DBConnection.h

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/*!********************************************************************
 
Audacity: A Digital Audio Editor
 
@file DBConnection.h
@brief Declare DBConnection, which maintains database connection and associated status and background thread
 
Paul Licameli -- split from ProjectFileIO.h
 
**********************************************************************/
 
#ifndef __AUDACITY_DB_CONNECTION__
#define __AUDACITY_DB_CONNECTION__
 
#include <atomic>
#include <condition_variable>
#include <functional>
#include <map>
#include <memory>
#include <mutex>
#include <thread>
 
#include "ClientData.h"
#include "Identifier.h"
 
struct sqlite3;
struct sqlite3_stmt;
class wxString;
class AudacityProject;
 
struct DBConnectionErrors
{
   TranslatableString mLastError;
   TranslatableString mLibraryError;
   int mErrorCode { 0 };
   wxString mLog;
};
 
class DBConnection
{
public:
   using CheckpointFailureCallback = std::function<void()>;
 
   DBConnection(
      const std::weak_ptr<AudacityProject> &pProject,
      const std::shared_ptr<DBConnectionErrors> &pErrors,
      CheckpointFailureCallback callback 
   );
   ~DBConnection();
 
   int Open(const FilePath fileName);
   bool Close();
 
   [[noreturn]] void ThrowException(
      bool write 
   ) const;
 
   int SafeMode(const char *schema = "main");
   int FastMode(const char* schema = "main");
   int SetPageSize(const char* schema = "main");
 
   bool Assign(sqlite3 *handle);
   sqlite3 *Detach();
 
   sqlite3 *DB();
 
   int GetLastRC() const ;
   const wxString GetLastMessage() const;
 
   enum StatementID
   {
      GetSamples,
      GetSummary256,
      GetSummary64k,
      LoadSampleBlock,
      InsertSampleBlock,
      DeleteSampleBlock,
      GetSampleBlockSize,
      GetAllSampleBlocksSize
   };
   sqlite3_stmt *Prepare(enum StatementID id, const char *sql);
 
   void SetBypass( bool bypass );
   bool ShouldBypass();
 
   void SetError(
      const TranslatableString &msg,
      const TranslatableString &libraryError = {}, 
      int errorCode = {});
 
   void SetDBError(
      const TranslatableString &msg,
      const TranslatableString& libraryError = {},
      int errorCode = -1);
 
private:
   int OpenStepByStep(const FilePath fileName);
   int ModeConfig(sqlite3 *db, const char *schema, const char *config);
 
   void CheckpointThread(sqlite3 *db, const FilePath &fileName);
   static int CheckpointHook(void *data, sqlite3 *db, const char *schema, int pages);
 
private:
   std::weak_ptr<AudacityProject> mpProject;
   sqlite3 *mDB;
   sqlite3 *mCheckpointDB;
 
   std::thread mCheckpointThread;
   std::condition_variable mCheckpointCondition;
   std::mutex mCheckpointMutex;
   std::atomic_bool mCheckpointStop{ false };
   std::atomic_bool mCheckpointPending{ false };
   std::atomic_bool mCheckpointActive{ false };
 
   std::mutex mStatementMutex;
   using StatementIndex = std::pair<enum StatementID, std::thread::id>;
   std::map<StatementIndex, sqlite3_stmt *> mStatements;
 
   std::shared_ptr<DBConnectionErrors> mpErrors;
   CheckpointFailureCallback mCallback;
 
   // Bypass transactions if database will be deleted after close
   bool mBypass;
};
 
using Connection = std::unique_ptr<DBConnection>;
 
// This object attached to the project simply holds the pointer to the
// project's current database connection, which is initialized on demand,
// and may be redirected, temporarily or permanently, to another connection
// when backing the project up or saving or saving-as.
class ConnectionPtr final
   : public ClientData::Base
   , public std::enable_shared_from_this< ConnectionPtr >
{
public:
   static ConnectionPtr &Get( AudacityProject &project );
   static const ConnectionPtr &Get( const AudacityProject &project );
 
   ~ConnectionPtr() override;
 
   Connection mpConnection;
};
 
#endif