Cache: Make Storage abstract

Storage is now abstract with StorageReal (that uses an actual
storage module) derived from it. This to prepare for a stackable
case where LRU behaviour is implemented in front of the actual
physcal storage.

server/modules/filter/cache/CMakeLists.txt

@@ -1,5 +1,5 @@
 if (JANSSON_FOUND)
-  add_library(cache SHARED cache.cc cachefilter.cc cachemt.cc cachept.cc cachesimple.cc cachest.cc rules.cc sessioncache.cc storage.cc storagefactory.cc)
+  add_library(cache SHARED cache.cc cachefilter.cc cachemt.cc cachept.cc cachesimple.cc cachest.cc rules.cc sessioncache.cc storage.cc storagefactory.cc storagereal.cc)
   target_link_libraries(cache maxscale-common jansson)
   set_target_properties(cache PROPERTIES VERSION "1.0.0")
   set_target_properties(cache PROPERTIES LINK_FLAGS -Wl,-z,defs)

server/modules/filter/cache/storage.cc

@@ -15,39 +15,10 @@
 #include "storage.h"
 
 
-Storage::Storage(CACHE_STORAGE_API* pApi, CACHE_STORAGE* pStorage)
-    : m_pApi(pApi)
-    , m_pStorage(pStorage)
+Storage::Storage()
 {
-    ss_dassert(m_pApi);
-    ss_dassert(m_pStorage);
 }
 
 Storage::~Storage()
 {
 }
-
-cache_result_t Storage::get_key(const char* zDefaultDb,
-                                const GWBUF* pQuery,
-                                CACHE_KEY* pKey)
-{
-    return m_pApi->getKey(m_pStorage, zDefaultDb, pQuery, pKey);
-}
-
-cache_result_t Storage::get_value(const CACHE_KEY& key,
-                                  uint32_t flags,
-                                  GWBUF** ppValue)
-{
-    return m_pApi->getValue(m_pStorage, &key, flags, ppValue);
-}
-
-cache_result_t Storage::put_value(const CACHE_KEY& key,
-                                  const GWBUF* pValue)
-{
-    return m_pApi->putValue(m_pStorage, &key, pValue);
-}
-
-cache_result_t Storage::del_value(const CACHE_KEY& key)
-{
-    return m_pApi->delValue(m_pStorage, &key);
-}

server/modules/filter/cache/storage.h

@@ -1,6 +1,4 @@
 #pragma once
-#ifndef _MAXSCALE_FILTER_CACHE_STORAGE_H
-#define _MAXSCALE_FILTER_CACHE_STORAGE_H
 /*
  * Copyright (c) 2016 MariaDB Corporation Ab
  *
@@ -20,32 +18,24 @@
 class Storage
 {
 public:
-    ~Storage();
+    virtual ~Storage();
 
-    cache_result_t get_key(const char* zDefaultDb,
-                          const GWBUF* pQuery,
-                          CACHE_KEY* pKey);
+    virtual cache_result_t get_key(const char* zDefaultDb,
+                                   const GWBUF* pQuery,
+                                   CACHE_KEY* pKey) = 0;
 
-    cache_result_t get_value(const CACHE_KEY& key,
-                            uint32_t flags,
-                            GWBUF** ppValue);
+    virtual cache_result_t get_value(const CACHE_KEY& key,
+                                     uint32_t flags,
+                                     GWBUF** ppValue) = 0;
 
-    cache_result_t put_value(const CACHE_KEY& key,
-                            const GWBUF* pValue);
+    virtual cache_result_t put_value(const CACHE_KEY& key,
+                                     const GWBUF* pValue) = 0;
 
-    cache_result_t del_value(const CACHE_KEY& key);
+    virtual cache_result_t del_value(const CACHE_KEY& key) = 0;
 
-private:
-    friend class StorageFactory;
-
-    Storage(CACHE_STORAGE_API* pApi, CACHE_STORAGE* pStorage);
+protected:
+    Storage();
 
     Storage(const Storage&);
     Storage& operator = (const Storage&);
-
-private:
-    CACHE_STORAGE_API* m_pApi;
-    CACHE_STORAGE*     m_pStorage;
 };
-
-#endif

server/modules/filter/cache/storagefactory.cc

@@ -19,7 +19,8 @@
 #include <maxscale/alloc.h>
 #include <maxscale/gwdirs.h>
 #include <maxscale/log_manager.h>
-#include "storage.h"
+#include "cachefilter.h"
+#include "storagereal.h"
 
 
 namespace
@@ -120,7 +121,7 @@ StorageFactory* StorageFactory::Open(const char* zName)
 
     if (open_cache_storage(zName, &handle, &pApi))
     {
-        pFactory = new (std::nothrow) StorageFactory(handle, pApi);
+        CPP_GUARD(pFactory = new StorageFactory(handle, pApi));
 
         if (!pFactory)
         {
@@ -144,7 +145,7 @@ Storage* StorageFactory::createStorage(cache_thread_model_t model,
 
     if (pRawStorage)
     {
-        pStorage = new (std::nothrow) Storage(m_pApi, pRawStorage);
+        CPP_GUARD(pStorage = new StorageReal(m_pApi, pRawStorage));
 
         if (!pStorage)
         {

server/modules/filter/cache/storagereal.cc

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#define MXS_MODULE_NAME "cache"
+#include "storagereal.h"
+
+
+StorageReal::StorageReal(CACHE_STORAGE_API* pApi, CACHE_STORAGE* pStorage)
+    : m_pApi(pApi)
+    , m_pStorage(pStorage)
+{
+    ss_dassert(m_pApi);
+    ss_dassert(m_pStorage);
+}
+
+StorageReal::~StorageReal()
+{
+}
+
+cache_result_t StorageReal::get_key(const char* zDefaultDb,
+                                const GWBUF* pQuery,
+                                CACHE_KEY* pKey)
+{
+    return m_pApi->getKey(m_pStorage, zDefaultDb, pQuery, pKey);
+}
+
+cache_result_t StorageReal::get_value(const CACHE_KEY& key,
+                                  uint32_t flags,
+                                  GWBUF** ppValue)
+{
+    return m_pApi->getValue(m_pStorage, &key, flags, ppValue);
+}
+
+cache_result_t StorageReal::put_value(const CACHE_KEY& key,
+                                  const GWBUF* pValue)
+{
+    return m_pApi->putValue(m_pStorage, &key, pValue);
+}
+
+cache_result_t StorageReal::del_value(const CACHE_KEY& key)
+{
+    return m_pApi->delValue(m_pStorage, &key);
+}

server/modules/filter/cache/storagereal.h

@@ -0,0 +1,47 @@
+#pragma once
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <maxscale/cdefs.h>
+#include "storage.h"
+
+class StorageReal : public Storage
+{
+public:
+    ~StorageReal();
+
+    cache_result_t get_key(const char* zDefaultDb,
+                           const GWBUF* pQuery,
+                           CACHE_KEY* pKey);
+
+    cache_result_t get_value(const CACHE_KEY& key,
+                             uint32_t flags,
+                             GWBUF** ppValue);
+
+    cache_result_t put_value(const CACHE_KEY& key,
+                             const GWBUF* pValue);
+
+    cache_result_t del_value(const CACHE_KEY& key);
+
+private:
+    friend class StorageFactory;
+
+    StorageReal(CACHE_STORAGE_API* pApi, CACHE_STORAGE* pStorage);
+
+    StorageReal(const StorageReal&);
+    StorageReal& operator = (const StorageReal&);
+
+private:
+    CACHE_STORAGE_API* m_pApi;
+    CACHE_STORAGE*     m_pStorage;
+};