fix: remove unsafe code in auto/manual heap dump (#12596)

Author: Eric Fu

src/compute/src/memory_management/policy.rs

@@ -122,9 +122,9 @@ impl JemallocMemoryControl {
                 .unwrap()
                 .to_string();
 
+            // `file_path_str` is leaked because `jemalloc_dump_mib.write` requires static lifetime
             let file_path_str = Box::leak(file_path.into_boxed_str());
-            let file_path_bytes = unsafe { file_path_str.as_bytes_mut() };
-            let file_path_ptr = file_path_bytes.as_mut_ptr();
+            let file_path_bytes = file_path_str.as_bytes();
             if let Err(e) = self
                 .jemalloc_dump_mib
                 .write(CStr::from_bytes_with_nul(file_path_bytes).unwrap())
@@ -133,7 +133,6 @@ impl JemallocMemoryControl {
             } else {
                 tracing::info!("Successfully dumped heap profile to {}", file_name);
             }
-            let _ = unsafe { Box::from_raw(file_path_ptr) };
         }
     }
 }

src/compute/src/rpc/service/monitor_service.rs

@@ -154,9 +154,9 @@ impl MonitorService for MonitorServiceImpl {
             .to_str()
             .ok_or_else(|| Status::internal("The file dir is not a UTF-8 String"))?;
 
+        // `file_path_str` is leaked because `prof::dump::write` requires static lifetime
         let file_path_str = Box::leak(file_path.to_string().into_boxed_str());
-        let file_path_bytes = unsafe { file_path_str.as_bytes_mut() };
-        let file_path_ptr = file_path_bytes.as_mut_ptr();
+        let file_path_bytes = file_path_str.as_bytes();
         let response = if let Err(e) = tikv_jemalloc_ctl::prof::dump::write(
             CStr::from_bytes_with_nul(file_path_bytes).unwrap(),
         ) {
@@ -165,7 +165,6 @@ impl MonitorService for MonitorServiceImpl {
         } else {
             Ok(Response::new(HeapProfilingResponse {}))
         };
-        let _ = unsafe { Box::from_raw(file_path_ptr) };
         response
     }