Further cleanup of catcache.c ilist changes.

Remove useless duplicate initialization of bucket headers, don't use a
dlist_mutable_iter in a performance-critical path that doesn't need it,
make some other cosmetic changes for consistency's sake.

diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index a293f570e1b28618bd6dd30733f9dfd586cd336b..9ae143272be15acdacb4e30ce03694b3117c89b6 100644 (file)
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -370,6 +370,7 @@ CatCacheRemoveCTup(CatCache *cache, CatCTup *ct)
        return;                 /* nothing left to do */
    }
 
+   /* delink from linked list */
    dlist_delete(&ct->cache_elem);
 
    /* free associated tuple data */
@@ -452,9 +453,9 @@ CatalogCacheIdInvalidate(int cacheId, uint32 hashValue)
     */
    slist_foreach(cache_iter, &CacheHdr->ch_caches)
    {
+       CatCache   *ccp = slist_container(CatCache, cc_next, cache_iter.cur);
        Index       hashIndex;
        dlist_mutable_iter iter;
-       CatCache   *ccp = slist_container(CatCache, cc_next, cache_iter.cur);
 
        if (cacheId != ccp->id)
            continue;
@@ -555,7 +556,7 @@ AtEOXact_CatCache(bool isCommit)
    {
        slist_iter  cache_iter;
 
-       slist_foreach(cache_iter, &(CacheHdr->ch_caches))
+       slist_foreach(cache_iter, &CacheHdr->ch_caches)
        {
            CatCache   *ccp = slist_container(CatCache, cc_next, cache_iter.cur);
            dlist_iter  iter;
@@ -682,7 +683,7 @@ CatalogCacheFlushCatalog(Oid catId)
 
    CACHE2_elog(DEBUG2, "CatalogCacheFlushCatalog called for %u", catId);
 
-   slist_foreach(iter, &(CacheHdr->ch_caches))
+   slist_foreach(iter, &CacheHdr->ch_caches)
    {
        CatCache   *cache = slist_container(CatCache, cc_next, iter.cur);
 
@@ -770,8 +771,10 @@ InitCatCache(int id,
 
    /*
     * allocate a new cache structure
+    *
+    * Note: we rely on zeroing to initialize all the dlist headers correctly
     */
-   cp = (CatCache *) palloc0(sizeof(CatCache) + nbuckets * sizeof(dlist_node));
+   cp = (CatCache *) palloc0(sizeof(CatCache) + nbuckets * sizeof(dlist_head));
 
    /*
     * initialize the cache's relation information for the relation
@@ -790,9 +793,6 @@ InitCatCache(int id,
    for (i = 0; i < nkeys; ++i)
        cp->cc_key[i] = key[i];
 
-   dlist_init(&cp->cc_lists);
-   MemSet(&cp->cc_bucket, 0, nbuckets * sizeof(dlist_head));
-
    /*
     * new cache is initialized as far as we can go for now. print some
     * debugging information, if appropriate.
@@ -1060,7 +1060,7 @@ SearchCatCache(CatCache *cache,
    ScanKeyData cur_skey[CATCACHE_MAXKEYS];
    uint32      hashValue;
    Index       hashIndex;
-   dlist_mutable_iter  iter;
+   dlist_iter  iter;
    dlist_head *bucket;
    CatCTup    *ct;
    Relation    relation;
@@ -1094,10 +1094,12 @@ SearchCatCache(CatCache *cache,
 
    /*
     * scan the hash bucket until we find a match or exhaust our tuples
+    *
+    * Note: it's okay to use dlist_foreach here, even though we modify the
+    * dlist within the loop, because we don't continue the loop afterwards.
     */
    bucket = &cache->cc_bucket[hashIndex];
-
-   dlist_foreach_modify(iter, bucket)
+   dlist_foreach(iter, bucket)
    {
        bool        res;
 
@@ -1382,6 +1384,9 @@ SearchCatCacheList(CatCache *cache,
 
    /*
     * scan the items until we find a match or exhaust our list
+    *
+    * Note: it's okay to use dlist_foreach here, even though we modify the
+    * dlist within the loop, because we don't continue the loop afterwards.
     */
    dlist_foreach(iter, &cache->cc_lists)
    {
@@ -1807,11 +1812,11 @@ PrepareToInvalidateCacheTuple(Relation relation,
     * ----------------
     */
 
-   slist_foreach(iter, &(CacheHdr->ch_caches))
+   slist_foreach(iter, &CacheHdr->ch_caches)
    {
+       CatCache   *ccp = slist_container(CatCache, cc_next, iter.cur);
        uint32      hashvalue;
        Oid         dbid;
-       CatCache   *ccp = slist_container(CatCache, cc_next, iter.cur);
 
        if (ccp->cc_reloid != reloid)
            continue;