SERVER-28435 Skeleton code for KeysCollectionCacheReader

4 files changed, 179 insertions, 0 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 3a8ee0e8168..667ef37e8db 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -1032,11 +1032,23 @@ env.Library(
 )
 
 env.Library(
+    target='keys_collection_manager',
+    source=[
+        'keys_collection_cache_reader.cpp',
+    ],
+    LIBDEPS=[
+        'keys_collection_document',
+        'logical_time',
+    ],
+)
+
+env.Library(
     target='logical_clock',
     source=[
         'logical_clock.cpp',
     ],
     LIBDEPS=[
+        'keys_collection_manager',
         'server_parameters',
         'service_context',
         'signed_logical_time',
diff --git a/src/mongo/db/keys_collection_cache.h b/src/mongo/db/keys_collection_cache.h
new file mode 100644
index 00000000000..2e7348e5687
--- /dev/null
+++ b/src/mongo/db/keys_collection_cache.h
@@ -0,0 +1,55 @@
+/**
+ *    Copyright (C) 2017 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/base/status_with.h"
+#include "mongo/db/keys_collection_document.h"
+
+namespace mongo {
+
+class LogicalTime;
+class OperationContext;
+
+class KeysCollectionCache {
+public:
+    virtual ~KeysCollectionCache() = default;
+
+    /**
+     * Refreshes cache and returns the latest key seen.
+     */
+    virtual StatusWith<KeysCollectionDocument> refresh(OperationContext* opCtx) = 0;
+
+    /**
+     * Returns the key in the cache that has the smallest expiresAt value that is also greater than
+     * the forThisTime argument.
+     */
+    virtual StatusWith<KeysCollectionDocument> getKey(const LogicalTime& forThisTime) = 0;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/db/keys_collection_cache_reader.cpp b/src/mongo/db/keys_collection_cache_reader.cpp
new file mode 100644
index 00000000000..5d90ba846e0
--- /dev/null
+++ b/src/mongo/db/keys_collection_cache_reader.cpp
@@ -0,0 +1,50 @@
+/**
+ *    Copyright (C) 2017 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.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/keys_collection_cache_reader.h"
+
+namespace mongo {
+
+KeysCollectionCacheReader::KeysCollectionCacheReader(std::string purpose)
+    : _purpose(std::move(purpose)) {}
+
+StatusWith<KeysCollectionDocument> KeysCollectionCacheReader::refresh(OperationContext* opCtx) {
+    // forThisTime = latest keyDoc.expiresAt or LogicalTime.MIN if _cache is empty
+    // read must be { level: 'majority' }.
+    // admin.system.keys.find({purpose: 'signLogicalTime', expiresAt: {$gt: <forThisTime>});
+    return {ErrorCodes::InternalError, "Not yet implemented"};
+}
+
+StatusWith<KeysCollectionDocument> KeysCollectionCacheReader::getKey(
+    const LogicalTime& forThisTime) {
+    return {ErrorCodes::InternalError, "Not yet implemented"};
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/keys_collection_cache_reader.h b/src/mongo/db/keys_collection_cache_reader.h
new file mode 100644
index 00000000000..001fb3e736f
--- /dev/null
+++ b/src/mongo/db/keys_collection_cache_reader.h
@@ -0,0 +1,62 @@
+/**
+ *    Copyright (C) 2017 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 <map>
+
+#include "mongo/db/keys_collection_cache.h"
+#include "mongo/stdx/mutex.h"
+
+namespace mongo {
+
+/**
+ * Keeps a local cache of the keys with the ability to refresh.
+ *
+ * Note: This assumes that user does not manually update the keys collection.
+ */
+class KeysCollectionCacheReader : public KeysCollectionCache {
+public:
+    KeysCollectionCacheReader(std::string purpose);
+    ~KeysCollectionCacheReader() = default;
+
+    /**
+     * Check if there are new documents expiresAt > latestKeyDoc.expiresAt.
+     */
+    StatusWith<KeysCollectionDocument> refresh(OperationContext* opCtx) override;
+
+    StatusWith<KeysCollectionDocument> getKey(const LogicalTime& forThisTime) override;
+
+private:
+    const std::string _purpose;
+
+    stdx::mutex _cacheMutex;
+    std::map<LogicalTime, KeysCollectionDocument> _cache;  // expiresAt -> KeysDocument
+};
+
+}  // namespace mongo