SERVER-19905 SERVER-19855 Put config server optime into its own subobject when sending with commands

2 files changed, 42 insertions, 0 deletions

diff --git a/src/mongo/rpc/metadata/sharding_metadata.cpp b/src/mongo/rpc/metadata/sharding_metadata.cpp
index 4fc3a2feae2..71566a2a5da 100644
--- a/src/mongo/rpc/metadata/sharding_metadata.cpp
+++ b/src/mongo/rpc/metadata/sharding_metadata.cpp
@@ -34,11 +34,14 @@
 
 #include "mongo/bson/util/bson_extract.h"
 #include "mongo/db/jsobj.h"
+#include "mongo/db/repl/optime.h"
 #include "mongo/util/mongoutils/str.h"
 
 namespace mongo {
 namespace rpc {
 
+const char ShardingRequestMetadata::kConfigsvrOpTimeFieldName[] = "configsvrOpTime";
+
 namespace {
 
 const char kGLEStatsFieldName[] = "$gleStats";
@@ -141,5 +144,18 @@ const OID& ShardingMetadata::getLastElectionId() const {
     return _lastElectionId;
 }
 
+StatusWith<boost::optional<repl::OpTime>>
+ShardingRequestMetadata::extractConfigServerOpTimeIfPresent(const BSONObj& cmdObj) {
+    repl::OpTime opTime;
+    Status status = bsonExtractOpTimeField(cmdObj, kConfigsvrOpTimeFieldName, &opTime);
+    if (status == ErrorCodes::NoSuchKey) {
+        return {boost::none};
+    } else if (!status.isOK()) {
+        return status;
+    }
+
+    return {opTime};
+}
+
 }  // namespace rpc
 }  // namespace mongo
diff --git a/src/mongo/rpc/metadata/sharding_metadata.h b/src/mongo/rpc/metadata/sharding_metadata.h
index 048473064b4..b18e415ffb4 100644
--- a/src/mongo/rpc/metadata/sharding_metadata.h
+++ b/src/mongo/rpc/metadata/sharding_metadata.h
@@ -27,6 +27,8 @@
  */
 #pragma once
 
+#include <boost/optional.hpp>
+
 #include "mongo/db/jsobj.h"
 
 namespace mongo {
@@ -35,11 +37,17 @@ class BSONObjBuilder;
 class Status;
 template <typename T>
 class StatusWith;
+
+namespace repl {
+class OpTime;
+}  // namespace repl
+
 namespace rpc {
 
 /**
  * This class compromises the reply metadata fields that concern sharding. MongoD attaches
  * this information to a command reply, which MongoS uses to process getLastError.
+ * TODO(spencer): Rename this to ShardingResponseMetadata.
  */
 class ShardingMetadata {
 public:
@@ -87,5 +95,23 @@ private:
     OID _lastElectionId;
 };
 
+class ShardingRequestMetadata {
+public:
+    static const char kConfigsvrOpTimeFieldName[];
+
+    /**
+     * Looks in the given command object for a field containing the config server optime, and
+     * returns it if present, or boost::none if not.  Returns a non-ok status on parsing error.
+     * Used for extracting the config server optime on mongod that was sent from a mongos.
+     *
+     * TODO(SERVER-20442): Currently this method extracts this information from the main command
+     * description rather than the actual OP_COMMAND metadata section.  Ideally this information
+     * should be in the metadata, but we currently have no good way to add metadata to all commands
+     * being *sent* to another server.
+     */
+    static StatusWith<boost::optional<repl::OpTime>> extractConfigServerOpTimeIfPresent(
+        const BSONObj& cmdObj);
+};
+
 }  // namespace rpc
 }  // namespace mongo