Add queue size metric

3 files changed, 5 insertions, 1 deletions

diff --git a/storage/src/tests/storageserver/mergethrottlertest.cpp b/storage/src/tests/storageserver/mergethrottlertest.cpp
index 12ed9ead1b6..3a153fef9c3 100644
--- a/storage/src/tests/storageserver/mergethrottlertest.cpp
+++ b/storage/src/tests/storageserver/mergethrottlertest.cpp
@@ -1233,6 +1233,7 @@ TEST_F(MergeThrottlerTest, busy_returned_on_full_queue) {
 
     // Wait till we have maxPending replies and maxQueue queued
     _topLinks[0]->waitForMessages(maxPending, _messageWaitTime);
+    EXPECT_EQ(19, _throttlers[0]->getMetrics().queueSize.getMaximum());
     waitUntilMergeQueueIs(*_throttlers[0], maxQueue, _messageWaitTime);
 
     // Clear all forwarded merges
diff --git a/storage/src/vespa/storage/storageserver/mergethrottler.cpp b/storage/src/vespa/storage/storageserver/mergethrottler.cpp
index dc8457769a2..6c3f0ac6fb1 100644
--- a/storage/src/vespa/storage/storageserver/mergethrottler.cpp
+++ b/storage/src/vespa/storage/storageserver/mergethrottler.cpp
@@ -71,6 +71,7 @@ MergeThrottler::ChainedMergeState::~ChainedMergeState() = default;
 MergeThrottler::Metrics::Metrics(metrics::MetricSet* owner)
     : metrics::MetricSet("mergethrottler", {}, "", owner),
       averageQueueWaitingTime("averagequeuewaitingtime", {}, "Average time a merge spends in the throttler queue", this),
+      queueSize("queuesize", {}, "Length of merge queue", this),
       bounced_due_to_back_pressure("bounced_due_to_back_pressure", {}, "Number of merges bounced due to resource exhaustion back-pressure", this),
       chaining("mergechains", this),
       local("locallyexecutedmerges", this)
@@ -415,6 +416,7 @@ MergeThrottler::enqueueMerge(
     if (!validateNewMerge(mergeCmd, nodeSeq, msgGuard)) {
         return;
     }
+    _metrics->queueSize.addValue(_queue.size());
     _queue.insert(MergePriorityQueue::value_type(msg, _queueSequence++));
 }
 
diff --git a/storage/src/vespa/storage/storageserver/mergethrottler.h b/storage/src/vespa/storage/storageserver/mergethrottler.h
index e8815eee680..0c608f29196 100644
--- a/storage/src/vespa/storage/storageserver/mergethrottler.h
+++ b/storage/src/vespa/storage/storageserver/mergethrottler.h
@@ -57,12 +57,13 @@ public:
         MergeFailureMetrics failures;
 
         MergeOperationMetrics(const std::string& name, metrics::MetricSet* owner);
-        ~MergeOperationMetrics();
+        ~MergeOperationMetrics() override;
     };
 
     class Metrics : public metrics::MetricSet {
     public:
         metrics::DoubleAverageMetric averageQueueWaitingTime;
+        metrics::LongValueMetric queueSize;
         metrics::LongCountMetric bounced_due_to_back_pressure;
         MergeOperationMetrics chaining;
         MergeOperationMetrics local;