Source/WebCore/Modules/webdatabase/SQLTransactionBackend.h

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#ifndef SQLTransactionBackend_h
#define SQLTransactionBackend_h

#include "DatabaseBasicTypes.h"
#include "SQLTransactionStateMachine.h"
#include <memory>
#include <wtf/Deque.h>
#include <wtf/Forward.h>
#include <wtf/Lock.h>
#include <wtf/text/WTFString.h>

namespace WebCore {

class Database;
class OriginLock;
class SQLError;
class SQLiteTransaction;
class SQLStatement;
class SQLTransaction;
class SQLTransactionBackend;
class SQLValue;

class SQLTransactionWrapper : public ThreadSafeRefCounted<SQLTransactionWrapper> {
public:
    virtual ~SQLTransactionWrapper() { }
    virtual bool performPreflight(SQLTransactionBackend*) = 0;
    virtual bool performPostflight(SQLTransactionBackend*) = 0;
    virtual SQLError* sqlError() const = 0;
    virtual void handleCommitFailedAfterPostflight(SQLTransactionBackend*) = 0;
};

class SQLTransactionBackend : public ThreadSafeRefCounted<SQLTransactionBackend>, public SQLTransactionStateMachine<SQLTransactionBackend> {
public:
    static Ref<SQLTransactionBackend> create(Database*, PassRefPtr<SQLTransaction>, PassRefPtr<SQLTransactionWrapper>, bool readOnly);

    virtual ~SQLTransactionBackend();

    void lockAcquired();
    void performNextStep();

    Database* database() { return m_database.get(); }
    bool isReadOnly() { return m_readOnly; }
    void notifyDatabaseThreadIsShuttingDown();

    // APIs called from the frontend published via SQLTransactionBackend:
    void requestTransitToState(SQLTransactionState);
    PassRefPtr<SQLError> transactionError();
    SQLStatement* currentStatement();
    void setShouldRetryCurrentStatement(bool);
    void executeSQL(std::unique_ptr<SQLStatement>);
    
private:
    SQLTransactionBackend(Database*, PassRefPtr<SQLTransaction>, PassRefPtr<SQLTransactionWrapper>, bool readOnly);

    void doCleanup();

    void enqueueStatementBackend(std::unique_ptr<SQLStatement>);

    // State Machine functions:
    virtual StateFunction stateFunctionFor(SQLTransactionState) override;
    void computeNextStateAndCleanupIfNeeded();

    // State functions:
    void acquireLock();
    void openTransactionAndPreflight();
    void runStatements();
    void cleanupAndTerminate();
    void cleanupAfterTransactionErrorCallback();

    NO_RETURN_DUE_TO_ASSERT void unreachableState();

    void getNextStatement();
    bool runCurrentStatement();
    void handleCurrentStatementError();
    void handleTransactionError();
    void postflightAndCommit();

    void acquireOriginLock();
    void releaseOriginLockIfNeeded();

    RefPtr<SQLTransaction> m_frontend; // Has a reference cycle, and will break in doCleanup().
    std::unique_ptr<SQLStatement> m_currentStatementBackend;

    RefPtr<Database> m_database;
    RefPtr<SQLTransactionWrapper> m_wrapper;
    RefPtr<SQLError> m_transactionError;

    bool m_hasCallback;
    bool m_hasSuccessCallback;
    bool m_hasErrorCallback;
    bool m_shouldRetryCurrentStatement;
    bool m_modifiedDatabase;
    bool m_lockAcquired;
    bool m_readOnly;
    bool m_hasVersionMismatch;

    Lock m_statementMutex;
    Deque<std::unique_ptr<SQLStatement>> m_statementQueue;

    std::unique_ptr<SQLiteTransaction> m_sqliteTransaction;
    RefPtr<OriginLock> m_originLock;
};

} // namespace WebCore

#endif // SQLTransactionBackend_h