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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2013-07-24 17:42:03 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2013-07-24 17:42:48 -0400 |
| commit | cf707aa70da6729a00593c49d5eb8a35ab27dd11 (patch) | |
| tree | 4cd9953b51727494b4079a4f0969d21915149d43 /src/backend/lib/ilist.c | |
| parent | 4a67a9ac13495d69b4d3b560b63cafda9318b4f4 (diff) | |
| download | postgresql-cf707aa70da6729a00593c49d5eb8a35ab27dd11.tar.gz postgresql-cf707aa70da6729a00593c49d5eb8a35ab27dd11.zip | |
Improve ilist.h's support for deletion of slist elements during iteration.
Previously one had to use slist_delete(), implying an additional scan of
the list, making this infrastructure considerably less efficient than
traditional Lists when deletion of element(s) in a long list is needed.
Modify the slist_foreach_modify() macro to support deleting the current
element in O(1) time, by keeping a "prev" pointer in addition to "cur"
and "next". Although this makes iteration with this macro a bit slower,
no real harm is done, since in any scenario where you're not going to
delete the current list element you might as well just use slist_foreach
instead. Improve the comments about when to use each macro.
Back-patch to 9.3 so that we'll have consistent semantics in all branches
that provide ilist.h. Note this is an ABI break for callers of
slist_foreach_modify().
Andres Freund and Tom Lane
Diffstat (limited to 'src/backend/lib/ilist.c')
| -rw-r--r-- | src/backend/lib/ilist.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/backend/lib/ilist.c b/src/backend/lib/ilist.c index 957a1181227..eb23fa1c687 100644 --- a/src/backend/lib/ilist.c +++ b/src/backend/lib/ilist.c @@ -28,7 +28,7 @@ * * It is not allowed to delete a 'node' which is is not in the list 'head' * - * Caution: this is O(n) + * Caution: this is O(n); consider using slist_delete_current() instead. */ void slist_delete(slist_head *head, slist_node *node) |