1 files changed, 150 insertions, 0 deletions
diff --git a/src/mongo/db/s/implicit_create_collection.cpp b/src/mongo/db/s/implicit_create_collection.cpp
new file mode 100644
index 00000000000..17f68349c30
--- /dev/null
+++ b/src/mongo/db/s/implicit_create_collection.cpp
@@ -0,0 +1,150 @@
+/**
+ *    Copyright (C) 2018 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.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/s/implicit_create_collection.h"
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include "mongo/db/catalog/catalog_raii.h"
+#include "mongo/db/commands.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/db/service_context.h"
+#include "mongo/s/grid.h"
+#include "mongo/s/request_types/create_collection_gen.h"
+
+#include "mongo/stdx/condition_variable.h"
+#include "mongo/stdx/mutex.h"
+#include "mongo/util/scopeguard.h"
+
+namespace mongo {
+
+namespace {
+
+/**
+ * Responsible for explicitly creating collections in the sharding catalog. Also takes care of
+ * making sure that concurrent attempts to create a collection for the same ns will be
+ * synchronized and avoid duplicate work as much as possible.
+ */
+
+class CreateCollectionSerializer {
+public:
+    explicit CreateCollectionSerializer(NamespaceString ns) : _ns(std::move(ns)) {}
+
+    /**
+     * Initialize this collection so it will be officially tracked in a sharded environment
+     * by sending the command to the config server to create an entry for this collection in
+     * the sharding catalog.
+     */
+    void onCannotImplicitlyCreateCollection(OperationContext* opCtx) {
+        invariant(!opCtx->lockState()->isLocked());
+
+        {
+            stdx::unique_lock<stdx::mutex> lg(_mutex);
+            while (_isInProgress) {
+                opCtx->waitForConditionOrInterrupt(_cvIsInProgress, lg);
+            }
+
+            _isInProgress = true;
+        }
+
+        ON_BLOCK_EXIT([&] {
+            stdx::lock_guard<stdx::mutex> lg(_mutex);
+            _isInProgress = false;
+            _cvIsInProgress.notify_one();
+        });
+
+        {
+            AutoGetCollection autoColl(opCtx, _ns, MODE_IS);
+            if (autoColl.getCollection() != nullptr) {
+                // Collection already created, no more work needs to be done.
+                return;
+            }
+        }
+
+        ConfigsvrCreateCollection configCreateCmd;
+        configCreateCmd.setNs(_ns);
+
+        uassertStatusOK(
+            Grid::get(opCtx)->shardRegistry()->getConfigShard()->runCommandWithFixedRetryAttempts(
+                opCtx,
+                ReadPreferenceSetting{ReadPreference::PrimaryOnly},
+                "admin",
+                CommandHelpers::appendMajorityWriteConcern(configCreateCmd.toBSON()),
+                Shard::RetryPolicy::kIdempotent));
+    }
+
+private:
+    const NamespaceString _ns;
+
+    stdx::mutex _mutex;
+    stdx::condition_variable _cvIsInProgress;
+    bool _isInProgress = false;
+};
+
+class CreateCollectionSerializerMap {
+public:
+    std::shared_ptr<CreateCollectionSerializer> getForNs(const NamespaceString& ns) {
+        stdx::lock_guard<stdx::mutex> lg(_mutex);
+        auto iter = _inProgressMap.find(ns.ns());
+        if (iter == _inProgressMap.end()) {
+            std::tie(iter, std::ignore) =
+                _inProgressMap.emplace(ns.ns(), std::make_shared<CreateCollectionSerializer>(ns));
+        }
+
+        return iter->second;
+    }
+
+    void cleanupNs(const NamespaceString& ns) {
+        stdx::lock_guard<stdx::mutex> lg(_mutex);
+        _inProgressMap.erase(ns.ns());
+    }
+
+private:
+    stdx::mutex _mutex;
+    std::map<std::string, std::shared_ptr<CreateCollectionSerializer>> _inProgressMap;
+};
+
+const auto createCollectionSerializerMap =
+    ServiceContext::declareDecoration<CreateCollectionSerializerMap>();
+
+}  // unnamed namespace
+
+void onCannotImplicitlyCreateCollection(OperationContext* opCtx, const NamespaceString& ns) {
+    auto& handlerMap = createCollectionSerializerMap(opCtx->getServiceContext());
+    handlerMap.getForNs(ns)->onCannotImplicitlyCreateCollection(opCtx);
+    handlerMap.cleanupNs(ns);
+}
+
+}  // namespace mongo