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SqliteDatabase.h
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SqliteDatabase.h
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#pragma once
#include <stddef.h> // for size_t
#include <stdint.h> // for int64_t
#include <mutex> // for mutex
#include <optional> // for optional
#include <stdexcept> // for invalid_argument
#include <string> // for string, allocator
#include <sqlite3.h> // for sqlite3, sqlite3_int64
#include <Sloppy/String.h> // for StringList
#include "Changelog.h" // for ChangeLogList, ChangeLogCallbackContext
#include "Defs.h" // for ConflictClause, OpenMode, TransactionDtor...
#include "SqlStatement.h" // for SqlStatement
namespace SqliteOverlay
{
// a forward definitions
class KeyValueTab;
class Transaction;
// a pseudo-always-false expression for conditional static_asserts
// in templates
template<typename T>
constexpr bool alwaysFalse = false;
// some free functions, mostly for creating SQL strings
/** \brief Creates a column constraint string for CREATE TABLE statements
* according to [this description](https://www.sqlite.org/syntax/column-constraint.html).
*
* Test case: implicit in `addColumn_foreignKey` of `DbTab`
*
* \returns a string with a column constraint clause for use in a CREATE TABLE statement.
*/
std::string buildColumnConstraint(
ConflictClause uniqueConflictClause, ///< unless set to `NotUsed` include a UNIQUE constraint and define what shall happen in violation
ConflictClause notNullConflictClause ///< unless set to `NotUsed` include a NOT NULL constraint and define what shall happen in violation
);
/** \brief Creates a column constraint string for CREATE TABLE statements
* according to [this description](https://www.sqlite.org/syntax/column-constraint.html).
*
* Test case: implicit in `addColumn_foreignKey` of `DbTab`
*
* \returns a string with a column constraint clause for use in a CREATE TABLE statement.
*/
template <typename T>
std::string buildColumnConstraint(
ConflictClause uniqueConflictClause, ///< unless set to `NotUsed` include a UNIQUE constraint and define what shall happen in violation
ConflictClause notNullConflictClause, ///< unless set to `NotUsed` include a NOT NULL constraint and define what shall happen in violation
const T& defaultVal ///< if `true`, we add a placeholder "?" for the default column value
)
{
std::string result = buildColumnConstraint(uniqueConflictClause, notNullConflictClause);
if (!(result.empty())) result += " ";
result += "DEFAULT " + std::to_string(defaultVal);
return result;
}
/** \brief Creates a column constraint string for CREATE TABLE statements
* according to [this description](https://www.sqlite.org/syntax/column-constraint.html).
*
* Test case: implicit in `addColumn_foreignKey` of `DbTab`
*
* \returns a string with a column constraint clause for use in a CREATE TABLE statement.
*/
std::string buildColumnConstraint(
ConflictClause uniqueConflictClause, ///< unless set to `NotUsed` include a UNIQUE constraint and define what shall happen in violation
ConflictClause notNullConflictClause, ///< unless set to `NotUsed` include a NOT NULL constraint and define what shall happen in violation
const std::string& defaulVal ///< if `true`, we add a placeholder "?" for the default column value
);
/** \brief Creates a column constraint string for CREATE TABLE statements
* according to [this description](https://www.sqlite.org/syntax/column-constraint.html).
*
* Test case: implicit in `addColumn_foreignKey` of `DbTab`
*
* \returns a string with a column constraint clause for use in a CREATE TABLE statement.
*/
std::string buildColumnConstraint(
ConflictClause uniqueConflictClause, ///< unless set to `NotUsed` include a UNIQUE constraint and define what shall happen in violation
ConflictClause notNullConflictClause, ///< unless set to `NotUsed` include a NOT NULL constraint and define what shall happen in violation
const char* defaulVal ///< if `true`, we add a placeholder "?" for the default column value
);
//----------------------------------------------------------------------------
/** \brief Creates a foreign key clause for CREATE TABLE statements
* according to [this description](https://www.sqlite.org/syntax/foreign-key-clause.html).
*
* Test case: not yet
*
* \returns a string with a foreign key clause for use in a CREATE TABLE statement.
*/
std::string buildForeignKeyClause(
std::string_view referedTable, ///< the name of the table that this column refers to
ConsistencyAction onDelete, ///< the action to be taken if the refered row is being deleted
ConsistencyAction onUpdate, ///< the action to be taken if the refered row is updated
std::string_view referedColumn="id" ///< the name of the column we're pointing to in the refered table
);
//----------------------------------------------------------------------------
/** \returns the type affinity for a given column type string according to the
* type affinity rules [specified here](https://www.sqlite.org/datatype3.html)
*
* Test case: not yet
*
*/
ColumnAffinity string2Affinity(const std::string& colType);
//----------------------------------------------------------------------------
//
// forward definitions
//
class DbTab;
class Transaction;
//----------------------------------------------------------------------------
/** \brief A class that handles a single database connection.
*
* \note If an instance of this class is shared by multiple threads you have to make sure on
* application level that no bad things happen. From SQLite's perspective, all
* statements are coming in over the same connection, no matter which thread
* actually sent them.
*
* \note This object is not inherently thread-safe. It uses no locking, mutexes
* or other magic before reading/writing its internal state.
*/
class SqliteDatabase
{
public:
/** \brief Default ctor, creates a blank in-memory database.
*
* \note `populateTables()` and `populateViews()` are NOT CALLED from
* this constructor. Since they are virtual methods that should be refined
* by derived classes, the base class ctor is not able to properly call them!
*
* Test case: not yet
*
*/
SqliteDatabase();
/** \brief Standard dtor for creating or opening a database file.
*
* \note `populateTables()` and `populateViews()` are NOT CALLED from
* this constructor. Since they are virtual methods that should be refined
* by derived classes, the base class ctor is not able to properly call them!
*
* \throws std::invalid_argument if the filename is empty or if a
* parameter combination makes no sense (e.g., read-only access to a
* blank in-memory database, force-create an existing file or strict open
* on a non-existing file).
*
* \throws GenericSqliteException incl. error code if anything goes wrong
* with SQLite
*
* Test case: yes
*
*/
SqliteDatabase(
std::string dbFilename, ///< the name of the database file to open or create
OpenMode om ///< the opening mode (e.g., read-only)
);
/** \brief Dtor; closes the database connections and cleans up table cache
*
* Test case: not yet
*
*/
virtual ~SqliteDatabase();
/** \brief Disabled copy ctor */
SqliteDatabase(const SqliteDatabase&) = delete;
/** \brief Disabled copy assignment */
SqliteDatabase& operator=(const SqliteDatabase&) = delete;
/** \brief Move ctor
*
* \warning Do not move database objects (neither as
* source nor target) if they are shared between threads or
* mysterious things might happen.
*
* \note If the changelog was enabled before the move operation
* we try to flawlessly move that over to the new object. But
* this has not been well tested so far. Good luck.
*/
SqliteDatabase(
SqliteDatabase&& other ///< the exising object from we construct a new one
);
/** \brief Move assignment operator
*
* For the possible exceptions see also the description
* of `close()` because internally we call `close()` on
* the existing connection before overwriting it with the
* other connection.
*
* \warning Do not move database objects (neither as
* source nor target) if they are shared between threads or
* mysterious things might happen.
*
* \note If the changelog was enabled before the move operation
* we try to flawlessly move that over to the new object. But
* this has not been well tested so far. Good luck.
*
* \throws BusyException if the target instance could not
* successfully `close()` its connection.
*
* \throws BusyException if the target instance could not
* successfully `close()` its connection.
*
*/
SqliteDatabase& operator=(
SqliteDatabase&& ///< the source that shall be moved
);
/** \brief Closes the database connection. The instance (or any
* dangling references to it) shouldn't be used anymore after calling this function.
*
* \warning Pending transactions will be rolled back by calling `close()`!
*
* \throws BusyException if the database has still un-finalized prepared statements
* or ongoing backup operations pending.
*
* \throws GenericSqliteException if anything else should go wrong.
*
* Test case: partially, as part of the ctor tests
*
*/
void close();
/** \returns `true` if the database connection is still open and `false` otherwise
*
* Test case: partially, as part of the ctor tests
*
*/
bool isAlive() const;
/** \brief Creates a new SQL statement for this database connection
*
* \throws std::invalid_argument if the provided SQL string is empty or if the connection has been closed before calling this method
*
* \throws SqlStatementCreationError if the statement could not be created, most likely due to invalid SQL syntax
*
* \returns a SqlStatement instance for the provided SQL text
*
* Test case: partially, as part of the database query tests
*
*/
SqlStatement prepStatement(
const std::string& sqlText ///< the SQL text for which to create the statement
) const;
/** \brief Executes a SQL statement that isn't expected to return any data.
*
* If the SQL statement consists of multiple steps, all steps are executed
* until the whole statement is finished.
*
* \throws std::invalid_argument if the provided SQL string is empty or if the connection has been closed before calling this method
*
* \throws SqlStatementCreationError if the statement could not be created, most likely due to invalid SQL syntax
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* Test case: implicitly in many other test cases
*
*/
void execNonQuery(
const std::string& sqlStatement ///< the SQL statement to execute
) const;
/** \brief Executes a SQL statement that isn't expected to return any data.
*
* If the SQL statement consists of multiple steps, all steps are executed
* until the whole statement is finished.
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* Test case: implicitly in many other test cases
*
*/
void execNonQuery(
SqlStatement& stmt ///< a prepared statement, ready for execution
) const;
/** \brief Executes a SQL statement that returns arbitrary data
*
* The first call to `step()` of the resulting SqlStatement is already
* executed by this function. Thus, the caller can directly start evaluating
* the first query results.
*
* \throws std::invalid_argument if the provided SQL string is empty or if the connection has been closed before calling this method
*
* \throws SqlStatementCreationError if the statement could not be created, most likely due to invalid SQL syntax
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* Test case: yes, but no exception testing
*
*/
SqlStatement execContentQuery(
const std::string& sqlStatement ///< the SQL statement to execute
) const;
/** \brief Executes a prepared SQL statement by calling `step()` once and returns the value
* in the first of column (index 0) of the returned row; all other rows and columns are ignored.
*
* \note The provided statement is modified in place and can be used in subsequent calls
* to `execScalarQuery` (or other) for retrieving more rows.
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws NoDataException if the SQL statement didn't return any data
*
* \throws NullValueException if the query returned NULL instead of a regular value
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns the first value in the result row as int
*
* Test case: yes, but only with partial exception testing
*
*/
template<typename T>
T execScalarQuery(
SqlStatement& stmt ///< a prepared statement, ready for execution
) const
{
// throws BusyException or GenericSqliteException
stmt.step();
// throws NoDataException
return stmt.get<T>(0);
}
/** \brief Executes a SQL statement by calling `step()` once and returns the value
* in the first of column (index 0) of the returned row; all other rows and columns are ignored.
*
* \note The column should contain a real value and not NULL
*
* \throws std::invalid_argument if the provided SQL string is empty or if the connection has been closed before calling this method
*
* \throws SqlStatementCreationError if the statement could not be created, most likely due to invalid SQL syntax
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws NoDataException if the SQL statement didn't return any data
*
* \throws NullValueException if the query returned NULL instead of a regular value
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns the first value in the first result row as int
*
* Test case: yes, but only with partial exception testing
*
*/
template<typename T>
T execScalarQuery(
const std::string& sqlStatement ///< the SQL statement to execute
) const
{
// throws invalid_argument or SqlStatementCreationError
SqlStatement stmt = prepStatement(sqlStatement);
// throws NoDataException
return execScalarQuery<T>(stmt);
}
/** \brief Executes a prepared SQL statement by calling `step()` once and returns the value
* in the first of column (index 0) of the returned row; all other rows and columns are ignored.
*
* \note The provided statement is modified in place and can be used in subsequent calls
* to `execScalarQuery2` (or other) for retrieving more rows.
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws NoDataException if the SQL statement didn't return any data
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns an `optional<T>` containing the first value in the result row; if the cell
* contained NULL the return value is empty.
*
* Test case: yes, but only with partial exception testing
*
*/
template<typename T>
std::optional<T> execScalarQuery2(
SqlStatement& stmt ///< a prepared statement, ready for execution
) const
{
// throws BusyException or GenericSqliteException
stmt.step();
// throws NoDataException
return stmt.get2<T>(0);
}
/** \brief Executes a SQL statement by calling `step()` once and returns the value
* in the first of column (index 0) of the returned row; all other rows and columns are ignored.
*
* \throws std::invalid_argument if the provided SQL string is empty or if the connection has been closed before calling this method
*
* \throws SqlStatementCreationError if the statement could not be created, most likely due to invalid SQL syntax
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws NoDataException if the SQL statement didn't return any data
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns an `optional<T>` containing the first value in the first result row; if the cell
* contained NULL the return value is empty.
*
* Test case: yes, but only with partial exception testing
*
*/
template<typename T>
std::optional<T> execScalarQuery2(
const std::string& sqlStatement ///< the SQL statement to execute
) const
{
// throws invalid_argument or SqlStatementCreationError
SqlStatement stmt = prepStatement(sqlStatement);
return execScalarQuery2<T>(stmt);
}
/** \brief Switches synchronous writes on or off
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* Test case: not explicitly, but it is called/tested implicitly in the ctor
*
*/
void enforceSynchronousWrites(
bool syncOn ///< `true`: activate sync write, `false`: deactivate sync writes
) const;
/** \brief Hook for derived database classes to fill in their code for populating
* all database tables.
*
* This hook is called whenever a database file is opened or created.
*/
virtual void populateTables() {}
/** \brief Hook for derived database classes to fill in their code for populating
* all database tables.
*
* This hook is called whenever a database file is opened or created.
*/
virtual void populateViews() {}
/** \brief Convenience function for easy creation of new views.
*
* \note If a view of the same name already exists, nothing happens.
*
* See `execNonQuery()` for possible exceptions.
*
* Test case: not yet
*
*/
void viewCreationHelper(
const std::string& viewName, ///< the name for the new view
const std::string& selectStmt ///< the SQL statement that represents the view's contents
) const;
/** \brief Convenience function for creating a new index that combines several columns
* of one table.
*
* If a view of the same name already exists, nothing happens.
*
* If any of the provided arguments (table name, index name, column list) is empty,
* the function returns without error and without doing anything.
*
* \throws NoSuchTableException if no table of the provided name exists
*
* See `execNonQuery()` for other possible exceptions.
*
* Test case: not yet
*
*/
void indexCreationHelper(
const std::string& tabName, ///< the table on which to create the new index
const std::string& idxName, ///< the name of the new index
const Sloppy::StringList& colNames, ///< a list of column names that shall be ANDed for the index
bool isUnique=false ///< determines whether the index shall enforce unique combinations of the column values
) const;
/** \brief Convenience function for creating a new index on a single column
* of one table.
*
* If a view of the same name already exists, nothing happens.
*
* If any of the provided arguments (table name, index name, column name) is empty,
* the function returns without error and without doing anything.
*
* \throws NoSuchTableException if no table of the provided name exists
*
* See `execNonQuery()` for other possible exceptions.
*
* Test case: not yet
*
*/
void indexCreationHelper(
const std::string& tabName, ///< the table on which to create the new index
const std::string& idxName, ///< the name of the new index
const std::string& colName, ///< the name of the column which should serve as an index
bool isUnique=false ///< determines whether the index shall enforce unique column values
) const;
/** \brief Convenience function for creating a new index with a canonically created name
* on a single column of one table.
*
* If a view of the same name already exists, nothing happens.
*
* If any of the provided arguments (table name, index name, column name) is empty,
* the function returns without error and without doing anything.
*
* \throws NoSuchTableException if no table of the provided name exists
*
* See `execNonQuery()` for other possible exceptions.
*
* Test case: not yet
*
*/
void indexCreationHelper(
const std::string& tabName, ///< the table on which to create the new index
const std::string& colName, ///< the name of the column which should serve as an index
bool isUnique=false ///< determines whether the index shall enforce unique column values
) const;
/** \returns a list of names of all tables or views in the DB
*
* Test case: yes
*
*/
Sloppy::StringList allTableNames(
bool getViews=false ///< `false`: get table names (default); `true`: get view names
) const;
/** \returns a list of names of all views in the DB
*
* Test case: yes
*
*/
Sloppy::StringList allViewNames() const;
/** \returns `true` if a table or view of the given name exists in the database
*
* Test case: implicitly in `StmtBlob` and also explicitly
*
*/
bool hasTable(
const std::string& name, ///< the name to search for (case-sensitive)
bool isView=false ///< `false`: search among all tables (default); `true`: search among all views
) const;
/** \returns `true` if a view of the given name exists in the database
*
* Test case: yes
*
*/
bool hasView(
const std::string& name ///< the name to search for (case-sensitive)
) const;
/** \returns the ID of the last inserted row
*
* See also [here](https://www.sqlite.org/c3ref/last_insert_rowid.html)
*
* Test case: yes
*
*/
int getLastInsertId() const;
/** \returns the number of rows modified, inserted or deleted by the most recently completed INSERT, UPDATE or DELETE statement
*
* See also [here](https://www.sqlite.org/c3ref/changes.html)
*
* Test case: yes
*
*/
int getRowsAffected() const;
/** \returns `true` if the database is in autocommit mode (read: no active transaction running), `false` otherwise.
*
* See also [here](https://www.sqlite.org/c3ref/get_autocommit.html)
*
* Test case: yes, included in the transaction tests
*
*/
bool isAutoCommit() const;
/** \brief Starts a new (and possibly nested) transaction on the database.
*
* The transaction is automatically finished when the transaction object's dtor is called.
*
* \throws BusyException if the DB was busy and the required lock could not be acquired
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns A new transaction object.
*
* Test case: yes
*
*/
Transaction startTransaction(
TransactionType tt=TransactionType::Immediate, ///< the type of transaction, see [here](https://www.sqlite.org/lang_transaction.html)
TransactionDtorAction _dtorAct = TransactionDtorAction::Rollback ///< what to do when the dtor is called
) const;
/** \brief Copies structure and, optionally, content of an exising table
* into a newly created table.
*
* The source table must exist and a table with the name of the destination table
* may not be existing.
*
* \throws BusyException if the statement couldn't be executed because the DB was busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns `true` if the operation was successful and `false` if it failed or if the
* parameters where invalid
*
* Test case: yes, but only happy path
*
*/
bool copyTable(
const std::string& srcTabName, ///< name of the source table for the copy-operation
const std::string& dstTabName, ///< name of the destination table (may not yet exist)
bool copyStructureOnly=false ///< `true`: copy on the table structure/schema; `false`: deep copy the table's contents
) const;
/** \brief Copies the content of whole database to a file on disk
*
* \note Only the `main` database is copied, not any attached database.
*
* \warning All content of the destination file will be overwritten!
*
* \throws std::invalid_argument if the provided destination file name is empty
*
* \throws BusyException if the source (the caller) or destination database (the filename) is busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns almost always `true` because most errors should be caught by exceptions; if `true`, the backup
* is guaranteed to be successful
*
* Test case: yes, but only happy path
*
*/
bool backupToFile(
const std::string& dstFileName ///< the name of the database file to copy the contents to
) const;
/** \brief Copies the content of a database file into the current database
*
* \note Only the `main` database is restored, not any attached database.
*
* \warning All content of the database will be overwritten!
*
* \throws std::invalid_argument if the provided source file name is empty
*
* \throws BusyException if the source (the caller) or destination database (the filename) is busy
*
* \throws GenericSqliteException incl. error code if anything else goes wrong
*
* \returns almost always `true` because most errors should be caught by exceptions; if `true`, the backup
* is guaranteed to be successful
*
* Test case: yes, but only happy path
*
*/
bool restoreFromFile(
const std::string& srcFileName ///< the name of the database file to read from
);
/** \returns `true` if the database contents have been modified by this or any other database connection
*
* Test case: yes
*
*/
bool isDirty() const;
/** \brief Resets the internal "dirty flag", so that only future modifications will be reported by
* `isDirty()`. This call resets the flags for all local and global/external changes.
*
* Test case: yes
*
*/
void resetDirtyFlag();
/** \returns the total number of rows inserted, modified or deleted by all INSERT,
* UPDATE or DELETE statements completed since the database connection was opened
*
* \note Modifications caused by other database connections are *not* reported
* by this call!
*
* Test case: yes
*
*/
int getLocalChangeCounter_total() const;
/** \brief Resets the internal flag for local data changes (local = on this connection);
* this does not affect the flag for external data changes through other connections.
*
* Test case: yes
*
*/
void resetLocalChangeCounter();
/** \returns `true` if the database contents have been modified by this database connection since
* the last call to `resetLocalChangeCounter()` (or since opening the connection, resp.); modifications
* applied through other connections are not reported here.
*
* Test case: yes
*
*/
bool hasLocalChanges() const;
/** \brief Resets the internal flag for external data changes (external = other than on this connection);
* this does not affect the flag for local data changes through this connections.
*
* Test case: yes
*
*/
void resetExternalChangeCounter();
/** \returns `true` if the database contents have been modified by other connections since
* the last call to `resetExternalChangeCounter()` (or since opening the connection, resp.); modifications
* applied through this connection are not reported here.
*
* Test case: yes
*
*/
bool hasExternalChanges() const;
/** \brief Sets a callback function that is called by SQLite whenever
* the database is modified.
*
* See also [here](https://www.sqlite.org/c3ref/update_hook.html)
*
* \returns the custom data pointer that was previously set or nullptr if there was none
*/
void* setDataChangeNotificationCallback(
void(*)(void*, int, const char*, const char*, sqlite3_int64), ///< the pointer to the callback function
void* customPtr ///< a pointer that will be passed to the callback function
);
/** \returns the current number of entries in the changelog
*/
size_t getChangeLogLength();
/** \returns all entries in the changelog and clears the log afterwards
*/
ChangeLogList getAllChangesAndClearQueue();
/** \brief Enables a built-in callback function that implements a simple
* changelog.
*
* \note This overrides any previously set callback function, e.g. when
* using `setDataChangeNotificationCallback` with a user-provided function.
*/
void enableChangeLog(
bool clearLog ///< indicates wheter the internal change log shall be cleared before activating the logging
);
/** \brief Disables any change log callback functions.
*/
void disableChangeLog(
bool clearLog ///< indicates wheter the internal change log shall be cleared after disabling the logging
);
/** \brief Defines the timeout for requests if the database is locked by another
* process (more precisely: another database connection); see [here](https://www.sqlite.org/c3ref/busy_timeout.html)
* for details.
*
* After the timeout has elapsed and the database has not become available,
* SQLite return SQLITE_BUSY which is translated
* into a BusyException. While waiting for the timeout, the triggering call blocks.
*
* Test case: not yet
*
*/
void setBusyTimeout(
int ms ///< the timeout in milliseconds; if less or equal to 0, we don't wait an throw BusyException immediately
);
/** \brief Creates a new SqliteDatabase object that works on the same database
* file as the current connection.
*
* The result is similar to calling the SqliteDatabase ctor with the database's
* filename. However, we do not call `populateTables()` or `populateViews()` on the new connection
* because we assume that the schema has been fully set up before.
*
* \note Only the main database ("main") will be cloned, not any other attached
* database.
*
* \throws std::invalid_argument if this method was called on a temporary or an
* in-memory database
*
* \throws GenericSqliteException incl. error code if anything goes wrong
* with SQLite
*
* \returns a new SqliteDatabase instance that works on the same database file
* as the current instance
*
* Test case: not yet
*
*/
template<class DB_CLASS = SqliteDatabase>
DB_CLASS duplicateConnection(
bool readOnly ///< `true`: open the new connection in read-only mode; `false`: open in r/w mode
)
{
static_assert (std::is_base_of_v<SqliteDatabase, DB_CLASS>);
std::string fn = filename();
if (fn.empty())
{
throw std::invalid_argument("duplicateConnection(): called on a temporary or in-memory database");
}
OpenMode om = readOnly ? OpenMode::OpenExisting_RO : OpenMode::OpenExisting_RW;
return DB_CLASS{fn, om};
}
/** \brief Function for creating a new, empty key-value-table in the database
*
* \throws std::invalid_argument if the provided table name is empty or already in use
*
* \returns a KeyValueTab instance for the newly created table
*/
KeyValueTab createNewKeyValueTab(
const std::string& tabName ///< the table name
);
/** \returns a string containing the path to the database file (empty for in-memory databases)
*
* \note Only the path for the main database ("main") will be returned! Other attached
* databases are ignored!
*
* Test case: implicitly as part of the `operator==()` and of `duplicateConnection()`
*/
std::string filename() const;
/** \brief Overloaded operator for "is equal", compares the path
* to the database file and the raw `sqlite3*` handle.
*
* If the values of the `sqlite3*` handles are identical, we
* return `true`. In all other cases, we compare the file paths
* of the underlying database files.
*
* \note The check applies only to the main database ("main"). Attached databases
* are ignored for this check.
*
* Test case: yes
*/
bool operator==(const SqliteDatabase& other) const;
/** \brief Overloaded operator for "is not equal", compares the path
* to the database file and the raw `sqlite3*` handle.
*
* \note The check applies only to the main database ("main"). Attached databases
* are ignored for this check.
*
* Test case: yes
*/
bool operator!=(const SqliteDatabase& other) const;
protected:
/** \brief Copies the contents of the source database into the destination database,
* original documentation of the backup process [here](https://www.sqlite.org/c3ref/backup_finish.html)
*
* \note Only the `main` database is copied, not any attached database.
*
* \warning All content of the destination database will be overwritten!
*
* \throws std::invalid_argument if source or destination database are `nullptr`
*
* \throws std::invalid_argument if source and destination are identical
*
* \throws BusyException if the destination database is busy and cannot be written
*
* \throws GenericSqliteException incl. error code (especially SQLITE_READONLY!) if anything else goes wrong
*
* \returns almost always `true` because most errors should be caught by exceptions; if `true`, the backup
* is guaranteed to be successful
*
* Test case: yes, but only happy path
*
*/
static bool copyDatabaseContents(
sqlite3* srcHandle, ///< the raw SQLite handle of the source database
sqlite3* dstHandle ///< the raw SQLite handle of the destination database
);
/**
* \brief the internal database handle
*/
sqlite3* dbPtr{nullptr};
// handling of a "dirty flag" that indicates whether the database has changed
// after a certain point in time
int localChangeCounter_resetValue; // used for calls to sqlite3_total_changes(), reporting changes on the local connection
int externalChangeCounter_resetValue; // used for calls to "PRAGMA data_version" which reports changes other than on the local connection
// a queue of changes
bool isChangeLogEnabled{false};
ChangeLogList changeLog;
std::mutex changeLogMutex;
ChangeLogCallbackContext logCallbackContext;
};
}