/*****************************************************************************

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Copyright (c) 2017, 2021, MariaDB Corporation.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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*****************************************************************************/

/**************************************************//**
@file include/que0que.h
Query graph

Created 5/27/1996 Heikki Tuuri
*******************************************************/

#ifndef que0que_h
#define que0que_h

#include "data0data.h"
#include "trx0trx.h"
#include "trx0roll.h"
#include "srv0srv.h"
#include "que0types.h"
#include "row0types.h"
#include "pars0types.h"

/***********************************************************************//**
Creates a query graph fork node.
@return own: fork node */
que_fork_t*
que_fork_create(
/*============*/
	que_t*		graph,		/*!< in: graph, if NULL then this
					fork node is assumed to be the
					graph root */
	que_node_t*	parent,		/*!< in: parent node */
	ulint		fork_type,	/*!< in: fork type */
	mem_heap_t*	heap);		/*!< in: memory heap where created */
/***********************************************************************//**
Gets the first thr in a fork. */
UNIV_INLINE
que_thr_t*
que_fork_get_first_thr(
/*===================*/
	que_fork_t*	fork);	/*!< in: query fork */
/***********************************************************************//**
Gets the child node of the first thr in a fork. */
UNIV_INLINE
que_node_t*
que_fork_get_child(
/*===============*/
	que_fork_t*	fork);	/*!< in: query fork */
/***********************************************************************//**
Sets the parent of a graph node. */
UNIV_INLINE
void
que_node_set_parent(
/*================*/
	que_node_t*	node,	/*!< in: graph node */
	que_node_t*	parent);/*!< in: parent */
/** Creates a query graph thread node.
@param[in]	parent		parent node, i.e., a fork node
@param[in]	heap		memory heap where created
@param[in]	prebuilt	row prebuilt structure
@return own: query thread node */
que_thr_t*
que_thr_create(
	que_fork_t*	parent,
	mem_heap_t*	heap,
	row_prebuilt_t*	prebuilt);
/**********************************************************************//**
Frees a query graph, but not the heap where it was created. Does not free
explicit cursor declarations, they are freed in que_graph_free. */
void
que_graph_free_recursive(
/*=====================*/
	que_node_t*	node);	/*!< in: query graph node */
/**********************************************************************//**
Frees a query graph. */
void
que_graph_free(
/*===========*/
	que_t*	graph);	/*!< in: query graph; we assume that the memory
			heap where this graph was created is private
			to this graph: if not, then use
			que_graph_free_recursive and free the heap
			afterwards! */
/**********************************************************************//**
Stops a query thread if graph or trx is in a state requiring it. The
conditions are tested in the order (1) graph, (2) trx. The lock_sys_t::mutex
has to be reserved.
@return TRUE if stopped */
ibool
que_thr_stop(
/*=========*/
	que_thr_t*	thr);	/*!< in: query thread */

/**********************************************************************//**
A patch for MySQL used to 'stop' a dummy query thread used in MySQL. The
query thread is stopped and made inactive, except in the case where
it was put to the lock wait state in lock0lock.cc, but the lock has already
been granted or the transaction chosen as a victim in deadlock resolution. */
void
que_thr_stop_for_mysql(
/*===================*/
	que_thr_t*	thr);	/*!< in: query thread */
/**********************************************************************//**
Run a query thread. Handles lock waits. */
void
que_run_threads(
/*============*/
	que_thr_t*	thr);	/*!< in: query thread */
/**********************************************************************//**
Moves a suspended query thread to the QUE_THR_RUNNING state and release
a worker thread to execute it. This function should be used to end
the wait state of a query thread waiting for a lock or a stored procedure
completion.
@return query thread instance of thread to wakeup or NULL */
que_thr_t*
que_thr_end_lock_wait(
/*==================*/
	trx_t*		trx);		/*!< in: transaction in the
					QUE_THR_LOCK_WAIT state */
/**********************************************************************//**
Starts execution of a command in a query fork. Picks a query thread which
is not in the QUE_THR_RUNNING state and moves it to that state. If none
can be chosen, a situation which may arise in parallelized fetches, NULL
is returned.
@return a query thread of the graph moved to QUE_THR_RUNNING state, or
NULL; the query thread should be executed by que_run_threads by the
caller */
que_thr_t*
que_fork_start_command(
/*===================*/
	que_fork_t*	fork);	/*!< in: a query fork */
/***********************************************************************//**
Gets the trx of a query thread. */
UNIV_INLINE
trx_t*
thr_get_trx(
/*========*/
	que_thr_t*	thr);	/*!< in: query thread */
/***********************************************************************//**
Gets the type of a graph node. */
UNIV_INLINE
ulint
que_node_get_type(
/*==============*/
	const que_node_t*	node);	/*!< in: graph node */
/***********************************************************************//**
Gets pointer to the value data type field of a graph node. */
UNIV_INLINE
dtype_t*
que_node_get_data_type(
/*===================*/
	que_node_t*	node);	/*!< in: graph node */
/***********************************************************************//**
Gets pointer to the value dfield of a graph node. */
UNIV_INLINE
dfield_t*
que_node_get_val(
/*=============*/
	que_node_t*	node);	/*!< in: graph node */
/***********************************************************************//**
Gets the value buffer size of a graph node.
@return val buffer size, not defined if val.data == NULL in node */
UNIV_INLINE
ulint
que_node_get_val_buf_size(
/*======================*/
	que_node_t*	node);	/*!< in: graph node */
/***********************************************************************//**
Sets the value buffer size of a graph node. */
UNIV_INLINE
void
que_node_set_val_buf_size(
/*======================*/
	que_node_t*	node,	/*!< in: graph node */
	ulint		size);	/*!< in: size */
/*********************************************************************//**
Gets the next list node in a list of query graph nodes. */
UNIV_INLINE
que_node_t*
que_node_get_next(
/*==============*/
	que_node_t*	node);	/*!< in: node in a list */
/*********************************************************************//**
Gets the parent node of a query graph node.
@return parent node or NULL */
UNIV_INLINE
que_node_t*
que_node_get_parent(
/*================*/
	que_node_t*	node);	/*!< in: node */
/****************************************************************//**
Get the first containing loop node (e.g. while_node_t or for_node_t) for the
given node, or NULL if the node is not within a loop.
@return containing loop node, or NULL. */
que_node_t*
que_node_get_containing_loop_node(
/*==============================*/
	que_node_t*	node);	/*!< in: node */
/*********************************************************************//**
Catenates a query graph node to a list of them, possible empty list.
@return one-way list of nodes */
UNIV_INLINE
que_node_t*
que_node_list_add_last(
/*===================*/
	que_node_t*	node_list,	/*!< in: node list, or NULL */
	que_node_t*	node);		/*!< in: node */
/*************************************************************************
Get the last node from the list.*/
UNIV_INLINE
que_node_t*
que_node_list_get_last(
/*===================*/
					/* out: node last node from list.*/
	que_node_t*	node_list);	/* in: node list, or NULL */
/*********************************************************************//**
Gets a query graph node list length.
@return length, for NULL list 0 */
UNIV_INLINE
ulint
que_node_list_get_len(
/*==================*/
	que_node_t*	node_list);	/*!< in: node list, or NULL */
/**********************************************************************//**
Checks if graph, trx, or session is in a state where the query thread should
be stopped.
@return TRUE if should be stopped; NOTE that if the peek is made
without reserving the trx_t::mutex, then another peek with the mutex
reserved is necessary before deciding the actual stopping */
UNIV_INLINE
ibool
que_thr_peek_stop(
/*==============*/
	que_thr_t*	thr);	/*!< in: query thread */
/***********************************************************************//**
Returns TRUE if the query graph is for a SELECT statement.
@return TRUE if a select */
UNIV_INLINE
ibool
que_graph_is_select(
/*================*/
	que_t*		graph);		/*!< in: graph */
/**********************************************************************//**
Prints info of an SQL query graph node. */
void
que_node_print_info(
/*================*/
	que_node_t*	node);	/*!< in: query graph node */
/*********************************************************************//**
Evaluate the given SQL
@return error code or DB_SUCCESS */
dberr_t
que_eval_sql(
/*=========*/
	pars_info_t*	info,	/*!< in: info struct, or NULL */
	const char*	sql,	/*!< in: SQL string */
	bool		reserve_dict_mutex,
				/*!< in: whether to acquire/release
				dict_sys.mutex around call to pars_sql. */
	trx_t*		trx);	/*!< in: trx */

/**********************************************************************//**
Round robin scheduler.
@return a query thread of the graph moved to QUE_THR_RUNNING state, or
NULL; the query thread should be executed by que_run_threads by the
caller */
que_thr_t*
que_fork_scheduler_round_robin(
/*===========================*/
	que_fork_t*	fork,		/*!< in: a query fork */
	que_thr_t*	thr);		/*!< in: current pos */

/** Query thread states */
enum que_thr_state_t {
	QUE_THR_RUNNING,
	/** in selects this means that the thread is at the end of its
	result set (or start, in case of a scroll cursor); in other
	statements, this means the thread has done its task */
	QUE_THR_COMPLETED,
	QUE_THR_COMMAND_WAIT,
	QUE_THR_LOCK_WAIT,
	QUE_THR_SUSPENDED
};

/** Query thread lock states */
enum que_thr_lock_t {
	QUE_THR_LOCK_NOLOCK,
	QUE_THR_LOCK_ROW,
	QUE_THR_LOCK_TABLE
};

/* Query graph query thread node: the fields are protected by the
trx_t::mutex with the exceptions named below */

struct que_thr_t{
	que_common_t	common;		/*!< type: QUE_NODE_THR */
	que_node_t*	child;		/*!< graph child node */
	que_t*		graph;		/*!< graph where this node belongs */
	que_thr_state_t	state;		/*!< state of the query thread */
	bool		is_active;	/*!< whether the thread is active */
	/*------------------------------*/
	/* The following fields are private to the OS thread executing the
	query thread, and are not protected by any mutex: */

	que_node_t*	run_node;	/*!< pointer to the node where the
					subgraph down from this node is
					currently executed */
	que_node_t*	prev_node;	/*!< pointer to the node from which
					the control came */
	ulint		resource;	/*!< resource usage of the query thread
					thus far */
	ulint		lock_state;	/*!< lock state of thread (table or
					row) */
	struct srv_slot_t*
			slot;		/* The thread slot in the wait
					array in srv_sys_t */
	/*------------------------------*/
	/* The following fields are links for the various lists that
	this type can be on. */
	UT_LIST_NODE_T(que_thr_t)
			thrs;		/*!< list of thread nodes of the fork
					node */
	UT_LIST_NODE_T(que_thr_t)
			queue;		/*!< list of runnable thread nodes in
					the server task queue */
	ulint		fk_cascade_depth; /*!< maximum cascading call depth
					supported for foreign key constraint
					related delete/updates */
	row_prebuilt_t*	prebuilt;	/*!< prebuilt structure processed by
					the query thread */

#ifdef UNIV_DEBUG
  /** Change the 'active' status */
  inline void set_active(bool active);
#endif
  /** Transition to the QUE_THR_RUNNING state. */
  inline void start_running()
  {
    ut_d(if (!is_active) set_active(true));
    is_active= true;
    state= QUE_THR_RUNNING;
  }

  /** Stop query execution when there is no error or lock wait. */
  void stop_no_error()
  {
    ut_ad(is_active);
    ut_d(set_active(false));
    state= QUE_THR_COMPLETED;
    is_active= false;
  }
};

/* Query graph fork node: its fields are protected by the query thread mutex */
struct que_fork_t{
	que_common_t	common;		/*!< type: QUE_NODE_FORK */
	que_t*		graph;		/*!< query graph of this node */
	ulint		fork_type;	/*!< fork type */
#ifdef UNIV_DEBUG
  /** For the query graph root, updated in set_active() */
  ulint n_active_thrs;
  /** Change the 'active' status */
  void set_active(bool active);
#endif
	trx_t*		trx;		/*!< transaction: this is set only in
					the root node */
	ulint		state;		/*!< state of the fork node */
	que_thr_t*	caller;		/*!< pointer to a possible calling query
					thread */
	UT_LIST_BASE_NODE_T(que_thr_t)
			thrs;		/*!< list of query threads */
	/*------------------------------*/
	/* The fields in this section are defined only in the root node */
	sym_tab_t*	sym_tab;	/*!< symbol table of the query,
					generated by the parser, or NULL
					if the graph was created 'by hand' */
	pars_info_t*	info;		/*!< info struct, or NULL */

	sel_node_t*	last_sel_node;	/*!< last executed select node, or NULL
					if none */
	UT_LIST_NODE_T(que_fork_t)
			graphs;		/*!< list of query graphs of a session
					or a stored procedure */
	/*------------------------------*/
	mem_heap_t*	heap;		/*!< memory heap where the fork was
					created */

};

#ifdef UNIV_DEBUG
inline void que_thr_t::set_active(bool active) { graph->set_active(active); };
#endif

/* Query fork (or graph) types */
#define QUE_FORK_SELECT_NON_SCROLL	1	/* forward-only cursor */
#define QUE_FORK_SELECT_SCROLL		2	/* scrollable cursor */
#define QUE_FORK_INSERT			3
#define QUE_FORK_UPDATE			4
#define QUE_FORK_ROLLBACK		5
			/* This is really the undo graph used in rollback,
			no signal-sending roll_node in this graph */
#define QUE_FORK_PURGE			6
#define	QUE_FORK_EXECUTE		7
#define QUE_FORK_PROCEDURE		8
#define QUE_FORK_PROCEDURE_CALL		9
#define QUE_FORK_MYSQL_INTERFACE	10
#define	QUE_FORK_RECOVERY		11

/* Query fork (or graph) states */
#define QUE_FORK_ACTIVE		1
#define QUE_FORK_COMMAND_WAIT	2
#define QUE_FORK_INVALID	3
#define QUE_FORK_BEING_FREED	4

/* Flag which is ORed to control structure statement node types */
#define QUE_NODE_CONTROL_STAT	1024

#include "que0que.ic"

#endif