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/*-------------------------------------------------------------------------
*
* proclist.h
* operations on doubly-linked lists of pgprocnos
*
* The interface is similar to dlist from ilist.h, but uses pgprocno instead
* of pointers. This allows proclist_head to be mapped at different addresses
* in different backends.
*
* See proclist_types.h for the structs that these functions operate on. They
* are separated to break a header dependency cycle with proc.h.
*
* Portions Copyright (c) 2016, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/include/storage/proclist.h
*-------------------------------------------------------------------------
*/
#ifndef PROCLIST_H
#define PROCLIST_H
#include "storage/proc.h"
#include "storage/proclist_types.h"
/*
* Initialize a proclist.
*/
static inline void
proclist_init(proclist_head *list)
{
list->head = list->tail = INVALID_PGPROCNO;
}
/*
* Is the list empty?
*/
static inline bool
proclist_is_empty(proclist_head *list)
{
return list->head == INVALID_PGPROCNO;
}
/*
* Get a pointer to a proclist_node inside a given PGPROC, given a procno and
* an offset.
*/
static inline proclist_node *
proclist_node_get(int procno, size_t node_offset)
{
char *entry = (char *) GetPGProcByNumber(procno);
return (proclist_node *) (entry + node_offset);
}
/*
* Insert a node at the beginning of a list.
*/
static inline void
proclist_push_head_offset(proclist_head *list, int procno, size_t node_offset)
{
proclist_node *node = proclist_node_get(procno, node_offset);
if (list->head == INVALID_PGPROCNO)
{
Assert(list->tail == INVALID_PGPROCNO);
node->next = node->prev = INVALID_PGPROCNO;
list->head = list->tail = procno;
}
else
{
Assert(list->tail != INVALID_PGPROCNO);
node->next = list->head;
proclist_node_get(node->next, node_offset)->prev = procno;
node->prev = INVALID_PGPROCNO;
list->head = procno;
}
}
/*
* Insert a node a the end of a list.
*/
static inline void
proclist_push_tail_offset(proclist_head *list, int procno, size_t node_offset)
{
proclist_node *node = proclist_node_get(procno, node_offset);
if (list->tail == INVALID_PGPROCNO)
{
Assert(list->head == INVALID_PGPROCNO);
node->next = node->prev = INVALID_PGPROCNO;
list->head = list->tail = procno;
}
else
{
Assert(list->head != INVALID_PGPROCNO);
node->prev = list->tail;
proclist_node_get(node->prev, node_offset)->next = procno;
node->next = INVALID_PGPROCNO;
list->tail = procno;
}
}
/*
* Delete a node. The node must be in the list.
*/
static inline void
proclist_delete_offset(proclist_head *list, int procno, size_t node_offset)
{
proclist_node *node = proclist_node_get(procno, node_offset);
if (node->prev == INVALID_PGPROCNO)
list->head = node->next;
else
proclist_node_get(node->prev, node_offset)->next = node->next;
if (node->next == INVALID_PGPROCNO)
list->tail = node->prev;
else
proclist_node_get(node->next, node_offset)->prev = node->prev;
}
/*
* Helper macros to avoid repetition of offsetof(PGPROC, <member>).
* 'link_member' is the name of a proclist_node member in PGPROC.
*/
#define proclist_delete(list, procno, link_member) \
proclist_delete_offset((list), (procno), offsetof(PGPROC, link_member))
#define proclist_push_head(list, procno, link_member) \
proclist_push_head_offset((list), (procno), offsetof(PGPROC, link_member))
#define proclist_push_tail(list, procno, link_member) \
proclist_push_tail_offset((list), (procno), offsetof(PGPROC, link_member))
/*
* Iterate through the list pointed at by 'lhead', storing the current
* position in 'iter'. 'link_member' is the name of a proclist_node member in
* PGPROC. Access the current position with iter.cur.
*
* The only list modification allowed while iterating is deleting the current
* node with proclist_delete(list, iter.cur, node_offset).
*/
#define proclist_foreach_modify(iter, lhead, link_member) \
for (AssertVariableIsOfTypeMacro(iter, proclist_mutable_iter), \
AssertVariableIsOfTypeMacro(lhead, proclist_head *), \
(iter).cur = (lhead)->head, \
(iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
proclist_node_get((iter).cur, \
offsetof(PGPROC, link_member))->next; \
(iter).cur != INVALID_PGPROCNO; \
(iter).cur = (iter).next, \
(iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
proclist_node_get((iter).cur, \
offsetof(PGPROC, link_member))->next)
#endif
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