embed_wamr_spawn_api.md

Thread related embedder API

This document explains wasm_runtime_spawn_exec_env and wasm_runtime_spawn_thread. Here is a sample to show how to use these APIs.

• spawn exec_env

  spawn exec_env API creates a new exec_env based on the original exec_env. You can use it in other threads. It's up to the embedder how to manage host threads to run the new exec_env.

  new_exec_env = wasm_runtime_spawn_exec_env(exec_env);
  
    /* Then you can use new_exec_env in your new thread */
    module_inst = wasm_runtime_get_module_inst(new_exec_env);
    func_inst = wasm_runtime_lookup_function(module_inst, ...);
    wasm_runtime_call_wasm(new_exec_env, func_inst, ...);
  
  /* you need to use this API to manually destroy the spawned exec_env */
  wasm_runtime_destroy_spawned_exec_env(new_exec_env);

• spawn thread

  Alternatively, you can use spawn thread API to avoid managing the extra exec_env and the corresponding host thread manually:

  wasm_thread_t wasm_tid;
  void *wamr_thread_cb(wasm_exec_env_t exec_env, void *arg)
  {
    module_inst = wasm_runtime_get_module_inst(exec_env);
    func_inst = wasm_runtime_lookup_function(module_inst, ...);
    wasm_runtime_call_wasm(exec_env, func_inst, ...);
  }
  wasm_runtime_spawn_thread(exec_env, &wasm_tid, wamr_thread_cb, NULL);
  /* Use wasm_runtime_join_thread to join the spawned thread */
  wasm_runtime_join_thread(wasm_tid, NULL);