additional statistics for alarm callbacks and alert counts

 - uses mongodb aggregation for group by, should be available starting with mongodb v2.2 but we need to verify

 requires alarm-stats branch of graylog2-server

Author: kroepke

src/main/java/org/graylog/plugins/usagestatistics/collectors/ClusterCollector.java

@@ -19,6 +19,7 @@
 import com.google.common.collect.ImmutableMap;
 import org.cliffc.high_scale_lib.Counter;
 import org.graylog.plugins.usagestatistics.UsageStatsMetaData;
+import org.graylog.plugins.usagestatistics.dto.AlarmStats;
 import org.graylog.plugins.usagestatistics.dto.ClusterDataSet;
 import org.graylog.plugins.usagestatistics.dto.ClusterStats;
 import org.graylog.plugins.usagestatistics.dto.LdapStats;
@@ -99,7 +100,8 @@ private ClusterStats buildClusterStats() {
                 clusterStats.contentPackCount(),
                 counts.total(),
                 buildStreamThroughput(),
-                buildLdapStats()
+                buildLdapStats(),
+                buildAlarmStats()
         );
     }
 
@@ -126,4 +128,9 @@ private LdapStats buildLdapStats() {
                                 ldapStats.roleMappingCount(),
                                 ldapStats.roleCount());
     }
+
+    private AlarmStats buildAlarmStats() {
+        final org.graylog2.system.stats.AlarmStats stats = clusterStatsService.alarmStats();
+        return AlarmStats.create(stats.alertCount(), stats.alarmcallbackCountByType());
+    }
 }

src/main/java/org/graylog/plugins/usagestatistics/dto/AlarmStats.java

@@ -0,0 +1,21 @@
+package org.graylog.plugins.usagestatistics.dto;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.auto.value.AutoValue;
+
+import java.util.Map;
+
+@JsonAutoDetect
+@AutoValue
+public abstract class AlarmStats {
+    @JsonProperty
+    public abstract long alertCount();
+
+    @JsonProperty
+    public abstract Map<String, Long> alarmcallbackCountByType();
+
+    public static AlarmStats create(long alertCount, Map<String, Long> alarmcallbackCountByType) {
+        return new AutoValue_AlarmStats(alertCount, alarmcallbackCountByType);
+    }
+}

src/main/java/org/graylog/plugins/usagestatistics/dto/ClusterStats.java

@@ -46,7 +46,8 @@ public static ClusterStats create(ElasticsearchClusterStats elasticsearchCluster
                                       long contentPackCount,
                                       long totalMessages,
                                       Map<String, Long> streamThroughput,
-                                      LdapStats ldapStats
+                                      LdapStats ldapStats,
+                                      AlarmStats alarmStats
     ) {
         return new AutoValue_ClusterStats(
                 elasticsearchCluster,
@@ -68,7 +69,8 @@ public static ClusterStats create(ElasticsearchClusterStats elasticsearchCluster
                 contentPackCount,
                 totalMessages,
                 streamThroughput,
-                ldapStats);
+                ldapStats,
+                alarmStats);
     }
 
     @JsonProperty
@@ -130,4 +132,7 @@ public static ClusterStats create(ElasticsearchClusterStats elasticsearchCluster
 
     @JsonProperty
     public abstract LdapStats ldapStats();
+
+    @JsonProperty
+    public abstract AlarmStats alarmStats();
 }