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Index SLRUs by 64-bit integers rather than by 32-bit integers

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We've had repeated bugs in the area of handling SLRU wraparound in the past,
some of which have caused data loss. Switching to an indexing system for SLRUs
that does not wrap around should allow us to get rid of a whole bunch
of problems and improve the overall reliability of the system.

This particular patch however only changes the indexing and doesn't address
the wraparound per se. This is going to be done in the following patches.

Author: Maxim Orlov, Aleksander Alekseev, Alexander Korotkov, Teodor Sigaev
Author: Nikita Glukhov, Pavel Borisov, Yura Sokolov
Reviewed-by: Jacob Champion, Heikki Linnakangas, Alexander Korotkov
Reviewed-by: Japin Li, Pavel Borisov, Tom Lane, Peter Eisentraut, Andres Freund
Reviewed-by: Andrey Borodin, Dilip Kumar, Aleksander Alekseev
Discussion: https://postgr.es/m/CACG%3DezZe1NQSCnfHOr78AtAZxJZeCvxrts0ygrxYwe%3DpyyjVWA%40mail.gmail.com
Discussion: https://postgr.es/m/CAJ7c6TPDOYBYrnCAeyndkBktO0WG2xSdYduTF0nxq%2BvfkmTF5Q%40mail.gmail.com
This commit is contained in:
Alexander Korotkov
2023-11-29 01:39:55 +02:00
parent a916b47e23
commit 4ed8f0913b
18 changed files with 303 additions and 202 deletions
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20
src/backend/commands/async.c
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@ -196,7 +196,7 @@ typedef struct AsyncQueueEntry
*/
typedef struct QueuePosition
{
int page; /* SLRU page number */
int64 page; /* SLRU page number */
int offset; /* byte offset within page */
} QueuePosition;
@ -443,8 +443,8 @@ static bool tryAdvanceTail = false;
bool Trace_notify = false;
/* local function prototypes */
static int asyncQueuePageDiff(int p, int q);
static bool asyncQueuePagePrecedes(int p, int q);
static int64 asyncQueuePageDiff(int64 p, int64 q);
static bool asyncQueuePagePrecedes(int64 p, int64 q);
static void queue_listen(ListenActionKind action, const char *channel);
static void Async_UnlistenOnExit(int code, Datum arg);
static void Exec_ListenPreCommit(void);
@ -477,10 +477,10 @@ static void ClearPendingActionsAndNotifies(void);
* Compute the difference between two queue page numbers (i.e., p - q),
* accounting for wraparound.
*/
static int
asyncQueuePageDiff(int p, int q)
static int64
asyncQueuePageDiff(int64 p, int64 q)
{
int diff;
int64 diff;
/*
* We have to compare modulo (QUEUE_MAX_PAGE+1)/2. Both inputs should be
@ -504,7 +504,7 @@ asyncQueuePageDiff(int p, int q)
* extant page, we need not assess entries within a page.
*/
static bool
asyncQueuePagePrecedes(int p, int q)
asyncQueuePagePrecedes(int64 p, int64 q)
{
return asyncQueuePageDiff(p, q) < 0;
}
@ -571,7 +571,7 @@ AsyncShmemInit(void)
NotifyCtl->PagePrecedes = asyncQueuePagePrecedes;
SimpleLruInit(NotifyCtl, "Notify", NUM_NOTIFY_BUFFERS, 0,
NotifySLRULock, "pg_notify", LWTRANCHE_NOTIFY_BUFFER,
SYNC_HANDLER_NONE);
SYNC_HANDLER_NONE, false);
if (!found)
{
@ -1336,7 +1336,7 @@ asyncQueueIsFull(void)
static bool
asyncQueueAdvance(volatile QueuePosition *position, int entryLength)
{
int pageno = QUEUE_POS_PAGE(*position);
int64 pageno = QUEUE_POS_PAGE(*position);
int offset = QUEUE_POS_OFFSET(*position);
bool pageJump = false;
@ -1409,7 +1409,7 @@ asyncQueueAddEntries(ListCell *nextNotify)
{
AsyncQueueEntry qe;
QueuePosition queue_head;
int pageno;
int64 pageno;
int offset;
int slotno;