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Ensure that all details of the ARC algorithm are hidden within freelist.c.

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This refactoring does not change any algorithms or data structures, just
remove visibility of the ARC datastructures from other source files.
This commit is contained in:
Tom Lane
2005-02-03 23:29:19 +00:00
parent ad893a361d
commit cc4f58f4cd
4 changed files with 129 additions and 93 deletions
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74
src/backend/storage/buffer/freelist.c
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@@ -3,6 +3,11 @@
* freelist.c
* routines for manipulating the buffer pool's replacement strategy.
*
* The name "freelist.c" is now a bit of a misnomer, since this module
* controls not only the list of free buffers per se, but the entire
* mechanism for looking up existing shared buffers and the strategy
* for choosing replacement victims when needed.
*
* Note: all routines in this file assume that the BufMgrLock is held
* by the caller, so no synchronization is needed.
*
@@ -12,7 +17,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.49 2004/12/31 22:00:49 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.50 2005/02/03 23:29:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -25,6 +30,51 @@
#include "storage/bufmgr.h"
/*
* Definitions for the buffer replacement strategy
*/
#define STRAT_LIST_UNUSED (-1)
#define STRAT_LIST_B1 0
#define STRAT_LIST_T1 1
#define STRAT_LIST_T2 2
#define STRAT_LIST_B2 3
#define STRAT_NUM_LISTS 4
/*
* The Cache Directory Block (CDB) of the Adaptive Replacement Cache (ARC)
*/
typedef struct
{
int prev; /* list links */
int next;
short list; /* ID of list it is currently in */
bool t1_vacuum; /* t => present only because of VACUUM */
TransactionId t1_xid; /* the xid this entry went onto T1 */
BufferTag buf_tag; /* page identifier */
int buf_id; /* currently assigned data buffer, or -1 */
} BufferStrategyCDB;
/*
* The shared ARC control information.
*/
typedef struct
{
int target_T1_size; /* What T1 size are we aiming for */
int listUnusedCDB; /* All unused StrategyCDB */
int listHead[STRAT_NUM_LISTS]; /* ARC lists B1, T1, T2
* and B2 */
int listTail[STRAT_NUM_LISTS];
int listSize[STRAT_NUM_LISTS];
Buffer listFreeBuffers; /* List of unused buffers */
long num_lookup; /* Some hit statistics */
long num_hit[STRAT_NUM_LISTS];
time_t stat_report;
/* Array of CDB's starts here */
BufferStrategyCDB cdb[1]; /* VARIABLE SIZE ARRAY */
} BufferStrategyControl;
/* GUC variable: time in seconds between statistics reports */
int DebugSharedBuffers = 0;
@@ -812,6 +862,28 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
}
/*
* StrategyShmemSize
*
* estimate the size of shared memory used by the freelist-related structures.
*/
int
StrategyShmemSize(void)
{
int size = 0;
/* size of CDB lookup hash table */
size += BufTableShmemSize(NBuffers * 2);
/* size of the shared replacement strategy control block */
size += MAXALIGN(sizeof(BufferStrategyControl));
/* size of the ARC directory blocks */
size += MAXALIGN(NBuffers * 2 * sizeof(BufferStrategyCDB));
return size;
}
/*
* StrategyInitialize -- initialize the buffer cache replacement
* strategy.