From 65d31997461adff86f191e2842413b0b07181432 Mon Sep 17 00:00:00 2001 From: Kirk McKusick Date: Tue, 16 Aug 2016 17:07:48 +0000 Subject: [PATCH] Add two new macros, SLIST_CONCAT and LIST_CONCAT. Note in both the queue.h header file and in the queue.3 manual page that they are O(n) so should be used only in low-usage paths with short lists (otherwise an STAILQ or TAILQ should be used). Reviewed by: kib --- share/man/man3/queue.3 | 42 +++++++++++++++++++++++++++++++++++++++++- sys/sys/queue.h | 38 ++++++++++++++++++++++++++++++++++++-- 2 files changed, 77 insertions(+), 3 deletions(-) diff --git a/share/man/man3/queue.3 b/share/man/man3/queue.3 index 87cfc8bd6ea9..1023c65a5640 100644 --- a/share/man/man3/queue.3 +++ b/share/man/man3/queue.3 @@ -28,12 +28,13 @@ .\" @(#)queue.3 8.2 (Berkeley) 1/24/94 .\" $FreeBSD$ .\" -.Dd June 24, 2015 +.Dd August 15, 2016 .Dt QUEUE 3 .Os .Sh NAME .Nm SLIST_CLASS_ENTRY , .Nm SLIST_CLASS_HEAD , +.Nm SLIST_CONCAT , .Nm SLIST_EMPTY , .Nm SLIST_ENTRY , .Nm SLIST_FIRST , @@ -75,6 +76,7 @@ .Nm STAILQ_SWAP , .Nm LIST_CLASS_ENTRY , .Nm LIST_CLASS_HEAD , +.Nm LIST_CONCAT , .Nm LIST_EMPTY , .Nm LIST_ENTRY , .Nm LIST_FIRST , @@ -125,6 +127,7 @@ lists and tail queues .\" .Fn SLIST_CLASS_ENTRY "CLASSTYPE" .Fn SLIST_CLASS_HEAD "HEADNAME" "CLASSTYPE" +.Fn SLIST_CONCAT "SLIST_HEAD *head1" "SLIST_HEAD *head2" "TYPE" "SLIST_ENTRY NAME" .Fn SLIST_EMPTY "SLIST_HEAD *head" .Fn SLIST_ENTRY "TYPE" .Fn SLIST_FIRST "SLIST_HEAD *head" @@ -168,6 +171,7 @@ lists and tail queues .\" .Fn LIST_CLASS_ENTRY "CLASSTYPE" .Fn LIST_CLASS_HEAD "HEADNAME" "CLASSTYPE" +.Fn LIST_CONCAT "LIST_HEAD *head1" "LIST_HEAD *head2" "TYPE" "LIST_ENTRY NAME" .Fn LIST_EMPTY "LIST_HEAD *head" .Fn LIST_ENTRY "TYPE" .Fn LIST_FIRST "LIST_HEAD *head" @@ -249,6 +253,8 @@ Singly-linked lists add the following functionality: .Bl -enum -compact -offset indent .It O(n) removal of any entry in the list. +.It +O(n) concatenation of two lists. .El .Pp Singly-linked tail queues add the following functionality: @@ -296,6 +302,8 @@ Linked lists are the simplest of the doubly linked data structures. They add the following functionality over the above: .Bl -enum -compact -offset indent .It +O(n) concatenation of two lists. +.It They may be traversed backwards. .El However: @@ -401,6 +409,19 @@ evaluates to an initializer for the list .Fa head . .Pp The macro +.Nm SLIST_CONCAT +concatenates the list headed by +.Fa head2 +onto the end of the one headed by +.Fa head1 +removing all entries from the former. +Use of this macro should be avoided as it traverses the entirety of the +.Fa head1 +list. +A singly-linked tail queue should be used if this macro is needed in +high-usage code paths or to operate on long lists. +.Pp +The macro .Nm SLIST_EMPTY evaluates to true if there are no elements in the list. .Pp @@ -508,6 +529,9 @@ The macro removes the element .Fa elm from the list. +Use of this macro should be avoided as it traverses the entire list. +A doubly-linked list should be used if this macro is needed in +high-usage code paths or to operate on long lists. .Pp The macro .Nm SLIST_SWAP @@ -724,6 +748,9 @@ The macro removes the element .Fa elm from the tail queue. +Use of this macro should be avoided as it traverses the entire list. +A doubly-linked tail queue should be used if this macro is needed in +high-usage code paths or to operate on long tail queues. .Pp The macro .Nm STAILQ_SWAP @@ -823,6 +850,19 @@ evaluates to an initializer for the list .Fa head . .Pp The macro +.Nm LIST_CONCAT +concatenates the list headed by +.Fa head2 +onto the end of the one headed by +.Fa head1 +removing all entries from the former. +Use of this macro should be avoided as it traverses the entirety of the +.Fa head1 +list. +A tail queue should be used if this macro is needed in +high-usage code paths or to operate on long lists. +.Pp +The macro .Nm LIST_EMPTY evaluates to true if there are no elements in the list. .Pp diff --git a/sys/sys/queue.h b/sys/sys/queue.h index 1be9e9cc737d..f26c492af1c7 100644 --- a/sys/sys/queue.h +++ b/sys/sys/queue.h @@ -76,6 +76,10 @@ * * For details on the use of these macros, see the queue(3) manual page. * + * Below is a summary of implemented functions where: + * + means the macro is available + * - means the macro is not available + * s means the macro is available but is slow (runs in O(n) time) * * SLIST LIST STAILQ TAILQ * _HEAD + + + + @@ -101,10 +105,10 @@ * _INSERT_BEFORE - + - + * _INSERT_AFTER + + + + * _INSERT_TAIL - - + + - * _CONCAT - - + + + * _CONCAT s s + + * _REMOVE_AFTER + - + - * _REMOVE_HEAD + - + - - * _REMOVE + + + + + * _REMOVE s + s + * _SWAP + + + + * */ @@ -183,6 +187,19 @@ struct { \ /* * Singly-linked List functions. */ +#define SLIST_CONCAT(head1, head2, type, field) do { \ + QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \ + if (curelm == NULL) { \ + if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \ + SLIST_INIT(head2); \ + } else if (SLIST_FIRST(head2) != NULL) { \ + while (SLIST_NEXT(curelm, field) != NULL) \ + curelm = SLIST_NEXT(curelm, field); \ + SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \ + SLIST_INIT(head2); \ + } \ +} while (0) + #define SLIST_EMPTY(head) ((head)->slh_first == NULL) #define SLIST_FIRST(head) ((head)->slh_first) @@ -447,6 +464,23 @@ struct { \ #define QMD_LIST_CHECK_PREV(elm, field) #endif /* (_KERNEL && INVARIANTS) */ +#define LIST_CONCAT(head1, head2, type, field) do { \ + QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \ + if (curelm == NULL) { \ + if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \ + LIST_FIRST(head2)->field.le_prev = \ + &LIST_FIRST((head1)); \ + LIST_INIT(head2); \ + } \ + } else if (LIST_FIRST(head2) != NULL) { \ + while (LIST_NEXT(curelm, field) != NULL) \ + curelm = LIST_NEXT(curelm, field); \ + LIST_NEXT(curelm, field) = LIST_FIRST(head2); \ + LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \ + LIST_INIT(head2); \ + } \ +} while (0) + #define LIST_EMPTY(head) ((head)->lh_first == NULL) #define LIST_FIRST(head) ((head)->lh_first)