SERVER-28670 Add sharding CatalogCache and donor metrics to serverStatus

Includes metrics for refresh, clone and migration critical section
duration.

1 files changed, 85 insertions, 0 deletions

diff --git a/src/mongo/db/s/sharding_statistics.h b/src/mongo/db/s/sharding_statistics.h
new file mode 100644
index 00000000000..c4eb7abd728
--- /dev/null
+++ b/src/mongo/db/s/sharding_statistics.h
@@ -0,0 +1,85 @@
+/**
+ *    Copyright (C) 2015 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    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
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    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 GNU Affero General 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/platform/atomic_word.h"
+
+namespace mongo {
+
+class BSONObjBuilder;
+class OperationContext;
+class ServiceContext;
+
+/**
+ * Encapsulates per-process statistics for the sharding subsystem.
+ */
+struct ShardingStatistics {
+    // Counts how many times threads hit stale config exception (which is what triggers metadata
+    // refreshes)
+    AtomicInt64 countStaleConfigErrors{0};
+
+    // Cumulative, always-increasing counter of how many chunks did this node start donating
+    // (whether they succeeded or not)
+    AtomicInt64 countDonorMoveChunkStarted{0};
+
+    // Cumulative, always-increasing counter of how much time the entire move chunk operation took
+    // (excluding range deletion)
+    AtomicInt64 totalDonorMoveChunkTimeMillis{0};
+
+    // Cumulative, always-increasing counter of how much time the clone phase took on the donor
+    // node, before it was appropriate to enter the critical section
+    AtomicInt64 totalDonorChunkCloneTimeMillis{0};
+
+    // Cumulative, always-increasing counter of how much time the critical section's commit phase
+    // took (this is the period of time when all operations on the collection are blocked, not just
+    // the reads)
+    AtomicInt64 totalCriticalSectionCommitTimeMillis{0};
+
+    // Cumulative, always-increasing counter of how much time the entire critical section took. It
+    // includes the time the recipient took to fetch the latest modifications from the donor and
+    // persist them plus the critical section commit time.
+    //
+    // The value of totalCriticalSectionTimeMillis - totalCriticalSectionCommitTimeMillis gives the
+    // duration of the catch-up phase of the critical section (where the last mods are transferred
+    // from the donor to the recipient).
+    AtomicInt64 totalCriticalSectionTimeMillis{0};
+
+    /**
+     * Obtains the per-process instance of the sharding statistics object.
+     */
+    static ShardingStatistics& get(ServiceContext* serviceContext);
+    static ShardingStatistics& get(OperationContext* opCtx);
+
+    /**
+     * Reports the accumulated statistics for serverStatus.
+     */
+    void report(BSONObjBuilder* builder) const;
+};
+
+}  // namespace mongo