Source/WebCore/Modules/webdatabase/SQLTransactionBackend.h

/*
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#ifndef SQLTransactionBackend_h
#define SQLTransactionBackend_h

#if ENABLE(SQL_DATABASE)

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

namespace WebCore {

class AbstractSQLTransaction;
class DatabaseBackend;
class OriginLock;
class SQLError;
class SQLiteTransaction;
class SQLStatementBackend;
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 SQLTransactionStateMachine<SQLTransactionBackend>, public AbstractSQLTransactionBackend {
public:
    static PassRefPtr<SQLTransactionBackend> create(DatabaseBackend*,
        PassRefPtr<AbstractSQLTransaction>, PassRefPtr<SQLTransactionWrapper>, bool readOnly);

    virtual ~SQLTransactionBackend();

    void lockAcquired();
    void performNextStep();

#if PLATFORM(IOS)
    bool shouldPerformWhilePaused() const;
#endif

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

private:
    SQLTransactionBackend(DatabaseBackend*, PassRefPtr<AbstractSQLTransaction>,
        PassRefPtr<SQLTransactionWrapper>, bool readOnly);

    // APIs called from the frontend published via AbstractSQLTransactionBackend:
    virtual void requestTransitToState(SQLTransactionState) override;
    virtual PassRefPtr<SQLError> transactionError() override;
    virtual AbstractSQLStatement* currentStatement() override;
    virtual void setShouldRetryCurrentStatement(bool) override;
    virtual void executeSQL(std::unique_ptr<AbstractSQLStatement>, const String& statement,
        const Vector<SQLValue>& arguments, int permissions) override;

    void doCleanup();

    void enqueueStatementBackend(PassRefPtr<SQLStatementBackend>);

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

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

    SQLTransactionState unreachableState();
    SQLTransactionState sendToFrontendState();

    SQLTransactionState nextStateForCurrentStatementError();
    SQLTransactionState nextStateForTransactionError();
    SQLTransactionState runCurrentStatementAndGetNextState();

    void getNextStatement();

    void acquireOriginLock();
    void releaseOriginLockIfNeeded();

    RefPtr<AbstractSQLTransaction> m_frontend; // Has a reference cycle, and will break in doCleanup().
    RefPtr<SQLStatementBackend> m_currentStatementBackend;

    RefPtr<DatabaseBackend> 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;

    Mutex m_statementMutex;
    Deque<RefPtr<SQLStatementBackend>> m_statementQueue;

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

} // namespace WebCore

#endif

#endif // SQLTransactionBackend_h