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// Copyright (C) 2016-2023 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef PGSQL_CONNECTION_H
#define PGSQL_CONNECTION_H
#include <asiolink/io_service.h>
#include <pgsql/pgsql_exchange.h>
#include <boost/scoped_ptr.hpp>
#include <vector>
#include <stdint.h>
namespace isc {
namespace db {
/// @brief Define the PostgreSQL backend version.
const uint32_t PGSQL_SCHEMA_VERSION_MAJOR = 18;
const uint32_t PGSQL_SCHEMA_VERSION_MINOR = 0;
// Maximum number of parameters that can be used a statement
// @todo This allows us to use an initializer list (since we can't
// require C++11). It's unlikely we'd go past this many a single
// statement.
const size_t PGSQL_MAX_PARAMETERS_IN_QUERY = 128;
/// @brief Define a PostgreSQL statement.
///
/// Each statement is associated with an index, which is used to reference the
/// associated prepared statement.
struct PgSqlTaggedStatement {
/// Number of parameters for a given query
int nbparams;
/// @brief OID types
///
/// Specify parameter types. See /usr/include/postgresql/catalog/pg_type.h.
/// For some reason that header does not export those parameters.
/// Those OIDs must match both input and output parameters.
const Oid types[PGSQL_MAX_PARAMETERS_IN_QUERY];
/// Short name of the query.
const char* name;
/// Text representation of the actual query.
const char* text;
};
/// @{
/// @brief Constants for PostgreSQL data types
/// These are defined by PostgreSQL in <catalog/pg_type.h>, but including
/// this file is extraordinarily convoluted, so we'll use these to fill-in.
/// @{
const size_t OID_NONE = 0; // PostgreSQL infers proper type
const size_t OID_BOOL = 16;
const size_t OID_BYTEA = 17;
const size_t OID_INT8 = 20; // 8 byte int
const size_t OID_INT2 = 21; // 2 byte int
const size_t OID_INT4 = 23; // 4 byte int
const size_t OID_TEXT = 25;
const size_t OID_VARCHAR = 1043;
const size_t OID_TIMESTAMP = 1114;
/// @}
/// @brief Postgresql connection handle Holder
///
/// Small RAII object for safer initialization, will close the database
/// connection upon destruction. This means that if an exception is thrown
/// during database initialization, resources allocated to the database are
/// guaranteed to be freed.
///
/// It makes no sense to copy an object of this class. After the copy, both
/// objects would contain pointers to the same PgSql context object. The
/// destruction of one would invalid the context in the remaining object.
/// For this reason, the class is declared noncopyable.
class PgSqlHolder : public boost::noncopyable {
public:
/// @brief Constructor
///
/// Sets the Postgresql API connector handle to NULL.
///
PgSqlHolder() : pgconn_(NULL) {
}
/// @brief Destructor
///
/// Frees up resources allocated by the connection.
~PgSqlHolder() {
if (pgconn_ != NULL) {
PQfinish(pgconn_);
}
}
/// @brief Sets the connection to the value given
///
/// @param connection - pointer to the Postgresql connection instance
void setConnection(PGconn* connection) {
if (pgconn_ != NULL) {
// Already set? Release the current connection first.
// Maybe this should be an error instead?
PQfinish(pgconn_);
}
pgconn_ = connection;
}
/// @brief Conversion Operator
///
/// Allows the PgSqlHolder object to be passed as the context argument to
/// PQxxxx functions.
operator PGconn*() const {
return (pgconn_);
}
/// @brief Boolean Operator
///
/// Allows testing the connection for emptiness: "if (holder)"
operator bool() const {
return (pgconn_);
}
private:
PGconn* pgconn_; ///< Postgresql connection
};
/// @brief Forward declaration to @ref PgSqlConnection.
class PgSqlConnection;
/// @brief RAII object representing a PostgreSQL transaction.
///
/// An instance of this class should be created in a scope where multiple
/// INSERT statements should be executed within a single transaction. The
/// transaction is started when the constructor of this class is invoked.
/// The transaction is ended when the @ref PgSqlTransaction::commit is
/// explicitly called or when the instance of this class is destroyed.
/// The @ref PgSqlTransaction::commit commits changes to the database.
/// If the class instance is destroyed before @ref PgSqlTransaction::commit
/// has been called, the transaction is rolled back. The rollback on
/// destruction guarantees that partial data is not stored in the database
/// when an error occurs during any of the operations within a transaction.
///
/// By default PostgreSQL performs a commit following each statement which
/// alters the database (i.e. "autocommit"). Starting a transaction
/// stops autocommit for the connection until the transaction is ended by
/// either commit or rollback. Other connections are unaffected.
class PgSqlTransaction : public boost::noncopyable {
public:
/// @brief Constructor.
///
/// Starts transaction by executing the SQL statement: "START TRANSACTION"
///
/// @param conn PostgreSQL connection to use for the transaction. This
/// connection will be later used to commit or rollback changes.
///
/// @throw DbOperationError if statement execution fails
PgSqlTransaction(PgSqlConnection& conn);
/// @brief Destructor.
///
/// If the transaction has not been committed, it is rolled back
/// by executing the SQL statement: "ROLLBACK"
///
/// @throw DbOperationError if statement execution fails
~PgSqlTransaction();
/// @brief Commits transaction.
///
/// Commits all changes made during the transaction by executing the
/// SQL statement: "COMMIT"
///
/// @throw DbOperationError if statement execution fails
void commit();
private:
/// @brief Holds reference to the PostgreSQL database connection.
PgSqlConnection& conn_;
/// @brief Boolean flag indicating if the transaction has been committed.
///
/// This flag is used in the class destructor to assess if the
/// transaction should be rolled back.
bool committed_;
};
/// @brief Common PgSql Connector Pool
///
/// This class provides common operations for PgSql database connection
/// used by both PgSqlLeaseMgr and PgSqlHostDataSource. It manages connecting
/// to the database and preparing compiled statements. Its fields are
/// public, because they are used (both set and retrieved) in classes
/// that use instances of PgSqlConnection.
class PgSqlConnection : public db::DatabaseConnection {
public:
/// @brief Define the PgSql error state for a duplicate key error.
static const char DUPLICATE_KEY[];
/// @brief Define the PgSql error state for a null foreign key error.
static const char NULL_KEY[];
/// @brief Function invoked to process fetched row.
typedef std::function<void(PgSqlResult&, int)> ConsumeResultRowFun;
/// @brief Emit the TLS support warning only once.
static bool warned_about_tls;
/// @brief Constructor
///
/// Initialize PgSqlConnection object with parameters needed for connection.
///
/// @param parameters Specify the connection details.
/// @param io_accessor The IOService accessor function.
/// @param callback The connection recovery callback.
PgSqlConnection(const ParameterMap& parameters,
IOServiceAccessorPtr io_accessor = IOServiceAccessorPtr(),
DbCallback callback = DbCallback())
: DatabaseConnection(parameters, callback),
io_service_accessor_(io_accessor), io_service_(),
transaction_ref_count_(0) {
}
/// @brief Destructor
virtual ~PgSqlConnection();
/// @brief Get the schema version.
///
/// @param parameters A data structure relating keywords and values
/// concerned with the database.
///
/// @return Version number as a pair of unsigned integers. "first" is the
/// major version number, "second" the minor number.
///
/// @throw isc::db::DbOperationError An operation on the open database has
/// failed.
static std::pair<uint32_t, uint32_t>
getVersion(const ParameterMap& parameters);
/// @brief Prepare Single Statement
///
/// Creates a prepared statement from the text given and adds it to the
/// statements_ vector at the given index.
///
/// @param statement SQL statement to be prepared.
///
/// @throw isc::db::DbOperationError An operation on the open database has
/// failed.
void prepareStatement(const PgSqlTaggedStatement& statement);
/// @brief Prepare statements
///
/// Creates the prepared statements for all of the SQL statements used
/// by the PostgreSQL backend.
///
/// @param start_statement Pointer to the first statement in range of the
/// statements to be compiled.
/// @param end_statement Pointer to the statement marking end of the
/// range of statements to be compiled. This last statement is not compiled.
///
/// @throw isc::db::DbOperationError An operation on the open database has
/// failed.
void prepareStatements(const PgSqlTaggedStatement* start_statement,
const PgSqlTaggedStatement* end_statement);
/// @brief Creates connection string from specified parameters.
///
/// This function is called from the unit tests.
///
/// @return connection string for @c openDatabase.
/// @throw NoDatabaseName Mandatory database name not given
/// @throw DbInvalidTimeout when the database timeout is wrong.
std::string getConnParameters();
private:
/// @brief Creates connection string from the specified parameters.
///
/// This is an internal implementation of the @c getConnParameters that
/// allows for controlling logging. In some cases, a caller can disable
/// logging warnings to avoid duplication of the log messages emitted
/// when the invocation is a result of calling @c getVersion before
/// opening the connection for the normal server operation.
///
/// @param logging boolean parameter controlling if logging should be
/// enabled (when true) or disabled (when false).
///
/// @return connection string for @c openDatabase.
/// @throw NoDatabaseName Mandatory database name not given
/// @throw DbInvalidTimeout when the database timeout is wrong.
std::string getConnParametersInternal(bool logging);
public:
/// @brief Open database with logging.
///
/// Opens the database using the information supplied in the parameters
/// passed to the constructor. It logs warnings resulting from the
/// @c getConnParameters.
///
/// @throw NoDatabaseName Mandatory database name not given
/// @throw DbOpenError Error opening the database
void openDatabase();
private:
/// @brief Internal implementation of the database opening.
///
/// It allows for controlling if the @c getConnParameterInternal function
/// should log the warnings.
///
/// @param logging boolean parameter controlling if logging should be
/// enabled (when true) or disabled (when false).
///
/// @throw NoDatabaseName Mandatory database name not given
/// @throw DbOpenError Error opening the database
void openDatabaseInternal(bool logging);
public:
/// @brief Starts new transaction
///
/// This function begins a new transaction by sending the START TRANSACTION
/// statement to the database. The transaction should be explicitly committed
/// by calling @c commit() or rolled back by calling @c rollback().
///
/// PostgreSQL does not support nested transactions directly. Issuing a
/// START TRANSACTION while already in a transaction will cause a warning to
/// be emitted but otherwise does not alter the state of the current transaction.
/// In other words, the transaction will still end upon the next COMMIT or
/// ROLLBACK statement.
///
/// Therefore, this function checks if a transaction has already started and
/// does not start a new transaction. However, it increments a transaction
/// reference counter which is later decremented when @c commit() or @c
/// rollback() is called. When this mechanism is used properly, it
/// guarantees that nested transactions are not attempted, thus avoiding
/// unexpected commits or rollbacks of the pending transaction.
void startTransaction();
/// @brief Checks if there is a transaction in progress.
///
/// @return true if a transaction has been started, false otherwise.
bool isTransactionStarted() const;
/// @brief Commits current transaction
///
/// Commits all pending database operations. On databases that don't
/// support transactions, this is a no-op.
///
/// When this method is called for a nested transaction it decrements the
/// transaction reference counter incremented during the call to
/// @c startTransaction.
///
/// @throw DbOperationError If the commit failed.
void commit();
/// @brief Rollbacks current transaction
///
/// Rolls back all pending database operations. On databases that don't
/// support transactions, this is a no-op.
///
/// When this method is called for a nested transaction it decrements the
/// transaction reference counter incremented during the call to
/// @c startTransaction.
///
/// @throw DbOperationError If the rollback failed.
void rollback();
/// @brief Creates a savepoint within the current transaction
///
/// Creates a named savepoint within the current transaction.
///
/// @param name name of the savepoint to create.
///
/// @throw InvalidOperation if called outside a transaction.
/// @throw DbOperationError If the savepoint cannot be created.
void createSavepoint(const std::string& name);
/// @brief Rollbacks to the given savepoint
///
/// Rolls back all pending database operations made after the
/// named savepoint.
///
/// @param name name of the savepoint to which to rollback.
///
/// @throw InvalidOperation if called outside a transaction.
/// @throw DbOperationError if the rollback failed.
void rollbackToSavepoint(const std::string& name);
/// @brief Executes the an SQL statement.
///
/// It executes the given SQL text after first checking the
/// connection for usability. After the statement is executed
/// @c checkStatementError() is invoked to ensure we detect
/// connectivity issues properly.
/// It is intended to be used to execute utility statements such
/// as commit, rollback et al, which have no parameters, return no
/// results, and are not pre-compiled.
///
/// @param sql SQL statement to execute.
void executeSQL(const std::string& sql);
/// @brief Checks a result set's SQL state against an error state.
///
/// @param r result set to check
/// @param error_state error state to compare against
///
/// @return True if the result set's SQL state equals the error_state,
/// false otherwise.
bool compareError(const PgSqlResult& r, const char* error_state);
/// @brief Checks result of the r object
///
/// This function is used to determine whether or not the SQL statement
/// execution succeeded, and in the event of failures, decide whether or
/// not the failures are recoverable.
///
/// If the error is recoverable, the function will throw a DbOperationError.
/// If the error is deemed unrecoverable, such as a loss of connectivity
/// with the server, the function will call startRecoverDbConnection() which
/// will start the connection recovery.
///
/// If the invocation returns true, this indicates the calling layer will
/// attempt recovery, and the function throws a DbOperationError to allow
/// the caller to error handle the failed db access attempt.
///
/// @param r result of the last PostgreSQL operation
/// @param statement - tagged statement that was executed
///
/// @throw isc::db::DbOperationError Detailed PostgreSQL failure
void checkStatementError(const PgSqlResult& r,
PgSqlTaggedStatement& statement);
/// @brief The recover connection
///
/// This function starts the recover process of the connection.
///
/// @note The recover function must be run on the IO Service thread.
void startRecoverDbConnection() {
if (callback_) {
if (!io_service_ && io_service_accessor_) {
io_service_ = (*io_service_accessor_)();
io_service_accessor_.reset();
}
if (io_service_) {
io_service_->post(std::bind(callback_, reconnectCtl()));
}
}
}
/// @brief Executes a prepared SQL statement.
///
/// It executes the given prepared SQL statement, after checking
/// for usability and input parameter sanity. After the statement
/// is executed @c checkStatementError() is invoked to ensure we detect
/// connectivity issues properly. Upon successful execution, the
/// the result set is returned. It may be used for any form of
/// prepared SQL statement (e.g query, insert, update, delete...),
/// with or without input parameters.
///
/// @param statement PgSqlTaggedStatement describing the prepared
/// statement to execute.
/// @param in_bindings array of input parameter bindings. If the SQL
/// statement requires no input arguments, this parameter should either
/// be omitted or an empty PsqlBindArray should be supplied.
/// @throw InvalidOperation if the number of parameters expected
/// by the statement does not match the size of the input bind array.
PgSqlResultPtr executePreparedStatement(PgSqlTaggedStatement& statement,
const PsqlBindArray& in_bindings
= PsqlBindArray());
/// @brief Executes SELECT query using prepared statement.
///
/// The statement parameter refers to an existing prepared statement
/// associated with the connection. The @c in_bindings size must match
/// the number of placeholders in the prepared statement.
///
/// This method executes prepared statement using provided input bindings and
/// calls @c process_result_row function for each returned row. The
/// @c process_result_row function is implemented by the caller and should
/// gather and store each returned row in an external data structure prior.
///
/// @param statement reference to the precompiled tagged statement to execute
/// @param in_bindings input bindings holding values to substitue placeholders
/// in the query.
/// @param process_result_row Pointer to the function to be invoked for each
/// retrieved row. This function consumes the retrieved data from the
/// result set.
void selectQuery(PgSqlTaggedStatement& statement,
const PsqlBindArray& in_bindings,
ConsumeResultRowFun process_result_row);
/// @brief Executes INSERT prepared statement.
///
/// The @c statement must refer to an existing prepared statement
/// associated with the connection. The @c in_bindings size must match
/// the number of placeholders in the prepared statement.
///
/// This method executes prepared statement using provided bindings to
/// insert data into the database.
///
/// @param statement reference to the precompiled tagged statement to execute
/// @param in_bindings input bindings holding values to substitue placeholders
/// in the query.
void insertQuery(PgSqlTaggedStatement& statement,
const PsqlBindArray& in_bindings);
/// @brief Executes UPDATE or DELETE prepared statement and returns
/// the number of affected rows.
///
/// The @c statement must refer to an existing prepared statement
/// associated with the connection. The @c in_bindings size must match
/// the number of placeholders in the prepared statement.
///
/// @param statement reference to the precompiled tagged statement to execute
/// @param in_bindings Input bindings holding values to substitute placeholders
/// in the query.
///
/// @return Number of affected rows.
uint64_t updateDeleteQuery(PgSqlTaggedStatement& statement,
const PsqlBindArray& in_bindings);
/// @brief PgSql connection handle
///
/// This field is public, because it is used heavily from PgSqlLeaseMgr
/// and from PgSqlHostDataSource.
PgSqlHolder conn_;
/// @brief Conversion Operator
///
/// Allows the PgConnection object to be passed as the context argument to
/// PQxxxx functions.
operator PGconn*() const {
return (conn_);
}
/// @brief Boolean Operator
///
/// Allows testing the PgConnection for initialized connection
operator bool() const {
return (conn_);
}
private:
/// @brief Convenience function parsing and setting an integer parameter,
/// if it exists.
///
/// If the parameter is not present, this function doesn't change the @c value.
/// Otherwise, it tries to convert the parameter to the type @c T. Finally,
/// it checks if the converted number is within the specified range.
///
/// @param name Parameter name.
/// @param min Expected minimal value.
/// @param max Expected maximal value.
/// @param [out] value Reference to a value returning the parsed parameter.
/// @tparam T Parameter type.
/// @throw BadValue if the parameter is not a valid number or if it is out
/// of range.
template<typename T>
void setIntParameterValue(const std::string& name, int64_t min, int64_t max, T& value);
public:
/// @brief Accessor function which returns the IOService that can be used to
/// recover the connection.
///
/// This accessor is used to lazy retrieve the IOService when the connection
/// is lost. It is useful to retrieve it at a later time to support hook
/// libraries which create managers on load and set IOService later on by
/// using the dhcp4_srv_configured and dhcp6_srv_configured hooks.
IOServiceAccessorPtr io_service_accessor_;
/// @brief IOService object, used for all ASIO operations.
isc::asiolink::IOServicePtr io_service_;
/// @brief Reference counter for transactions.
///
/// It precludes starting and committing nested transactions. PostgreSQL
/// logs but ignores START TRANSACTIONs (or BEGINs) issued from within an
/// ongoing transaction. We do not want to start new transactions when one
/// is already in progress.
int transaction_ref_count_;
};
/// @brief Defines a pointer to a PgSqlConnection
typedef boost::shared_ptr<PgSqlConnection> PgSqlConnectionPtr;
} // end of isc::db namespace
} // end of isc namespace
#endif // PGSQL_CONNECTION_H
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