Add a C API to query MMTk plan name.

Author: wks

mmtk/src/api.rs

@@ -97,6 +97,11 @@ pub extern "C" fn mmtk_enable_collection() {
     memory_manager::enable_collection(&SINGLETON)
 }
 
+#[no_mangle]
+pub extern "C" fn mmtk_plan_name() -> *const libc::c_char {
+    crate::binding().get_plan_name_c()
+}
+
 #[no_mangle]
 pub extern "C" fn mmtk_used_bytes() -> usize {
     memory_manager::used_bytes(&SINGLETON)

mmtk/src/binding.rs

@@ -1,11 +1,15 @@
+use std::ffi::CString;
 use std::ptr::null;
+use std::sync::Mutex;
 
+use crate::SINGLETON;
 use crate::abi;
 use crate::finalize;
 
 pub struct RubyBinding {
     pub upcalls: *const abi::RubyUpcalls,
     pub finalizer_processor: finalize::FinalizerProcessor,
+    pub plan_name: Mutex<Option<CString>>,
 }
 
 unsafe impl Sync for RubyBinding {}
@@ -15,6 +19,7 @@ impl RubyBinding {
         Self {
             upcalls: null(),
             finalizer_processor: finalize::FinalizerProcessor::new(),
+            plan_name: Mutex::new(None),
         }
     }
 
@@ -25,4 +30,17 @@ impl RubyBinding {
     pub fn upcalls(&self) -> &'static abi::RubyUpcalls {
         unsafe { &*self.upcalls as &'static abi::RubyUpcalls }
     }
+
+    pub fn get_plan_name_c(&self) -> *const libc::c_char {
+        let mut plan_name = self.plan_name.lock().unwrap();
+        if plan_name.is_none() {
+            let name_string = format!("{:?}", SINGLETON.get_options().plan.value);
+            let c_string = CString::new(name_string).unwrap_or_else(|e| {
+                panic!("Failed converting plan name to CString: {}",
+                    e)
+            });
+            *plan_name = Some(c_string);
+        }
+        plan_name.as_deref().unwrap().as_ptr()
+    }
 }