SERVER-18766 Convert ClusterClientCursor to an interface

6 files changed, 82 insertions, 33 deletions

diff --git a/src/mongo/s/query/SConscript b/src/mongo/s/query/SConscript
index b8c091e9a2a..89ab61a04f3 100644
--- a/src/mongo/s/query/SConscript
+++ b/src/mongo/s/query/SConscript
@@ -15,7 +15,7 @@ env.Library(
 env.Library(
     target="cluster_client_cursor",
     source=[
-        "cluster_client_cursor.cpp",
+        "cluster_client_cursor_impl.cpp",
         "async_cluster_client_cursor.cpp",
     ],
     LIBDEPS=[
diff --git a/src/mongo/s/query/async_cluster_client_cursor_test.cpp b/src/mongo/s/query/async_cluster_client_cursor_test.cpp
index f6b412aacb4..b70480d999c 100644
--- a/src/mongo/s/query/async_cluster_client_cursor_test.cpp
+++ b/src/mongo/s/query/async_cluster_client_cursor_test.cpp
@@ -28,7 +28,7 @@
 
 #include "mongo/platform/basic.h"
 
-#include "mongo/s/query/cluster_client_cursor.h"
+#include "mongo/s/query/async_cluster_client_cursor.h"
 
 #include "mongo/db/json.h"
 #include "mongo/db/query/getmore_response.h"
diff --git a/src/mongo/s/query/cluster_client_cursor.h b/src/mongo/s/query/cluster_client_cursor.h
index e2ea3a72e59..a0e0db58621 100644
--- a/src/mongo/s/query/cluster_client_cursor.h
+++ b/src/mongo/s/query/cluster_client_cursor.h
@@ -30,14 +30,13 @@
 
 #include <boost/optional.hpp>
 
-#include "mongo/base/status_with.h"
-#include "mongo/executor/task_executor.h"
-#include "mongo/s/query/cluster_client_cursor_params.h"
-#include "mongo/s/query/async_cluster_client_cursor.h"
-#include "mongo/util/net/hostandport.h"
+#include "mongo/db/jsobj.h"
 
 namespace mongo {
 
+template <typename T>
+class StatusWith;
+
 /**
  * ClusterClientCursor is used to generate results from cursor-generating commands on one or
  * more remote hosts. A cursor-generating command (e.g. the find command) is one that
@@ -52,12 +51,7 @@ namespace mongo {
  */
 class ClusterClientCursor {
 public:
-    /**
-     * Constructs a cluster client cursor.
-     */
-    ClusterClientCursor(executor::TaskExecutor* executor,
-                        const ClusterClientCursorParams& params,
-                        const std::vector<HostAndPort>& remotes);
+    virtual ~ClusterClientCursor(){};
 
     /**
      * Returns the next available result document (along with an ok status). May block waiting
@@ -68,7 +62,7 @@ public:
      *
      * A non-ok status is returned in case of any error.
      */
-    StatusWith<boost::optional<BSONObj>> next();
+    virtual StatusWith<boost::optional<BSONObj>> next() = 0;
 
     /**
      * Must be called before destruction to abandon a not-yet-exhausted cursor. If next() has
@@ -76,16 +70,7 @@ public:
      *
      * May block waiting for responses from remote hosts.
      */
-    void kill();
-
-private:
-    // Not owned here.
-    executor::TaskExecutor* _executor;
-
-    const ClusterClientCursorParams _params;
-
-    // Does work of scheduling remote work and merging results.
-    AsyncClusterClientCursor _accc;
+    virtual void kill() = 0;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/s/query/cluster_client_cursor.cpp b/src/mongo/s/query/cluster_client_cursor_impl.cpp
index ff0558473b7..c8db908a0e5 100644
--- a/src/mongo/s/query/cluster_client_cursor.cpp
+++ b/src/mongo/s/query/cluster_client_cursor_impl.cpp
@@ -30,20 +30,20 @@
 
 #include "mongo/platform/basic.h"
 
-#include "mongo/s/query/cluster_client_cursor.h"
+#include "mongo/s/query/cluster_client_cursor_impl.h"
 
 #include "mongo/util/scopeguard.h"
 
 namespace mongo {
 
-ClusterClientCursor::ClusterClientCursor(executor::TaskExecutor* executor,
-                                         const ClusterClientCursorParams& params,
-                                         const std::vector<HostAndPort>& remotes)
+ClusterClientCursorImpl::ClusterClientCursorImpl(executor::TaskExecutor* executor,
+                                                 const ClusterClientCursorParams& params,
+                                                 const std::vector<HostAndPort>& remotes)
     : _executor(executor), _params(params), _accc(executor, params, remotes) {}
 
-StatusWith<boost::optional<BSONObj>> ClusterClientCursor::next() {
+StatusWith<boost::optional<BSONObj>> ClusterClientCursorImpl::next() {
     // On error, kill the underlying ACCC.
-    ScopeGuard cursorKiller = MakeGuard(&ClusterClientCursor::kill, this);
+    ScopeGuard cursorKiller = MakeGuard(&ClusterClientCursorImpl::kill, this);
 
     while (!_accc.ready()) {
         auto nextEventStatus = _accc.nextEvent();
@@ -63,7 +63,7 @@ StatusWith<boost::optional<BSONObj>> ClusterClientCursor::next() {
     return statusWithNext;
 }
 
-void ClusterClientCursor::kill() {
+void ClusterClientCursorImpl::kill() {
     auto killEvent = _accc.kill();
     _executor->waitForEvent(killEvent);
 }
diff --git a/src/mongo/s/query/cluster_client_cursor_impl.h b/src/mongo/s/query/cluster_client_cursor_impl.h
new file mode 100644
index 00000000000..ad162e9db2d
--- /dev/null
+++ b/src/mongo/s/query/cluster_client_cursor_impl.h
@@ -0,0 +1,64 @@
+/**
+ *    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/executor/task_executor.h"
+#include "mongo/s/query/async_cluster_client_cursor.h"
+#include "mongo/s/query/cluster_client_cursor.h"
+#include "mongo/s/query/cluster_client_cursor_params.h"
+#include "mongo/util/net/hostandport.h"
+
+namespace mongo {
+
+class ClusterClientCursorImpl final : public ClusterClientCursor {
+    MONGO_DISALLOW_COPYING(ClusterClientCursorImpl);
+
+public:
+    /**
+     * Constructs a cluster client cursor.
+     */
+    ClusterClientCursorImpl(executor::TaskExecutor* executor,
+                            const ClusterClientCursorParams& params,
+                            const std::vector<HostAndPort>& remotes);
+
+    StatusWith<boost::optional<BSONObj>> next() final;
+
+    void kill() final;
+
+private:
+    // Not owned here.
+    executor::TaskExecutor* _executor;
+
+    const ClusterClientCursorParams _params;
+
+    // Does work of scheduling remote work and merging results.
+    AsyncClusterClientCursor _accc;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/s/query/cluster_find.cpp b/src/mongo/s/query/cluster_find.cpp
index 7e0ceb2e5ea..871ac58f395 100644
--- a/src/mongo/s/query/cluster_find.cpp
+++ b/src/mongo/s/query/cluster_find.cpp
@@ -43,7 +43,7 @@
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/config.h"
 #include "mongo/s/grid.h"
-#include "mongo/s/query/cluster_client_cursor.h"
+#include "mongo/s/query/cluster_client_cursor_impl.h"
 
 namespace mongo {
 
@@ -94,7 +94,7 @@ StatusWith<CursorId> ClusterFind::runQuery(OperationContext* txn,
     params.cmdObj = query.getParsed().asFindCommand();
     params.sort = query.getParsed().getSort();
 
-    ClusterClientCursor ccc(shardRegistry->getExecutor(), params, remotes);
+    ClusterClientCursorImpl ccc(shardRegistry->getExecutor(), params, remotes);
 
     // TODO: this should implement the batching logic rather than fully exhausting the cursor. It
     // should allocate a cursor id and save the ClusterClientCursor rather than always returning a