From a05649c620cf15740f7f84ade69d7646c63711b4 Mon Sep 17 00:00:00 2001
From: Kevin Hoxha <kevin.hoxha@snowflake.com>
Date: Mon, 12 Dec 2022 11:02:10 -0800
Subject: [PATCH] metrics: Add knob to control emission of DDSketch buckets

---
 fdbrpc/Stats.actor.cpp    | 25 ++++++++++++++++---------
 flow/Knobs.cpp            |  1 +
 flow/include/flow/Knobs.h |  1 +
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/fdbrpc/Stats.actor.cpp b/fdbrpc/Stats.actor.cpp
index ae6489c547..dd065d0ba8 100644
--- a/fdbrpc/Stats.actor.cpp
+++ b/fdbrpc/Stats.actor.cpp
@@ -259,16 +259,23 @@ void LatencySample::logSample() {
 		std::string port_str = std::to_string(addr.port);
 		switch (model) {
 		case MetricsDataModel::OTLP: {
-			if (metrics->histMap.find(IMetric::id) != metrics->histMap.end()) {
-				metrics->histMap[IMetric::id].points.emplace_back(
-				    sketch.getErrorGuarantee(), sketch.getSamples(), sketch.min(), sketch.max(), sketch.getSum());
-			} else {
-				metrics->histMap[IMetric::id] = OTEL::OTELHistogram(
-				    name, sketch.getErrorGuarantee(), sketch.getSamples(), sketch.min(), sketch.max(), sketch.getSum());
+			// We only want to emit the entire DDSketch if the knob is set
+			if (FLOW_KNOBS->METRICS_EMIT_DDSKETCH) {
+				if (metrics->histMap.find(IMetric::id) != metrics->histMap.end()) {
+					metrics->histMap[IMetric::id].points.emplace_back(
+					    sketch.getErrorGuarantee(), sketch.getSamples(), sketch.min(), sketch.max(), sketch.getSum());
+				} else {
+					metrics->histMap[IMetric::id] = OTEL::OTELHistogram(name,
+					                                                    sketch.getErrorGuarantee(),
+					                                                    sketch.getSamples(),
+					                                                    sketch.min(),
+					                                                    sketch.max(),
+					                                                    sketch.getSum());
+				}
+				metrics->histMap[IMetric::id].points.back().addAttribute("ip", ip_str);
+				metrics->histMap[IMetric::id].points.back().addAttribute("port", port_str);
+				metrics->histMap[IMetric::id].points.back().startTime = sampleEmit;
 			}
-			metrics->histMap[IMetric::id].points.back().addAttribute("ip", ip_str);
-			metrics->histMap[IMetric::id].points.back().addAttribute("port", port_str);
-			metrics->histMap[IMetric::id].points.back().startTime = sampleEmit;
 			createOtelGauge(p50id, name + "p50", p50);
 			createOtelGauge(p90id, name + "p90", p90);
 			createOtelGauge(p95id, name + "p95", p95);
diff --git a/flow/Knobs.cpp b/flow/Knobs.cpp
index eedeb689ba..ee8c9e4ed6 100644
--- a/flow/Knobs.cpp
+++ b/flow/Knobs.cpp
@@ -95,6 +95,7 @@ void FlowKnobs::initialize(Randomize randomize, IsSimulated isSimulated) {
 	init( STATSD_UDP_EMISSION_PORT,                           8125 );
 	init( OTEL_UDP_EMISSION_ADDR,                       "127.0.0.1");
 	init( OTEL_UDP_EMISSION_PORT,                             8903 );
+	init( METRICS_EMIT_DDSKETCH,                             false ); // Determines if DDSketch buckets will get emitted
 
 	//connectionMonitor
 	init( CONNECTION_MONITOR_LOOP_TIME,   isSimulated ? 0.75 : 1.0 ); if( randomize && BUGGIFY ) CONNECTION_MONITOR_LOOP_TIME = 6.0;
diff --git a/flow/include/flow/Knobs.h b/flow/include/flow/Knobs.h
index 1ff40625ba..4fc0ee5e8a 100644
--- a/flow/include/flow/Knobs.h
+++ b/flow/include/flow/Knobs.h
@@ -152,6 +152,7 @@ public:
 	std::string OTEL_UDP_EMISSION_ADDR;
 	int STATSD_UDP_EMISSION_PORT;
 	int OTEL_UDP_EMISSION_PORT;
+	bool METRICS_EMIT_DDSKETCH;
 
 	// run loop profiling
 	double RUN_LOOP_PROFILING_INTERVAL;