wasmtime_benchmark fix

Cargo.toml

@@ -17,6 +17,10 @@ members = [
 # In current implementation, as_std has conflict features (e.g. `panic_def` and 
 # `unwinding`). Of course, if add "user/" to members, will also have problem of 
 # feature gate. 
+#
+# When building projects and user applications, if there are invalid soft links, 
+# you need to manually clean up the user crate cache.
+
 exclude = ["user/", "common_service/", "baseline/"]
 default-members = ["bins/asvisor"]
 resolver = "2"

as_std/src/agent.rs

@@ -69,9 +69,16 @@ mod refer_based_impl {
                 }
             } else {
                 let fingerprint = T::__fingerprint();
-
-                libos!(buffer_alloc(&slot, l, fingerprint)).expect("alloc failed.") as *mut T
-
+                let ptr = libos!(buffer_alloc(&slot, l, fingerprint));
+                let ptr = ptr.expect("alloc failed.") as *mut T;
+                if ptr.is_null() {
+                    panic!("buffer_alloc returned null pointer!");
+                }
+                // key：Initialize memory immediately after allocation
+                unsafe {
+                    core::ptr::write(ptr, T::default());
+                }
+                ptr
                 // let val = T::default();
                 // println!("will write addr=0x{:x}", addr as usize);
                 // unsafe { core::ptr::write(addr, val) };

doc/testing_a_workflow.md

@@ -72,10 +72,32 @@ reducer3 has counted 362 words
 ```
 
 ### Testing Other Workflows
+```
 The same 3-step process applies to any workflow:
 
 1.Build services: `just all_libos`
 
 2.Build functions: `just rust_func <function_name>`
 
-3.Execute workflow: `target/release/asvisor --files isol_config/<workflow_name>.json`
+3.Execute workflow: `target/release/asvisor --files isol_config/<workflow_name>.json`
+```
+
+### Custom parameters recompile for Wasmtime module
+```
+Pre-install wasmtime-cli 22.0.0 、WASI-sdk
+
+Modify the build.sh script in the user corresponding function directory.
+
+User manually sets environment variables
+export CC="/opt/wasi-sdk/bin/clang"
+export CPP="/opt/wasi-sdk/bin/clang++"
+
+wasmtime_wordcount：
+just cwasm_compile_wordcount *args:
+
+wasmtime_parallel_sort：
+just cwasm_compile_parallel_sort *args:
+
+Run before testing or compile other modules:
+unset CC && export CC=/usr/bin/clang && echo "CC is now: $CC" 
+```