Hi Tels, Thanks a lot for the review!
> "corresponding" Fixed. > Also a question: Some one-line comments are > > /* Comment. */ > > while others are > > /* > * Comment. > */ > > Why the difference? I'm trying to follow a code stile used in a code I'm modifying. In this case I got an impression that second style of one-line comments is used more often an I tried to follow it but apparently I didn't succeed :) This is fixed as well. On Thu, Mar 09, 2017 at 06:40:39PM -0500, Tels wrote: > Hi Aleksander, > > noticed this in your patch: > > > * Add a corespinding entry to pgStatTabHash. > > "corresponding" > > Also a question: Some one-line comments are > > /* Comment. */ > > while others are > > /* > * Comment. > */ > > Why the difference? > > Hope this helps, > > Tels -- Best regards, Aleksander Alekseev
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 7cacb1e9b2..a22a5a37c8 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -161,6 +161,20 @@ typedef struct TabStatusArray
static TabStatusArray *pgStatTabList = NULL;
/*
+ * pgStatTabHash entry
+ */
+typedef struct TabStatHashEntry
+{
+ Oid t_id;
+ PgStat_TableStatus* tsa_entry;
+} TabStatHashEntry;
+
+/*
+ * Hash table for O(1) t_id -> tsa_entry lookup
+ */
+static HTAB *pgStatTabHash = NULL;
+
+/*
* Backends store per-function info that's waiting to be sent to the collector
* in this hash table (indexed by function OID).
*/
@@ -815,7 +829,13 @@ pgstat_report_stat(bool force)
pgstat_send_tabstat(this_msg);
this_msg->m_nentries = 0;
}
+
+ /*
+ * Entry will be zeroed soon so we need to remove it from the lookup table.
+ */
+ hash_search(pgStatTabHash, &entry->t_id, HASH_REMOVE, NULL);
}
+
/* zero out TableStatus structs after use */
MemSet(tsa->tsa_entries, 0,
tsa->tsa_used * sizeof(PgStat_TableStatus));
@@ -1667,59 +1687,77 @@ pgstat_initstats(Relation rel)
}
/*
+ * Make sure pgStatTabList and pgStatTabHash are initialized.
+ */
+static void
+make_sure_stat_tab_initialized()
+{
+ HASHCTL ctl;
+
+ if (pgStatTabList)
+ return;
+
+ Assert(!pgStatTabHash);
+
+ memset(&ctl, 0, sizeof(ctl));
+ ctl.keysize = sizeof(Oid);
+ ctl.entrysize = sizeof(TabStatHashEntry);
+ ctl.hcxt = TopMemoryContext;
+
+ pgStatTabHash = hash_create("pgstat t_id to tsa_entry lookup table",
+ TABSTAT_QUANTUM, &ctl, HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+
+ pgStatTabList = (TabStatusArray *) MemoryContextAllocZero(TopMemoryContext,
+ sizeof(TabStatusArray));
+}
+
+/*
* get_tabstat_entry - find or create a PgStat_TableStatus entry for rel
*/
static PgStat_TableStatus *
get_tabstat_entry(Oid rel_id, bool isshared)
{
+ TabStatHashEntry* hash_entry;
PgStat_TableStatus *entry;
TabStatusArray *tsa;
- TabStatusArray *prev_tsa;
- int i;
+ bool found;
+
+ make_sure_stat_tab_initialized();
+
+ /*
+ * Find an entry or create a new one.
+ */
+ hash_entry = hash_search(pgStatTabHash, &rel_id, HASH_ENTER, &found);
+ if(found)
+ return hash_entry->tsa_entry;
/*
- * Search the already-used tabstat slots for this relation.
+ * `hash_entry` was just created and now we have to fill it.
+ * First make sure there is a free space in a last element of pgStatTabList.
*/
- prev_tsa = NULL;
- for (tsa = pgStatTabList; tsa != NULL; prev_tsa = tsa, tsa = tsa->tsa_next)
+ tsa = pgStatTabList;
+ while(tsa->tsa_used == TABSTAT_QUANTUM)
{
- for (i = 0; i < tsa->tsa_used; i++)
+ if(tsa->tsa_next == NULL)
{
- entry = &tsa->tsa_entries[i];
- if (entry->t_id == rel_id)
- return entry;
+ tsa->tsa_next = (TabStatusArray *) MemoryContextAllocZero(TopMemoryContext,
+ sizeof(TabStatusArray));
}
- if (tsa->tsa_used < TABSTAT_QUANTUM)
- {
- /*
- * It must not be present, but we found a free slot instead. Fine,
- * let's use this one. We assume the entry was already zeroed,
- * either at creation or after last use.
- */
- entry = &tsa->tsa_entries[tsa->tsa_used++];
- entry->t_id = rel_id;
- entry->t_shared = isshared;
- return entry;
- }
+ tsa = tsa->tsa_next;
}
/*
- * We ran out of tabstat slots, so allocate more. Be sure they're zeroed.
- */
- tsa = (TabStatusArray *) MemoryContextAllocZero(TopMemoryContext,
- sizeof(TabStatusArray));
- if (prev_tsa)
- prev_tsa->tsa_next = tsa;
- else
- pgStatTabList = tsa;
-
- /*
- * Use the first entry of the new TabStatusArray.
+ * Add an entry.
*/
entry = &tsa->tsa_entries[tsa->tsa_used++];
entry->t_id = rel_id;
entry->t_shared = isshared;
+
+ /*
+ * Add a corresponding entry to pgStatTabHash.
+ */
+ hash_entry->tsa_entry = entry;
return entry;
}
@@ -1731,22 +1769,19 @@ get_tabstat_entry(Oid rel_id, bool isshared)
PgStat_TableStatus *
find_tabstat_entry(Oid rel_id)
{
- PgStat_TableStatus *entry;
- TabStatusArray *tsa;
- int i;
+ TabStatHashEntry* hash_entry;
- for (tsa = pgStatTabList; tsa != NULL; tsa = tsa->tsa_next)
- {
- for (i = 0; i < tsa->tsa_used; i++)
- {
- entry = &tsa->tsa_entries[i];
- if (entry->t_id == rel_id)
- return entry;
- }
- }
+ /*
+ * There are no entries at all.
+ */
+ if(!pgStatTabHash)
+ return NULL;
- /* Not present */
- return NULL;
+ hash_entry = hash_search(pgStatTabHash, &rel_id, HASH_FIND, NULL);
+ if(!hash_entry)
+ return NULL;
+
+ return hash_entry->tsa_entry;
}
/*
signature.asc
Description: PGP signature
