Imported Upstream version 2.0.3

1 files changed, 458 insertions, 0 deletions

diff --git a/src/test_pcache.c b/src/test_pcache.c
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+/*
+** 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 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;
+  }
+
+  /* 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].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 */
+  unsigned highStress         /* Call xStress agressively */
+){
+  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);
+  testpcacheGlobal.highStress = highStress;
+  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;
+  }
+}