added createMetadataDb to IStorageFactory + implementations

Former-commit-id: a2acf75484d2af93aad9d03a20bd402893044860

src/IStorage.h

@@ -9,6 +9,7 @@ public:
 
     virtual ~IStorageFactory() {}
     virtual class IStorage *create(int db, key_load_iterator itr, void *privdata) = 0;
+    virtual class IStorage *createMetadataDb() = 0;
     virtual const char *name() const = 0;
     virtual size_t totalDiskspaceUsed() const = 0;
     virtual bool FSlow() const = 0;

src/server.cpp

@@ -3984,6 +3984,10 @@ void initServer(void) {
     slowlogInit();
     latencyMonitorInit();
 
+    if (g_pserver->m_pstorageFactory) {
+        g_pserver->metadataDb = g_pserver->m_pstorageFactory->createMetadataDb();
+    }
+
     /* We have to initialize storage providers after the cluster has been initialized */
     for (int idb = 0; idb < cserver.dbnum; ++idb)
     {

src/server.h

@@ -2170,6 +2170,7 @@ struct redisServer {
     mode_t umask;               /* The umask value of the process on startup */
     std::atomic<int> hz;        /* serverCron() calls frequency in hertz */
     int in_fork_child;          /* indication that this is a fork child */
+    IStorage *metadataDb = nullptr;
     redisDb **db = nullptr;
     dict *commands;             /* Command table */
     dict *orig_commands;        /* Command table before command renaming. */

src/storage/rocksdbfactor_internal.h

@@ -14,6 +14,7 @@ public:
     ~RocksDBStorageFactory();
 
     virtual IStorage *create(int db, key_load_iterator iter, void *privdata) override;
+    virtual IStorage *createMetadataDb() override;
     virtual const char *name() const override;
 
     virtual size_t totalDiskspaceUsed() const override;

src/storage/rocksdbfactory.cpp

@@ -32,6 +32,7 @@ IStorageFactory *CreateRocksDBStorageFactory(const char *path, int dbnum, const
 RocksDBStorageFactory::RocksDBStorageFactory(const char *dbfile, int dbnum, const char *rgchConfig, size_t cchConfig)
     : m_path(dbfile)
 {
+    dbnum++; // create an extra db for metadata
     // Get the count of column families in the actual database
     std::vector<std::string> vecT;
     auto status = rocksdb::DB::ListColumnFamilies(rocksdb::Options(), dbfile, &vecT);
@@ -134,6 +135,11 @@ std::string RocksDBStorageFactory::getTempFolder()
     return path;
 }
 
+IStorage *RocksDBStorageFactory::createMetadataDb()
+{
+    return this->create(-1, nullptr, nullptr);
+}
+
 IStorage *RocksDBStorageFactory::create(int db, key_load_iterator iter, void *privdata)
 {
     ++db;   // skip default col family

src/storage/teststorageprovider.cpp

@@ -6,6 +6,11 @@ IStorage *TestStorageFactory::create(int, key_load_iterator, void *)
     return new (MALLOC_LOCAL) TestStorageProvider();
 }
 
+IStorage *TestStorageFactory::createMetadataDb()
+{
+    return new (MALLOC_LOCAL) TestStorageProvider();
+}
+
 const char *TestStorageFactory::name() const
 {
     return "TEST Storage Provider";

src/storage/teststorageprovider.h

@@ -5,6 +5,7 @@
 class TestStorageFactory : public IStorageFactory
 {
     virtual class IStorage *create(int db, key_load_iterator itr, void *privdata) override;
+    virtual class IStorage *createMetadataDb() override;
     virtual const char *name() const override;
     virtual size_t totalDiskspaceUsed() const override { return 0; }
     virtual bool FSlow() const { return false; }