Add a connection pool metric for connections in establishment. (#436)

ExpediaGroup · Jun 18, 2019 · f08f39b · f08f39b
1 parent 84ab718
commit f08f39b
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Showing 7 changed files with 40 additions and 19 deletions.
diff --git a/components/client/src/main/java/com/hotels/styx/client/Connection.java b/components/client/src/main/java/com/hotels/styx/client/Connection.java
@@ -23,7 +23,6 @@
 
 import java.io.Closeable;
 import java.util.EventListener;
-import java.util.concurrent.CompletableFuture;
 
 /**
  * A connection to an origin.

diff --git a/components/client/src/main/java/com/hotels/styx/client/connectionpool/ConnectionPool.java b/components/client/src/main/java/com/hotels/styx/client/connectionpool/ConnectionPool.java
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2013-2018 Expedia Inc.
+  Copyright (C) 2013-2019 Expedia Inc.
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
@@ -85,6 +85,13 @@ interface Stats {
          * @return
          */
         int terminatedConnections();
+
+        /**
+         * Number of connections being established at the moment.
+         *
+         * @return
+         */
+        int connectionsInEstablishment();
     }
 
     /**

diff --git a/...ents/client/src/main/java/com/hotels/styx/client/connectionpool/SimpleConnectionPool.java b/...ents/client/src/main/java/com/hotels/styx/client/connectionpool/SimpleConnectionPool.java
@@ -40,6 +40,7 @@
  */
 public class SimpleConnectionPool implements ConnectionPool, Connection.Listener {
     private static final Logger LOG = getLogger(SimpleConnectionPool.class);
+    private static final int MAX_ATTEMPTS = 3;
 
     private final ConnectionPoolSettings poolSettings;
     private final ConnectionSettings connectionSettings;
@@ -104,7 +105,7 @@ public Publisher<Connection> borrowConnection() {
 
     private void newConnection() {
         connectionAttempts.incrementAndGet();
-        newConnection(3)
+        newConnection(MAX_ATTEMPTS)
                 .doOnNext(it -> it.addConnectionListener(SimpleConnectionPool.this))
                 .subscribe(
                         connection -> {
@@ -224,6 +225,11 @@ public int terminatedConnections() {
             return terminatedConnections.get();
         }
 
+        @Override
+        public int connectionsInEstablishment() {
+            return connectionsInEstablishment.get();
+        }
+
         @Override
         public String toString() {
             return MoreObjects.toStringHelper(this)

diff --git a/...ent/src/main/java/com/hotels/styx/client/connectionpool/StatsReportingConnectionPool.java b/...ent/src/main/java/com/hotels/styx/client/connectionpool/StatsReportingConnectionPool.java
@@ -81,11 +81,16 @@ public void close() {
         removeMetrics();
     }
 
-    private void removeMetrics() {
-        MetricRegistry scopedRegistry = getMetricScope(connectionPool);
-        asList("busy-connections", "pending-connections", "available-connections", "ttfb",
-                "connection-attempts", "connection-failures", "connections-closed", "connections-terminated")
-                .forEach(scopedRegistry::deregister);
+    private static void registerMetrics(ConnectionPool hostConnectionPool, MetricRegistry scopedRegistry) {
+        ConnectionPool.Stats stats = hostConnectionPool.stats();
+        scopedRegistry.register("busy-connections", (Gauge<Integer>) stats::busyConnectionCount);
+        scopedRegistry.register("pending-connections", (Gauge<Integer>) stats::pendingConnectionCount);
+        scopedRegistry.register("available-connections", (Gauge<Integer>) stats::availableConnectionCount);
+        scopedRegistry.register("connection-attempts", (Gauge<Integer>) () -> (int) stats.connectionAttempts());
+        scopedRegistry.register("connection-failures", (Gauge<Integer>) () -> (int) stats.connectionFailures());
+        scopedRegistry.register("connections-closed", (Gauge<Integer>) () -> (int) stats.closedConnections());
+        scopedRegistry.register("connections-terminated", (Gauge<Integer>) () -> (int) stats.terminatedConnections());
+        scopedRegistry.register("in-establishment", (Gauge<Integer>) () -> (int) stats.connectionsInEstablishment());
     }
 
     private void registerMetrics() {
@@ -98,15 +103,12 @@ private void registerMetrics() {
         }
     }
 
-    private static void registerMetrics(ConnectionPool hostConnectionPool, MetricRegistry scopedRegistry) {
-        ConnectionPool.Stats stats = hostConnectionPool.stats();
-        scopedRegistry.register("busy-connections", (Gauge<Integer>) stats::busyConnectionCount);
-        scopedRegistry.register("pending-connections", (Gauge<Integer>) stats::pendingConnectionCount);
-        scopedRegistry.register("available-connections", (Gauge<Integer>) stats::availableConnectionCount);
-        scopedRegistry.register("connection-attempts", (Gauge<Integer>) () -> (int) stats.connectionAttempts());
-        scopedRegistry.register("connection-failures", (Gauge<Integer>) () -> (int) stats.connectionFailures());
-        scopedRegistry.register("connections-closed", (Gauge<Integer>) () -> (int) stats.closedConnections());
-        scopedRegistry.register("connections-terminated", (Gauge<Integer>) () -> (int) stats.terminatedConnections());
+    private void removeMetrics() {
+        MetricRegistry scopedRegistry = getMetricScope(connectionPool);
+        asList("busy-connections", "pending-connections", "available-connections", "ttfb",
+                "connection-attempts", "connection-failures", "connections-closed", "connections-terminated",
+                "in-establishment")
+                .forEach(scopedRegistry::deregister);
     }
 
     private MetricRegistry getMetricScope(ConnectionPool hostConnectionPool) {

diff --git a/...test/unit/java/com/hotels/styx/client/connectionpool/SimpleConnectionPoolFactoryTest.java b/...test/unit/java/com/hotels/styx/client/connectionpool/SimpleConnectionPoolFactoryTest.java
@@ -48,7 +48,8 @@ public void registersMetricsUnderOriginsScope() {
         assertThat(metricRegistry.getGauges().keySet(), hasItems(
                 "origins.test-app.origin-X.connectionspool.pending-connections",
                 "origins.test-app.origin-X.connectionspool.available-connections",
-                "origins.test-app.origin-X.connectionspool.busy-connections"
+                "origins.test-app.origin-X.connectionspool.busy-connections",
+                "origins.test-app.origin-X.connectionspool.in-establishment"
         ));
     }
 }
diff --git a/...est/unit/java/com/hotels/styx/client/connectionpool/StatsReportingConnectionPoolTest.java b/...est/unit/java/com/hotels/styx/client/connectionpool/StatsReportingConnectionPoolTest.java
@@ -45,6 +45,7 @@ public void removesRegisteredMetricsOnClose() {
                 "origins.generic-app.backend-01.connectionspool.busy-connections",
                 "origins.generic-app.backend-01.connectionspool.pending-connections",
                 "origins.generic-app.backend-01.connectionspool.connection-attempts",
+                "origins.generic-app.backend-01.connectionspool.in-establishment",
                 "origins.generic-app.backend-01.connectionspool.connection-failures",
                 "origins.generic-app.backend-01.connectionspool.connections-closed",
                 "origins.generic-app.backend-01.connectionspool.connections-terminated"

diff --git a/...nt/src/test/unit/java/com/hotels/styx/client/netty/connectionpool/StubConnectionPool.java b/...nt/src/test/unit/java/com/hotels/styx/client/netty/connectionpool/StubConnectionPool.java
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2013-2018 Expedia Inc.
+  Copyright (C) 2013-2019 Expedia Inc.
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
@@ -115,6 +115,11 @@ public int closedConnections() {
             public int terminatedConnections() {
                 return 0;
             }
+
+            @Override
+            public int connectionsInEstablishment() {
+                return 0;
+            }
         };
     }