Preallocating new lists, fixing off by one.

Graylog2 · May 6, 2015 · af150bd · af150bd
1 parent 5f38f91
commit af150bd
Show file tree

Hide file tree

Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/graylog2-server/src/main/java/org/graylog2/alarmcallbacks/EmailAlarmCallback.java b/graylog2-server/src/main/java/org/graylog2/alarmcallbacks/EmailAlarmCallback.java
@@ -97,9 +97,10 @@ public void call(Stream stream, AlertCondition.CheckResult result) {
 
     protected List<Message> getAlarmBacklog(AlertCondition.CheckResult result) {
         final AlertCondition alertCondition = result.getTriggeredCondition();
+        final int effectiveBacklogSize = Math.min(alertCondition.getBacklog(), result.getMatchingMessages().size());
         final List<MessageSummary> backlogSummaries = result.getMatchingMessages()
-                .subList(0, Math.min(alertCondition.getBacklog(), result.getMatchingMessages().size()));
-        final List<Message> backlog = Lists.newArrayList();
+                .subList(0, effectiveBacklogSize-1);
+        final List<Message> backlog = Lists.newArrayListWithCapacity(effectiveBacklogSize);
 
         for (MessageSummary messageSummary : backlogSummaries) {
             backlog.add(messageSummary.getRawMessage());

diff --git a/graylog2-server/src/main/java/org/graylog2/alerts/types/FieldValueAlertCondition.java b/graylog2-server/src/main/java/org/graylog2/alerts/types/FieldValueAlertCondition.java
@@ -36,6 +36,7 @@
 
 import javax.annotation.Nullable;
 import java.text.DecimalFormat;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
@@ -140,17 +141,21 @@ protected CheckResult runCheck() {
             }
 
             if (triggered) {
-                final List<MessageSummary> summaries = Lists.newArrayList();
                 final String resultDescription = "Field " + field + " had a " + type + " of "
                         + decimalFormat.format(result) + " in the last " + time + " minutes with trigger condition "
                         + thresholdType + " than " + decimalFormat.format(threshold) + ". "
                         + "(Current grace time: " + grace + " minutes)";
 
+                final List<MessageSummary> summaries;
                 if (getBacklog() > 0) {
-                    for (ResultMessage resultMessage : fieldStatsResult.getSearchHits()) {
+                    final List<ResultMessage> searchHits = fieldStatsResult.getSearchHits();
+                    summaries = Lists.newArrayListWithCapacity(searchHits.size());
+                    for (ResultMessage resultMessage : searchHits) {
                         final Message msg = new Message(resultMessage.getMessage());
                         summaries.add(new MessageSummary(resultMessage.getIndex(), msg));
                     }
+                } else {
+                    summaries = Collections.emptyList();
                 }
 
                 return new CheckResult(true, this, resultDescription, Tools.iso8601(), summaries);