#define N_THREAD 26
static Thread threadset[N_THREAD];


/*
** The main loop for a thread.  Threads use busy waiting. 
*/
static void *thread_main(void *pArg){
  Thread *p = (Thread*)pArg;
  if( p->db ){
    sqlite3_close(p->db);
  }
  sqlite3_open(p->zFilename, &p->db);
  if( SQLITE_OK!=sqlite3_errcode(p->db) ){
    p->zErr = strdup(sqlite3_errmsg(p->db));
................................................................................
    return TCL_ERROR;
  }
  threadset[i].busy = 1;
  sqlite3_free(threadset[i].zFilename);
  threadset[i].zFilename = sqlite3_mprintf("%s", argv[2]);
  threadset[i].opnum = 1;
  threadset[i].completed = 0;
  rc = pthread_create(&x, 0, thread_main, &threadset[i]);
  if( rc ){
    Tcl_AppendResult(interp, "failed to create the thread", 0);
    sqlite3_free(threadset[i].zFilename);
    threadset[i].busy = 0;
    return TCL_ERROR;
  }
  pthread_detach(x);
  return TCL_OK;
}

/*
** Wait for a thread to reach its idle state.
*/
static void thread_wait(Thread *p){
  while( p->opnum>p->completed ) sched_yield();
}

/*
** Usage:  thread_wait ID
**
** Wait on thread ID to reach its idle state.
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  return TCL_OK;
}

/*
** Stop a thread.
*/
static void stop_thread(Thread *p){
  thread_wait(p);
  p->xOp = 0;
  p->opnum++;
  thread_wait(p);
  sqlite3_free(p->zArg);
  p->zArg = 0;
  sqlite3_free(p->zFilename);
  p->zFilename = 0;
  p->busy = 0;
}

................................................................................
  if( argc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " ID", 0);
    return TCL_ERROR;
  }
  if( argv[1][0]=='*' && argv[1][1]==0 ){
    for(i=0; i<N_THREAD; i++){
      if( threadset[i].busy ) stop_thread(&threadset[i]);
    }
  }else{
    i = parse_thread_id(interp, argv[1]);
    if( i<0 ) return TCL_ERROR;
    if( !threadset[i].busy ){
      Tcl_AppendResult(interp, "no such thread", 0);
      return TCL_ERROR;
    }
    stop_thread(&threadset[i]);
  }
  return TCL_OK;
}

/*
** Usage: thread_argc  ID
**
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", threadset[i].argc);
  Tcl_AppendResult(interp, zBuf, 0);
  return TCL_OK;
}

/*
** Usage: thread_argv  ID   N
................................................................................
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  thread_wait(&threadset[i]);
  if( n<0 || n>=threadset[i].argc ){
    Tcl_AppendResult(interp, "column number out of range", 0);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, threadset[i].argv[n], 0);
  return TCL_OK;
}
................................................................................
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  thread_wait(&threadset[i]);
  if( n<0 || n>=threadset[i].argc ){
    Tcl_AppendResult(interp, "column number out of range", 0);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, threadset[i].colv[n], 0);
  return TCL_OK;
}
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  zName = sqlite3ErrName(threadset[i].rc);
  Tcl_AppendResult(interp, zName, 0);
  return TCL_OK;
}

/*
** Usage: thread_error  ID
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  Tcl_AppendResult(interp, threadset[i].zErr, 0);
  return TCL_OK;
}

/*
** This procedure runs in the thread to compile an SQL statement.
*/
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  threadset[i].xOp = do_compile;
  sqlite3_free(threadset[i].zArg);
  threadset[i].zArg = sqlite3_mprintf("%s", argv[2]);
  threadset[i].opnum++;
  return TCL_OK;
}

................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  threadset[i].xOp = do_step;
  threadset[i].opnum++;
  return TCL_OK;
}

/*
** This procedure runs in the thread to finalize a virtual machine.
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  threadset[i].xOp = do_finalize;
  sqlite3_free(threadset[i].zArg);
  threadset[i].zArg = 0;
  threadset[i].opnum++;
  return TCL_OK;
}

................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  j = parse_thread_id(interp, argv[2]);
  if( j<0 ) return TCL_ERROR;
  if( !threadset[j].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[j]);
  temp = threadset[i].db;
  threadset[i].db = threadset[j].db;
  threadset[j].db = temp;
  return TCL_OK;
}

/*
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  sqlite3TestMakePointerStr(interp, zBuf, threadset[i].db);
  threadset[i].db = 0;
  Tcl_AppendResult(interp, zBuf, (char*)0);
  return TCL_OK;
}

/*
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  assert( !threadset[i].db );
  threadset[i].db = (sqlite3*)sqlite3TestTextToPtr(argv[2]);
  return TCL_OK;
}

/*
** Usage: thread_stmt_get ID
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  thread_wait(&threadset[i]);
  sqlite3TestMakePointerStr(interp, zBuf, threadset[i].pStmt);
  threadset[i].pStmt = 0;
  Tcl_AppendResult(interp, zBuf, (char*)0);
  return TCL_OK;
}

/*

#define N_THREAD 26
static Thread threadset[N_THREAD];


/*
** The main loop for a thread.  Threads use busy waiting. 
*/
static void *test_thread_main(void *pArg){
  Thread *p = (Thread*)pArg;
  if( p->db ){
    sqlite3_close(p->db);
  }
  sqlite3_open(p->zFilename, &p->db);
  if( SQLITE_OK!=sqlite3_errcode(p->db) ){
    p->zErr = strdup(sqlite3_errmsg(p->db));
................................................................................
    return TCL_ERROR;
  }
  threadset[i].busy = 1;
  sqlite3_free(threadset[i].zFilename);
  threadset[i].zFilename = sqlite3_mprintf("%s", argv[2]);
  threadset[i].opnum = 1;
  threadset[i].completed = 0;
  rc = pthread_create(&x, 0, test_thread_main, &threadset[i]);
  if( rc ){
    Tcl_AppendResult(interp, "failed to create the thread", 0);
    sqlite3_free(threadset[i].zFilename);
    threadset[i].busy = 0;
    return TCL_ERROR;
  }
  pthread_detach(x);
  return TCL_OK;
}

/*
** Wait for a thread to reach its idle state.
*/
static void test_thread_wait(Thread *p){
  while( p->opnum>p->completed ) sched_yield();
}

/*
** Usage:  thread_wait ID
**
** Wait on thread ID to reach its idle state.
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  return TCL_OK;
}

/*
** Stop a thread.
*/
static void test_stop_thread(Thread *p){
  test_thread_wait(p);
  p->xOp = 0;
  p->opnum++;
  test_thread_wait(p);
  sqlite3_free(p->zArg);
  p->zArg = 0;
  sqlite3_free(p->zFilename);
  p->zFilename = 0;
  p->busy = 0;
}

................................................................................
  if( argc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " ID", 0);
    return TCL_ERROR;
  }
  if( argv[1][0]=='*' && argv[1][1]==0 ){
    for(i=0; i<N_THREAD; i++){
      if( threadset[i].busy ) test_stop_thread(&threadset[i]);
    }
  }else{
    i = parse_thread_id(interp, argv[1]);
    if( i<0 ) return TCL_ERROR;
    if( !threadset[i].busy ){
      Tcl_AppendResult(interp, "no such thread", 0);
      return TCL_ERROR;
    }
    test_stop_thread(&threadset[i]);
  }
  return TCL_OK;
}

/*
** Usage: thread_argc  ID
**
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", threadset[i].argc);
  Tcl_AppendResult(interp, zBuf, 0);
  return TCL_OK;
}

/*
** Usage: thread_argv  ID   N
................................................................................
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  test_thread_wait(&threadset[i]);
  if( n<0 || n>=threadset[i].argc ){
    Tcl_AppendResult(interp, "column number out of range", 0);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, threadset[i].argv[n], 0);
  return TCL_OK;
}
................................................................................
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &n) ) return TCL_ERROR;
  test_thread_wait(&threadset[i]);
  if( n<0 || n>=threadset[i].argc ){
    Tcl_AppendResult(interp, "column number out of range", 0);
    return TCL_ERROR;
  }
  Tcl_AppendResult(interp, threadset[i].colv[n], 0);
  return TCL_OK;
}
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  zName = sqlite3ErrName(threadset[i].rc);
  Tcl_AppendResult(interp, zName, 0);
  return TCL_OK;
}

/*
** Usage: thread_error  ID
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  Tcl_AppendResult(interp, threadset[i].zErr, 0);
  return TCL_OK;
}

/*
** This procedure runs in the thread to compile an SQL statement.
*/
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  threadset[i].xOp = do_compile;
  sqlite3_free(threadset[i].zArg);
  threadset[i].zArg = sqlite3_mprintf("%s", argv[2]);
  threadset[i].opnum++;
  return TCL_OK;
}

................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  threadset[i].xOp = do_step;
  threadset[i].opnum++;
  return TCL_OK;
}

/*
** This procedure runs in the thread to finalize a virtual machine.
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  threadset[i].xOp = do_finalize;
  sqlite3_free(threadset[i].zArg);
  threadset[i].zArg = 0;
  threadset[i].opnum++;
  return TCL_OK;
}

................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  j = parse_thread_id(interp, argv[2]);
  if( j<0 ) return TCL_ERROR;
  if( !threadset[j].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[j]);
  temp = threadset[i].db;
  threadset[i].db = threadset[j].db;
  threadset[j].db = temp;
  return TCL_OK;
}

/*
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  sqlite3TestMakePointerStr(interp, zBuf, threadset[i].db);
  threadset[i].db = 0;
  Tcl_AppendResult(interp, zBuf, (char*)0);
  return TCL_OK;
}

/*
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  assert( !threadset[i].db );
  threadset[i].db = (sqlite3*)sqlite3TestTextToPtr(argv[2]);
  return TCL_OK;
}

/*
** Usage: thread_stmt_get ID
................................................................................
  }
  i = parse_thread_id(interp, argv[1]);
  if( i<0 ) return TCL_ERROR;
  if( !threadset[i].busy ){
    Tcl_AppendResult(interp, "no such thread", 0);
    return TCL_ERROR;
  }
  test_thread_wait(&threadset[i]);
  sqlite3TestMakePointerStr(interp, zBuf, threadset[i].pStmt);
  threadset[i].pStmt = 0;
  Tcl_AppendResult(interp, zBuf, (char*)0);
  return TCL_OK;
}

/*