Switch to using metric names from EIP-2159. (#1634)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/chain/DefaultMutableBlockchain.java

@@ -69,9 +69,9 @@ public class DefaultMutableBlockchain implements MutableBlockchain {
     chainHeadOmmerCount = chainHeadBody.getOmmers().size();
 
     metricsSystem.createLongGauge(
-        PantheonMetricCategory.BLOCKCHAIN,
-        "height",
-        "Height of the chainhead",
+        PantheonMetricCategory.ETHEREUM,
+        "blockchain_height",
+        "The current height of the canonical chain",
         this::getChainHeadBlockNumber);
     metricsSystem.createLongGauge(
         PantheonMetricCategory.BLOCKCHAIN,

ethereum/eth/src/main/java/tech/pegasys/pantheon/ethereum/eth/sync/DefaultSynchronizer.java

@@ -98,9 +98,9 @@ public class DefaultSynchronizer<C> implements Synchronizer {
             clock);
 
     metricsSystem.createLongGauge(
-        PantheonMetricCategory.SYNCHRONIZER,
-        "best_known_block",
-        "Height of best known block from any connected peer",
+        PantheonMetricCategory.ETHEREUM,
+        "best_known_block_number",
+        "The estimated highest block available",
         () -> syncState.syncStatus().getHighestBlock());
     metricsSystem.createIntegerGauge(
         PantheonMetricCategory.SYNCHRONIZER,

ethereum/p2p/src/main/java/tech/pegasys/pantheon/ethereum/p2p/rlpx/RlpxAgent.java

@@ -96,15 +96,15 @@ public class RlpxAgent {
         metricsSystem.createCounter(
             PantheonMetricCategory.PEERS, "connected_total", "Total number of peers connected");
 
-    metricsSystem.createGauge(
-        PantheonMetricCategory.PEERS,
-        "peer_count_current",
-        "Number of peers currently connected",
-        () -> (double) getConnectionCount());
     metricsSystem.createIntegerGauge(
-        PantheonMetricCategory.NETWORK,
-        "peers_limit",
-        "Maximum P2P peer connections that can be established",
+        PantheonMetricCategory.ETHEREUM,
+        "peer_count",
+        "The current number of peers connected",
+        this::getConnectionCount);
+    metricsSystem.createIntegerGauge(
+        PantheonMetricCategory.ETHEREUM,
+        "peer_limit",
+        "The maximum number of peers this node allows to connect",
         () -> maxPeers);
   }
 

metrics/core/src/main/java/tech/pegasys/pantheon/metrics/PantheonMetricCategory.java

@@ -20,6 +20,7 @@ import com.google.common.collect.ImmutableSet;
 
 public enum PantheonMetricCategory implements MetricCategory {
   BLOCKCHAIN("blockchain"),
+  ETHEREUM("ethereum", false),
   EXECUTORS("executors"),
   NETWORK("network"),
   PEERS("peers"),