit jobserver from env for all kinds of runner

weihanglo · weihanglo · commit 678f3ff487b7 · 2024-01-19T18:36:35.000-05:00
External subcommands are already able to inherit the jobserver from env since #10511. However, users reported that they've expected `cargo run` to behave the same as external subcommands. A popular example "cargo-xtask" pattern is used as scripting to run arbitrary tasks. Users may want to invoke `cargo run` from Make and expect some parallelism. This PR provides such an ability to the general `target.<...>.runner`, which affects `cargo test`, `cargo bench`, and `cargo run`. Note that this PR doesn't create any jobserver client if there is no existing jobserver from the environment. Nor `-j`/`--jobs` would create a new client. Reasons for this decision: * There might be crates don't want the jobserver to pollute their file descriptors, although they might be rare * Creating a jobsever driver with the new FIFO named pipe style is not yet supported as of `jobserver@0.1.26`. Once we can create a named pipe-based jobserver, it will be less risky and inheritance by default can be implemented.
diff --git a/src/cargo/core/compiler/compilation.rs b/src/cargo/core/compiler/compilation.rs
@@ -257,7 +257,13 @@ impl<'cfg> Compilation<'cfg> {
         } else {
             ProcessBuilder::new(cmd)
         };
-        self.fill_env(builder, pkg, script_meta, kind, false)
+        let mut builder = self.fill_env(builder, pkg, script_meta, kind, false)?;
+
+        if let Some(client) = self.config.jobserver_from_env() {
+            builder.inherit_jobserver(client);
+        }
+
+        Ok(builder)
     }
 
     /// Prepares a new process with an appropriate environment to run against
diff --git a/tests/testsuite/jobserver.rs b/tests/testsuite/jobserver.rs
@@ -192,33 +192,25 @@ test-runner:
         .env("CARGO", cargo_exe())
         .arg("run")
         .arg("-j2")
-        .with_status(2)
-        .with_stderr_contains("[..]no jobserver from env[..]")
         .run();
     p.process(make)
         .env("PATH", path)
         .env("CARGO", cargo_exe())
         .arg("run-runner")
         .arg("-j2")
-        .with_status(2)
         .with_stderr_contains("[..]this is a runner[..]")
-        .with_stderr_contains("[..]no jobserver from env[..]")
         .run();
     p.process(make)
         .env("CARGO", cargo_exe())
         .arg("test")
         .arg("-j2")
-        .with_status(2)
-        .with_stdout_contains("[..]no jobserver from env[..]")
         .run();
     p.process(make)
         .env("PATH", path)
         .env("CARGO", cargo_exe())
         .arg("test-runner")
         .arg("-j2")
-        .with_status(2)
         .with_stderr_contains("[..]this is a runner[..]")
-        .with_stdout_contains("[..]no jobserver from env[..]")
         .run();
 
     // but not from `-j` flag
