mirror of https://github.com/postgres/postgres
Prior to commit 7882c3b0b9, it was
possible to use LWLocks within DSM segments, but that commit broke
this use case by switching from a doubly linked list to a circular
linked list. Switch back, using a new bit of general infrastructure
for maintaining lists of PGPROCs.
Thomas Munro, reviewed by me.
pull/31/head
Robert Haas
9 years ago
parent
2bf06f7561
commit
b25b6c9701
@ -0,0 +1,154 @@ |
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/*-------------------------------------------------------------------------
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* |
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* proclist.h |
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* operations on doubly-linked lists of pgprocnos |
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* |
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* The interface is similar to dlist from ilist.h, but uses pgprocno instead |
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* of pointers. This allows proclist_head to be mapped at different addresses |
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* in different backends. |
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* |
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* See proclist_types.h for the structs that these functions operate on. They |
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* are separated to break a header dependency cycle with proc.h. |
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* |
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* Portions Copyright (c) 2016, PostgreSQL Global Development Group |
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* |
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* IDENTIFICATION |
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* src/include/storage/proclist.h |
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*------------------------------------------------------------------------- |
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*/ |
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#ifndef PROCLIST_H |
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#define PROCLIST_H |
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#include "storage/proc.h" |
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#include "storage/proclist_types.h" |
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/*
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* Initialize a proclist. |
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*/ |
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static inline void |
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proclist_init(proclist_head *list) |
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{ |
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list->head = list->tail = INVALID_PGPROCNO; |
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} |
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/*
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* Is the list empty? |
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*/ |
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static inline bool |
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proclist_is_empty(proclist_head *list) |
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{ |
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return list->head == INVALID_PGPROCNO; |
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} |
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/*
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* Get a pointer to a proclist_node inside a given PGPROC, given a procno and |
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* an offset. |
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*/ |
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static inline proclist_node * |
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proclist_node_get(int procno, size_t node_offset) |
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{ |
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char *entry = (char *) GetPGProcByNumber(procno); |
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return (proclist_node *) (entry + node_offset); |
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} |
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/*
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* Insert a node at the beginning of a list. |
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*/ |
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static inline void |
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proclist_push_head_offset(proclist_head *list, int procno, size_t node_offset) |
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{ |
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proclist_node *node = proclist_node_get(procno, node_offset); |
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if (list->head == INVALID_PGPROCNO) |
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{ |
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Assert(list->tail == INVALID_PGPROCNO); |
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node->next = node->prev = INVALID_PGPROCNO; |
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list->head = list->tail = procno; |
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} |
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else |
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{ |
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Assert(list->tail != INVALID_PGPROCNO); |
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node->next = list->head; |
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proclist_node_get(node->next, node_offset)->prev = procno; |
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node->prev = INVALID_PGPROCNO; |
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list->head = procno; |
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} |
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} |
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/*
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* Insert a node a the end of a list. |
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*/ |
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static inline void |
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proclist_push_tail_offset(proclist_head *list, int procno, size_t node_offset) |
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{ |
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proclist_node *node = proclist_node_get(procno, node_offset); |
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if (list->tail == INVALID_PGPROCNO) |
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{ |
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Assert(list->head == INVALID_PGPROCNO); |
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node->next = node->prev = INVALID_PGPROCNO; |
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list->head = list->tail = procno; |
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} |
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else |
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{ |
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Assert(list->head != INVALID_PGPROCNO); |
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node->prev = list->tail; |
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proclist_node_get(node->prev, node_offset)->next = procno; |
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node->next = INVALID_PGPROCNO; |
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list->tail = procno; |
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} |
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} |
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/*
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* Delete a node. The node must be in the list. |
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*/ |
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static inline void |
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proclist_delete_offset(proclist_head *list, int procno, size_t node_offset) |
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{ |
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proclist_node *node = proclist_node_get(procno, node_offset); |
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if (node->prev == INVALID_PGPROCNO) |
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list->head = node->next; |
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else |
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proclist_node_get(node->prev, node_offset)->next = node->next; |
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if (node->next == INVALID_PGPROCNO) |
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list->tail = node->prev; |
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else |
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proclist_node_get(node->next, node_offset)->prev = node->prev; |
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} |
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/*
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* Helper macros to avoid repetition of offsetof(PGPROC, <member>). |
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* 'link_member' is the name of a proclist_node member in PGPROC. |
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*/ |
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#define proclist_delete(list, procno, link_member) \ |
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proclist_delete_offset((list), (procno), offsetof(PGPROC, link_member)) |
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#define proclist_push_head(list, procno, link_member) \ |
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proclist_push_head_offset((list), (procno), offsetof(PGPROC, link_member)) |
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#define proclist_push_tail(list, procno, link_member) \ |
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proclist_push_tail_offset((list), (procno), offsetof(PGPROC, link_member)) |
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/*
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* Iterate through the list pointed at by 'lhead', storing the current |
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* position in 'iter'. 'link_member' is the name of a proclist_node member in |
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* PGPROC. Access the current position with iter.cur. |
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* |
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* The only list modification allowed while iterating is deleting the current |
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* node with proclist_delete(list, iter.cur, node_offset). |
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*/ |
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#define proclist_foreach_modify(iter, lhead, link_member) \ |
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for (AssertVariableIsOfTypeMacro(iter, proclist_mutable_iter), \
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AssertVariableIsOfTypeMacro(lhead, proclist_head *), \
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(iter).cur = (lhead)->head, \
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(iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
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proclist_node_get((iter).cur, \
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offsetof(PGPROC, link_member))->next; \
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(iter).cur != INVALID_PGPROCNO; \
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(iter).cur = (iter).next, \
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(iter).next = (iter).cur == INVALID_PGPROCNO ? INVALID_PGPROCNO : \
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proclist_node_get((iter).cur, \
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offsetof(PGPROC, link_member))->next) |
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#endif |
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@ -0,0 +1,45 @@ |
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/*-------------------------------------------------------------------------
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* |
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* proclist_types.h |
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* doubly-linked lists of pgprocnos |
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* |
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* See proclist.h for functions that operate on these types. |
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* |
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* Portions Copyright (c) 2016, PostgreSQL Global Development Group |
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* |
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* IDENTIFICATION |
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* src/include/storage/proclist_types.h |
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*------------------------------------------------------------------------- |
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*/ |
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#ifndef PROCLIST_TYPES_H |
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#define PROCLIST_TYPES_H |
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/*
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* A node in a list of processes. |
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*/ |
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typedef struct proclist_node |
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{ |
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int next; /* pgprocno of the next PGPROC */ |
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int prev; /* pgprocno of the prev PGPROC */ |
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} proclist_node; |
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/*
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* Head of a doubly-linked list of PGPROCs, identified by pgprocno. |
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*/ |
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typedef struct proclist_head |
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{ |
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int head; /* pgprocno of the head PGPROC */ |
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int tail; /* pgprocno of the tail PGPROC */ |
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} proclist_head; |
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/*
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* List iterator allowing some modifications while iterating. |
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*/ |
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typedef struct proclist_mutable_iter |
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{ |
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int cur; /* pgprocno of the current PGPROC */ |
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int next; /* pgprocno of the next PGPROC */ |
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} proclist_mutable_iter; |
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#endif |
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