Link statically

Pull Request resolved: #2085

Link everything into monarch statically, or dlopen it.

This makes the rdma related libraries and libc++ linked statically for increased portability. This means monarch built with rdma support and with a different version of libc++ than the current system can still be used.

By building rdma-core from source, we can also make sure Dennis' 64-bit patch is applied.

Total size of our so is 63MB now with no uncommon deps:

```
(monarch) [zdevito@devgpu014 /data/users/zdevito/fbsource/fbcode/monarch]$ ldd ./python/monarch/_rust_bindings.so
        linux-vdso.so.1 (0x00007f347a684000)
        libpython3.11.so.1.0 => /home/zdevito/local/miniconda3/envs/monarch/lib/libpython3.11.so.1.0 (0x00007f3477200000)
        libgcc_s.so.1 => /home/zdevito/local/miniconda3/envs/monarch/lib/libgcc_s.so.1 (0x00007f347a664000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f3477125000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f3476e00000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f347a686000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f347a64a000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f347a645000)
        libutil.so.1 => /lib64/libutil.so.1 (0x00007f347a640000)
(monarch) [zdevito@devgpu014 /data/users/zdevito/fbsource/fbcode/monarch]$ du -h ./python/monarch/_rust_bindings.so
63M     ./python/monarch/_rust_bindings.so
```
ghstack-source-id: 328274952

Differential Revision: [D88540873](https://our.internmc.facebook.com/intern/diff/D88540873/)

Author: zdevito

.gitignore

@@ -33,4 +33,3 @@ docs/_build/**
 docs/build/**
 docs/**/generated/**
 */sg_execution_times.rst
-nccl/**

Cargo.toml

@@ -17,6 +17,7 @@ members = [
     "monarch_rdma",
     "monarch_tensor_worker",
     "monarch_types",
+    "monarch_cpp_static_libs",
     "nccl-sys",
     "ndslice",
     "preempt_rwlock",

build_utils/src/lib.rs

@@ -276,6 +276,100 @@ pub fn print_cuda_lib_error_help() {
     eprintln!("Or: export CUDA_LIB_DIR=/usr/lib64");
 }
 
+/// Emit cargo directives to statically link libstdc++
+///
+/// This finds the GCC library path containing libstdc++.a and emits the
+/// appropriate cargo directives to link it statically. This avoids runtime
+/// dependency on system libstdc++.so which can cause GLIBCXX version conflicts.
+///
+/// Uses the `cc` crate to detect the C++ compiler, ensuring we use the same
+/// compiler that `cc::Build` and `cxx_build` would use.
+pub fn link_libstdcpp_static() {
+    // Use cc crate to get the C++ compiler, same as cc::Build and cxx_build use
+    let compiler = cc::Build::new().cpp(true).get_compiler();
+    let gcc_lib_path = std::process::Command::new(compiler.path())
+        .args(["-print-file-name=libstdc++.a"])
+        .output()
+        .ok()
+        .and_then(|output| {
+            if output.status.success() {
+                String::from_utf8(output.stdout).ok().and_then(|s| {
+                    let path = PathBuf::from(s.trim());
+                    path.parent().map(|p| p.to_path_buf())
+                })
+            } else {
+                None
+            }
+        });
+    if let Some(gcc_lib_path) = gcc_lib_path {
+        println!("cargo:rustc-link-search=native={}", gcc_lib_path.display());
+    }
+    println!("cargo:rustc-link-lib=static=stdc++");
+}
+
+/// Configuration for rdma-core static libraries from monarch_cpp_static_libs.
+///
+/// Use `CppStaticLibsConfig::from_env()` to get the paths, then use the include
+/// paths for bindgen/cc, and call `emit_link_directives()` to link.
+pub struct CppStaticLibsConfig {
+    pub rdma_include: String,
+    pub rdma_lib_dir: String,
+    pub rdma_util_dir: String,
+}
+
+impl CppStaticLibsConfig {
+    /// Load configuration from DEP_* environment variables set by monarch_cpp_static_libs.
+    ///
+    /// The monarch_cpp_static_libs crate must be listed as a build-dependency.
+    pub fn from_env() -> Self {
+        Self {
+            rdma_include: std::env::var("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_INCLUDE")
+                .expect("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_INCLUDE not set - add monarch_cpp_static_libs as build-dependency"),
+            rdma_lib_dir: std::env::var("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_LIB_DIR")
+                .expect("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_LIB_DIR not set - add monarch_cpp_static_libs as build-dependency"),
+            rdma_util_dir: std::env::var("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_UTIL_DIR")
+                .expect("DEP_MONARCH_CPP_STATIC_LIBS_RDMA_UTIL_DIR not set - add monarch_cpp_static_libs as build-dependency"),
+        }
+    }
+
+    /// Emit all cargo link directives for static linking of rdma-core.
+    ///
+    /// This emits search paths and link-lib directives for:
+    /// - libmlx5.a
+    /// - libibverbs.a
+    /// - librdma_util.a
+    pub fn emit_link_directives(&self) {
+        // Emit link search paths
+        println!("cargo::rustc-link-search=native={}", self.rdma_lib_dir);
+        println!("cargo::rustc-link-search=native={}", self.rdma_util_dir);
+
+        // Use whole-archive for rdma-core static libraries
+        println!("cargo::rustc-link-arg=-Wl,--whole-archive");
+        println!("cargo::rustc-link-lib=static=mlx5");
+        println!("cargo::rustc-link-lib=static=ibverbs");
+        println!("cargo::rustc-link-arg=-Wl,--no-whole-archive");
+
+        // rdma_util helper library
+        println!("cargo::rustc-link-lib=static=rdma_util");
+    }
+}
+
+/// Convenience function to set up rdma-core static linking.
+///
+/// Returns the config with include paths, and emits all link directives.
+/// The monarch_cpp_static_libs crate must be listed as a build-dependency.
+///
+/// Example:
+/// ```ignore
+/// let config = build_utils::setup_cpp_static_libs();
+/// // Use config.rdma_include for bindgen/cc
+/// ```
+pub fn setup_cpp_static_libs() -> CppStaticLibsConfig {
+    let config = CppStaticLibsConfig::from_env();
+    config.emit_link_directives();
+    config
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

monarch_cpp_static_libs/Cargo.toml

@@ -0,0 +1,13 @@
+# @generated by autocargo from //monarch/monarch_cpp_static_libs:monarch_cpp_static_libs
+
+[package]
+name = "monarch_cpp_static_libs"
+version = "0.0.1"
+authors = ["Facebook"]
+edition = "2021"
+license = "MIT"
+description = "Builds static rdma-core libraries from source"
+links = "monarch_cpp_static_libs"
+
+[build-dependencies]
+build_utils = { path = "../build_utils" }