SERVER-38998 Create serverStatus metrics for writeConcern

16 files changed, 305 insertions, 11 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 03f577b3e53..aa53f6d31d7 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -682,7 +682,6 @@ env.Library(
     source=[
         'catalog_raii.cpp',
         'retryable_writes_stats.cpp',
-        'server_read_concern_metrics.cpp',
         'server_transactions_metrics.cpp',
         'session_catalog_mongod.cpp',
         'single_transaction_stats.cpp',
@@ -692,7 +691,6 @@ env.Library(
         'transaction_participant.cpp',
         's/recover_transaction_decision_from_local_participant.cpp',
         env.Idlc('session_txn_record.idl')[0],
-        env.Idlc('read_concern_stats.idl')[0],
         env.Idlc('transactions_stats.idl')[0],
     ],
     LIBDEPS=[
@@ -895,6 +893,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/rw_concern_d',
         '$BUILD_DIR/mongo/db/s/sharding_api_d',
         '$BUILD_DIR/mongo/db/stats/counters',
+        '$BUILD_DIR/mongo/db/stats/server_read_concern_write_concern_metrics',
         '$BUILD_DIR/mongo/db/stats/top',
         '$BUILD_DIR/mongo/db/storage/storage_engine_lock_file',
         '$BUILD_DIR/mongo/db/storage/storage_engine_metadata',
diff --git a/src/mongo/db/commands/SConscript b/src/mongo/db/commands/SConscript
index 21d9929984a..19896af6656 100644
--- a/src/mongo/db/commands/SConscript
+++ b/src/mongo/db/commands/SConscript
@@ -266,6 +266,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/query_exec',
         '$BUILD_DIR/mongo/db/rw_concern_d',
         '$BUILD_DIR/mongo/db/stats/counters',
+        '$BUILD_DIR/mongo/db/stats/server_read_concern_write_concern_metrics',
         '$BUILD_DIR/mongo/db/storage/storage_engine_common',
         '$BUILD_DIR/mongo/db/views/views_mongod',
         'core',
diff --git a/src/mongo/db/commands/find_cmd.cpp b/src/mongo/db/commands/find_cmd.cpp
index df0bcc38423..0febcfc38c3 100644
--- a/src/mongo/db/commands/find_cmd.cpp
+++ b/src/mongo/db/commands/find_cmd.cpp
@@ -49,9 +49,9 @@
 #include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/s/collection_sharding_state.h"
 #include "mongo/db/server_parameters.h"
-#include "mongo/db/server_read_concern_metrics.h"
 #include "mongo/db/service_context.h"
 #include "mongo/db/stats/counters.h"
+#include "mongo/db/stats/server_read_concern_metrics.h"
 #include "mongo/db/transaction_participant.h"
 #include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/util/log.h"
diff --git a/src/mongo/db/ops/SConscript b/src/mongo/db/ops/SConscript
index 2725c1219d1..3141a119179 100644
--- a/src/mongo/db/ops/SConscript
+++ b/src/mongo/db/ops/SConscript
@@ -17,6 +17,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/repl/oplog',
         '$BUILD_DIR/mongo/db/repl/repl_coordinator_interface',
         '$BUILD_DIR/mongo/db/stats/counters',
+        '$BUILD_DIR/mongo/db/stats/server_read_concern_write_concern_metrics',
         '$BUILD_DIR/mongo/db/write_ops',
         '$BUILD_DIR/mongo/util/fail_point',
         '$BUILD_DIR/mongo/util/log_and_backoff',
diff --git a/src/mongo/db/ops/write_ops_exec.cpp b/src/mongo/db/ops/write_ops_exec.cpp
index bf46d4fe3eb..6a7c4528f44 100644
--- a/src/mongo/db/ops/write_ops_exec.cpp
+++ b/src/mongo/db/ops/write_ops_exec.cpp
@@ -68,6 +68,7 @@
 #include "mongo/db/s/operation_sharding_state.h"
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/db/stats/counters.h"
+#include "mongo/db/stats/server_write_concern_metrics.h"
 #include "mongo/db/stats/top.h"
 #include "mongo/db/storage/duplicate_key_error_info.h"
 #include "mongo/db/transaction_participant.h"
@@ -390,6 +391,8 @@ bool insertBatchAndHandleErrors(OperationContext* opCtx,
                 opCtx, collection->getCollection(), batch.begin(), batch.end(), fromMigrate);
             lastOpFixer->finishedOpSuccessfully();
             globalOpCounters.gotInserts(batch.size());
+            ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInserts(
+                opCtx->getWriteConcern(), batch.size());
             SingleWriteResult result;
             result.setN(1);
 
@@ -414,6 +417,8 @@ bool insertBatchAndHandleErrors(OperationContext* opCtx,
     // for batches that failed all-at-once inserting.
     for (auto it = batch.begin(); it != batch.end(); ++it) {
         globalOpCounters.gotInsert();
+        ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInsert(
+            opCtx->getWriteConcern());
         try {
             writeConflictRetry(opCtx, "insert", wholeOp.getNamespace().ns(), [&] {
                 try {
@@ -545,6 +550,8 @@ WriteResult performInserts(OperationContext* opCtx,
 
         if (canContinue && !fixedDoc.isOK()) {
             globalOpCounters.gotInsert();
+            ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInsert(
+                opCtx->getWriteConcern());
             try {
                 uassertStatusOK(fixedDoc.getStatus());
                 MONGO_UNREACHABLE;
@@ -653,6 +660,7 @@ static SingleWriteResult performSingleUpdateOpWithDupKeyRetry(OperationContext*
                                                               StmtId stmtId,
                                                               const write_ops::UpdateOpEntry& op) {
     globalOpCounters.gotUpdate();
+    ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForUpdate(opCtx->getWriteConcern());
     auto& curOp = *CurOp::get(opCtx);
     {
         stdx::lock_guard<Client> lk(*opCtx->getClient());
@@ -784,6 +792,7 @@ static SingleWriteResult performSingleDeleteOp(OperationContext* opCtx,
                 !opCtx->getTxnNumber() || !op.getMulti());
 
     globalOpCounters.gotDelete();
+    ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForDelete(opCtx->getWriteConcern());
     auto& curOp = *CurOp::get(opCtx);
     {
         stdx::lock_guard<Client> lk(*opCtx->getClient());
diff --git a/src/mongo/db/repl/SConscript b/src/mongo/db/repl/SConscript
index fb8a4a18619..f78940a728d 100644
--- a/src/mongo/db/repl/SConscript
+++ b/src/mongo/db/repl/SConscript
@@ -27,6 +27,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/index_d',
         '$BUILD_DIR/mongo/db/op_observer',
         '$BUILD_DIR/mongo/db/stats/counters',
+        '$BUILD_DIR/mongo/db/stats/server_read_concern_write_concern_metrics',
         '$BUILD_DIR/mongo/idl/idl_parser',
     ],
 )
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index be070da1b4b..03bc09fd04b 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -83,6 +83,7 @@
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/service_context.h"
 #include "mongo/db/stats/counters.h"
+#include "mongo/db/stats/server_write_concern_metrics.h"
 #include "mongo/db/storage/storage_engine.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/db/transaction_participant.h"
@@ -275,6 +276,10 @@ void createIndexForApplyOps(OperationContext* opCtx,
 
     OpCounters* opCounters = opCtx->writesAreReplicated() ? &globalOpCounters : &replOpCounters;
     opCounters->gotInsert();
+    if (opCtx->writesAreReplicated()) {
+        ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInsert(
+            opCtx->getWriteConcern());
+    }
 
     const auto constraints =
         ReplicationCoordinator::get(opCtx)->shouldRelaxIndexConstraints(opCtx, indexNss)
@@ -1102,10 +1107,9 @@ Status applyOperation_inlock(OperationContext* opCtx,
     // Choose opCounters based on running on standalone/primary or secondary by checking
     // whether writes are replicated. Atomic applyOps command is an exception, which runs
     // on primary/standalone but disables write replication.
-    OpCounters* opCounters =
-        (mode == repl::OplogApplication::Mode::kApplyOpsCmd || opCtx->writesAreReplicated())
-        ? &globalOpCounters
-        : &replOpCounters;
+    const bool shouldUseGlobalOpCounters =
+        mode == repl::OplogApplication::Mode::kApplyOpsCmd || opCtx->writesAreReplicated();
+    OpCounters* opCounters = shouldUseGlobalOpCounters ? &globalOpCounters : &replOpCounters;
 
     std::array<StringData, 8> names = {"ts", "t", "o", "ui", "ns", "op", "b", "o2"};
     std::array<BSONElement, 8> fields;
@@ -1317,6 +1321,10 @@ Status applyOperation_inlock(OperationContext* opCtx,
             wuow.commit();
             for (auto entry : insertObjs) {
                 opCounters->gotInsert();
+                if (shouldUseGlobalOpCounters) {
+                    ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInsert(
+                        opCtx->getWriteConcern());
+                }
                 if (incrementOpsAppliedStats) {
                     incrementOpsAppliedStats();
                 }
@@ -1324,6 +1332,10 @@ Status applyOperation_inlock(OperationContext* opCtx,
         } else {
             // Single insert.
             opCounters->gotInsert();
+            if (shouldUseGlobalOpCounters) {
+                ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForInsert(
+                    opCtx->getWriteConcern());
+            }
 
             // No _id.
             // This indicates an issue with the upstream server:
@@ -1420,6 +1432,10 @@ Status applyOperation_inlock(OperationContext* opCtx,
         }
     } else if (*opType == 'u') {
         opCounters->gotUpdate();
+        if (shouldUseGlobalOpCounters) {
+            ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForUpdate(
+                opCtx->getWriteConcern());
+        }
 
         auto idField = o2["_id"];
         uassert(ErrorCodes::NoSuchKey,
@@ -1502,6 +1518,10 @@ Status applyOperation_inlock(OperationContext* opCtx,
         }
     } else if (*opType == 'd') {
         opCounters->gotDelete();
+        if (shouldUseGlobalOpCounters) {
+            ServerWriteConcernMetrics::get(opCtx)->recordWriteConcernForDelete(
+                opCtx->getWriteConcern());
+        }
 
         auto idField = o["_id"];
         uassert(ErrorCodes::NoSuchKey,
diff --git a/src/mongo/db/service_entry_point_common.cpp b/src/mongo/db/service_entry_point_common.cpp
index e8ff824ea78..0541047348c 100644
--- a/src/mongo/db/service_entry_point_common.cpp
+++ b/src/mongo/db/service_entry_point_common.cpp
@@ -69,11 +69,11 @@
 #include "mongo/db/s/operation_sharding_state.h"
 #include "mongo/db/s/sharded_connection_info.h"
 #include "mongo/db/s/sharding_state.h"
-#include "mongo/db/server_read_concern_metrics.h"
 #include "mongo/db/service_entry_point_common.h"
 #include "mongo/db/session_catalog_mongod.h"
 #include "mongo/db/snapshot_window_util.h"
 #include "mongo/db/stats/counters.h"
+#include "mongo/db/stats/server_read_concern_metrics.h"
 #include "mongo/db/stats/top.h"
 #include "mongo/db/transaction_coordinator_factory.h"
 #include "mongo/db/transaction_participant.h"
diff --git a/src/mongo/db/stats/SConscript b/src/mongo/db/stats/SConscript
index e8bce249241..6d2c333bf7e 100644
--- a/src/mongo/db/stats/SConscript
+++ b/src/mongo/db/stats/SConscript
@@ -68,6 +68,22 @@ env.Library(
 )
 
 env.Library(
+    target='server_read_concern_write_concern_metrics',
+    source=[
+        'server_read_concern_metrics.cpp',
+        'server_write_concern_metrics.cpp',
+        env.Idlc('read_concern_stats.idl')[0],
+    ],
+    LIBDEPS=[
+        '$BUILD_DIR/mongo/base',
+        '$BUILD_DIR/mongo/db/commands/server_status',
+        '$BUILD_DIR/mongo/db/repl/read_concern_args',
+        '$BUILD_DIR/mongo/db/write_concern_options',
+        '$BUILD_DIR/mongo/idl/idl_parser',
+    ],
+)
+
+env.Library(
     target='fill_locker_info',
     source=[
         'fill_locker_info.cpp',
diff --git a/src/mongo/db/read_concern_stats.idl b/src/mongo/db/stats/read_concern_stats.idl
index 60636cf0c08..60636cf0c08 100644
--- a/src/mongo/db/read_concern_stats.idl
+++ b/src/mongo/db/stats/read_concern_stats.idl
diff --git a/src/mongo/db/server_read_concern_metrics.cpp b/src/mongo/db/stats/server_read_concern_metrics.cpp
index 76b2a987442..97e77079140 100644
--- a/src/mongo/db/server_read_concern_metrics.cpp
+++ b/src/mongo/db/stats/server_read_concern_metrics.cpp
@@ -29,12 +29,11 @@
 
 #include "mongo/platform/basic.h"
 
-#include "mongo/db/server_read_concern_metrics.h"
+#include "mongo/db/stats/server_read_concern_metrics.h"
 
 #include "mongo/db/commands/server_status.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/operation_context.h"
-#include "mongo/db/read_concern_stats_gen.h"
 #include "mongo/db/service_context.h"
 
 namespace mongo {
diff --git a/src/mongo/db/server_read_concern_metrics.h b/src/mongo/db/stats/server_read_concern_metrics.h
index 53644e08d78..a79a7cea49e 100644
--- a/src/mongo/db/server_read_concern_metrics.h
+++ b/src/mongo/db/stats/server_read_concern_metrics.h
@@ -31,9 +31,9 @@
 #pragma once
 
 #include "mongo/db/operation_context.h"
-#include "mongo/db/read_concern_stats_gen.h"
 #include "mongo/db/repl/read_concern_args.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/stats/read_concern_stats_gen.h"
 
 namespace mongo {
 
diff --git a/src/mongo/db/stats/server_write_concern_metrics.cpp b/src/mongo/db/stats/server_write_concern_metrics.cpp
new file mode 100644
index 00000000000..3bcf1fe99af
--- /dev/null
+++ b/src/mongo/db/stats/server_write_concern_metrics.cpp
@@ -0,0 +1,131 @@
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/stats/server_write_concern_metrics.h"
+
+#include "mongo/db/commands/server_status.h"
+#include "mongo/db/jsobj.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/db/service_context.h"
+
+namespace mongo {
+namespace {
+const auto ServerWriteConcernMetricsDecoration =
+    ServiceContext::declareDecoration<ServerWriteConcernMetrics>();
+}  // namespace
+
+ServerWriteConcernMetrics* ServerWriteConcernMetrics::get(ServiceContext* service) {
+    return &ServerWriteConcernMetricsDecoration(service);
+}
+
+ServerWriteConcernMetrics* ServerWriteConcernMetrics::get(OperationContext* opCtx) {
+    return get(opCtx->getServiceContext());
+}
+
+BSONObj ServerWriteConcernMetrics::toBSON() const {
+    stdx::lock_guard<stdx::mutex> lg(_mutex);
+
+    BSONObjBuilder builder;
+
+    BSONObjBuilder insertBuilder(builder.subobjStart("insert"));
+    _insertMetrics.toBSON(&insertBuilder);
+    insertBuilder.done();
+
+    BSONObjBuilder updateBuilder(builder.subobjStart("update"));
+    _updateMetrics.toBSON(&updateBuilder);
+    updateBuilder.done();
+
+    BSONObjBuilder deleteBuilder(builder.subobjStart("delete"));
+    _deleteMetrics.toBSON(&deleteBuilder);
+    deleteBuilder.done();
+
+    return builder.obj();
+}
+
+void ServerWriteConcernMetrics::WriteConcernMetricsForOperationType::recordWriteConcern(
+    const WriteConcernOptions& writeConcernOptions, size_t numOps) {
+    if (writeConcernOptions.usedDefaultW) {
+        noWCount += numOps;
+        return;
+    }
+
+    if (!writeConcernOptions.wMode.empty()) {
+        if (writeConcernOptions.wMode == WriteConcernOptions::kMajority) {
+            wMajorityCount += numOps;
+            return;
+        }
+
+        wTagCounts[writeConcernOptions.wMode] += numOps;
+        return;
+    }
+
+    wNumCounts[writeConcernOptions.wNumNodes] += numOps;
+}
+
+void ServerWriteConcernMetrics::WriteConcernMetricsForOperationType::toBSON(
+    BSONObjBuilder* builder) const {
+    builder->append("wmajority", wMajorityCount);
+
+    BSONObjBuilder wNumBuilder(builder->subobjStart("wnum"));
+    for (auto const& pair : wNumCounts) {
+        wNumBuilder.append(std::to_string(pair.first), pair.second);
+    }
+    wNumBuilder.done();
+
+    BSONObjBuilder wTagBuilder(builder->subobjStart("wtag"));
+    for (auto const& pair : wTagCounts) {
+        wTagBuilder.append(pair.first, pair.second);
+    }
+    wTagBuilder.done();
+
+    builder->append("none", noWCount);
+}
+
+namespace {
+class OpWriteConcernCountersSSS : public ServerStatusSection {
+public:
+    OpWriteConcernCountersSSS() : ServerStatusSection("opWriteConcernCounters") {}
+
+    ~OpWriteConcernCountersSSS() override = default;
+
+    bool includeByDefault() const override {
+        return true;
+    }
+
+    BSONObj generateSection(OperationContext* opCtx,
+                            const BSONElement& configElement) const override {
+        return ServerWriteConcernMetrics::get(opCtx)->toBSON();
+    }
+
+} opWriteConcernCountersSSS;
+}  // namespace
+
+}  // namespace mongo
diff --git a/src/mongo/db/stats/server_write_concern_metrics.h b/src/mongo/db/stats/server_write_concern_metrics.h
new file mode 100644
index 00000000000..355a63bff90
--- /dev/null
+++ b/src/mongo/db/stats/server_write_concern_metrics.h
@@ -0,0 +1,111 @@
+
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/db/operation_context.h"
+#include "mongo/db/service_context.h"
+#include "mongo/db/write_concern_options.h"
+
+namespace mongo {
+
+/**
+ * Container for server-wide statistics on writeConcern levels used by operations.
+ */
+class ServerWriteConcernMetrics {
+    MONGO_DISALLOW_COPYING(ServerWriteConcernMetrics);
+
+public:
+    ServerWriteConcernMetrics() = default;
+
+    static ServerWriteConcernMetrics* get(ServiceContext* service);
+    static ServerWriteConcernMetrics* get(OperationContext* opCtx);
+
+    /**
+     * Updates the insert metrics 'numInserts' times according to the 'w' value of
+     * 'writeConcernOptions'.
+     */
+    void recordWriteConcernForInserts(const WriteConcernOptions& writeConcernOptions,
+                                      size_t numInserts) {
+        _insertMetrics.recordWriteConcern(writeConcernOptions, numInserts);
+    }
+
+    /**
+     * Updates the insert metrics according to the 'w' value of 'writeConcernOptions'.
+     */
+    void recordWriteConcernForInsert(const WriteConcernOptions& writeConcernOptions) {
+        recordWriteConcernForInserts(writeConcernOptions, 1);
+    }
+
+    /**
+     * Updates the update metrics according to the 'w' value of 'writeConcernOptions'.
+     */
+    void recordWriteConcernForUpdate(const WriteConcernOptions& writeConcernOptions) {
+        _updateMetrics.recordWriteConcern(writeConcernOptions);
+    }
+
+    /**
+     * Updates the delete metrics according to the 'w' value of 'writeConcernOptions'.
+     */
+    void recordWriteConcernForDelete(const WriteConcernOptions& writeConcernOptions) {
+        _deleteMetrics.recordWriteConcern(writeConcernOptions);
+    }
+
+    BSONObj toBSON() const;
+
+private:
+    struct WriteConcernMetricsForOperationType {
+        /**
+         * Updates counter for the 'w' value of 'writeConcernOptions'.
+         */
+        void recordWriteConcern(const WriteConcernOptions& writeConcernOptions, size_t numOps = 1);
+
+        void toBSON(BSONObjBuilder* builder) const;
+
+        // Count of operations with writeConcern w:"majority".
+        long long wMajorityCount = 0;
+
+        // Count of operations without a writeConcern "w" value.
+        long long noWCount = 0;
+
+        // Counts of operations with writeConcern w:<num>.
+        std::map<int, long long> wNumCounts;
+
+        // Counts of operations with writeConcern w:"tag".
+        StringMap<long long> wTagCounts;
+    };
+
+    mutable stdx::mutex _mutex;
+    WriteConcernMetricsForOperationType _insertMetrics;
+    WriteConcernMetricsForOperationType _updateMetrics;
+    WriteConcernMetricsForOperationType _deleteMetrics;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/db/write_concern_options.cpp b/src/mongo/db/write_concern_options.cpp
index 4f92515f26b..96b3af194be 100644
--- a/src/mongo/db/write_concern_options.cpp
+++ b/src/mongo/db/write_concern_options.cpp
@@ -153,8 +153,10 @@ Status WriteConcernOptions::parse(const BSONObj& obj) {
 
     if (wEl.isNumber()) {
         wNumNodes = wEl.numberInt();
+        usedDefaultW = false;
     } else if (wEl.type() == String) {
         wMode = wEl.valuestrsafe();
+        usedDefaultW = false;
     } else if (wEl.eoo() || wEl.type() == jstNULL || wEl.type() == Undefined) {
         wNumNodes = 1;
     } else {
@@ -174,6 +176,7 @@ StatusWith<WriteConcernOptions> WriteConcernOptions::extractWCFromCommand(
     const BSONObj& cmdObj, const WriteConcernOptions& defaultWC) {
     WriteConcernOptions writeConcern = defaultWC;
     writeConcern.usedDefault = true;
+    writeConcern.usedDefaultW = true;
     if (writeConcern.wNumNodes == 0 && writeConcern.wMode.empty()) {
         writeConcern.wNumNodes = 1;
     }
diff --git a/src/mongo/db/write_concern_options.h b/src/mongo/db/write_concern_options.h
index 8ff5bc050c1..86b2e418ac6 100644
--- a/src/mongo/db/write_concern_options.h
+++ b/src/mongo/db/write_concern_options.h
@@ -120,6 +120,9 @@ public:
 
     // True if the default write concern was used.
     bool usedDefault = false;
+
+    // True if the default 'w' value of w:1 was used.
+    bool usedDefaultW = false;
 };
 
 }  // namespace mongo