SERVER-5905 Add operation latency histogram

Signed-off-by: Kyle Suarez <kyle.suarez@mongodb.com>

1 files changed, 76 insertions, 3 deletions

diff --git a/src/mongo/db/stats/top.cpp b/src/mongo/db/stats/top.cpp
index be251870d94..3cfb01fd386 100644
--- a/src/mongo/db/stats/top.cpp
+++ b/src/mongo/db/stats/top.cpp
@@ -33,6 +33,8 @@
 
 #include "mongo/db/stats/top.h"
 
+#include "mongo/db/commands/server_status_metric.h"
+#include "mongo/db/curop.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/service_context.h"
 #include "mongo/util/log.h"
@@ -72,7 +74,12 @@ Top& Top::get(ServiceContext* service) {
     return getTop(service);
 }
 
-void Top::record(StringData ns, LogicalOp logicalOp, int lockType, long long micros, bool command) {
+void Top::record(OperationContext* txn,
+                 StringData ns,
+                 LogicalOp logicalOp,
+                 int lockType,
+                 long long micros,
+                 bool command) {
     if (ns[0] == '?')
         return;
 
@@ -87,10 +94,14 @@ void Top::record(StringData ns, LogicalOp logicalOp, int lockType, long long mic
     }
 
     CollectionData& coll = _usage[hashedNs];
-    _record(coll, logicalOp, lockType, micros);
+    _record(txn, coll, logicalOp, lockType, micros);
 }
 
-void Top::_record(CollectionData& c, LogicalOp logicalOp, int lockType, long long micros) {
+void Top::_record(
+    OperationContext* txn, CollectionData& c, LogicalOp logicalOp, int lockType, long long micros) {
+
+    _incrementHistogram(txn, micros, &c.opLatencyHistogram);
+
     c.total.inc(micros);
 
     if (lockType > 0)
@@ -180,4 +191,66 @@ void Top::_appendStatsEntry(BSONObjBuilder& b, const char* statsName, const Usag
     bb.appendNumber("count", map.count);
     bb.done();
 }
+
+void Top::appendLatencyStats(StringData ns, BSONObjBuilder* builder) {
+    auto hashedNs = UsageMap::HashedKey(ns);
+    stdx::lock_guard<SimpleMutex> lk(_lock);
+    BSONObjBuilder latencyStatsBuilder;
+    _usage[hashedNs].opLatencyHistogram.append(&latencyStatsBuilder);
+    builder->append("latencyStats", latencyStatsBuilder.obj());
+}
+
+void Top::incrementGlobalLatencyStats(OperationContext* txn, uint64_t latency) {
+    stdx::lock_guard<SimpleMutex> guard(_lock);
+    _incrementHistogram(txn, latency, &_globalHistogramStats);
+}
+
+void Top::appendGlobalLatencyStats(BSONObjBuilder* builder) {
+    stdx::lock_guard<SimpleMutex> guard(_lock);
+    _globalHistogramStats.append(builder);
+}
+
+Command::ReadWriteType Top::_getReadWriteType(Command* cmd, LogicalOp logicalOp) {
+    // For legacy operations, cmd may be a nullptr.
+    if (cmd) {
+        return cmd->getReadWriteType();
+    }
+    switch (logicalOp) {
+        case LogicalOp::opGetMore:
+        case LogicalOp::opQuery:
+            return Command::ReadWriteType::kRead;
+        case LogicalOp::opUpdate:
+        case LogicalOp::opInsert:
+        case LogicalOp::opDelete:
+            return Command::ReadWriteType::kWrite;
+        default:
+            return Command::ReadWriteType::kCommand;
+    }
+}
+
+void Top::_incrementHistogram(OperationContext* txn,
+                              long long latency,
+                              OperationLatencyHistogram* histogram) {
+    // Only update histogram if operation came from a user.
+    Client* client = txn->getClient();
+    if (client->isFromUserConnection() && !client->isInDirectClient()) {
+        CurOp* curOp = CurOp::get(txn);
+        Command* cmd = curOp->getCommand();
+        Command::ReadWriteType readWriteType = _getReadWriteType(cmd, curOp->getLogicalOp());
+        histogram->increment(latency, readWriteType);
+    }
 }
+
+/**
+ * Appends the global histogram to the server status.
+ */
+class GlobalHistogramServerStatusMetric : public ServerStatusMetric {
+public:
+    GlobalHistogramServerStatusMetric() : ServerStatusMetric(".metrics.latency") {}
+    virtual void appendAtLeaf(BSONObjBuilder& builder) const {
+        BSONObjBuilder latencyBuilder;
+        Top::get(getGlobalServiceContext()).appendGlobalLatencyStats(&latencyBuilder);
+        builder.append("latency", latencyBuilder.obj());
+    }
+} globalHistogramServerStatusMetric;
+}  // namespace mongo