From 9663c52f50dcf064ef790e5b5de54619ad7ce394 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20M=C3=A4kel=C3=A4?= <markus.makela@mariadb.com>
Date: Mon, 20 Aug 2018 13:04:49 +0300
Subject: [PATCH] MXS-2015: Remove buffer iterator

The iterator to the buffer isn't really needed as the beginning of the
buffer can be used instead. This should make the code more robust. Changed
the internal buffer from a vector to a deque as the latter is more
appropriate for insertion on one end and consumption on the other.
---
 connectors/cdc-connector/cdc_connector.cpp | 34 +++++++++-------------
 connectors/cdc-connector/cdc_connector.h   |  4 +--
 2 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/connectors/cdc-connector/cdc_connector.cpp b/connectors/cdc-connector/cdc_connector.cpp
index aa014b56e..00eb808dc 100644
--- a/connectors/cdc-connector/cdc_connector.cpp
+++ b/connectors/cdc-connector/cdc_connector.cpp
@@ -186,7 +186,6 @@ Connection::Connection(const std::string& address,
     m_timeout(timeout),
     m_connected(false)
 {
-    m_buf_ptr = m_buffer.begin();
 }
 
 Connection::~Connection()
@@ -283,8 +282,9 @@ bool Connection::connect(const std::string& table, const std::string& gtid)
                 }
                 else
                 {
-                    m_error += ". Data received so far: ";
+                    m_error += ". Data received so far: '";
                     std::copy(m_buffer.begin(), m_buffer.end(), std::back_inserter(m_error));
+                    m_error += "'";
                 }
             }
         }
@@ -545,11 +545,13 @@ bool Connection::read_row(std::string& dest)
     {
         if (!m_buffer.empty())
         {
-            std::vector<char>::iterator it = std::find(m_buf_ptr, m_buffer.end(), '\n');
+            std::deque<char>::iterator it = std::find(m_buffer.begin(), m_buffer.end(), '\n');
+
             if (it != m_buffer.end())
             {
-                dest.assign(m_buf_ptr, it);
-                m_buf_ptr = it + 1;
+                dest.assign(m_buffer.begin(), it);
+                m_buffer.erase(m_buffer.begin(), std::next(it));
+                assert(m_buffer.empty() || m_buffer[0] != '\n');
                 break;
             }
         }
@@ -572,22 +574,14 @@ bool Connection::read_row(std::string& dest)
             break;
         }
 
-        if (!m_connected)
-        {
-            // This is here to work around a missing newline in MaxScale error messages
-            buf[rc] = '\0';
-
-            if (is_error(buf))
-            {
-                rval = false;
-                break;
-            }
-        }
-
-        m_buffer.erase(m_buffer.begin(), m_buf_ptr);
         assert(std::find(m_buffer.begin(), m_buffer.end(), '\n') == m_buffer.end());
-        m_buffer.insert(m_buffer.end(), buf, buf + rc);
-        m_buf_ptr = m_buffer.begin();
+        std::copy(buf, buf + rc, std::back_inserter(m_buffer));
+
+        if (is_error(&m_buffer[0]))
+        {
+            rval = false;
+            break;
+        }
     }
 
     if (is_error(dest.c_str()))
diff --git a/connectors/cdc-connector/cdc_connector.h b/connectors/cdc-connector/cdc_connector.h
index fa01ac28b..e91c371f1 100644
--- a/connectors/cdc-connector/cdc_connector.h
+++ b/connectors/cdc-connector/cdc_connector.h
@@ -21,6 +21,7 @@
 #include <string>
 #include <tr1/memory>
 #include <vector>
+#include <deque>
 #include <map>
 #include <algorithm>
 #include <jansson.h>
@@ -137,8 +138,7 @@ private:
     SValueVector m_keys;
     SValueVector m_types;
     int m_timeout;
-    std::vector<char> m_buffer;
-    std::vector<char>::iterator m_buf_ptr;
+    std::deque<char> m_buffer;
     SRow m_first_row;
     bool m_connected;