Guide to adding custom stats to nano node with example (#61)

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documentation on how to add custom stats to the nano node with an example

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adding link to custom stats page

* Rename adding_custom_stats.md to adding-custom-stats.md

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docs/getting-started-devs/adding-custom-stats.md

@@ -0,0 +1,96 @@
+---
+title: Custom Internal Stats
+description: Adding Custom Internal Stats
+tags: nano, integration, guide, building, development
+---
+
+# Custom Internal Stats
+The reference Nano node has internal stat counters that are used to monitor a number of aspects of the node such as incoming and outgoing tcp traffic, they can be accessed via the <a href="https://docs.nano.org/commands/rpc-protocol/#stats">stats RPC</a>. While the node is setup to monitor a large number of elements it may be necessary to add your own custom counters for current or future features.
+
+## Adding a Custom Stat
+If we wanted to measure the number of incoming messages from our peers we could setup an internal counter with a custom type as `traffic_count` and then add an additional detail `traffic_incoming` which would be a subset within this custom type. To setup this custom type we need to edit:
+- <a href="https://github.com/nanocurrency/nano-node/blob/develop/nano/lib/stats.cpp">nano/lib/stats.cpp</a>
+  - Add a new case to this <a href="https://github.com/nanocurrency/nano-node/blob/6386ab78e88f1a437f2fed22918d2723c1673ca7/nano/lib/stats.cpp#L466">switch</a> 
+
+```
+    case nano::stat::type::vote_generator:
+            res = "vote_generator";
+            break;
++       case nano::stat::type::traffic_count:
++           res = "traffic_count";
++           break;
+        }
+        return res;
+```
+- <a href="https://github.com/nanocurrency/nano-node/blob/develop/nano/lib/stats.cpp">nano/lib/stats.cpp</a>
+  - Add a new case to this <a href="https://github.com/nanocurrency/nano-node/blob/6386ab78e88f1a437f2fed22918d2723c1673ca7/nano/lib/stats.cpp#L544">switch</a> 
+
+
+```
+    case nano::stat::detail::invalid_network:
+        res = "invalid_network";
+        break;
++   case nano::stat::detail::traffic_incoming:
++       res = "traffic_incoming";
++       break;
+        }
+        return res;
+```
+
+- <a href="https://github.com/nanocurrency/nano-node/blob/develop/nano/lib/stats.hpp">nano/lib/stats.hpp</a>
+  - Add the custom `type` to this <a href="https://github.com/nanocurrency/nano-node/blob/6386ab78e88f1a437f2fed22918d2723c1673ca7/nano/lib/stats.hpp#L220">public class</a>
+````
+                requests,
+                filter,
+                telemetry,
+-               vote_generator
++               vote_generator,
++                traffic_count
+        };
+````
+- <a href="https://github.com/nanocurrency/nano-node/blob/develop/nano/lib/stats.hpp">nano/lib/stats.hpp</a>
+  - Add the custom `detail` to this <a href="https://github.com/nanocurrency/nano-node/blob/6386ab78e88f1a437f2fed22918d2723c1673ca7/nano/lib/stats.hpp#L248">public class</a>
+````
+                generator_replies_discarded,
+-               generator_spacing
++               generator_spacing,
++
++               traffic_incoming
+        };
+````
+- <a href="https://github.com/nanocurrency/nano-node/blob/develop/nano/node/network.cpp">nano/node/network.cpp</a>
+  - Now you can add your custom counter to the point in the node code to start counting. In this example we are putting it in `nano/node/network.cpp` inside the <a href="https://github.com/nanocurrency/nano-node/blob/6386ab78e88f1a437f2fed22918d2723c1673ca7/nano/node/network.cpp#L14">nano::network::network</a> function:
+ ````
+                 if (message.header.network == id)
+                {
+                        process_message (message, channel);
++                       this->node.stats.inc (nano::stat::type::traffic_count, nano::stat::detail::traffic_incoming);
++
+                }
+                else
+                {
+ ````
+
+## Accessing your custom stat
+When testing on the beta network you can get your custom stats using this command:
+
+`curl -d '{ "action" : "stats", "type" : "counters" }' 127.0.0.1:55000`
+
+This will give an output for example:
+```
+            "time": "20:45:33",
+            "type": "traffic_count",
+            "detail": "all",
+            "dir": "in",
+            "value": "5593"
+        },
+        {
+            "time": "20:45:33",
+            "type": "traffic_count",
+            "detail": "traffic_incoming",
+            "dir": "in",
+            "value": "5593"
+        }
+    ],
+    "stat_duration_seconds": "155"
+```

docs/getting-started-devs/documentation.md

@@ -10,3 +10,4 @@ tags: nano, docs, documentation, crypto, protocol, development
 - <a href="https://docs.nano.org/commands/command-line-interface/" target="_blank">Command Line Interface</a>
 - <a href="https://docs.nano.org/glossary/" target="_blank">Glossary</a>
 - [Protocol](/getting-started-devs/protocol-reference)
+- [Adding Custom Stats](/getting-started-devs/adding-custom-stats)