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Commit51384cc

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Add detached node functions to ilist
These allow to test whether an element is in a list by checking whetherprev/next are NULL. Needed to replace SHMQueueIsDetached() when convertingfrom SHM_QUEUE to ilist.h style lists.Reviewed-by: Thomas Munro <thomas.munro@gmail.com>Discussion:https://postgr.es/m/20221120055930.t6kl3tyivzhlrzu2@awork3.anarazel.deDiscussion:https://postgr.es/m/20200211042229.msv23badgqljrdg2@alap3.anarazel.de
1 parent2b16208 commit51384cc

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‎src/include/lib/ilist.h‎

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Original file line numberDiff line numberDiff line change
@@ -316,6 +316,17 @@ dlist_init(dlist_head *head)
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head->head.next=head->head.prev=&head->head;
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}
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/*
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* Initialize a doubly linked list element.
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*
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* This is only needed when dlist_node_is_detached() may be needed.
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*/
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staticinlinevoid
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dlist_node_init(dlist_node*node)
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{
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node->next=node->prev=NULL;
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}
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/*
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* Is the list empty?
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*
@@ -397,6 +408,19 @@ dlist_delete(dlist_node *node)
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node->next->prev=node->prev;
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}
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/*
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* Like dlist_delete(), but also sets next/prev to NULL to signal not being in
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* a list.
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*/
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staticinlinevoid
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dlist_delete_thoroughly(dlist_node*node)
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{
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node->prev->next=node->next;
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node->next->prev=node->prev;
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node->next=NULL;
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node->prev=NULL;
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}
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/*
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* Same as dlist_delete, but performs checks in ILIST_DEBUG builds to ensure
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* that 'node' belongs to 'head'.
@@ -408,6 +432,17 @@ dlist_delete_from(dlist_head *head, dlist_node *node)
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dlist_delete(node);
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}
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/*
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* Like dlist_delete_from, but also sets next/prev to NULL to signal not
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* being in a list.
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*/
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staticinlinevoid
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dlist_delete_from_thoroughly(dlist_head*head,dlist_node*node)
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{
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dlist_member_check(head,node);
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dlist_delete_thoroughly(node);
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}
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/*
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* Remove and return the first node from a list (there must be one).
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*/
@@ -480,6 +515,21 @@ dlist_has_prev(const dlist_head *head, const dlist_node *node)
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returnnode->prev!=&head->head;
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}
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/*
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* Check if node is detached. A node is only detached if it either has been
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* initialized with dlist_init_node(), or deleted with
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* dlist_delete_thoroughly() / dlist_delete_from_thoroughly() /
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* dclist_delete_from_thoroughly().
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*/
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staticinlinebool
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dlist_node_is_detached(constdlist_node*node)
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{
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Assert((node->next==NULL&&node->prev==NULL)||
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(node->next!=NULL&&node->prev!=NULL));
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returnnode->next==NULL;
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}
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/*
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* Return the next node in the list (there must be one).
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*/
@@ -718,6 +768,19 @@ dclist_delete_from(dclist_head *head, dlist_node *node)
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head->count--;
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}
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/*
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* Like dclist_delete_from(), but also sets next/prev to NULL to signal not
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* being in a list.
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*/
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staticinlinevoid
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dclist_delete_from_thoroughly(dclist_head*head,dlist_node*node)
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{
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Assert(head->count>0);
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dlist_delete_from_thoroughly(&head->dlist,node);
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head->count--;
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}
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/*
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* dclist_pop_head_node
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*Remove and return the first node from a list (there must be one).

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