SERVER-65271 serverStatus should allow fine-grained metrics exclusion

(cherry picked from commit d964e2b912e26a96ee61cf4272102c8b4415fd2e)

4 files changed, 127 insertions, 9 deletions

diff --git a/jstests/noPassthrough/server_status_metrics_exclusion.js b/jstests/noPassthrough/server_status_metrics_exclusion.js
new file mode 100644
index 00000000000..2127882c9a3
--- /dev/null
+++ b/jstests/noPassthrough/server_status_metrics_exclusion.js
@@ -0,0 +1,65 @@
+/**
+ * Tests that serverStatus metrics are filtered when requested.
+ */
+(function() {
+"use strict";
+const mongod = MongoRunner.runMongod();
+const dbName = jsTestName();
+const db = mongod.getDB(dbName);
+
+// Verify some assumptions about metrics structure for later tests.
+let serverStatusMetrics = db.serverStatus().metrics;
+
+assert(serverStatusMetrics.document.hasOwnProperty("deleted"));
+assert(serverStatusMetrics.document.hasOwnProperty("inserted"));
+assert(serverStatusMetrics.query.hasOwnProperty("planCacheTotalSizeEstimateBytes"));
+
+// Exclude the "document.deleted" field.
+serverStatusMetrics = db.serverStatus({metrics: {document: {deleted: false}}}).metrics;
+
+assert(!serverStatusMetrics.document.hasOwnProperty("deleted"));
+assert(serverStatusMetrics.document.hasOwnProperty("inserted"));
+
+// Exclude the "document.deleted" and "document.inserted" fields.
+serverStatusMetrics =
+    db.serverStatus({metrics: {document: {deleted: false, inserted: false}}}).metrics;
+
+assert(!serverStatusMetrics.document.hasOwnProperty("deleted"));
+assert(!serverStatusMetrics.document.hasOwnProperty("inserted"));
+
+// Exclude the "document.deleted" and "query.planCacheTotalSizeEstimateBytes" fields.
+serverStatusMetrics =
+    db.serverStatus({
+          metrics: {document: {deleted: false}, query: {planCacheTotalSizeEstimateBytes: false}}
+      }).metrics;
+
+assert(!serverStatusMetrics.document.hasOwnProperty("deleted"));
+assert(!serverStatusMetrics.query.hasOwnProperty("planCacheTotalSizeEstimateBytes"));
+
+// Include a "true" value for the "document.deleted" field. It should be included (ie, no-op).
+serverStatusMetrics = db.serverStatus({metrics: {document: {deleted: true}}}).metrics;
+
+assert(serverStatusMetrics.document.hasOwnProperty("deleted"));
+assert(serverStatusMetrics.document.hasOwnProperty("inserted"));
+
+// Attempt a non-boolean values which should be rejected (uassert).
+assert.commandFailedWithCode(db.serverStatus({metrics: {document: "Non-boolean"}}),
+                             [ErrorCodes.TypeMismatch]);
+
+assert.commandFailedWithCode(db.serverStatus({metrics: {document: {deleted: "Non-boolean"}}}),
+                             [ErrorCodes.TypeMismatch]);
+
+assert.commandFailedWithCode(db.serverStatus({metrics: {document: {deleted: ["Non-boolean"]}}}),
+                             [ErrorCodes.TypeMismatch]);
+
+assert.commandFailedWithCode(
+    db.serverStatus({metrics: {document: {deleted: {invalidObjectAtLeftLevel: 1}}}}),
+    [ErrorCodes.TypeMismatch]);
+
+// Exclude the "document" subtree.
+serverStatusMetrics = db.serverStatus({metrics: {document: false}}).metrics;
+
+assert(!serverStatusMetrics.hasOwnProperty("document"));
+
+MongoRunner.stopMongod(mongod);
+})();
diff --git a/src/mongo/db/commands/server_status_command.cpp b/src/mongo/db/commands/server_status_command.cpp
index c5691a7b4ad..482ad472fb2 100644
--- a/src/mongo/db/commands/server_status_command.cpp
+++ b/src/mongo/db/commands/server_status_command.cpp
@@ -128,11 +128,17 @@ public:
 
         // --- counters
         bool includeMetricTree = MetricTree::theMetricTree != nullptr;
-        if (cmdObj["metrics"].type() && !cmdObj["metrics"].trueValue())
+        auto metricsEl = cmdObj["metrics"_sd];
+        if (metricsEl.type() && !metricsEl.trueValue())
             includeMetricTree = false;
 
         if (includeMetricTree) {
-            MetricTree::theMetricTree->appendTo(result);
+            if (metricsEl.type() == BSONType::Object) {
+                MetricTree::theMetricTree->appendTo(BSON("metrics" << metricsEl.embeddedObject()),
+                                                    result);
+            } else {
+                MetricTree::theMetricTree->appendTo(result);
+            }
         }
 
         // --- some hard coded global things hard to pull out
diff --git a/src/mongo/db/commands/server_status_internal.cpp b/src/mongo/db/commands/server_status_internal.cpp
index c981a65fd4b..82698b5e59a 100644
--- a/src/mongo/db/commands/server_status_internal.cpp
+++ b/src/mongo/db/commands/server_status_internal.cpp
@@ -31,6 +31,7 @@
 
 #include <iostream>
 
+#include "mongo/bson/bsontypes.h"
 #include "mongo/db/commands/server_status_metric.h"
 #include "mongo/util/str.h"
 
@@ -71,16 +72,53 @@ void MetricTree::_add(const string& path, ServerStatusMetric* metric) {
 }
 
 void MetricTree::appendTo(BSONObjBuilder& b) const {
-    for (map<string, ServerStatusMetric*>::const_iterator i = _metrics.begin(); i != _metrics.end();
-         ++i) {
-        i->second->appendAtLeaf(b);
+    for (const auto& i : _metrics) {
+        i.second->appendAtLeaf(b);
     }
 
-    for (map<string, MetricTree*>::const_iterator i = _subtrees.begin(); i != _subtrees.end();
-         ++i) {
-        BSONObjBuilder bb(b.subobjStart(i->first));
-        i->second->appendTo(bb);
+    for (const auto& i : _subtrees) {
+        BSONObjBuilder bb(b.subobjStart(i.first));
+        i.second->appendTo(bb);
         bb.done();
     }
 }
+
+void MetricTree::appendTo(const BSONObj& excludePaths, BSONObjBuilder& b) const {
+    auto fieldNamesInExclude = excludePaths.getFieldNames<stdx::unordered_set<std::string>>();
+    for (const auto& i : _metrics) {
+        auto key = i.first;
+        auto el = fieldNamesInExclude.contains(key) ? excludePaths.getField(key) : BSONElement();
+        if (el) {
+            uassert(ErrorCodes::TypeMismatch,
+                    "Exclusion value for a leaf must be a boolean.",
+                    el.type() == Bool);
+            if (el.boolean() == false) {
+                continue;
+            }
+        }
+        i.second->appendAtLeaf(b);
+    }
+
+    for (const auto& i : _subtrees) {
+        auto key = i.first;
+        auto el = fieldNamesInExclude.contains(key) ? excludePaths.getField(key) : BSONElement();
+        if (el) {
+            uassert(ErrorCodes::TypeMismatch,
+                    "Exclusion value must be a boolean or a nested object.",
+                    el.type() == Bool || el.type() == Object);
+            if (el.isBoolean() && el.boolean() == false) {
+                continue;
+            }
+        }
+
+        BSONObjBuilder bb(b.subobjStart(key));
+        if (el.type() == Object) {
+            i.second->appendTo(el.embeddedObject(), bb);
+        } else {
+            i.second->appendTo(bb);
+        }
+        bb.done();
+    }
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/commands/server_status_internal.h b/src/mongo/db/commands/server_status_internal.h
index f9bde775db3..b59b0b36762 100644
--- a/src/mongo/db/commands/server_status_internal.h
+++ b/src/mongo/db/commands/server_status_internal.h
@@ -42,8 +42,17 @@ class MetricTree {
 public:
     void add(ServerStatusMetric* metric);
 
+    /**
+     * Append the metrics tree to the given BSON builder.
+     */
     void appendTo(BSONObjBuilder& b) const;
 
+    /**
+     * Implementation of appendTo which allows tree of exclude paths. The alternative overload is
+     * preferred to avoid overhead when no excludes are present.
+     */
+    void appendTo(const BSONObj& excludePaths, BSONObjBuilder& b) const;
+
     static MetricTree* theMetricTree;
 
 private: