SERVER-45202 Improve command alias infrastructurer3.6.20-rc1

(cherry picked from commit 3cd3a6da3fe0b6f022b721094bda0b97c3527d23)

2 files changed, 27 insertions, 5 deletions

diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index f7aa71e9184..9f3afeda2a4 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -186,7 +186,7 @@ ResourcePattern Command::parseResourcePattern(const std::string& dbname,
     return ResourcePattern::forExactNamespace(NamespaceString(ns));
 }
 
-Command::Command(StringData name, StringData oldName)
+Command::Command(StringData name, std::vector<StringData> aliases)
     : _name(name.toString()),
       _commandsExecutedMetric("commands." + _name + ".total", &_commandsExecuted),
       _commandsFailedMetric("commands." + _name + ".failed", &_commandsFailed) {
@@ -201,8 +201,12 @@ Command::Command(StringData name, StringData oldName)
     c = this;
     (*_commandsByBestName)[name] = this;
 
-    if (!oldName.empty())
-        (*_commands)[oldName.toString()] = this;
+    for (auto key : aliases) {
+        if (key.empty()) {
+            continue;
+        }
+        (*_commands)[key.toString()] = this;
+    }
 }
 
 void Command::help(stringstream& help) const {
@@ -388,6 +392,10 @@ void Command::generateHelpResponse(OperationContext* opCtx,
     replyBuilder->setMetadata(rpc::makeEmptyMetadata());
 }
 
+bool Command::hasAlias(const StringData& alias) const {
+    return findCommand(alias) == this;
+}
+
 namespace {
 const stdx::unordered_set<std::string> userManagementCommands{"createUser",
                                                               "updateUser",
diff --git a/src/mongo/db/commands.h b/src/mongo/db/commands.h
index 779500a8a12..23c8f0e23e4 100644
--- a/src/mongo/db/commands.h
+++ b/src/mongo/db/commands.h
@@ -268,9 +268,15 @@ public:
      * Constructs a new command and causes it to be registered with the global commands list. It is
      * not safe to construct commands other than when the server is starting up.
      *
-     * @param oldName an optional old, deprecated name for the command
+     * @param oldName an old, deprecated name for the command
      */
-    Command(StringData name, StringData oldName = StringData());
+    Command(StringData name, StringData oldName)
+        : Command(name, std::vector<StringData>({oldName})) {}
+
+    /**
+     * @param aliases the optional list of aliases (e.g., old names) for the command
+     */
+    Command(StringData name, std::vector<StringData> aliases = {});
 
     // NOTE: Do not remove this declaration, or relocate it in this class. We
     // are using this method to control where the vtable is emitted.
@@ -373,6 +379,11 @@ public:
     static Counter64 unknownCommands;
 
     /**
+     * Checks if the command is also known by the provided alias.
+     */
+    bool hasAlias(const StringData& alias) const;
+
+    /**
      * Runs a command directly and returns the result. Does not do any other work normally handled
      * by command dispatch, such as checking auth, dealing with CurOp or waiting for write concern.
      * It is illegal to call this if the command does not exist.
@@ -551,6 +562,9 @@ private:
     // The full name of the command
     const std::string _name;
 
+    // The list of aliases for the command
+    const std::vector<StringData> _aliases;
+
     // Pointers to hold the metrics tree references
     ServerStatusMetricField<Counter64> _commandsExecutedMetric;
     ServerStatusMetricField<Counter64> _commandsFailedMetric;