Working with anyref

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This example demonstrates using anyref values.

Wasm Source

(module
  (table $table (export "table") 10 anyref)

  (global $global (export "global") (mut anyref) (ref.null any))

  (func (export "take_anyref") (param anyref)
    nop
  )

  (func (export "return_anyref") (result anyref)
    i32.const 42
    ref.i31
  )
)

Host Source

//! Small example of how to use `anyref`s.

// You can execute this example with `cargo run --example anyref`

use wasmtime::*;

fn main() -> Result<()> {
    println!("Initializing...");
    let mut config = Config::new();
    config.wasm_reference_types(true);
    config.wasm_function_references(true);
    config.wasm_gc(true);
    let engine = Engine::new(&config)?;
    let mut store = Store::new(&engine, ());

    println!("Compiling module...");
    let module = Module::from_file(&engine, "examples/anyref.wat")?;

    println!("Instantiating module...");
    let instance = Instance::new(&mut store, &module, &[])?;

    println!("Creating new `anyref` from i31...");
    let i31 = I31::wrapping_u32(1234);
    let anyref = AnyRef::from_i31(&mut store, i31);
    assert!(anyref.is_i31(&store)?);
    assert_eq!(anyref.as_i31(&store)?, Some(i31));

    println!("Touching `anyref` table...");
    let table = instance.get_table(&mut store, "table").unwrap();
    table.set(&mut store, 3, anyref.into())?;
    let elem = table
        .get(&mut store, 3)
        .unwrap() // assert in bounds
        .unwrap_any() // assert it's an anyref table
        .copied()
        .unwrap(); // assert the anyref isn't null
    assert!(Rooted::ref_eq(&store, &elem, &anyref)?);

    println!("Touching `anyref` global...");
    let global = instance.get_global(&mut store, "global").unwrap();
    global.set(&mut store, Some(anyref).into())?;
    let global_val = global.get(&mut store).unwrap_anyref().copied().unwrap();
    assert!(Rooted::ref_eq(&store, &global_val, &anyref)?);

    println!("Passing `anyref` into func...");
    let func = instance.get_typed_func::<Option<Rooted<AnyRef>>, ()>(&mut store, "take_anyref")?;
    func.call(&mut store, Some(anyref))?;

    println!("Getting `anyref` from func...");
    let func =
        instance.get_typed_func::<(), Option<Rooted<AnyRef>>>(&mut store, "return_anyref")?;
    let ret = func.call(&mut store, ())?;
    assert!(ret.is_some());
    assert_eq!(ret.unwrap().unwrap_i31(&store)?, I31::wrapping_u32(42));

    println!("GCing within the store...");
    store.gc(None);

    println!("Done.");
    Ok(())
}
/*
Example of using `anyref` values.

You can build using cmake:

mkdir build && cd build && cmake .. && \
  cmake --build . --target wasmtime-anyref
*/

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wasm.h>
#include <wasmtime.h>

static void exit_with_error(const char *message, wasmtime_error_t *error,
                            wasm_trap_t *trap);

int main() {
  bool ok = true;
  // Create a new configuration with Wasm GC enabled.
  printf("Initializing...\n");
  wasm_config_t *config = wasm_config_new();
  assert(config != NULL);
  wasmtime_config_wasm_reference_types_set(config, true);
  wasmtime_config_wasm_function_references_set(config, true);
  wasmtime_config_wasm_gc_set(config, true);

  // Create an *engine*, which is a compilation context, with our configured
  // options.
  wasm_engine_t *engine = wasm_engine_new_with_config(config);
  assert(engine != NULL);

  // With an engine we can create a *store* which is a group of wasm instances
  // that can interact with each other.
  wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL);
  assert(store != NULL);
  wasmtime_context_t *context = wasmtime_store_context(store);

  // Read our input file, which in this case is a wasm text file.
  FILE *file = fopen("examples/anyref.wat", "r");
  assert(file != NULL);
  fseek(file, 0L, SEEK_END);
  size_t file_size = ftell(file);
  fseek(file, 0L, SEEK_SET);
  wasm_byte_vec_t wat;
  wasm_byte_vec_new_uninitialized(&wat, file_size);
  if (fread(wat.data, file_size, 1, file) != 1) {
    printf("> Error loading module!\n");
    return 1;
  }
  fclose(file);

  // Parse the wat into the binary wasm format
  wasm_byte_vec_t wasm;
  wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &wasm);
  if (error != NULL)
    exit_with_error("failed to parse wat", error, NULL);
  wasm_byte_vec_delete(&wat);

  // Now that we've got our binary webassembly we can compile our module.
  printf("Compiling module...\n");
  wasmtime_module_t *module = NULL;
  error = wasmtime_module_new(engine, (uint8_t *)wasm.data, wasm.size, &module);
  wasm_byte_vec_delete(&wasm);
  if (error != NULL)
    exit_with_error("failed to compile module", error, NULL);

  // Instantiate the module.
  printf("Instantiating module...\n");
  wasm_trap_t *trap = NULL;
  wasmtime_instance_t instance;
  error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap);
  if (error != NULL || trap != NULL)
    exit_with_error("failed to instantiate", error, trap);

  printf("Creating new `anyref` from i31...\n");

  // Create a new `anyref` value from an i31 (`i31ref` is a subtype of
  // `anyref`).
  wasmtime_anyref_t anyref;
  wasmtime_anyref_from_i31(context, 1234, &anyref);
  assert(!wasmtime_anyref_is_null(&anyref));

  // The `anyref`'s inner i31 value should be 1234.
  uint32_t i31val = 0;
  bool is_i31 = wasmtime_anyref_i31_get_u(context, &anyref, &i31val);
  assert(is_i31);
  assert(i31val == 1234);

  printf("Touching `anyref` table...\n");

  wasmtime_extern_t item;

  // Lookup the `table` export.
  ok = wasmtime_instance_export_get(context, &instance, "table",
                                    strlen("table"), &item);
  assert(ok);
  assert(item.kind == WASMTIME_EXTERN_TABLE);

  // Set `table[3]` to our `anyref`.
  wasmtime_val_t anyref_val;
  anyref_val.kind = WASMTIME_ANYREF;
  anyref_val.of.anyref = anyref;
  error = wasmtime_table_set(context, &item.of.table, 3, &anyref_val);
  if (error != NULL)
    exit_with_error("failed to set table", error, NULL);

  // `table[3]` should now be our `anyref`.
  wasmtime_val_t elem;
  ok = wasmtime_table_get(context, &item.of.table, 3, &elem);
  assert(ok);
  assert(elem.kind == WASMTIME_ANYREF);
  is_i31 = false;
  i31val = 0;
  is_i31 = wasmtime_anyref_i31_get_u(context, &elem.of.anyref, &i31val);
  assert(is_i31);
  assert(i31val == 1234);
  wasmtime_val_unroot(context, &elem);

  printf("Touching `anyref` global...\n");

  // Lookup the `global` export.
  ok = wasmtime_instance_export_get(context, &instance, "global",
                                    strlen("global"), &item);
  assert(ok);
  assert(item.kind == WASMTIME_EXTERN_GLOBAL);

  // Set the global to our `anyref`.
  error = wasmtime_global_set(context, &item.of.global, &anyref_val);
  if (error != NULL)
    exit_with_error("failed to set global", error, NULL);

  // Get the global, and it should return our `anyref` again.
  wasmtime_val_t global_val;
  wasmtime_global_get(context, &item.of.global, &global_val);
  assert(global_val.kind == WASMTIME_ANYREF);
  is_i31 = false;
  i31val = 0;
  is_i31 = wasmtime_anyref_i31_get_u(context, &global_val.of.anyref, &i31val);
  assert(is_i31);
  assert(i31val == 1234);
  wasmtime_val_unroot(context, &global_val);

  printf("Passing `anyref` into func...\n");

  // Lookup the `take_anyref` export.
  ok = wasmtime_instance_export_get(context, &instance, "take_anyref",
                                    strlen("take_anyref"), &item);
  assert(ok);
  assert(item.kind == WASMTIME_EXTERN_FUNC);

  // And call it!
  error = wasmtime_func_call(context, &item.of.func, &anyref_val, 1, NULL, 0,
                             &trap);
  if (error != NULL || trap != NULL)
    exit_with_error("failed to call function", error, trap);

  printf("Getting `anyref` from func...\n");

  // Lookup the `return_anyref` export.
  ok = wasmtime_instance_export_get(context, &instance, "return_anyref",
                                    strlen("return_anyref"), &item);
  assert(ok);
  assert(item.kind == WASMTIME_EXTERN_FUNC);

  // And call it!
  wasmtime_val_t results[1];
  error =
      wasmtime_func_call(context, &item.of.func, NULL, 0, results, 1, &trap);
  if (error != NULL || trap != NULL)
    exit_with_error("failed to call function", error, trap);

  // `return_anyfunc` returns an `i31ref` that wraps `42`.
  assert(results[0].kind == WASMTIME_ANYREF);
  is_i31 = false;
  i31val = 0;
  is_i31 = wasmtime_anyref_i31_get_u(context, &results[0].of.anyref, &i31val);
  assert(is_i31);
  assert(i31val == 42);
  wasmtime_val_unroot(context, &results[0]);
  wasmtime_val_unroot(context, &anyref_val);

  // We can GC any now-unused references to our anyref that the store is
  // holding.
  printf("GCing within the store...\n");
  wasmtime_context_gc(context);

  // Clean up after ourselves at this point
  printf("All finished!\n");

  wasmtime_store_delete(store);
  wasmtime_module_delete(module);
  wasm_engine_delete(engine);
  return 0;
}

static void exit_with_error(const char *message, wasmtime_error_t *error,
                            wasm_trap_t *trap) {
  fprintf(stderr, "error: %s\n", message);
  wasm_byte_vec_t error_message;
  if (error != NULL) {
    wasmtime_error_message(error, &error_message);
    wasmtime_error_delete(error);
  } else {
    wasm_trap_message(trap, &error_message);
    wasm_trap_delete(trap);
  }
  fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data);
  wasm_byte_vec_delete(&error_message);
  exit(1);
}

/*
Example of using `anyref` values.

You can build the example using CMake:

mkdir build && (cd build && cmake .. && \
  cmake --build . --target wasmtime-anyref-cpp)

And then run it:

build/wasmtime-anyref-cpp
*/

#include <fstream>
#include <iostream>
#include <sstream>
#include <wasmtime.hh>

using namespace wasmtime;

std::string readFile(const char *name) {
  std::ifstream watFile;
  watFile.open(name);
  std::stringstream strStream;
  strStream << watFile.rdbuf();
  return strStream.str();
}

int main() {
  std::cout << "Initializing...\n";
  Config config;
  config.wasm_reference_types(true);
  config.wasm_function_references(true);
  config.wasm_gc(true);
  Engine engine(std::move(config));
  Store store(engine);

  std::cout << "Compiling module...\n";
  auto wat = readFile("examples/anyref.wat");
  Module module = Module::compile(engine, wat).unwrap();

  std::cout << "Instantiating module...\n";
  Instance instance = Instance::create(store, module, {}).unwrap();

  std::cout << "Creating new `anyref` from i31...\n";
  // Create an i31ref wrapping 1234
  auto cx = store.context();
  AnyRef i31 = AnyRef::i31(cx, 1234);
  Val anyref_val(i31);
  auto opt_any = anyref_val.anyref(cx);
  if (!opt_any || !opt_any->u31(cx) || *opt_any->u31(cx) != 1234) {
    std::cerr << "> Error creating i31 anyref\n";
    return 1;
  }

  std::cout << "Touching `anyref` table...\n";
  Table table = std::get<Table>(*instance.get(store, "table"));
  table.set(store, 3, anyref_val).unwrap();
  auto elem_opt = table.get(store, 3);
  if (!elem_opt) {
    std::cerr << "> Error getting table element\n";
    return 1;
  }
  auto elem_any = elem_opt->anyref(cx);
  if (!elem_any || !elem_any->u31(cx) || *elem_any->u31(cx) != 1234) {
    std::cerr << "> Error verifying table element\n";
    return 1;
  }

  std::cout << "Touching `anyref` global...\n";
  Global global = std::get<Global>(*instance.get(store, "global"));
  global.set(store, anyref_val).unwrap();
  Val global_val = global.get(store);
  auto global_any = global_val.anyref(cx);
  if (!global_any || !global_any->u31(cx) || *global_any->u31(cx) != 1234) {
    std::cerr << "> Error verifying global value\n";
    return 1;
  }

  std::cout << "Passing `anyref` into func...\n";
  Func take_anyref = std::get<Func>(*instance.get(store, "take_anyref"));
  take_anyref.call(store, {anyref_val}).unwrap();

  std::cout << "Getting `anyref` from func...\n";
  Func return_anyref = std::get<Func>(*instance.get(store, "return_anyref"));
  auto results = return_anyref.call(store, {}).unwrap();
  if (results.size() != 1) {
    std::cerr << "> Unexpected number of results\n";
    return 1;
  }
  auto ret_any = results[0].anyref(cx);
  if (!ret_any || !ret_any->u31(cx) || *ret_any->u31(cx) != 42) {
    std::cerr << "> Error verifying returned anyref\n";
    return 1;
  }

  std::cout << "GCing within the store...\n";
  store.context().gc();

  std::cout << "Done.\n";
  return 0;
}