Simplify obmc console buffers

Backpressure on incoming bytes helps both to simplify the layering of
the console, as well as prevent some cases of OOM crashes.

Similar to what we did with nbd_proxy, move obmc console over to the new
sendEx interface, allowing for backpressure, and fixed size std::array
buffers.

Tested:
Made sure single console can see the data.
Made sure two consoles can see the data.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I63d142fc5e8f8a734f3a7b8d0aa3f0d8c263d5ba

1 files changed, 15 insertions, 11 deletions

diff --git a/include/obmc_console.hpp b/include/obmc_console.hpp
index 70253cf825..7eaa15360f 100644
--- a/include/obmc_console.hpp
+++ b/include/obmc_console.hpp
@@ -75,13 +75,21 @@ class ConsoleHandler : public std::enable_shared_from_this<ConsoleHandler>
             });
     }
 
-    void doRead()
+    static void afterSendEx(const std::weak_ptr<ConsoleHandler>& weak)
     {
-        std::size_t bytes = outputBuffer.capacity() - outputBuffer.size();
+        std::shared_ptr<ConsoleHandler> self = weak.lock();
+        if (self == nullptr)
+        {
+            return;
+        }
+        self->doRead();
+    }
 
+    void doRead()
+    {
         BMCWEB_LOG_DEBUG << "Reading from socket";
         hostSocket.async_read_some(
-            outputBuffer.prepare(bytes),
+            boost::asio::buffer(outputBuffer),
             [this, weakSelf(weak_from_this())](
                 const boost::system::error_code& ec, std::size_t bytesRead) {
             BMCWEB_LOG_DEBUG << "read done.  Read " << bytesRead << " bytes";
@@ -97,13 +105,9 @@ class ConsoleHandler : public std::enable_shared_from_this<ConsoleHandler>
                 conn.close("Error connecting to host port");
                 return;
             }
-            outputBuffer.commit(bytesRead);
-            std::string_view payload(
-                static_cast<const char*>(outputBuffer.data().data()),
-                bytesRead);
-            conn.sendBinary(payload);
-            outputBuffer.consume(bytesRead);
-            doRead();
+            std::string_view payload(outputBuffer.data(), bytesRead);
+            self->conn.sendEx(crow::websocket::MessageType::Binary, payload,
+                              std::bind_front(afterSendEx, weak_from_this()));
             });
     }
 
@@ -129,7 +133,7 @@ class ConsoleHandler : public std::enable_shared_from_this<ConsoleHandler>
 
     boost::asio::local::stream_protocol::socket hostSocket;
 
-    boost::beast::flat_static_buffer<4096> outputBuffer;
+    std::array<char, 4096> outputBuffer{};
 
     std::string inputBuffer;
     bool doingWrite = false;