[hyperactor] mesh: make it work with cargo on a mac

Pull Request resolved: #1425

1) PR_DEATHSIG is a Linux feature; hide it behind a feature flag
2) heuristically find cargo-built resources in place of buck

Note that (2) is not a true solution: Cargo does not take these binaries as a dependence on the tests, and thus will not automatically rebuild them. Cargo apparently will do this for integration tests, however; we should consider converting the relevant tests to integration tests.
ghstack-source-id: 314156439

Differential Revision: [D83882828](https://our.internmc.facebook.com/intern/diff/D83882828/)

**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D83882828/)!

Author: mariusae

hyperactor_mesh/src/actor_mesh.rs

@@ -1345,9 +1345,9 @@ mod tests {
         use crate::alloc::process::ProcessAllocator;
 
         fn process_allocator() -> ProcessAllocator {
-            ProcessAllocator::new(Command::new(
-                buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
-            ))
+            ProcessAllocator::new(Command::new(crate::testresource::get(
+                "monarch/hyperactor_mesh/bootstrap",
+            )))
         }
 
         #[cfg(fbcode_build)] // we use an external binary, produced by buck

hyperactor_mesh/src/alloc.rs

@@ -713,8 +713,9 @@ pub(crate) mod testing {
             Duration::from_secs(1),
         );
 
-        let command =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let command = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let mut allocator = ProcessAllocator::new(command);
         let mut alloc = allocator
             .allocate(AllocSpec {

hyperactor_mesh/src/alloc/process.rs

@@ -603,12 +603,12 @@ mod tests {
 
     #[cfg(fbcode_build)] // we use an external binary, produced by buck
     crate::alloc_test_suite!(ProcessAllocator::new(Command::new(
-        buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap()
+        crate::testresource::get("monarch/hyperactor_mesh/bootstrap")
     )));
 
     #[tokio::test]
     async fn test_sigterm_on_group_fail() {
-        let bootstrap_binary = buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap();
+        let bootstrap_binary = crate::testresource::get("monarch/hyperactor_mesh/bootstrap");
         let mut allocator = ProcessAllocator::new(Command::new(bootstrap_binary));
 
         let mut alloc = allocator

hyperactor_mesh/src/alloc/remoteprocess.rs

@@ -2042,13 +2042,15 @@ mod test_alloc {
         let task1_allocator = RemoteProcessAllocator::new();
         let task1_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task1_addr_string = task1_addr.to_string();
-        let task1_cmd =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let task1_cmd = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let task2_allocator = RemoteProcessAllocator::new();
         let task2_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task2_addr_string = task2_addr.to_string();
-        let task2_cmd =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let task2_cmd = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let task1_allocator_copy = task1_allocator.clone();
         let task1_allocator_handle = tokio::spawn(async move {
             tracing::info!("spawning task1");
@@ -2169,13 +2171,15 @@ mod test_alloc {
         let task1_allocator = RemoteProcessAllocator::new();
         let task1_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task1_addr_string = task1_addr.to_string();
-        let task1_cmd =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let task1_cmd = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let task2_allocator = RemoteProcessAllocator::new();
         let task2_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task2_addr_string = task2_addr.to_string();
-        let task2_cmd =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let task2_cmd = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let task1_allocator_copy = task1_allocator.clone();
         let task1_allocator_handle = tokio::spawn(async move {
             tracing::info!("spawning task1");
@@ -2297,8 +2301,9 @@ mod test_alloc {
         let task1_allocator = RemoteProcessAllocator::new();
         let task1_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task1_addr_string = task1_addr.to_string();
-        let task1_cmd =
-            Command::new(buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap());
+        let task1_cmd = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        ));
         let task2_allocator = RemoteProcessAllocator::new();
         let task2_addr = ChannelAddr::any(ChannelTransport::Unix);
         let task2_addr_string = task2_addr.to_string();
@@ -2421,10 +2426,9 @@ mod test_alloc {
         let remote_process_allocators = addresses
             .iter()
             .map(|addr| {
-                Command::new(
-                    buck_resources::get("monarch/hyperactor_mesh/remote_process_allocator")
-                        .unwrap(),
-                )
+                Command::new(crate::testresource::get(
+                    "monarch/hyperactor_mesh/remote_process_allocator",
+                ))
                 .env("RUST_LOG", "info")
                 .arg(format!("--addr={addr}"))
                 .stdout(std::process::Stdio::piped())
@@ -2436,9 +2440,9 @@ mod test_alloc {
         let done_allocating_addr = ChannelAddr::any(ChannelTransport::Unix);
         let (done_allocating_addr, mut done_allocating_rx) =
             channel::serve::<()>(done_allocating_addr).unwrap();
-        let mut remote_process_alloc = Command::new(
-            buck_resources::get("monarch/hyperactor_mesh/remote_process_alloc").unwrap(),
-        )
+        let mut remote_process_alloc = Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/remote_process_alloc",
+        ))
         .arg(format!("--done-allocating-addr={}", done_allocating_addr))
         .arg(format!("--addresses={}", addresses.join(",")))
         .arg(format!("--num-proc-meshes={}", num_proc_meshes))

hyperactor_mesh/src/bootstrap.rs

@@ -401,11 +401,14 @@ impl Bootstrap {
 
 /// Install "kill me if parent dies" and close the race window.
 pub fn install_pdeathsig_kill() -> io::Result<()> {
-    // SAFETY: Calling into libc; does not dereference memory, just
-    // asks the kernel to deliver SIGKILL on parent death.
-    let rc = unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL as c_int) };
-    if rc != 0 {
-        return Err(io::Error::last_os_error());
+    #[cfg(target_os = "linux")]
+    {
+        // SAFETY: Calling into libc; does not dereference memory, just
+        // asks the kernel to deliver SIGKILL on parent death.
+        let rc = unsafe { libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGKILL as c_int) };
+        if rc != 0 {
+            return Err(io::Error::last_os_error());
+        }
     }
     // Race-close: if the parent died between our exec and prctl(),
     // we won't get a signal, so detect that and exit now.
@@ -1348,7 +1351,7 @@ impl BootstrapCommand {
     #[cfg(test)]
     pub(crate) fn test() -> Self {
         Self {
-            program: buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
+            program: crate::testresource::get("monarch/hyperactor_mesh/bootstrap"),
             arg0: None,
             args: vec![],
             env: HashMap::new(),
@@ -2553,7 +2556,7 @@ mod tests {
         let manager = BootstrapProcManager::new(command);
 
         // Spawn a fast-exiting child.
-        let mut cmd = Command::new("/bin/true");
+        let mut cmd = Command::new("true");
         cmd.stdout(Stdio::null()).stderr(Stdio::null());
         let child = cmd.spawn().expect("spawn true");
 
@@ -3230,9 +3233,9 @@ mod tests {
         let (instance, _handle) = proc.instance("client").unwrap();
 
         // Configure a ProcessAllocator with the bootstrap binary.
-        let mut allocator = ProcessAllocator::new(Command::new(
-            buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
-        ));
+        let mut allocator = ProcessAllocator::new(Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        )));
         // Request a new allocation of procs from the ProcessAllocator.
         let alloc = allocator
             .allocate(AllocSpec {

hyperactor_mesh/src/lib.rs

@@ -32,6 +32,7 @@ mod router;
 pub mod shared_cell;
 pub mod shortuuid;
 pub mod test_utils;
+mod testresource;
 pub mod v1;
 
 pub use actor_mesh::RootActorMesh;

hyperactor_mesh/src/testresource.rs

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#![cfg(test)]
+
+use std::path::PathBuf;
+
+/// Fetch the named (BUCK) named resource, heuristically falling back on
+/// the cargo-built path when possible. Beware! This is not actually a
+/// true cargo dependency, so the binaries have to be built independently.
+///
+/// We should convert these tests to integration tests, so that cargo can
+/// also manage the binaries.
+pub fn get<S>(name: S) -> PathBuf
+where
+    S: AsRef<str>,
+{
+    let name = name.as_ref().to_owned();
+    // TODO: actually check if we're running in Buck context or not.
+    if let Ok(path) = buck_resources::get(name.clone()) {
+        return path;
+    }
+
+    assert!(
+        name.starts_with("monarch/hyperactor_mesh/"),
+        "invalid resource {}: must start with \"monarch/hyperactor_mesh/\"",
+        name
+    );
+
+    let path: PathBuf = name
+        .replace(
+            "monarch/hyperactor_mesh/",
+            "../target/debug/hyperactor_mesh_test_",
+        )
+        .into();
+
+    assert!(
+        path.exists(),
+        "no cargo-built resource at {}",
+        path.display()
+    );
+
+    path
+}

hyperactor_mesh/src/v1/host_mesh.rs

@@ -831,7 +831,7 @@ mod tests {
         let config = hyperactor::config::global::lock();
         let _guard = config.override_key(crate::bootstrap::MESH_BOOTSTRAP_ENABLE_PDEATHSIG, false);
 
-        let program = buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap();
+        let program = crate::testresource::get("monarch/hyperactor_mesh/bootstrap");
 
         let hosts = vec![free_localhost_addr(), free_localhost_addr()];
 

hyperactor_mesh/src/v1/testing.rs

@@ -65,9 +65,9 @@ pub async fn proc_meshes(cx: &impl context::Actor, extent: Extent) -> Vec<ProcMe
     });
 
     meshes.push({
-        let mut allocator = ProcessAllocator::new(Command::new(
-            buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
-        ));
+        let mut allocator = ProcessAllocator::new(Command::new(crate::testresource::get(
+            "monarch/hyperactor_mesh/bootstrap",
+        )));
         let alloc = allocator
             .allocate(AllocSpec {
                 extent,
@@ -98,9 +98,9 @@ pub async fn allocs(extent: Extent) -> Vec<Box<dyn Alloc + Send + Sync>> {
     vec![
         // Box::new(LocalAllocator.allocate(spec.clone()).await.unwrap()),
         Box::new(
-            ProcessAllocator::new(Command::new(
-                buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
-            ))
+            ProcessAllocator::new(Command::new(crate::testresource::get(
+                "monarch/hyperactor_mesh/bootstrap",
+            )))
             .allocate(spec.clone())
             .await
             .unwrap(),
@@ -135,9 +135,9 @@ pub async fn local_proc_mesh(extent: Extent) -> (ProcMesh, Instance<()>, DialMai
 
 /// Create a host mesh using multiple processes running on the test machine.
 pub async fn host_mesh(extent: Extent) -> HostMesh {
-    let mut allocator = ProcessAllocator::new(Command::new(
-        buck_resources::get("monarch/hyperactor_mesh/bootstrap").unwrap(),
-    ));
+    let mut allocator = ProcessAllocator::new(Command::new(crate::testresource::get(
+        "monarch/hyperactor_mesh/bootstrap",
+    )));
     let alloc = allocator
         .allocate(AllocSpec {
             extent,