Import SQLite 3.7.6.3.

third_party/sqlite/src/test/threadtest3.c

+
+/*
+** The code in this file runs a few multi-threaded test cases using the
+** SQLite library. It can be compiled to an executable on unix using the
+** following command:
+**
+**   gcc -O2 threadtest3.c sqlite3.c -ldl -lpthread -lm
+**
+** Then run the compiled program. The exit status is non-zero if any tests
+** failed (hopefully there is also some output to stdout to clarify what went
+** wrong).
+**
+** There are three parts to the code in this file, in the following order:
+**
+**   1. Code for the SQL aggregate function md5sum() copied from 
+**      tclsqlite.c in the SQLite distribution. The names of all the 
+**      types and functions in this section begin with "MD5" or "md5".
+**
+**   2. A set of utility functions that may be used to implement
+**      multi-threaded test cases. These are all called by test code
+**      via macros that help with error reporting. The macros are defined
+**      immediately below this comment.
+**
+**   3. The test code itself. And a main() routine to drive the test 
+**      code.
+*/
+
+/*************************************************************************
+** Start of test code/infrastructure interface macros.
+**
+** The following macros constitute the interface between the test
+** programs and the test infrastructure. Test infrastructure code 
+** does not itself use any of these macros. Test code should not
+** call any of the macroname_x() functions directly.
+**
+** See the header comments above the corresponding macroname_x()
+** function for a description of each interface.
+*/
+
+/* Database functions */
+#define opendb(w,x,y,z)         (SEL(w), opendb_x(w,x,y,z))
+#define closedb(y,z)            (SEL(y), closedb_x(y,z))
+
+/* Functions to execute SQL */
+#define sql_script(x,y,z)       (SEL(x), sql_script_x(x,y,z))
+#define integrity_check(x,y)    (SEL(x), integrity_check_x(x,y))
+#define execsql_i64(x,y,...)    (SEL(x), execsql_i64_x(x,y,__VA_ARGS__))
+#define execsql_text(x,y,z,...) (SEL(x), execsql_text_x(x,y,z,__VA_ARGS__))
+#define execsql(x,y,...)        (SEL(x), (void)execsql_i64_x(x,y,__VA_ARGS__))
+
+/* Thread functions */
+#define launch_thread(w,x,y,z)  (SEL(w), launch_thread_x(w,x,y,z))
+#define join_all_threads(y,z)   (SEL(y), join_all_threads_x(y,z))
+
+/* Timer functions */
+#define setstoptime(y,z)        (SEL(y), setstoptime_x(y,z))
+#define timetostop(z)           (SEL(z), timetostop_x(z))
+
+/* Report/clear errors. */
+#define test_error(z, ...)      test_error_x(z, sqlite3_mprintf(__VA_ARGS__))
+#define clear_error(y,z)        clear_error_x(y, z)
+
+/* File-system operations */
+#define filesize(y,z)           (SEL(y), filesize_x(y,z))
+#define filecopy(x,y,z)         (SEL(x), filecopy_x(x,y,z))
+
+/*
+** End of test code/infrastructure interface macros.
+*************************************************************************/
+
+
+
+
+#include <sqlite3.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <pthread.h>
+#include <assert.h>
+#include <sys/types.h> 
+#include <sys/stat.h> 
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+
+/*
+ * This code implements the MD5 message-digest algorithm.
+ * The algorithm is due to Ron Rivest.  This code was
+ * written by Colin Plumb in 1993, no copyright is claimed.
+ * This code is in the public domain; do with it what you wish.
+ *
+ * Equivalent code is available from RSA Data Security, Inc.
+ * This code has been tested against that, and is equivalent,
+ * except that you don't need to include two pages of legalese
+ * with every copy.
+ *
+ * To compute the message digest of a chunk of bytes, declare an
+ * MD5Context structure, pass it to MD5Init, call MD5Update as
+ * needed on buffers full of bytes, and then call MD5Final, which
+ * will fill a supplied 16-byte array with the digest.
+ */
+
+/*
+ * If compiled on a machine that doesn't have a 32-bit integer,
+ * you just set "uint32" to the appropriate datatype for an
+ * unsigned 32-bit integer.  For example:
+ *
+ *       cc -Duint32='unsigned long' md5.c
+ *
+ */
+#ifndef uint32
+#  define uint32 unsigned int
+#endif
+
+struct MD5Context {
+  int isInit;
+  uint32 buf[4];
+  uint32 bits[2];
+  unsigned char in[64];
+};
+typedef struct MD5Context MD5Context;
+
+/*
+ * Note: this code is harmless on little-endian machines.
+ */
+static void byteReverse (unsigned char *buf, unsigned longs){
+  uint32 t;
+  do {
+    t = (uint32)((unsigned)buf[3]<<8 | buf[2]) << 16 |
+          ((unsigned)buf[1]<<8 | buf[0]);
+    *(uint32 *)buf = t;
+    buf += 4;
+  } while (--longs);
+}
+/* The four core functions - F1 is optimized somewhat */
+
+/* #define F1(x, y, z) (x & y | ~x & z) */
+#define F1(x, y, z) (z ^ (x & (y ^ z)))
+#define F2(x, y, z) F1(z, x, y)
+#define F3(x, y, z) (x ^ y ^ z)
+#define F4(x, y, z) (y ^ (x | ~z))
+
+/* This is the central step in the MD5 algorithm. */
+#define MD5STEP(f, w, x, y, z, data, s) \
+  ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )
+
+/*
+ * The core of the MD5 algorithm, this alters an existing MD5 hash to
+ * reflect the addition of 16 longwords of new data.  MD5Update blocks
+ * the data and converts bytes into longwords for this routine.
+ */
+static void MD5Transform(uint32 buf[4], const uint32 in[16]){
+  register uint32 a, b, c, d;
+
+  a = buf[0];
+  b = buf[1];
+  c = buf[2];
+  d = buf[3];
+
+  MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478,  7);
+  MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
+  MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
+  MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
+  MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf,  7);
+  MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
+  MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
+  MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
+  MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8,  7);
+  MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
+  MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
+  MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
+  MD5STEP(F1, a, b, c, d, in[12]+0x6b901122,  7);
+  MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
+  MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
+  MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
+
+  MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562,  5);
+  MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340,  9);
+  MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
+  MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
+  MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d,  5);
+  MD5STEP(F2, d, a, b, c, in[10]+0x02441453,  9);
+  MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
+  MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
+  MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6,  5);
+  MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6,  9);
+  MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
+  MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
+  MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905,  5);
+  MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8,  9);
+  MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
+  MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
+
+  MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942,  4);
+  MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
+  MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
+  MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
+  MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44,  4);
+  MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
+  MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
+  MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
+  MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6,  4);
+  MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
+  MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
+  MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
+  MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039,  4);
+  MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
+  MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
+  MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
+
+  MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244,  6);
+  MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
+  MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
+  MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
+  MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3,  6);
+  MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
+  MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
+  MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
+  MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f,  6);
+  MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
+  MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
+  MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
+  MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82,  6);
+  MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
+  MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
+  MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
+
+  buf[0] += a;
+  buf[1] += b;
+  buf[2] += c;
+  buf[3] += d;
+}
+
+/*
+ * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
+ * initialization constants.
+ */
+static void MD5Init(MD5Context *ctx){
+  ctx->isInit = 1;
+  ctx->buf[0] = 0x67452301;
+  ctx->buf[1] = 0xefcdab89;
+  ctx->buf[2] = 0x98badcfe;
+  ctx->buf[3] = 0x10325476;
+  ctx->bits[0] = 0;
+  ctx->bits[1] = 0;
+}
+
+/*
+ * Update context to reflect the concatenation of another buffer full
+ * of bytes.
+ */
+static 
+void MD5Update(MD5Context *ctx, const unsigned char *buf, unsigned int len){
+  uint32 t;
+
+  /* Update bitcount */
+
+  t = ctx->bits[0];
+  if ((ctx->bits[0] = t + ((uint32)len << 3)) < t)
+    ctx->bits[1]++; /* Carry from low to high */
+  ctx->bits[1] += len >> 29;
+
+  t = (t >> 3) & 0x3f;    /* Bytes already in shsInfo->data */
+
+  /* Handle any leading odd-sized chunks */
+
+  if ( t ) {
+    unsigned char *p = (unsigned char *)ctx->in + t;
+
+    t = 64-t;
+    if (len < t) {
+      memcpy(p, buf, len);
+      return;
+    }
+    memcpy(p, buf, t);
+    byteReverse(ctx->in, 16);
+    MD5Transform(ctx->buf, (uint32 *)ctx->in);
+    buf += t;
+    len -= t;
+  }
+
+  /* Process data in 64-byte chunks */
+
+  while (len >= 64) {
+    memcpy(ctx->in, buf, 64);
+    byteReverse(ctx->in, 16);
+    MD5Transform(ctx->buf, (uint32 *)ctx->in);
+    buf += 64;
+    len -= 64;
+  }
+
+  /* Handle any remaining bytes of data. */
+
+  memcpy(ctx->in, buf, len);
+}
+
+/*
+ * Final wrapup - pad to 64-byte boundary with the bit pattern 
+ * 1 0* (64-bit count of bits processed, MSB-first)
+ */
+static void MD5Final(unsigned char digest[16], MD5Context *ctx){
+  unsigned count;
+  unsigned char *p;
+
+  /* Compute number of bytes mod 64 */
+  count = (ctx->bits[0] >> 3) & 0x3F;
+
+  /* Set the first char of padding to 0x80.  This is safe since there is
+     always at least one byte free */
+  p = ctx->in + count;
+  *p++ = 0x80;
+
+  /* Bytes of padding needed to make 64 bytes */
+  count = 64 - 1 - count;
+
+  /* Pad out to 56 mod 64 */
+  if (count < 8) {
+    /* Two lots of padding:  Pad the first block to 64 bytes */
+    memset(p, 0, count);
+    byteReverse(ctx->in, 16);
+    MD5Transform(ctx->buf, (uint32 *)ctx->in);
+
+    /* Now fill the next block with 56 bytes */
+    memset(ctx->in, 0, 56);
+  } else {
+    /* Pad block to 56 bytes */
+    memset(p, 0, count-8);
+  }
+  byteReverse(ctx->in, 14);
+
+  /* Append length in bits and transform */
+  ((uint32 *)ctx->in)[ 14 ] = ctx->bits[0];
+  ((uint32 *)ctx->in)[ 15 ] = ctx->bits[1];
+
+  MD5Transform(ctx->buf, (uint32 *)ctx->in);
+  byteReverse((unsigned char *)ctx->buf, 4);
+  memcpy(digest, ctx->buf, 16);
+  memset(ctx, 0, sizeof(ctx));    /* In case it is sensitive */
+}
+
+/*
+** Convert a 128-bit MD5 digest into a 32-digit base-16 number.
+*/
+static void MD5DigestToBase16(unsigned char *digest, char *zBuf){
+  static char const zEncode[] = "0123456789abcdef";
+  int i, j;
+
+  for(j=i=0; i<16; i++){
+    int a = digest[i];
+    zBuf[j++] = zEncode[(a>>4)&0xf];
+    zBuf[j++] = zEncode[a & 0xf];
+  }
+  zBuf[j] = 0;
+}
+
+/*
+** During testing, the special md5sum() aggregate function is available.
+** inside SQLite.  The following routines implement that function.
+*/
+static void md5step(sqlite3_context *context, int argc, sqlite3_value **argv){
+  MD5Context *p;
+  int i;
+  if( argc<1 ) return;
+  p = sqlite3_aggregate_context(context, sizeof(*p));
+  if( p==0 ) return;
+  if( !p->isInit ){
+    MD5Init(p);
+  }
+  for(i=0; i<argc; i++){
+    const char *zData = (char*)sqlite3_value_text(argv[i]);
+    if( zData ){
+      MD5Update(p, (unsigned char*)zData, strlen(zData));
+    }
+  }
+}
+static void md5finalize(sqlite3_context *context){
+  MD5Context *p;
+  unsigned char digest[16];
+  char zBuf[33];
+  p = sqlite3_aggregate_context(context, sizeof(*p));
+  MD5Final(digest,p);
+  MD5DigestToBase16(digest, zBuf);
+  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+}
+
+/*************************************************************************
+** End of copied md5sum() code.
+*/
+
+typedef sqlite3_int64 i64;
+
+typedef struct Error Error;
+typedef struct Sqlite Sqlite;
+typedef struct Statement Statement;
+
+typedef struct Threadset Threadset;
+typedef struct Thread Thread;
+
+/* Total number of errors in this process so far. */
+static int nGlobalErr = 0;
+
+/* Set to true to run in "process" instead of "thread" mode. */
+static int bProcessMode = 0;
+
+struct Error {
+  int rc;
+  int iLine;
+  char *zErr;
+};
+
+struct Sqlite {
+  sqlite3 *db;                    /* Database handle */
+  Statement *pCache;              /* Linked list of cached statements */
+  int nText;                      /* Size of array at aText[] */
+  char **aText;                   /* Stored text results */
+};
+
+struct Statement {
+  sqlite3_stmt *pStmt;            /* Pre-compiled statement handle */
+  Statement *pNext;               /* Next statement in linked-list */
+};
+
+struct Thread {
+  int iTid;                       /* Thread number within test */
+  int iArg;                       /* Integer argument passed by caller */
+
+  pthread_t tid;                  /* Thread id */
+  char *(*xProc)(int, int);       /* Thread main proc */
+  Thread *pNext;                  /* Next in this list of threads */
+};
+
+struct Threadset {
+  int iMaxTid;                    /* Largest iTid value allocated so far */
+  Thread *pThread;                /* Linked list of threads */
+};
+
+static void free_err(Error *p){
+  sqlite3_free(p->zErr);
+  p->zErr = 0;
+  p->rc = 0;
+}
+
+static void print_err(Error *p){
+  if( p->rc!=SQLITE_OK ){
+    printf("Error: (%d) \"%s\" at line %d\n", p->rc, p->zErr, p->iLine);
+    nGlobalErr++;
+  }
+}
+
+static void print_and_free_err(Error *p){
+  print_err(p);
+  free_err(p);
+}
+
+static void system_error(Error *pErr, int iSys){
+  pErr->rc = iSys;
+  pErr->zErr = (char *)sqlite3_malloc(512);
+  strerror_r(iSys, pErr->zErr, 512);
+  pErr->zErr[511] = '\0';
+}
+
+static void sqlite_error(
+  Error *pErr, 
+  Sqlite *pDb, 
+  const char *zFunc
+){
+  pErr->rc = sqlite3_errcode(pDb->db);
+  pErr->zErr = sqlite3_mprintf(
+      "sqlite3_%s() - %s (%d)", zFunc, sqlite3_errmsg(pDb->db),
+      sqlite3_extended_errcode(pDb->db)
+  );
+}
+
+static void test_error_x(
+  Error *pErr,
+  char *zErr
+){
+  if( pErr->rc==SQLITE_OK ){
+    pErr->rc = 1;
+    pErr->zErr = zErr;
+  }else{
+    sqlite3_free(zErr);
+  }
+}
+
+static void clear_error_x(
+  Error *pErr,
+  int rc
+){
+  if( pErr->rc==rc ){
+    pErr->rc = SQLITE_OK;
+    sqlite3_free(pErr->zErr);
+    pErr->zErr = 0;
+  }
+}
+
+static int busyhandler(void *pArg, int n){
+  usleep(10*1000);
+  return 1;
+}
+
+static void opendb_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* OUT: Database handle */
+  const char *zFile,              /* Database file name */
+  int bDelete                     /* True to delete db file before opening */
+){
+  if( pErr->rc==SQLITE_OK ){
+    int rc;
+    if( bDelete ) unlink(zFile);
+    rc = sqlite3_open(zFile, &pDb->db);
+    if( rc ){
+      sqlite_error(pErr, pDb, "open");
+      sqlite3_close(pDb->db);
+      pDb->db = 0;
+    }else{
+      sqlite3_create_function(
+          pDb->db, "md5sum", -1, SQLITE_UTF8, 0, 0, md5step, md5finalize
+      );
+      sqlite3_busy_handler(pDb->db, busyhandler, 0);
+      sqlite3_exec(pDb->db, "PRAGMA synchronous=OFF", 0, 0, 0);
+    }
+  }
+}
+
+static void closedb_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb                     /* OUT: Database handle */
+){
+  int rc;
+  int i;
+  Statement *pIter;
+  Statement *pNext;
+  for(pIter=pDb->pCache; pIter; pIter=pNext){
+    pNext = pIter->pNext;
+    sqlite3_finalize(pIter->pStmt);
+    sqlite3_free(pIter);
+  }
+  for(i=0; i<pDb->nText; i++){
+    sqlite3_free(pDb->aText[i]);
+  }
+  sqlite3_free(pDb->aText);
+  rc = sqlite3_close(pDb->db);
+  if( rc && pErr->rc==SQLITE_OK ){
+    pErr->zErr = sqlite3_mprintf("%s", sqlite3_errmsg(pDb->db));
+  }
+  memset(pDb, 0, sizeof(Sqlite));
+}
+
+static void sql_script_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* Database handle */
+  const char *zSql                /* SQL script to execute */
+){
+  if( pErr->rc==SQLITE_OK ){
+    pErr->rc = sqlite3_exec(pDb->db, zSql, 0, 0, &pErr->zErr);
+  }
+}
+
+static Statement *getSqlStatement(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* Database handle */
+  const char *zSql                /* SQL statement */
+){
+  Statement *pRet;
+  int rc;
+
+  for(pRet=pDb->pCache; pRet; pRet=pRet->pNext){
+    if( 0==strcmp(sqlite3_sql(pRet->pStmt), zSql) ){
+      return pRet;
+    }
+  }
+
+  pRet = sqlite3_malloc(sizeof(Statement));
+  rc = sqlite3_prepare_v2(pDb->db, zSql, -1, &pRet->pStmt, 0);
+  if( rc!=SQLITE_OK ){
+    sqlite_error(pErr, pDb, "prepare_v2");
+    return 0;
+  }
+  assert( 0==strcmp(sqlite3_sql(pRet->pStmt), zSql) );
+
+  pRet->pNext = pDb->pCache;
+  pDb->pCache = pRet;
+  return pRet;
+}
+
+static sqlite3_stmt *getAndBindSqlStatement(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* Database handle */
+  va_list ap                      /* SQL followed by parameters */
+){
+  Statement *pStatement;          /* The SQLite statement wrapper */
+  sqlite3_stmt *pStmt;            /* The SQLite statement to return */
+  int i;                          /* Used to iterate through parameters */
+
+  pStatement = getSqlStatement(pErr, pDb, va_arg(ap, const char *));
+  if( !pStatement ) return 0;
+  pStmt = pStatement->pStmt;
+  for(i=1; i<=sqlite3_bind_parameter_count(pStmt); i++){
+    const char *zName = sqlite3_bind_parameter_name(pStmt, i);
+    void * pArg = va_arg(ap, void*);
+
+    switch( zName[1] ){
+      case 'i':
+        sqlite3_bind_int64(pStmt, i, *(i64 *)pArg);
+        break;
+
+      default:
+        pErr->rc = 1;
+        pErr->zErr = sqlite3_mprintf("Cannot discern type: \"%s\"", zName);
+        pStmt = 0;
+        break;
+    }
+  }
+
+  return pStmt;
+}
+
+static i64 execsql_i64_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* Database handle */
+  ...                             /* SQL and pointers to parameter values */
+){
+  i64 iRet = 0;
+  if( pErr->rc==SQLITE_OK ){
+    sqlite3_stmt *pStmt;          /* SQL statement to execute */
+    va_list ap;                   /* ... arguments */
+    int i;                        /* Used to iterate through parameters */
+    va_start(ap, pDb);
+    pStmt = getAndBindSqlStatement(pErr, pDb, ap);
+    if( pStmt ){
+      int rc;
+      int first = 1;
+      while( SQLITE_ROW==sqlite3_step(pStmt) ){
+        if( first && sqlite3_column_count(pStmt)>0 ){
+          iRet = sqlite3_column_int64(pStmt, 0);
+        }
+        first = 0;
+      }
+      if( SQLITE_OK!=sqlite3_reset(pStmt) ){
+        sqlite_error(pErr, pDb, "reset");
+      }
+    }
+    va_end(ap);
+  }
+  return iRet;
+}
+
+static char * execsql_text_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb,                    /* Database handle */
+  int iSlot,                      /* Db handle slot to store text in */
+  ...                             /* SQL and pointers to parameter values */
+){
+  char *zRet = 0;
+
+  if( iSlot>=pDb->nText ){
+    int nByte = sizeof(char *)*(iSlot+1);
+    pDb->aText = (char **)sqlite3_realloc(pDb->aText, nByte);
+    memset(&pDb->aText[pDb->nText], 0, sizeof(char*)*(iSlot+1-pDb->nText));
+    pDb->nText = iSlot+1;
+  }
+
+  if( pErr->rc==SQLITE_OK ){
+    sqlite3_stmt *pStmt;          /* SQL statement to execute */
+    va_list ap;                   /* ... arguments */
+    int i;                        /* Used to iterate through parameters */
+    va_start(ap, iSlot);
+    pStmt = getAndBindSqlStatement(pErr, pDb, ap);
+    if( pStmt ){
+      int rc;
+      int first = 1;
+      while( SQLITE_ROW==sqlite3_step(pStmt) ){
+        if( first && sqlite3_column_count(pStmt)>0 ){
+          zRet = sqlite3_mprintf("%s", sqlite3_column_text(pStmt, 0));
+          sqlite3_free(pDb->aText[iSlot]);
+          pDb->aText[iSlot] = zRet;
+        }
+        first = 0;
+      }
+      if( SQLITE_OK!=sqlite3_reset(pStmt) ){
+        sqlite_error(pErr, pDb, "reset");
+      }
+    }
+    va_end(ap);
+  }
+
+  return zRet;
+}
+
+static void integrity_check_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Sqlite *pDb                     /* Database handle */
+){
+  if( pErr->rc==SQLITE_OK ){
+    Statement *pStatement;        /* Statement to execute */
+    int rc;                       /* Return code */
+    char *zErr = 0;               /* Integrity check error */
+
+    pStatement = getSqlStatement(pErr, pDb, "PRAGMA integrity_check");
+    if( pStatement ){
+      sqlite3_stmt *pStmt = pStatement->pStmt;
+      while( SQLITE_ROW==sqlite3_step(pStmt) ){
+        const char *z = sqlite3_column_text(pStmt, 0);
+        if( strcmp(z, "ok") ){
+          if( zErr==0 ){
+            zErr = sqlite3_mprintf("%s", z);
+          }else{
+            zErr = sqlite3_mprintf("%z\n%s", zErr, z);
+          }
+        }
+      }
+      sqlite3_reset(pStmt);
+
+      if( zErr ){
+        pErr->zErr = zErr;
+        pErr->rc = 1;
+      }
+    }
+  }
+}
+
+static void *launch_thread_main(void *pArg){
+  Thread *p = (Thread *)pArg;
+  return (void *)p->xProc(p->iTid, p->iArg);
+}
+
+static void launch_thread_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Threadset *pThreads,            /* Thread set */
+  char *(*xProc)(int, int),       /* Proc to run */
+  int iArg                        /* Argument passed to thread proc */
+){
+  if( pErr->rc==SQLITE_OK ){
+    int iTid = ++pThreads->iMaxTid;
+    Thread *p;
+    int rc;
+
+    p = (Thread *)sqlite3_malloc(sizeof(Thread));
+    memset(p, 0, sizeof(Thread));
+    p->iTid = iTid;
+    p->iArg = iArg;
+    p->xProc = xProc;
+
+    rc = pthread_create(&p->tid, NULL, launch_thread_main, (void *)p);
+    if( rc!=0 ){
+      system_error(pErr, rc);
+      sqlite3_free(p);
+    }else{
+      p->pNext = pThreads->pThread;
+      pThreads->pThread = p;
+    }
+  }
+}
+
+static void join_all_threads_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  Threadset *pThreads             /* Thread set */
+){
+  Thread *p;
+  Thread *pNext;
+  for(p=pThreads->pThread; p; p=pNext){
+    void *ret;
+    pNext = p->pNext;
+    int rc;
+    rc = pthread_join(p->tid, &ret);
+    if( rc!=0 ){
+      if( pErr->rc==SQLITE_OK ) system_error(pErr, rc);
+    }else{
+      printf("Thread %d says: %s\n", p->iTid, (ret==0 ? "..." : (char *)ret));
+    }
+    sqlite3_free(p);
+  }
+  pThreads->pThread = 0;
+}
+
+static i64 filesize_x(
+  Error *pErr,
+  const char *zFile
+){
+  i64 iRet = 0;
+  if( pErr->rc==SQLITE_OK ){
+    struct stat sStat;
+    if( stat(zFile, &sStat) ){
+      iRet = -1;
+    }else{
+      iRet = sStat.st_size;
+    }
+  }
+  return iRet;
+}
+
+static void filecopy_x(
+  Error *pErr,
+  const char *zFrom,
+  const char *zTo
+){
+  if( pErr->rc==SQLITE_OK ){
+    i64 nByte = filesize_x(pErr, zFrom);
+    if( nByte<0 ){
+      test_error_x(pErr, sqlite3_mprintf("no such file: %s", zFrom));
+    }else{
+      i64 iOff;
+      char aBuf[1024];
+      int fd1;
+      int fd2;
+      unlink(zTo);
+
+      fd1 = open(zFrom, O_RDONLY);
+      if( fd1<0 ){
+        system_error(pErr, errno);
+        return;
+      }
+      fd2 = open(zTo, O_RDWR|O_CREAT|O_EXCL, 0644);
+      if( fd2<0 ){
+        system_error(pErr, errno);
+        close(fd1);
+        return;
+      }
+
+      iOff = 0;
+      while( iOff<nByte ){
+        int nCopy = sizeof(aBuf);
+        if( nCopy+iOff>nByte ){
+          nCopy = nByte - iOff;
+        }
+        if( nCopy!=read(fd1, aBuf, nCopy) ){
+          system_error(pErr, errno);
+          break;
+        }
+        if( nCopy!=write(fd2, aBuf, nCopy) ){
+          system_error(pErr, errno);
+          break;
+        }
+        iOff += nCopy;
+      }
+
+      close(fd1);
+      close(fd2);
+    }
+  }
+}
+
+/* 
+** Used by setstoptime() and timetostop().
+*/
+static double timelimit = 0.0;
+static sqlite3_vfs *pTimelimitVfs = 0;
+
+static void setstoptime_x(
+  Error *pErr,                    /* IN/OUT: Error code */
+  int nMs                         /* Milliseconds until "stop time" */
+){
+  if( pErr->rc==SQLITE_OK ){
+    double t;
+    int rc;
+    pTimelimitVfs = sqlite3_vfs_find(0);
+    rc = pTimelimitVfs->xCurrentTime(pTimelimitVfs, &t);
+    if( rc!=SQLITE_OK ){
+      pErr->rc = rc;
+    }else{
+      timelimit = t + ((double)nMs)/(1000.0*60.0*60.0*24.0);
+    }
+  }
+}
+
+static int timetostop_x(
+  Error *pErr                     /* IN/OUT: Error code */
+){
+  int ret = 1;
+  if( pErr->rc==SQLITE_OK ){
+    double t;
+    int rc;
+    rc = pTimelimitVfs->xCurrentTime(pTimelimitVfs, &t);
+    if( rc!=SQLITE_OK ){
+      pErr->rc = rc;
+    }else{
+      ret = (t >= timelimit);
+    }
+  }
+  return ret;
+}
+
+/* 
+** The "Set Error Line" macro.
+*/
+#define SEL(e) ((e)->iLine = ((e)->rc ? (e)->iLine : __LINE__))
+
+
+/*************************************************************************
+**************************************************************************
+**************************************************************************
+** End infrastructure. Begin tests.
+*/
+
+#define WALTHREAD1_NTHREAD  10
+#define WALTHREAD3_NTHREAD  6
+
+static char *walthread1_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int nIter = 0;                  /* Iterations so far */
+
+  opendb(&err, &db, "test.db", 0);
+  while( !timetostop(&err) ){
+    const char *azSql[] = {
+      "SELECT md5sum(x) FROM t1 WHERE rowid != (SELECT max(rowid) FROM t1)",
+      "SELECT x FROM t1 WHERE rowid = (SELECT max(rowid) FROM t1)",
+    };
+    char *z1, *z2, *z3;
+
+    execsql(&err, &db, "BEGIN");
+    integrity_check(&err, &db);
+    z1 = execsql_text(&err, &db, 1, azSql[0]);
+    z2 = execsql_text(&err, &db, 2, azSql[1]);
+    z3 = execsql_text(&err, &db, 3, azSql[0]);
+    execsql(&err, &db, "COMMIT");
+
+    if( strcmp(z1, z2) || strcmp(z1, z3) ){
+      test_error(&err, "Failed read: %s %s %s", z1, z2, z3);
+    }
+
+    sql_script(&err, &db,
+        "BEGIN;"
+          "INSERT INTO t1 VALUES(randomblob(100));"
+          "INSERT INTO t1 VALUES(randomblob(100));"
+          "INSERT INTO t1 SELECT md5sum(x) FROM t1;"
+        "COMMIT;"
+    );
+    nIter++;
+  }
+  closedb(&err, &db);
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("%d iterations", nIter);
+}
+
+static char *walthread1_ckpt_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int nCkpt = 0;                  /* Checkpoints so far */
+
+  opendb(&err, &db, "test.db", 0);
+  while( !timetostop(&err) ){
+    usleep(500*1000);
+    execsql(&err, &db, "PRAGMA wal_checkpoint");
+    if( err.rc==SQLITE_OK ) nCkpt++;
+    clear_error(&err, SQLITE_BUSY);
+  }
+  closedb(&err, &db);
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("%d checkpoints", nCkpt);
+}
+
+static void walthread1(int nMs){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  Threadset threads = {0};        /* Test threads */
+  int i;                          /* Iterator variable */
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db,
+      "PRAGMA journal_mode = WAL;"
+      "CREATE TABLE t1(x PRIMARY KEY);"
+      "INSERT INTO t1 VALUES(randomblob(100));"
+      "INSERT INTO t1 VALUES(randomblob(100));"
+      "INSERT INTO t1 SELECT md5sum(x) FROM t1;"
+  );
+
+  setstoptime(&err, nMs);
+  for(i=0; i<WALTHREAD1_NTHREAD; i++){
+    launch_thread(&err, &threads, walthread1_thread, 0);
+  }
+  launch_thread(&err, &threads, walthread1_ckpt_thread, 0);
+  join_all_threads(&err, &threads);
+
+  print_and_free_err(&err);
+}
+
+static char *walthread2_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int anTrans[2] = {0, 0};        /* Number of WAL and Rollback transactions */
+
+  const char *zJournal = "PRAGMA journal_mode = WAL";
+  if( iArg ){ zJournal = "PRAGMA journal_mode = DELETE"; }
+
+  while( !timetostop(&err) ){
+    int journal_exists = 0;
+    int wal_exists = 0;
+
+    opendb(&err, &db, "test.db", 0);
+
+    sql_script(&err, &db, zJournal);
+    clear_error(&err, SQLITE_BUSY);
+    sql_script(&err, &db, "BEGIN");
+    sql_script(&err, &db, "INSERT INTO t1 VALUES(NULL, randomblob(100))");
+
+    journal_exists = (filesize(&err, "test.db-journal") >= 0);
+    wal_exists = (filesize(&err, "test.db-wal") >= 0);
+    if( (journal_exists+wal_exists)!=1 ){
+      test_error(&err, "File system looks incorrect (%d, %d)", 
+          journal_exists, wal_exists
+      );
+    }
+    anTrans[journal_exists]++;
+
+    sql_script(&err, &db, "COMMIT");
+    integrity_check(&err, &db);
+    closedb(&err, &db);
+  }
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("W %d R %d", anTrans[0], anTrans[1]);
+}
+
+static void walthread2(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db, "CREATE TABLE t1(x INTEGER PRIMARY KEY, y UNIQUE)");
+  closedb(&err, &db);
+
+  setstoptime(&err, nMs);
+  launch_thread(&err, &threads, walthread2_thread, 0);
+  launch_thread(&err, &threads, walthread2_thread, 0);
+  launch_thread(&err, &threads, walthread2_thread, 1);
+  launch_thread(&err, &threads, walthread2_thread, 1);
+  join_all_threads(&err, &threads);
+
+  print_and_free_err(&err);
+}
+
+static char *walthread3_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  i64 iNextWrite;                 /* Next value this thread will write */
+
+  opendb(&err, &db, "test.db", 0);
+  sql_script(&err, &db, "PRAGMA wal_autocheckpoint = 10");
+
+  iNextWrite = iArg+1;
+  while( 1 ){
+    i64 sum1;
+    i64 sum2;
+    int stop = 0;                 /* True to stop executing (test timed out) */
+
+    while( 0==(stop = timetostop(&err)) ){
+      i64 iMax = execsql_i64(&err, &db, "SELECT max(cnt) FROM t1");
+      if( iMax+1==iNextWrite ) break;
+    }
+    if( stop ) break;
+
+    sum1 = execsql_i64(&err, &db, "SELECT sum(cnt) FROM t1");
+    sum2 = execsql_i64(&err, &db, "SELECT sum(sum1) FROM t1");
+    execsql_i64(&err, &db, 
+        "INSERT INTO t1 VALUES(:iNextWrite, :iSum1, :iSum2)",
+        &iNextWrite, &sum1, &sum2
+    );
+    integrity_check(&err, &db);
+
+    iNextWrite += WALTHREAD3_NTHREAD;
+  }
+
+  closedb(&err, &db);
+  print_and_free_err(&err);
+  return 0;
+}
+
+static void walthread3(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+  int i;
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db, 
+      "PRAGMA journal_mode = WAL;"
+      "CREATE TABLE t1(cnt PRIMARY KEY, sum1, sum2);"
+      "CREATE INDEX i1 ON t1(sum1);"
+      "CREATE INDEX i2 ON t1(sum2);"
+      "INSERT INTO t1 VALUES(0, 0, 0);"
+  );
+  closedb(&err, &db);
+
+  setstoptime(&err, nMs);
+  for(i=0; i<WALTHREAD3_NTHREAD; i++){
+    launch_thread(&err, &threads, walthread3_thread, i);
+  }
+  join_all_threads(&err, &threads);
+
+  print_and_free_err(&err);
+}
+
+static char *walthread4_reader_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+
+  opendb(&err, &db, "test.db", 0);
+  while( !timetostop(&err) ){
+    integrity_check(&err, &db);
+  }
+  closedb(&err, &db);
+
+  print_and_free_err(&err);
+  return 0;
+}
+
+static char *walthread4_writer_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  i64 iRow = 1;
+
+  opendb(&err, &db, "test.db", 0);
+  sql_script(&err, &db, "PRAGMA wal_autocheckpoint = 15;");
+  while( !timetostop(&err) ){
+    execsql_i64(
+        &err, &db, "REPLACE INTO t1 VALUES(:iRow, randomblob(300))", &iRow
+    );
+    iRow++;
+    if( iRow==10 ) iRow = 0;
+  }
+  closedb(&err, &db);
+
+  print_and_free_err(&err);
+  return 0;
+}
+
+static void walthread4(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db, 
+      "PRAGMA journal_mode = WAL;"
+      "CREATE TABLE t1(a INTEGER PRIMARY KEY, b UNIQUE);"
+  );
+  closedb(&err, &db);
+
+  setstoptime(&err, nMs);
+  launch_thread(&err, &threads, walthread4_reader_thread, 0);
+  launch_thread(&err, &threads, walthread4_writer_thread, 0);
+  join_all_threads(&err, &threads);
+
+  print_and_free_err(&err);
+}
+
+static char *walthread5_thread(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  i64 nRow;
+
+  opendb(&err, &db, "test.db", 0);
+  nRow = execsql_i64(&err, &db, "SELECT count(*) FROM t1");
+  closedb(&err, &db);
+
+  if( nRow!=65536 ) test_error(&err, "Bad row count: %d", (int)nRow);
+  print_and_free_err(&err);
+  return 0;
+}
+static void walthread5(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db, 
+      "PRAGMA wal_autocheckpoint = 0;"
+      "PRAGMA page_size = 1024;"
+      "PRAGMA journal_mode = WAL;"
+      "CREATE TABLE t1(x);"
+      "BEGIN;"
+      "INSERT INTO t1 VALUES(randomblob(900));"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*     2 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*     4 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*     8 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*    16 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*    32 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*    64 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*   128 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*   256 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*   512 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*  1024 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*  2048 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*  4096 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /*  8192 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /* 16384 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /* 32768 */"
+      "INSERT INTO t1 SELECT randomblob(900) FROM t1;      /* 65536 */"
+      "COMMIT;"
+  );
+  filecopy(&err, "test.db", "test_sv.db");
+  filecopy(&err, "test.db-wal", "test_sv.db-wal");
+  closedb(&err, &db);
+
+  filecopy(&err, "test_sv.db", "test.db");
+  filecopy(&err, "test_sv.db-wal", "test.db-wal");
+
+  if( err.rc==SQLITE_OK ){
+    printf("  WAL file is %d bytes,", (int)filesize(&err,"test.db-wal"));
+    printf(" DB file is %d.\n", (int)filesize(&err,"test.db"));
+  }
+
+  setstoptime(&err, nMs);
+  launch_thread(&err, &threads, walthread5_thread, 0);
+  launch_thread(&err, &threads, walthread5_thread, 0);
+  launch_thread(&err, &threads, walthread5_thread, 0);
+  launch_thread(&err, &threads, walthread5_thread, 0);
+  launch_thread(&err, &threads, walthread5_thread, 0);
+  join_all_threads(&err, &threads);
+
+  if( err.rc==SQLITE_OK ){
+    printf("  WAL file is %d bytes,", (int)filesize(&err,"test.db-wal"));
+    printf(" DB file is %d.\n", (int)filesize(&err,"test.db"));
+  }
+
+  print_and_free_err(&err);
+}
+
+/*------------------------------------------------------------------------
+** Test case "cgt_pager_1"
+*/
+#define CALLGRINDTEST1_NROW 10000
+static void cgt_pager_1_populate(Error *pErr, Sqlite *pDb){
+  const char *zInsert = "INSERT INTO t1 VALUES(:iRow, zeroblob(:iBlob))";
+  i64 iRow;
+  sql_script(pErr, pDb, "BEGIN");
+  for(iRow=1; iRow<=CALLGRINDTEST1_NROW; iRow++){
+    i64 iBlob = 600 + (iRow%300);
+    execsql(pErr, pDb, zInsert, &iRow, &iBlob);
+  }
+  sql_script(pErr, pDb, "COMMIT");
+}
+static void cgt_pager_1_update(Error *pErr, Sqlite *pDb){
+  const char *zUpdate = "UPDATE t1 SET b = zeroblob(:iBlob) WHERE a = :iRow";
+  i64 iRow;
+  sql_script(pErr, pDb, "BEGIN");
+  for(iRow=1; iRow<=CALLGRINDTEST1_NROW; iRow++){
+    i64 iBlob = 600 + ((iRow+100)%300);
+    execsql(pErr, pDb, zUpdate, &iBlob, &iRow);
+  }
+  sql_script(pErr, pDb, "COMMIT");
+}
+static void cgt_pager_1_read(Error *pErr, Sqlite *pDb){
+  i64 iRow;
+  sql_script(pErr, pDb, "BEGIN");
+  for(iRow=1; iRow<=CALLGRINDTEST1_NROW; iRow++){
+    execsql(pErr, pDb, "SELECT * FROM t1 WHERE a = :iRow", &iRow);
+  }
+  sql_script(pErr, pDb, "COMMIT");
+}
+static void cgt_pager_1(int nMs){
+  void (*xSub)(Error *, Sqlite *);
+  Error err = {0};
+  Sqlite db = {0};
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db,
+      "PRAGMA cache_size = 2000;"
+      "PRAGMA page_size = 1024;"
+      "CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB);"
+  );
+
+  xSub = cgt_pager_1_populate; xSub(&err, &db);
+  xSub = cgt_pager_1_update;   xSub(&err, &db);
+  xSub = cgt_pager_1_read;     xSub(&err, &db);
+
+  closedb(&err, &db);
+  print_and_free_err(&err);
+}
+
+/*------------------------------------------------------------------------
+** Test case "dynamic_triggers"
+**
+**   Two threads executing statements that cause deeply nested triggers
+**   to fire. And one thread busily creating and deleting triggers. This
+**   is an attempt to find a bug reported to us.
+*/
+
+static char *dynamic_triggers_1(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  int nDrop = 0;
+  int nCreate = 0;
+
+  opendb(&err, &db, "test.db", 0);
+  while( !timetostop(&err) ){
+    int i;
+
+    for(i=1; i<9; i++){
+      char *zSql = sqlite3_mprintf(
+        "CREATE TRIGGER itr%d BEFORE INSERT ON t%d BEGIN "
+          "INSERT INTO t%d VALUES(new.x, new.y);"
+        "END;", i, i, i+1
+      );
+      execsql(&err, &db, zSql);
+      sqlite3_free(zSql);
+      nCreate++;
+    }
+
+    for(i=1; i<9; i++){
+      char *zSql = sqlite3_mprintf(
+        "CREATE TRIGGER dtr%d BEFORE DELETE ON t%d BEGIN "
+          "DELETE FROM t%d WHERE x = old.x; "
+        "END;", i, i, i+1
+      );
+      execsql(&err, &db, zSql);
+      sqlite3_free(zSql);
+      nCreate++;
+    }
+
+    for(i=1; i<9; i++){
+      char *zSql = sqlite3_mprintf("DROP TRIGGER itr%d", i);
+      execsql(&err, &db, zSql);
+      sqlite3_free(zSql);
+      nDrop++;
+    }
+
+    for(i=1; i<9; i++){
+      char *zSql = sqlite3_mprintf("DROP TRIGGER dtr%d", i);
+      execsql(&err, &db, zSql);
+      sqlite3_free(zSql);
+      nDrop++;
+    }
+  }
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("%d created, %d dropped", nCreate, nDrop);
+}
+
+static char *dynamic_triggers_2(int iTid, int iArg){
+  Error err = {0};                /* Error code and message */
+  Sqlite db = {0};                /* SQLite database connection */
+  i64 iVal = 0;
+  int nInsert = 0;
+  int nDelete = 0;
+
+  opendb(&err, &db, "test.db", 0);
+  while( !timetostop(&err) ){
+    do {
+      iVal = (iVal+1)%100;
+      execsql(&err, &db, "INSERT INTO t1 VALUES(:iX, :iY+1)", &iVal, &iVal);
+      nInsert++;
+    } while( iVal );
+
+    do {
+      iVal = (iVal+1)%100;
+      execsql(&err, &db, "DELETE FROM t1 WHERE x = :iX", &iVal);
+      nDelete++;
+    } while( iVal );
+  }
+
+  print_and_free_err(&err);
+  return sqlite3_mprintf("%d inserts, %d deletes", nInsert, nDelete);
+}
+
+static void dynamic_triggers(int nMs){
+  Error err = {0};
+  Sqlite db = {0};
+  Threadset threads = {0};
+
+  opendb(&err, &db, "test.db", 1);
+  sql_script(&err, &db, 
+      "PRAGMA page_size = 1024;"
+      "PRAGMA journal_mode = WAL;"
+      "CREATE TABLE t1(x, y);"
+      "CREATE TABLE t2(x, y);"
+      "CREATE TABLE t3(x, y);"
+      "CREATE TABLE t4(x, y);"
+      "CREATE TABLE t5(x, y);"
+      "CREATE TABLE t6(x, y);"
+      "CREATE TABLE t7(x, y);"
+      "CREATE TABLE t8(x, y);"
+      "CREATE TABLE t9(x, y);"
+  );
+
+  setstoptime(&err, nMs);
+
+  sqlite3_enable_shared_cache(1);
+  launch_thread(&err, &threads, dynamic_triggers_2, 0);
+  launch_thread(&err, &threads, dynamic_triggers_2, 0);
+  sqlite3_enable_shared_cache(0);
+
+  sleep(2);
+
+  launch_thread(&err, &threads, dynamic_triggers_2, 0);
+  launch_thread(&err, &threads, dynamic_triggers_1, 0);
+
+  join_all_threads(&err, &threads);
+
+  print_and_free_err(&err);
+}
+
+#include "tt3_checkpoint.c"
+
+int main(int argc, char **argv){
+  struct ThreadTest {
+    void (*xTest)(int);
+    const char *zTest;
+    int nMs;
+  } aTest[] = {
+    { walthread1, "walthread1", 20000 },
+    { walthread2, "walthread2", 20000 },
+    { walthread3, "walthread3", 20000 },
+    { walthread4, "walthread4", 20000 },
+    { walthread5, "walthread5",  1000 },
+    { walthread5, "walthread5",  1000 },
+    
+    { cgt_pager_1,      "cgt_pager_1", 0 },
+    { dynamic_triggers, "dynamic_triggers", 20000 },
+
+    { checkpoint_starvation_1, "checkpoint_starvation_1", 10000 },
+    { checkpoint_starvation_2, "checkpoint_starvation_2", 10000 },
+  };
+
+  int i;
+  char *zTest = 0;
+  int nTest = 0;
+  int bTestfound = 0;
+  int bPrefix = 0;
+
+  if( argc>2 ) goto usage;
+  if( argc==2 ){
+    zTest = argv[1];
+    nTest = strlen(zTest);
+    if( zTest[nTest-1]=='*' ){
+      nTest--;
+      bPrefix = 1;
+    }
+  }
+
+  sqlite3_config(SQLITE_CONFIG_MULTITHREAD);
+
+  for(i=0; i<sizeof(aTest)/sizeof(aTest[0]); i++){
+    char const *z = aTest[i].zTest;
+    int n = strlen(z);
+    if( !zTest || ((bPrefix || n==nTest) && 0==strncmp(zTest, z, nTest)) ){
+      printf("Running %s for %d seconds...\n", z, aTest[i].nMs/1000);
+      aTest[i].xTest(aTest[i].nMs);
+      bTestfound++;
+    }
+  }
+  if( bTestfound==0 ) goto usage;
+
+  printf("Total of %d errors across all tests\n", nGlobalErr);
+  return (nGlobalErr>0 ? 255 : 0);
+
+ usage:
+  printf("Usage: %s [testname|testprefix*]\n", argv[0]);
+  printf("Available tests are:\n");
+  for(i=0; i<sizeof(aTest)/sizeof(aTest[0]); i++){
+    printf("   %s\n", aTest[i].zTest);
+  }
+
+  return 254;
+}
+
+