Tidy up example docs and some names

fix #1450

example/echo-op/echo_op.cpp

@@ -140,8 +140,13 @@ async_echo(
     // The class template `async_op_base` holds the caller's completion
     // handler for us, and provides all of the boilerplate for forwarding
     // the associated allocator and associated executor from the caller's
-    // handler to our operation. We declare this type alias to make the
-    // code easier to read.
+    // handler to our operation. It also maintains a `net::executor_work_guard`
+    // for the executor associated with the stream. This work guard is
+    // inexpensive, and prevents the execution context from running out
+    // of work. It is usually necessary although rarely it can be skipped
+    // depending on the operation (this echo example needs it because it
+    // performs more than one asynchronous operation in a row).
+    // We declare this type alias to make the code easier to read.
 
     using base_type = beast::async_op_base<
         handler_type, /*< The type of the completion handler obtained from the token >*/

include/boost/beast/core/async_op_base.hpp

@@ -188,7 +188,7 @@ class async_op_base
         "Executor requirements not met");
 
     Handler h_;
-    net::executor_work_guard<Executor1> wg_;
+    net::executor_work_guard<Executor1> wg1_;
 
     virtual
     void
@@ -230,7 +230,7 @@ public:
         Handler_&& handler,
         Executor1 const& ex1)
         : h_(std::forward<Handler_>(handler))
-        , wg_(ex1)
+        , wg1_(ex1)
     {
     }
 
@@ -242,7 +242,7 @@ public:
         : boost::empty_value<Allocator>(
             boost::empty_init_t{}, alloc)
         , h_(std::forward<Handler_>(handler))
-        , wg_(ex1)
+        , wg1_(ex1)
     {
     }
 #endif
@@ -291,7 +291,7 @@ public:
     get_executor() const noexcept
     {
         return net::get_associated_executor(
-            h_, wg_.get_executor());
+            h_, wg1_.get_executor());
     }
 
     /// Returns the handler associated with this object
@@ -329,7 +329,7 @@ public:
     invoke(Args&&... args)
     {
         this->before_invoke_hook();
-        wg_.reset();
+        wg1_.reset();
         h_(std::forward<Args>(args)...);
     }
 

include/boost/beast/core/impl/saved_handler.hpp

@@ -65,13 +65,13 @@ class saved_handler::impl final : public base
 
     ebo_pair v_;
     net::executor_work_guard<
-        net::associated_executor_t<Handler>> wg_;
+        net::associated_executor_t<Handler>> wg2_;
 
 public:
     template<class Handler_>
     impl(alloc_type const& a, Handler_&& h)
         : v_(a, std::forward<Handler_>(h))
-        , wg_(net::get_associated_executor(v_.h))
+        , wg2_(net::get_associated_executor(v_.h))
     {
     }