From 44ca73a0e84dd4f463f2487c12722906041ac7e9 Mon Sep 17 00:00:00 2001
From: Matt McCormick <matt@mmmccormick.com>
Date: Wed, 15 Jan 2025 23:21:02 -0500
Subject: [PATCH] WIP: Add wasmtime_linker_define_wasi_threads to the c-api

To define `wasi_threads` on the linker to support rrunning wasm threads.
---
 Cargo.lock                              |  1 +
 crates/c-api/Cargo.toml                 |  2 ++
 crates/c-api/artifact/Cargo.toml        |  2 ++
 crates/c-api/build.rs                   |  1 +
 crates/c-api/cmake/features.cmake       |  1 +
 crates/c-api/include/wasmtime/conf.h.in |  1 +
 crates/c-api/src/linker.rs              | 24 ++++++++++++++++++++++++
 7 files changed, 32 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index bfb0a2df0331..f3059902d05c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4056,6 +4056,7 @@ dependencies = [
  "wasmtime",
  "wasmtime-c-api-macros",
  "wasmtime-wasi",
+ "wasmtime-wasi-threads",
  "wat",
 ]
 
diff --git a/crates/c-api/Cargo.toml b/crates/c-api/Cargo.toml
index d77312f42788..93f1f29526f5 100644
--- a/crates/c-api/Cargo.toml
+++ b/crates/c-api/Cargo.toml
@@ -34,6 +34,7 @@ wat = { workspace = true, optional = true }
 cap-std = { workspace = true, optional = true }
 tokio = { workspace = true, optional = true, features = ["fs"] }
 wasmtime-wasi = { workspace = true, optional = true, features = ["preview1"] }
+wasmtime-wasi-threads = { workspace = true, optional = true }
 
 # Optional dependencies for the `async` feature
 futures = { workspace = true, optional = true }
@@ -57,5 +58,6 @@ gc-null = ["wasmtime/gc-null"]
 cranelift = ['wasmtime/cranelift']
 winch = ['wasmtime/winch']
 debug-builtins = ['wasmtime/debug-builtins']
+wasi-threads = ['wasmtime-wasi-threads']
 # ... if you add a line above this be sure to change the other locations
 # marked WASMTIME_FEATURE_LIST
diff --git a/crates/c-api/artifact/Cargo.toml b/crates/c-api/artifact/Cargo.toml
index 8aa846d23344..b5a0ff3bed03 100644
--- a/crates/c-api/artifact/Cargo.toml
+++ b/crates/c-api/artifact/Cargo.toml
@@ -26,6 +26,7 @@ default = [
   'profiling',
   'wat',
   'wasi',
+  'wasi-threads',
   'cache',
   'parallel-compilation',
   'async',
@@ -47,6 +48,7 @@ profiling = ["wasmtime-c-api/profiling"]
 cache = ["wasmtime-c-api/cache"]
 parallel-compilation = ['wasmtime-c-api/parallel-compilation']
 wasi = ['wasmtime-c-api/wasi']
+wasi-threads = ['wasmtime-c-api/wasi-threads']
 logging = ['wasmtime-c-api/logging']
 disable-logging = ["wasmtime-c-api/disable-logging"]
 coredump = ["wasmtime-c-api/coredump"]
diff --git a/crates/c-api/build.rs b/crates/c-api/build.rs
index 12bc0b5016e8..b447840251d1 100644
--- a/crates/c-api/build.rs
+++ b/crates/c-api/build.rs
@@ -8,6 +8,7 @@ const FEATURES: &[&str] = &[
     "CACHE",
     "PARALLEL_COMPILATION",
     "WASI",
+    "WASI_THREADS",
     "LOGGING",
     "DISABLE_LOGGING",
     "COREDUMP",
diff --git a/crates/c-api/cmake/features.cmake b/crates/c-api/cmake/features.cmake
index 727412a0433c..a80f8ef4fe75 100644
--- a/crates/c-api/cmake/features.cmake
+++ b/crates/c-api/cmake/features.cmake
@@ -31,6 +31,7 @@ feature(wat ON)
 feature(cache ON)
 feature(parallel-compilation ON)
 feature(wasi ON)
+feature(wasi-threads ON)
 feature(logging ON)
 feature(disable-logging OFF)
 feature(coredump ON)
diff --git a/crates/c-api/include/wasmtime/conf.h.in b/crates/c-api/include/wasmtime/conf.h.in
index 03f4debf92d1..f5b5aae814e5 100644
--- a/crates/c-api/include/wasmtime/conf.h.in
+++ b/crates/c-api/include/wasmtime/conf.h.in
@@ -13,6 +13,7 @@
 #cmakedefine WASMTIME_FEATURE_CACHE
 #cmakedefine WASMTIME_FEATURE_PARALLEL_COMPILATION
 #cmakedefine WASMTIME_FEATURE_WASI
+#cmakedefine WASMTIME_FEATURE_WASI_THREADS
 #cmakedefine WASMTIME_FEATURE_LOGGING
 #cmakedefine WASMTIME_FEATURE_DISABLE_LOGGING
 #cmakedefine WASMTIME_FEATURE_COREDUMP
diff --git a/crates/c-api/src/linker.rs b/crates/c-api/src/linker.rs
index 28fa087153ae..224a58bcd068 100644
--- a/crates/c-api/src/linker.rs
+++ b/crates/c-api/src/linker.rs
@@ -6,8 +6,12 @@ use crate::{
 use std::ffi::c_void;
 use std::mem::MaybeUninit;
 use std::str;
+use std::sync::Arc;
 use wasmtime::{Func, Instance, Linker};
 
+#[cfg(feature = "wasi-threads")]
+use wasmtime_wasi_threads::WasiThreadsCtx;
+
 #[repr(C)]
 pub struct wasmtime_linker_t {
     pub(crate) linker: Linker<crate::WasmtimeStoreData>,
@@ -119,6 +123,26 @@ pub extern "C" fn wasmtime_linker_define_wasi(
     )
 }
 
+#[cfg(feature = "wasi-threads")]
+#[unsafe(no_mangle)]
+pub extern "C" fn wasmtime_linker_define_wasi_threads(
+    linker: &mut wasmtime_linker_t,
+    store: WasmtimeStoreContextMut<'_>,
+    module: &wasmtime_module_t,
+) -> Option<Box<wasmtime_error_t>> {
+    handle_result(|| {
+        let linker = &mut linker.linker;
+        store.data_mut().wasi_threads = Some(Arc::new(WasiThreadsCtx::new(
+            &module.module.clone(),
+            Arc::new(linker.clone()),
+        )?));
+        wasmtime_wasi_threads::add_to_linker(linker, store, &module.module, |host| {
+            host.wasi_threads.as_ref().unwrap()
+        })?;
+        Ok(())
+    })
+}
+
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn wasmtime_linker_define_instance(
     linker: &mut wasmtime_linker_t,