/*

** 2003 December 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.

**

*************************************************************************

** Code for testing the the SQLite library in a multithreaded environment.

**

** $Id: test4.c,v 1.23 2008/07/28 19:34:54 drh Exp $

*/

#include "sqliteInt.h"

#include "tcl.h"

#if defined(SQLITE_OS_UNIX) && OS_UNIX==1 && SQLITE_THREADSAFE

#include <stdlib.h>

#include <string.h>

#include <pthread.h>

#include <sched.h>

#include <ctype.h>

/*

** Each thread is controlled by an instance of the following

** structure.

*/

typedef struct Thread Thread;

struct Thread {

  /* The first group of fields are writable by the master and read-only

  ** to the thread. */

  char *zFilename;       /* Name of database file */

  void (*xOp)(Thread*);  /* next operation to do */

  char *zArg;            /* argument usable by xOp */

  int opnum;             /* Operation number */

  int busy;              /* True if this thread is in use */

  /* The next group of fields are writable by the thread but read-only to the

  ** master. */

  int completed;        /* Number of operations completed */

  sqlite3 *db;           /* Open database */

  sqlite3_stmt *pStmt;     /* Pending operation */

  char *zErr;           /* operation error */

  char *zStaticErr;     /* Static error message */

  int rc;               /* operation return code */

  int argc;             /* number of columns in result */

  const char *argv[100];    /* result columns */

  const char *colv[100];    /* result column names */

};

/*

** There can be as many as 26 threads running at once.  Each is named

** by a capital letter: A, B, C, ..., Y, Z.

*/

#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));

    sqlite3_close(p->db);

    p->db = 0;

  }

  p->pStmt = 0;

  p->completed = 1;

  while( p->opnum<=p->completed ) sched_yield();

  while( p->xOp ){

    if( p->zErr && p->zErr!=p->zStaticErr ){

      sqlite3_free(p->zErr);

      p->zErr = 0;

    }

    (*p->xOp)(p);

    p->completed++;

    while( p->opnum<=p->completed ) sched_yield();

  }

  if( p->pStmt ){

    sqlite3_finalize(p->pStmt);

    p->pStmt = 0;

  }

  if( p->db ){

    sqlite3_close(p->db);

    p->db = 0;

  }

  if( p->zErr && p->zErr!=p->zStaticErr ){

    sqlite3_free(p->zErr);

    p->zErr = 0;

  }

  p->completed++;

  sqlite3_thread_cleanup();

  return 0;

}

/*

** Get a thread ID which is an upper case letter.  Return the index.

** If the argument is not a valid thread ID put an error message in

** the interpreter and return -1.

*/

static int parse_thread_id(Tcl_Interp *interp, const char *zArg){

  if( zArg==0 || zArg[0]==0 || zArg[1]!=0 || !isupper((unsigned char)zArg[0]) ){

    Tcl_AppendResult(interp, "thread ID must be an upper case letter", 0);

    return -1;

  }

  return zArg[0] - 'A';

}

/*

** Usage:    thread_create NAME  FILENAME

**

** NAME should be an upper case letter.  Start the thread running with

** an open connection to the given database.

*/

static int tcl_thread_create(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  pthread_t x;

  int rc;

  if( argc!=3 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID FILENAME", 0);

    return TCL_ERROR;

  }

  i = parse_thread_id(interp, argv[1]);

  if( i<0 ) return TCL_ERROR;

  if( threadset[i].busy ){

    Tcl_AppendResult(interp, "thread ", argv[1], " is already running", 0);

    return TCL_ERROR;

  }

  threadset[i].busy = 1;

  sqlite3_free(threadset[i].zFilename);

  threadset[i].zFilename = sqlite3DbStrDup(0, 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.

*/

static int tcl_thread_wait(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  if( argc!=2 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID", 0);

    return TCL_ERROR;

  }

  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;

}

/*

** Usage:  thread_halt ID

**

** Cause a thread to shut itself down.  Wait for the shutdown to be

** completed.  If ID is "*" then stop all threads.

*/

static int tcl_thread_halt(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  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

**

** Wait on the most recent thread_step to complete, then return the

** number of columns in the result set.

*/

static int tcl_thread_argc(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  char zBuf[100];

  if( argc!=2 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID", 0);

    return TCL_ERROR;

  }

  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]);

  sprintf(zBuf, "%d", threadset[i].argc);

  Tcl_AppendResult(interp, zBuf, 0);

  return TCL_OK;

}

/*

** Usage: thread_argv  ID   N

**

** Wait on the most recent thread_step to complete, then return the

** value of the N-th columns in the result set.

*/

static int tcl_thread_argv(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  int n;

  if( argc!=3 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID N", 0);

    return TCL_ERROR;

  }

  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;

}

/*

** Usage: thread_colname  ID   N

**

** Wait on the most recent thread_step to complete, then return the

** name of the N-th columns in the result set.

*/

static int tcl_thread_colname(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  int n;

  if( argc!=3 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID N", 0);

    return TCL_ERROR;

  }

  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;

}

/*

** Usage: thread_result  ID

**

** Wait on the most recent operation to complete, then return the

** result code from that operation.

*/

static int tcl_thread_result(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  const char *zName;

  if( argc!=2 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID", 0);

    return TCL_ERROR;

  }

  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]);

  switch( threadset[i].rc ){

    case SQLITE_OK:         zName = "SQLITE_OK";          break;

    case SQLITE_ERROR:      zName = "SQLITE_ERROR";       break;

    case SQLITE_PERM:       zName = "SQLITE_PERM";        break;

    case SQLITE_ABORT:      zName = "SQLITE_ABORT";       break;

    case SQLITE_BUSY:       zName = "SQLITE_BUSY";        break;

    case SQLITE_LOCKED:     zName = "SQLITE_LOCKED";      break;

    case SQLITE_NOMEM:      zName = "SQLITE_NOMEM";       break;

    case SQLITE_READONLY:   zName = "SQLITE_READONLY";    break;

    case SQLITE_INTERRUPT:  zName = "SQLITE_INTERRUPT";   break;

    case SQLITE_IOERR:      zName = "SQLITE_IOERR";       break;

    case SQLITE_CORRUPT:    zName = "SQLITE_CORRUPT";     break;

    case SQLITE_FULL:       zName = "SQLITE_FULL";        break;

    case SQLITE_CANTOPEN:   zName = "SQLITE_CANTOPEN";    break;

    case SQLITE_PROTOCOL:   zName = "SQLITE_PROTOCOL";    break;

    case SQLITE_EMPTY:      zName = "SQLITE_EMPTY";       break;

    case SQLITE_SCHEMA:     zName = "SQLITE_SCHEMA";      break;

    case SQLITE_CONSTRAINT: zName = "SQLITE_CONSTRAINT";  break;

    case SQLITE_MISMATCH:   zName = "SQLITE_MISMATCH";    break;

    case SQLITE_MISUSE:     zName = "SQLITE_MISUSE";      break;

    case SQLITE_NOLFS:      zName = "SQLITE_NOLFS";       break;

    case SQLITE_AUTH:       zName = "SQLITE_AUTH";        break;

    case SQLITE_FORMAT:     zName = "SQLITE_FORMAT";      break;

    case SQLITE_RANGE:      zName = "SQLITE_RANGE";       break;

    case SQLITE_ROW:        zName = "SQLITE_ROW";         break;

    case SQLITE_DONE:       zName = "SQLITE_DONE";        break;

    default:                zName = "SQLITE_Unknown";     break;

  }

  Tcl_AppendResult(interp, zName, 0);

  return TCL_OK;

}

/*

** Usage: thread_error  ID

**

** Wait on the most recent operation to complete, then return the

** error string.

*/

static int tcl_thread_error(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  if( argc!=2 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID", 0);

    return TCL_ERROR;

  }

  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.

*/

static void do_compile(Thread *p){

  if( p->db==0 ){

    p->zErr = p->zStaticErr = "no database is open";

    p->rc = SQLITE_ERROR;

    return;

  }

  if( p->pStmt ){

    sqlite3_finalize(p->pStmt);

    p->pStmt = 0;

  }

  p->rc = sqlite3_prepare(p->db, p->zArg, -1, &p->pStmt, 0);

}

/*

** Usage: thread_compile ID SQL

**

** Compile a new virtual machine.

*/

static int tcl_thread_compile(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  if( argc!=3 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " ID SQL", 0);

    return TCL_ERROR;

  }

  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 = sqlite3DbStrDup(0, argv[2]);

  threadset[i].opnum++;

  return TCL_OK;

}

/*

** This procedure runs in the thread to step the virtual machine.

*/

static void do_step(Thread *p){

  int i;

  if( p->pStmt==0 ){

    p->zErr = p->zStaticErr = "no virtual machine available";

    p->rc = SQLITE_ERROR;

    return;

  }

  p->rc = sqlite3_step(p->pStmt);

  if( p->rc==SQLITE_ROW ){

    p->argc = sqlite3_column_count(p->pStmt);

    for(i=0; i<sqlite3_data_count(p->pStmt); i++){

      p->argv[i] = (char*)sqlite3_column_text(p->pStmt, i);

    }

    for(i=0; i<p->argc; i++){

      p->colv[i] = sqlite3_column_name(p->pStmt, i);

    }

  }

}

/*

** Usage: thread_step ID

**

** Advance the virtual machine by one step

*/

static int tcl_thread_step(

  void *NotUsed,

  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */

  int argc,              /* Number of arguments */

  const char **argv      /* Text of each argument */

){

  int i;

  if( argc!=2 ){

    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],

       " IDL", 0);

    return TCL_ERROR;

  }

  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;

  }