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Diffstat (limited to 'src/test_pcache.c')
| -rw-r--r-- | src/test_pcache.c | 467 |
1 files changed, 467 insertions, 0 deletions
diff --git a/src/test_pcache.c b/src/test_pcache.c new file mode 100644 index 0000000..8fcfe7e --- /dev/null +++ b/src/test_pcache.c @@ -0,0 +1,467 @@ +/* +** 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. +*/ +#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 (0-100) */ + unsigned prngSeed; /* Seed for the PRNG */ + unsigned highStress; /* Call xStress agressively */ +}; +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. +** +** The number of pages is a hard upper bound in this test module. +** If more pages are requested, sqlite3PcacheFetch() returns NULL. +** +** If testing with in-memory temp tables, provide a larger pcache. +** Some of the test cases need this. +*/ +#if defined(SQLITE_TEMP_STORE) && SQLITE_TEMP_STORE>=2 +# define TESTPCACHE_NPAGE 499 +#else +# define TESTPCACHE_NPAGE 217 +#endif +#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 szExtra; /* Size of extra data that accompanies each page */ + 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 { + sqlite3_pcache_page page; /* Base class */ + unsigned key; /* The key for this page. 0 means unallocated */ + int isPinned; /* True if the page is pinned */ + } 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 szExtra, + int bPurgeable +){ + int nMem; + char *x; + testpcache *p; + int i; + assert( testpcacheGlobal.pDummy!=0 ); + szPage = (szPage+7)&~7; + nMem = sizeof(testpcache) + TESTPCACHE_NPAGE*(szPage+szExtra); + p = sqlite3_malloc( nMem ); + if( p==0 ) return 0; + x = (char*)&p[1]; + p->szPage = szPage; + p->szExtra = szExtra; + 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+szExtra)){ + p->a[i].key = 0; + p->a[i].isPinned = 0; + p->a[i].page.pBuf = (void*)x; + p->a[i].page.pExtra = (void*)&x[szPage]; + } + 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( 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 sqlite3_pcache_page *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].page; + } + } + + /* 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; + } + + /* Do not allocate if highStress is enabled and createFlag is not 2. + ** + ** The highStress setting causes pagerStress() to be called much more + ** often, which exercises the pager logic more intensely. + */ + if( testpcacheGlobal.highStress && 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].page.pBuf, 0, p->szPage); + memset(p->a[j].page.pExtra, 0, p->szExtra); + p->nPinned++; + p->nFree--; + assert( p->nPinned <= TESTPCACHE_NPAGE - p->nFree ); + return &p->a[j].page; + } + } + + /* 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].page.pBuf, 0, p->szPage); + memset(p->a[j].page.pExtra, 0, p->szExtra); + p->nPinned++; + assert( p->nPinned <= TESTPCACHE_NPAGE - p->nFree ); + return &p->a[j].page; + } + } + + /* The previous loop always finds a page to recycle. */ + assert(0); + return 0; +} + +/* +** Unpin a page. +*/ +static void testpcacheUnpin( + sqlite3_pcache *pCache, + sqlite3_pcache_page *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].page==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, + sqlite3_pcache_page *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].page==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 */ + unsigned highStress /* Call xStress agressively */ +){ + static const sqlite3_pcache_methods2 testPcache = { + 1, + (void*)&testpcacheGlobal, + testpcacheInit, + testpcacheShutdown, + testpcacheCreate, + testpcacheCachesize, + testpcachePagecount, + testpcacheFetch, + testpcacheUnpin, + testpcacheRekey, + testpcacheTruncate, + testpcacheDestroy, + }; + static sqlite3_pcache_methods2 defaultPcache; + static int isInstalled = 0; + + assert( testpcacheGlobal.nInstance==0 ); + assert( testpcacheGlobal.pDummy==0 ); + assert( discardChance<=100 ); + testpcacheGlobal.discardChance = discardChance; + testpcacheGlobal.prngSeed = prngSeed ^ (prngSeed<<16); + testpcacheGlobal.highStress = highStress; + if( installFlag!=isInstalled ){ + if( installFlag ){ + sqlite3_config(SQLITE_CONFIG_GETPCACHE2, &defaultPcache); + assert( defaultPcache.xCreate!=testpcacheCreate ); + sqlite3_config(SQLITE_CONFIG_PCACHE2, &testPcache); + }else{ + assert( defaultPcache.xCreate!=0 ); + sqlite3_config(SQLITE_CONFIG_PCACHE2, &defaultPcache); + } + isInstalled = installFlag; + } +} |