Add an alternative application-defined pcache implementation and add test
cases to permutations.test to invoke it. Added the SQLITE_CONFIG_GETPCACHE
method to sqlite3_config(). (CVS 5920)
FossilOrigin-Name: 16f1e6ec2ad92f68c0079a0c2b5ca08a3b4af816
diff --git a/src/main.c b/src/main.c
index 3662697..16f89b7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,7 +14,7 @@
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
-** $Id: main.c,v 1.512 2008/11/13 14:28:29 danielk1977 Exp $
+** $Id: main.c,v 1.513 2008/11/19 01:20:26 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -315,6 +315,14 @@
break;
}
+ case SQLITE_CONFIG_GETPCACHE: {
+ if( sqlite3GlobalConfig.pcache.xInit==0 ){
+ sqlite3PCacheSetDefault();
+ }
+ *va_arg(ap, sqlite3_pcache_methods*) = sqlite3GlobalConfig.pcache;
+ break;
+ }
+
#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
case SQLITE_CONFIG_HEAP: {
/* Designate a buffer for heap memory space */
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 39070f7..8f1c734 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -30,7 +30,7 @@
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
-** @(#) $Id: sqlite.h.in,v 1.414 2008/11/18 19:18:09 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.415 2008/11/19 01:20:26 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
@@ -6683,8 +6683,9 @@
**
** The xRekey() method is used to change the key value associated with the
** page passed as the second argument from oldKey to newKey. If the cache
-** contains an entry associated with oldKey, it should be discarded. Any
-** cache entry associated with oldKey is guaranteed not to be pinned.
+** previously contains an entry associated with newKey, it should be
+** discarded. Any prior cache entry associated with newKey is guaranteed not
+** to be pinned.
**
** When SQLite calls the xTruncate() method, the cache must discard all
** existing cache entries with page numbers (keys) greater than or equal
diff --git a/src/test_malloc.c b/src/test_malloc.c
index bcf18d2..2009f54 100644
--- a/src/test_malloc.c
+++ b/src/test_malloc.c
@@ -13,7 +13,7 @@
** This file contains code used to implement test interfaces to the
** memory allocation subsystem.
**
-** $Id: test_malloc.c,v 1.50 2008/11/10 18:05:36 shane Exp $
+** $Id: test_malloc.c,v 1.51 2008/11/19 01:20:26 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
@@ -946,6 +946,42 @@
}
/*
+** Usage: sqlite3_config_alt_pcache INSTALL_FLAG DISCARD_CHANCE PRNG_SEED
+**
+** Set up the alternative test page cache. Install if INSTALL_FLAG is
+** true and uninstall (reverting to the default page cache) if INSTALL_FLAG
+** is false. DISCARD_CHANGE is an integer between 0 and 100 inclusive
+** which determines the chance of discarding a page when unpinned. 100
+** is certainty. 0 is never. PRNG_SEED is the pseudo-random number generator
+** seed.
+*/
+static int test_alt_pcache(
+ void * clientData,
+ Tcl_Interp *interp,
+ int objc,
+ Tcl_Obj *CONST objv[]
+){
+ int installFlag;
+ int discardChance;
+ int prngSeed;
+ extern void installTestPCache(int,unsigned,unsigned);
+ if( objc!=4 ){
+ Tcl_WrongNumArgs(interp, 1, objv, "INSTALLFLAG DISCARDCHANCE PRNGSEEED");
+ return TCL_ERROR;
+ }
+ if( Tcl_GetIntFromObj(interp, objv[1], &installFlag) ) return TCL_ERROR;
+ if( Tcl_GetIntFromObj(interp, objv[2], &discardChance) ) return TCL_ERROR;
+ if( Tcl_GetIntFromObj(interp, objv[3], &prngSeed) ) return TCL_ERROR;
+ if( discardChance<0 || discardChance>100 ){
+ Tcl_AppendResult(interp, "discard-chance should be between 0 and 100",
+ (char*)0);
+ return TCL_ERROR;
+ }
+ installTestPCache(installFlag, (unsigned)discardChance, (unsigned)prngSeed);
+ return TCL_OK;
+}
+
+/*
** Usage: sqlite3_config_memstatus BOOLEAN
**
** Enable or disable memory status reporting using SQLITE_CONFIG_MEMSTATUS.
@@ -1312,6 +1348,7 @@
{ "sqlite3_memdebug_log", test_memdebug_log ,0 },
{ "sqlite3_config_scratch", test_config_scratch ,0 },
{ "sqlite3_config_pagecache", test_config_pagecache ,0 },
+ { "sqlite3_config_alt_pcache", test_alt_pcache ,0 },
{ "sqlite3_status", test_status ,0 },
{ "sqlite3_db_status", test_db_status ,0 },
{ "install_malloc_faultsim", test_install_malloc_faultsim ,0 },
@@ -1321,7 +1358,7 @@
{ "sqlite3_config_error", test_config_error ,0 },
{ "sqlite3_db_config_lookaside",test_db_config_lookaside ,0 },
{ "sqlite3_dump_memsys3", test_dump_memsys3 ,3 },
- { "sqlite3_dump_memsys5", test_dump_memsys3 ,5 }
+ { "sqlite3_dump_memsys5", test_dump_memsys3 ,5 },
};
int i;
for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
diff --git a/src/test_pcache.c b/src/test_pcache.c
new file mode 100644
index 0000000..58f5b39
--- /dev/null
+++ b/src/test_pcache.c
@@ -0,0 +1,438 @@
+/*
+** 2008 November 18
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used for testing the SQLite system.
+** None of the code in this file goes into a deliverable build.
+**
+** This file contains an application-defined pager cache
+** implementation that can be plugged in in place of the
+** default pcache. This alternative pager cache will throw
+** some errors that the default cache does not.
+**
+** This pagecache implementation is designed for simplicity
+** not speed.
+**
+** $Id: test_pcache.c,v 1.1 2008/11/19 01:20:26 drh Exp $
+*/
+#include "sqlite3.h"
+#include <string.h>
+#include <assert.h>
+
+/*
+** Global data used by this test implementation. There is no
+** mutexing, which means this page cache will not work in a
+** multi-threaded test.
+*/
+typedef struct testpcacheGlobalType testpcacheGlobalType;
+struct testpcacheGlobalType {
+ void *pDummy; /* Dummy allocation to simulate failures */
+ int nInstance; /* Number of current instances */
+ unsigned discardChance; /* Chance of discarding on an unpin */
+ unsigned prngSeed; /* Seed for the PRNG */
+};
+static testpcacheGlobalType testpcacheGlobal;
+
+/*
+** Initializer.
+**
+** Verify that the initializer is only called when the system is
+** uninitialized. Allocate some memory and report SQLITE_NOMEM if
+** the allocation fails. This provides a means to test the recovery
+** from a failed initialization attempt. It also verifies that the
+** the destructor always gets call - otherwise there would be a
+** memory leak.
+*/
+static int testpcacheInit(void *pArg){
+ assert( pArg==(void*)&testpcacheGlobal );
+ assert( testpcacheGlobal.pDummy==0 );
+ assert( testpcacheGlobal.nInstance==0 );
+ testpcacheGlobal.pDummy = sqlite3_malloc(10);
+ return testpcacheGlobal.pDummy==0 ? SQLITE_NOMEM : SQLITE_OK;
+}
+
+/*
+** Destructor
+**
+** Verify that this is only called after initialization.
+** Free the memory allocated by the initializer.
+*/
+static void testpcacheShutdown(void *pArg){
+ assert( pArg==(void*)&testpcacheGlobal );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance==0 );
+ sqlite3_free( testpcacheGlobal.pDummy );
+ testpcacheGlobal.pDummy = 0;
+}
+
+/*
+** Number of pages in a cache
+*/
+#define TESTPCACHE_NPAGE 217
+#define TESTPCACHE_RESERVE 17
+
+/*
+** Magic numbers used to determine validity of the page cache.
+*/
+#define TESTPCACHE_VALID 0x364585fd
+#define TESTPCACHE_CLEAR 0xd42670d4
+
+/*
+** Private implementation of a page cache.
+*/
+typedef struct testpcache testpcache;
+struct testpcache {
+ int szPage; /* Size of each page. Multiple of 8. */
+ int bPurgeable; /* True if the page cache is purgeable */
+ int nFree; /* Number of unused slots in a[] */
+ int nPinned; /* Number of pinned slots in a[] */
+ unsigned iRand; /* State of the PRNG */
+ unsigned iMagic; /* Magic number for sanity checking */
+ struct testpcachePage {
+ unsigned key; /* The key for this page. 0 means unallocated */
+ int isPinned; /* True if the page is pinned */
+ void *pData; /* Data for this page */
+ } a[TESTPCACHE_NPAGE]; /* All pages in the cache */
+};
+
+/*
+** Get a random number using the PRNG in the given page cache.
+*/
+static unsigned testpcacheRandom(testpcache *p){
+ unsigned x = 0;
+ int i;
+ for(i=0; i<4; i++){
+ p->iRand = (p->iRand*69069 + 5);
+ x = (x<<8) | ((p->iRand>>16)&0xff);
+ }
+ return x;
+}
+
+
+/*
+** Allocate a new page cache instance.
+*/
+static sqlite3_pcache *testpcacheCreate(int szPage, int bPurgeable){
+ int nMem;
+ char *x;
+ testpcache *p;
+ int i;
+ assert( testpcacheGlobal.pDummy!=0 );
+ szPage = (szPage+7)&~7;
+ nMem = sizeof(testpcache) + TESTPCACHE_NPAGE*szPage;
+ p = sqlite3_malloc( nMem );
+ if( p==0 ) return 0;
+ x = (char*)&p[1];
+ p->szPage = szPage;
+ p->nFree = TESTPCACHE_NPAGE;
+ p->nPinned = 0;
+ p->iRand = testpcacheGlobal.prngSeed;
+ p->bPurgeable = bPurgeable;
+ p->iMagic = TESTPCACHE_VALID;
+ for(i=0; i<TESTPCACHE_NPAGE; i++, x += szPage){
+ p->a[i].key = 0;
+ p->a[i].isPinned = 0;
+ p->a[i].pData = (void*)x;
+ }
+ testpcacheGlobal.nInstance++;
+ return (sqlite3_pcache*)p;
+}
+
+/*
+** Set the cache size
+*/
+static void testpcacheCachesize(sqlite3_pcache *pCache, int newSize){
+ testpcache *p = (testpcache*)pCache;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( newSize>=1 );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+}
+
+/*
+** Return the number of pages in the cache that are being used.
+** This includes both pinned and unpinned pages.
+*/
+static int testpcachePagecount(sqlite3_pcache *pCache){
+ testpcache *p = (testpcache*)pCache;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+ return TESTPCACHE_NPAGE - p->nFree;
+}
+
+/*
+** Fetch a page.
+*/
+static void *testpcacheFetch(
+ sqlite3_pcache *pCache,
+ unsigned key,
+ int createFlag
+){
+ testpcache *p = (testpcache*)pCache;
+ int i, j;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+
+ /* See if the page is already in cache. Return immediately if it is */
+ for(i=0; i<TESTPCACHE_NPAGE; i++){
+ if( p->a[i].key==key ){
+ if( !p->a[i].isPinned ){
+ p->nPinned++;
+ assert( p->nPinned <= TESTPCACHE_NPAGE - p->nFree );
+ p->a[i].isPinned = 1;
+ }
+ return p->a[i].pData;
+ }
+ }
+
+ /* If createFlag is 0, never allocate a new page */
+ if( createFlag==0 ){
+ return 0;
+ }
+
+ /* If no pages are available, always fail */
+ if( p->nPinned==TESTPCACHE_NPAGE ){
+ return 0;
+ }
+
+ /* Do not allocate the last TESTPCACHE_RESERVE pages unless createFlag is 2 */
+ if( p->nPinned>=TESTPCACHE_NPAGE-TESTPCACHE_RESERVE && createFlag<2 ){
+ return 0;
+ }
+
+ /* Find a free page to allocate if there are any free pages.
+ ** Withhold TESTPCACHE_RESERVE free pages until createFlag is 2.
+ */
+ if( p->nFree>TESTPCACHE_RESERVE || (createFlag==2 && p->nFree>0) ){
+ j = testpcacheRandom(p) % TESTPCACHE_NPAGE;
+ for(i=0; i<TESTPCACHE_NPAGE; i++, j = (j+1)%TESTPCACHE_NPAGE){
+ if( p->a[j].key==0 ){
+ p->a[j].key = key;
+ p->a[j].isPinned = 1;
+ memset(p->a[j].pData, 0, p->szPage);
+ p->nPinned++;
+ p->nFree--;
+ assert( p->nPinned <= TESTPCACHE_NPAGE - p->nFree );
+ return p->a[j].pData;
+ }
+ }
+
+ /* The prior loop always finds a freepage to allocate */
+ assert( 0 );
+ }
+
+ /* If this cache is not purgeable then we have to fail.
+ */
+ if( p->bPurgeable==0 ){
+ return 0;
+ }
+
+ /* If there are no free pages, recycle a page. The page to
+ ** recycle is selected at random from all unpinned pages.
+ */
+ j = testpcacheRandom(p) % TESTPCACHE_NPAGE;
+ for(i=0; i<TESTPCACHE_NPAGE; i++, j = (j+1)%TESTPCACHE_NPAGE){
+ if( p->a[j].key>0 && p->a[j].isPinned==0 ){
+ p->a[j].key = key;
+ p->a[j].isPinned = 1;
+ memset(p->a[j].pData, 0, p->szPage);
+ p->nPinned++;
+ assert( p->nPinned <= TESTPCACHE_NPAGE - p->nFree );
+ return p->a[j].pData;
+ }
+ }
+
+ /* The previous loop always finds a page to recycle. */
+ assert(0);
+ return 0;
+}
+
+/*
+** Unpin a page.
+*/
+static void testpcacheUnpin(
+ sqlite3_pcache *pCache,
+ void *pOldPage,
+ int discard
+){
+ testpcache *p = (testpcache*)pCache;
+ int i;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+
+ /* Randomly discard pages as they are unpinned according to the
+ ** discardChance setting. If discardChance is 0, the random discard
+ ** never happens. If discardChance is 100, it always happens.
+ */
+ if( p->bPurgeable
+ && (100-testpcacheGlobal.discardChance) <= (testpcacheRandom(p)%100)
+ ){
+ discard = 1;
+ }
+
+ for(i=0; i<TESTPCACHE_NPAGE; i++){
+ if( p->a[i].pData==pOldPage ){
+ /* The pOldPage pointer always points to a pinned page */
+ assert( p->a[i].isPinned );
+ p->a[i].isPinned = 0;
+ p->nPinned--;
+ assert( p->nPinned>=0 );
+ if( discard ){
+ p->a[i].key = 0;
+ p->nFree++;
+ assert( p->nFree<=TESTPCACHE_NPAGE );
+ }
+ return;
+ }
+ }
+
+ /* The pOldPage pointer always points to a valid page */
+ assert( 0 );
+}
+
+
+/*
+** Rekey a single page.
+*/
+static void testpcacheRekey(
+ sqlite3_pcache *pCache,
+ void *pOldPage,
+ unsigned oldKey,
+ unsigned newKey
+){
+ testpcache *p = (testpcache*)pCache;
+ int i;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+
+ /* If there already exists another page at newKey, verify that
+ ** the other page is unpinned and discard it.
+ */
+ for(i=0; i<TESTPCACHE_NPAGE; i++){
+ if( p->a[i].key==newKey ){
+ /* The new key is never a page that is already pinned */
+ assert( p->a[i].isPinned==0 );
+ p->a[i].key = 0;
+ p->nFree++;
+ assert( p->nFree<=TESTPCACHE_NPAGE );
+ break;
+ }
+ }
+
+ /* Find the page to be rekeyed and rekey it.
+ */
+ for(i=0; i<TESTPCACHE_NPAGE; i++){
+ if( p->a[i].key==oldKey ){
+ /* The oldKey and pOldPage parameters match */
+ assert( p->a[i].pData==pOldPage );
+ /* Page to be rekeyed must be pinned */
+ assert( p->a[i].isPinned );
+ p->a[i].key = newKey;
+ return;
+ }
+ }
+
+ /* Rekey is always given a valid page to work with */
+ assert( 0 );
+}
+
+
+/*
+** Truncate the page cache. Every page with a key of iLimit or larger
+** is discarded.
+*/
+static void testpcacheTruncate(sqlite3_pcache *pCache, unsigned iLimit){
+ testpcache *p = (testpcache*)pCache;
+ unsigned int i;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+ for(i=0; i<TESTPCACHE_NPAGE; i++){
+ if( p->a[i].key>=iLimit ){
+ p->a[i].key = 0;
+ if( p->a[i].isPinned ){
+ p->nPinned--;
+ assert( p->nPinned>=0 );
+ }
+ p->nFree++;
+ assert( p->nFree<=TESTPCACHE_NPAGE );
+ }
+ }
+}
+
+/*
+** Destroy a page cache.
+*/
+static void testpcacheDestroy(sqlite3_pcache *pCache){
+ testpcache *p = (testpcache*)pCache;
+ assert( p->iMagic==TESTPCACHE_VALID );
+ assert( testpcacheGlobal.pDummy!=0 );
+ assert( testpcacheGlobal.nInstance>0 );
+ p->iMagic = TESTPCACHE_CLEAR;
+ sqlite3_free(p);
+ testpcacheGlobal.nInstance--;
+}
+
+
+/*
+** Invoke this routine to register or unregister the testing pager cache
+** implemented by this file.
+**
+** Install the test pager cache if installFlag is 1 and uninstall it if
+** installFlag is 0.
+**
+** When installing, discardChance is a number between 0 and 100 that
+** indicates the probability of discarding a page when unpinning the
+** page. 0 means never discard (unless the discard flag is set).
+** 100 means always discard.
+*/
+void installTestPCache(
+ int installFlag, /* True to install. False to uninstall. */
+ unsigned discardChance, /* 0-100. Chance to discard on unpin */
+ unsigned prngSeed /* Seed for the PRNG */
+){
+ static const sqlite3_pcache_methods testPcache = {
+ (void*)&testpcacheGlobal,
+ testpcacheInit,
+ testpcacheShutdown,
+ testpcacheCreate,
+ testpcacheCachesize,
+ testpcachePagecount,
+ testpcacheFetch,
+ testpcacheUnpin,
+ testpcacheRekey,
+ testpcacheTruncate,
+ testpcacheDestroy,
+ };
+ static sqlite3_pcache_methods defaultPcache;
+ static int isInstalled = 0;
+
+ assert( testpcacheGlobal.nInstance==0 );
+ assert( testpcacheGlobal.pDummy==0 );
+ assert( discardChance<=100 );
+ testpcacheGlobal.discardChance = discardChance;
+ testpcacheGlobal.prngSeed = prngSeed ^ (prngSeed<<16);
+ if( installFlag!=isInstalled ){
+ if( installFlag ){
+ sqlite3_config(SQLITE_CONFIG_GETPCACHE, &defaultPcache);
+ assert( defaultPcache.xCreate!=testpcacheCreate );
+ sqlite3_config(SQLITE_CONFIG_PCACHE, &testPcache);
+ }else{
+ assert( defaultPcache.xCreate!=0 );
+ sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultPcache);
+ }
+ isInstalled = installFlag;
+ }
+}