proclist_types.h

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/*-------------------------------------------------------------------------
 *
 * proclist_types.h
 *      doubly-linked lists of pgprocnos
 *
 * See proclist.h for functions that operate on these types.
 *
 * Portions Copyright (c) 2016-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/include/storage/proclist_types.h
 *-------------------------------------------------------------------------
 */
 
#ifndef PROCLIST_TYPES_H
#define PROCLIST_TYPES_H
 
#include "storage/procnumber.h"
 
/*
 * A node in a doubly-linked list of processes.  The link fields contain
 * the 0-based PGPROC indexes of the next and previous process, or
 * INVALID_PROC_NUMBER in the next-link of the last node and the prev-link
 * of the first node.  A node that is currently not in any list
 * should have next == prev == 0; this is not a possible state for a node
 * that is in a list, because we disallow circularity.
 */
typedef struct proclist_node
{
    ProcNumber  next;           /* pgprocno of the next PGPROC */
    ProcNumber  prev;           /* pgprocno of the prev PGPROC */
} proclist_node;
 
/*
 * Header of a doubly-linked list of PGPROCs, identified by pgprocno.
 * An empty list is represented by head == tail == INVALID_PROC_NUMBER.
 */
typedef struct proclist_head
{
    ProcNumber  head;           /* pgprocno of the head PGPROC */
    ProcNumber  tail;           /* pgprocno of the tail PGPROC */
} proclist_head;
 
/*
 * List iterator allowing some modifications while iterating.
 */
typedef struct proclist_mutable_iter
{
    ProcNumber  cur;            /* pgprocno of the current PGPROC */
    ProcNumber  next;           /* pgprocno of the next PGPROC */
} proclist_mutable_iter;
 
#endif                          /* PROCLIST_TYPES_H */