SERVER-73863 allow cluster admin to reset telemetry store to 0 bytes

7 files changed, 67 insertions, 17 deletions

diff --git a/jstests/noPassthrough/telemetry/clear_telemetry_store.js b/jstests/noPassthrough/telemetry/clear_telemetry_store.js
new file mode 100644
index 00000000000..3682b16ce66
--- /dev/null
+++ b/jstests/noPassthrough/telemetry/clear_telemetry_store.js
@@ -0,0 +1,46 @@
+/**
+ * Test that the telemetry store can be cleared when the cache size is reset to 0.
+ * @tags: [featureFlagTelemetry]
+ */
+load("jstests/libs/telemetry_utils.js");  // For verifyMetrics.
+
+(function() {
+"use strict";
+
+// Turn on the collecting of telemetry metrics.
+let options = {
+    setParameter: {
+        internalQueryConfigureTelemetrySamplingRate: 2147483647,
+        internalQueryConfigureTelemetryCacheSize: "10MB"
+    },
+};
+
+const conn = MongoRunner.runMongod(options);
+const testDB = conn.getDB('test');
+var coll = testDB[jsTestName()];
+coll.drop();
+
+let query = {};
+for (var j = 0; j < 10; ++j) {
+    query["foo.field.xyz." + j] = 1;
+    query["bar.field.xyz." + j] = 2;
+    query["baz.field.xyz." + j] = 3;
+    coll.aggregate([{$match: query}]).itcount();
+}
+
+// Confirm number of entries in the store and that none have been evicted.
+let telemetryResults = testDB.getSiblingDB("admin").aggregate([{$telemetry: {}}]).toArray();
+assert.eq(telemetryResults.length, 10, telemetryResults);
+assert.eq(testDB.serverStatus().metrics.telemetry.numEvicted, 0);
+
+// Command to clear the cache.
+assert.commandWorked(
+    testDB.adminCommand({setParameter: 1, internalQueryConfigureTelemetryCacheSize: "0MB"}));
+
+// 10 regular queries plus the $telemetry query, means 11 entries evicted when the cache is cleared.
+assert.eq(testDB.serverStatus().metrics.telemetry.numEvicted, 11);
+
+// Calling $telemetry should fail when the telemetry store size is 0 bytes.
+assert.throwsWithCode(() => testDB.getSiblingDB("admin").aggregate([{$telemetry: {}}]), 6579000);
+MongoRunner.stopMongod(conn);
+}());
diff --git a/jstests/noPassthrough/telemetry/redactFieldnames_parameter.js b/jstests/noPassthrough/telemetry/redactFieldnames_parameter.js
index 7c4ee35ce27..5efbbf07529 100644
--- a/jstests/noPassthrough/telemetry/redactFieldnames_parameter.js
+++ b/jstests/noPassthrough/telemetry/redactFieldnames_parameter.js
@@ -6,7 +6,6 @@
 (function() {
 "use strict";
 
-load("jstests/libs/feature_flag_util.js");    // For FeatureFlagUtil.
 load("jstests/aggregation/extras/utils.js");  // For assertAdminDBErrCodeAndErrMsgContains.
 
 // Turn on the collecting of telemetry metrics.
diff --git a/jstests/noPassthrough/telemetry/redact_queries_with_nonobject_fields.js b/jstests/noPassthrough/telemetry/redact_queries_with_nonobject_fields.js
index 0606ce3d27b..9ef3cabbb54 100644
--- a/jstests/noPassthrough/telemetry/redact_queries_with_nonobject_fields.js
+++ b/jstests/noPassthrough/telemetry/redact_queries_with_nonobject_fields.js
@@ -3,7 +3,6 @@
  * @tags: [featureFlagTelemetry]
  */
 load('jstests/libs/analyze_plan.js');
-load("jstests/libs/feature_flag_util.js");
 
 (function() {
 "use strict";
diff --git a/jstests/noPassthrough/telemetry/telemetry_metrics_across_getMore_calls.js b/jstests/noPassthrough/telemetry/telemetry_metrics_across_getMore_calls.js
index b87c2039362..27fdfb7d1d2 100644
--- a/jstests/noPassthrough/telemetry/telemetry_metrics_across_getMore_calls.js
+++ b/jstests/noPassthrough/telemetry/telemetry_metrics_across_getMore_calls.js
@@ -3,8 +3,7 @@
  * calls.
  * @tags: [featureFlagTelemetry]
  */
-load("jstests/libs/feature_flag_util.js");  // For FeatureFlagUtil.
-load("jstests/libs/telemetry_utils.js");    // For verifyMetrics.
+load("jstests/libs/telemetry_utils.js");  // For verifyMetrics.
 
 (function() {
 "use strict";
diff --git a/jstests/noPassthrough/telemetry/telemetry_sampling_rate.js b/jstests/noPassthrough/telemetry/telemetry_sampling_rate.js
index fd3b4105529..823991d652b 100644
--- a/jstests/noPassthrough/telemetry/telemetry_sampling_rate.js
+++ b/jstests/noPassthrough/telemetry/telemetry_sampling_rate.js
@@ -4,7 +4,6 @@
  * @tags: [featureFlagTelemetry]
  */
 load('jstests/libs/analyze_plan.js');
-load("jstests/libs/feature_flag_util.js");
 
 (function() {
 "use strict";
diff --git a/jstests/noPassthrough/telemetry/telemetry_server_status_metrics.js b/jstests/noPassthrough/telemetry/telemetry_server_status_metrics.js
index 0f8bf224e58..cafb42fa3dc 100644
--- a/jstests/noPassthrough/telemetry/telemetry_server_status_metrics.js
+++ b/jstests/noPassthrough/telemetry/telemetry_server_status_metrics.js
@@ -3,7 +3,6 @@
  * @tags: [featureFlagTelemetry]
  */
 load('jstests/libs/analyze_plan.js');
-load("jstests/libs/feature_flag_util.js");
 
 (function() {
 "use strict";
diff --git a/src/mongo/db/query/telemetry.cpp b/src/mongo/db/query/telemetry.cpp
index 89a95f19989..c0c5bd5be8e 100644
--- a/src/mongo/db/query/telemetry.cpp
+++ b/src/mongo/db/query/telemetry.cpp
@@ -64,13 +64,6 @@ namespace telemetry {
 // files/libraries here. Instead define here as well.
 static const std::string kTelemetryKeyInShardedCommand = "hashedTelemetryKey";
 
-bool isTelemetryEnabled() {
-    // During initialization FCV may not yet be setup but queries could be run. We can't
-    // check whether telemetry should be enabled without FCV, so default to not recording
-    // those queries.
-    return serverGlobalParams.featureCompatibility.isVersionInitialized() &&
-        feature_flags::gFeatureFlagTelemetry.isEnabled(serverGlobalParams.featureCompatibility);
-}
 
 ShardedTelemetryStoreKey telemetryKeyToShardedStoreId(const BSONObj& key, std::string hostAndPort) {
     md5digest finishedMD5;
@@ -367,7 +360,7 @@ size_t capTelemetryStoreSize(size_t requestedSize) {
 size_t getTelemetryStoreSize() {
     auto status = memory_util::MemorySize::parse(queryTelemetryStoreSize.get());
     uassertStatusOK(status);
-    size_t requestedSize = memory_util::getRequestedMemSizeInBytes(status.getValue());
+    size_t requestedSize = memory_util::convertToSizeInBytes(status.getValue());
     return capTelemetryStoreSize(requestedSize);
 }
 
@@ -408,9 +401,8 @@ const auto telemetryRateLimiter =
 class TelemetryOnParamChangeUpdaterImpl final : public telemetry_util::OnParamChangeUpdater {
 public:
     void updateCacheSize(ServiceContext* serviceCtx, memory_util::MemorySize memSize) final {
-        auto requestedSize = memory_util::getRequestedMemSizeInBytes(memSize);
+        auto requestedSize = memory_util::convertToSizeInBytes(memSize);
         auto cappedSize = capTelemetryStoreSize(requestedSize);
-
         auto& telemetryStoreManager = telemetryStoreDecoration(serviceCtx);
         auto&& telemetryStore = telemetryStoreManager->getTelemetryStore();
         size_t numEvicted = telemetryStore.reset(cappedSize);
@@ -556,6 +548,7 @@ void appendWithRedactedLiterals(BSONObjBuilder& builder, const BSONElement& el)
 
 }  // namespace
 
+
 const BSONObj& TelemetryMetrics::redactKey(const BSONObj& key, bool redactFieldNames) const {
     // The redacted key for each entry is cached on first computation. However, if the redaction
     // straegy has flipped (from no redaction to SHA256, vice versa), we just return the key passed
@@ -615,6 +608,19 @@ const BSONObj& TelemetryMetrics::redactKey(const BSONObj& key, bool redactFieldN
     return *_redactedKey;
 }
 
+/**
+ * Top-level checks for whether telemetry collection is enabled. If this returns false, we must go
+ * no further.
+ */
+bool isTelemetryEnabled() {
+    // During initialization FCV may not yet be setup but queries could be run. We can't
+    // check whether telemetry should be enabled without FCV, so default to not recording
+    // those queries.
+    return serverGlobalParams.featureCompatibility.isVersionInitialized() &&
+        feature_flags::gFeatureFlagTelemetry.isEnabled(serverGlobalParams.featureCompatibility) &&
+        getTelemetryStoreSize() != 0;
+}
+
 // The originating command/query does not persist through the end of query execution. In order to
 // pair the telemetry metrics that are collected at the end of execution with the original query, it
 // is necessary to register the original query during planning and persist it after
@@ -717,7 +723,10 @@ void registerFindRequest(const FindCommandRequest& request,
 }
 
 TelemetryStore& getTelemetryStore(OperationContext* opCtx) {
-    uassert(6579000, "Telemetry is not enabled without the feature flag on", isTelemetryEnabled());
+    uassert(6579000,
+            "Telemetry is not enabled without the feature flag on and a cache size greater than 0 "
+            "bytes",
+            isTelemetryEnabled());
     return telemetryStoreDecoration(opCtx->getServiceContext())->getTelemetryStore();
 }