title: async_eb_func v.s. async_tm_func
body: <p>I am reading some thrift service code and found a lot of names like this:</p>
  
  <pre><code>async_eb_function_name(...) or async_tm_function_name(...)
  </code></pre>
  
  <p>What are they? It seems to me the prefix: async_eb_ and  async_tm_ are both auto added. What are they and what's the difference?</p>