vdbe.c

最新的sqlite3.6.2源代码

      }else{
        zBuf[k++] = '.';
      }
    }
    zBuf[k++] = ']';
    sqlite3_snprintf(100,&zBuf[k], encnames[pMem->enc]);
    k += strlen(&zBuf[k]);
    zBuf[k++] = 0;
  }
}
#endif

#ifdef SQLITE_DEBUG
/*
** Print the value of a register for tracing purposes:
*/
static void memTracePrint(FILE *out, Mem *p){
  if( p->flags & MEM_Null ){
    fprintf(out, " NULL");
  }else if( (p->flags & (MEM_Int|MEM_Str))==(MEM_Int|MEM_Str) ){
    fprintf(out, " si:%lld", p->u.i);
  }else if( p->flags & MEM_Int ){
    fprintf(out, " i:%lld", p->u.i);
  }else if( p->flags & MEM_Real ){
    fprintf(out, " r:%g", p->r);
  }else{
    char zBuf[200];
    sqlite3VdbeMemPrettyPrint(p, zBuf);
    fprintf(out, " ");
    fprintf(out, "%s", zBuf);
  }
}
static void registerTrace(FILE *out, int iReg, Mem *p){
  fprintf(out, "REG[%d] = ", iReg);
  memTracePrint(out, p);
  fprintf(out, "\n");
}
#endif

#ifdef SQLITE_DEBUG
#  define REGISTER_TRACE(R,M) if(p->trace)registerTrace(p->trace,R,M)
#else
#  define REGISTER_TRACE(R,M)
#endif


#ifdef VDBE_PROFILE

/* 
** hwtime.h contains inline assembler code for implementing 
** high-performance timing routines.
*/
#include "hwtime.h"

#endif

/*
** The CHECK_FOR_INTERRUPT macro defined here looks to see if the
** sqlite3_interrupt() routine has been called.  If it has been, then
** processing of the VDBE program is interrupted.
**
** This macro added to every instruction that does a jump in order to
** implement a loop.  This test used to be on every single instruction,
** but that meant we more testing that we needed.  By only testing the
** flag on jump instructions, we get a (small) speed improvement.
*/
#define CHECK_FOR_INTERRUPT \
   if( db->u1.isInterrupted ) goto abort_due_to_interrupt;

#ifdef SQLITE_DEBUG
static int fileExists(sqlite3 *db, const char *zFile){
  int res = 0;
  int rc = SQLITE_OK;
#ifdef SQLITE_TEST
  /* If we are currently testing IO errors, then do not call OsAccess() to
  ** test for the presence of zFile. This is because any IO error that
  ** occurs here will not be reported, causing the test to fail.
  */
  extern int sqlite3_io_error_pending;
  if( sqlite3_io_error_pending<=0 )
#endif
    rc = sqlite3OsAccess(db->pVfs, zFile, SQLITE_ACCESS_EXISTS, &res);
  return (res && rc==SQLITE_OK);
}
#endif

/*
** Execute as much of a VDBE program as we can then return.
**
** sqlite3VdbeMakeReady() must be called before this routine in order to
** close the program with a final OP_Halt and to set up the callbacks
** and the error message pointer.
**
** Whenever a row or result data is available, this routine will either
** invoke the result callback (if there is one) or return with
** SQLITE_ROW.
**
** If an attempt is made to open a locked database, then this routine
** will either invoke the busy callback (if there is one) or it will
** return SQLITE_BUSY.
**
** If an error occurs, an error message is written to memory obtained
** from sqlite3_malloc() and p->zErrMsg is made to point to that memory.
** The error code is stored in p->rc and this routine returns SQLITE_ERROR.
**
** If the callback ever returns non-zero, then the program exits
** immediately.  There will be no error message but the p->rc field is
** set to SQLITE_ABORT and this routine will return SQLITE_ERROR.
**
** A memory allocation error causes p->rc to be set to SQLITE_NOMEM and this
** routine to return SQLITE_ERROR.
**
** Other fatal errors return SQLITE_ERROR.
**
** After this routine has finished, sqlite3VdbeFinalize() should be
** used to clean up the mess that was left behind.
*/
int sqlite3VdbeExec(
  Vdbe *p                    /* The VDBE */
){
  int pc;                    /* The program counter */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite3 *db = p->db;       /* The database */
  u8 encoding = ENC(db);     /* The database encoding */
  Mem *pIn1, *pIn2, *pIn3;   /* Input operands */
  Mem *pOut;                 /* Output operand */
  u8 opProperty;
  int iCompare = 0;          /* Result of last OP_Compare operation */
  int *aPermute = 0;         /* Permuation of columns for OP_Compare */
#ifdef VDBE_PROFILE
  u64 start;                 /* CPU clock count at start of opcode */
  int origPc;                /* Program counter at start of opcode */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int nProgressOps = 0;      /* Opcodes executed since progress callback. */
#endif
  UnpackedRecord aTempRec[16]; /* Space to hold a transient UnpackedRecord */


  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  assert( db->magic==SQLITE_MAGIC_BUSY );
  sqlite3BtreeMutexArrayEnter(&p->aMutex);
  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    goto no_mem;
  }
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0 
   && ((p->db->flags & SQLITE_VdbeListing) || fileExists(db, "vdbe_explain"))
  ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &p->aOp[i]);
    }
  }
  if( fileExists(db, "vdbe_trace") ){
    p->trace = stdout;
  }
  sqlite3EndBenignMalloc();
#endif
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    if( db->mallocFailed ) goto no_mem;
#ifdef VDBE_PROFILE
    origPc = pc;
    start = sqlite3Hwtime();
#endif
    pOp = &p->aOp[pc];

    /* Only allow tracing if SQLITE_DEBUG is defined.
    */
#ifdef SQLITE_DEBUG
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 ){
      sqlite3BeginBenignMalloc();
      if( fileExists(db, "vdbe_sqltrace") ){
        sqlite3VdbePrintSql(p);
      }
      sqlite3EndBenignMalloc();
    }
#endif
      

    /* Check to see if we need to simulate an interrupt.  This only happens
    ** if we have a special test build.
    */
#ifdef SQLITE_TEST
    if( sqlite3_interrupt_count>0 ){
      sqlite3_interrupt_count--;
      if( sqlite3_interrupt_count==0 ){
        sqlite3_interrupt(db);
      }
    }
#endif

#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
    /* Call the progress callback if it is configured and the required number
    ** of VDBE ops have been executed (either since this invocation of
    ** sqlite3VdbeExec() or since last time the progress callback was called).
    ** If the progress callback returns non-zero, exit the virtual machine with
    ** a return code SQLITE_ABORT.
    */
    if( db->xProgress ){
      if( db->nProgressOps==nProgressOps ){
        int prc;
        if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
        prc =db->xProgress(db->pProgressArg);
        if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;
        if( prc!=0 ){
          rc = SQLITE_INTERRUPT;
          goto vdbe_error_halt;
        }
        nProgressOps = 0;
      }
      nProgressOps++;
    }
#endif

    /* Do common setup processing for any opcode that is marked
    ** with the "out2-prerelease" tag.  Such opcodes have a single
    ** output which is specified by the P2 parameter.  The P2 register
    ** is initialized to a NULL.
    */
    opProperty = opcodeProperty[pOp->opcode];
    if( (opProperty & OPFLG_OUT2_PRERELEASE)!=0 ){
      assert( pOp->p2>0 );
      assert( pOp->p2<=p->nMem );
      pOut = &p->aMem[pOp->p2];
      sqlite3VdbeMemReleaseExternal(pOut);
      pOut->flags = MEM_Null;
    }else
 
    /* Do common setup for opcodes marked with one of the following
    ** combinations of properties.
    **
    **           in1
    **           in1 in2
    **           in1 in2 out3
    **           in1 in3
    **
    ** Variables pIn1, pIn2, and pIn3 are made to point to appropriate
    ** registers for inputs.  Variable pOut points to the output register.
    */
    if( (opProperty & OPFLG_IN1)!=0 ){
      assert( pOp->p1>0 );
      assert( pOp->p1<=p->nMem );
      pIn1 = &p->aMem[pOp->p1];
      REGISTER_TRACE(pOp->p1, pIn1);
      if( (opProperty & OPFLG_IN2)!=0 ){
        assert( pOp->p2>0 );
        assert( pOp->p2<=p->nMem );
        pIn2 = &p->aMem[pOp->p2];
        REGISTER_TRACE(pOp->p2, pIn2);
        if( (opProperty & OPFLG_OUT3)!=0 ){
          assert( pOp->p3>0 );
          assert( pOp->p3<=p->nMem );
          pOut = &p->aMem[pOp->p3];
        }
      }else if( (opProperty & OPFLG_IN3)!=0 ){
        assert( pOp->p3>0 );
        assert( pOp->p3<=p->nMem );
        pIn3 = &p->aMem[pOp->p3];
        REGISTER_TRACE(pOp->p3, pIn3);
      }
    }else if( (opProperty & OPFLG_IN2)!=0 ){
      assert( pOp->p2>0 );
      assert( pOp->p2<=p->nMem );
      pIn2 = &p->aMem[pOp->p2];
      REGISTER_TRACE(pOp->p2, pIn2);
    }else if( (opProperty & OPFLG_IN3)!=0 ){
      assert( pOp->p3>0 );
      assert( pOp->p3<=p->nMem );
      pIn3 = &p->aMem[pOp->p3];
      REGISTER_TRACE(pOp->p3, pIn3);
    }

    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a
** separate instruction in the virtual machine.  If we follow the usual
** indentation conventions, each case should be indented by 6 spaces.  But
** that is a lot of wasted space on the left margin.  So the code within
** the switch statement will break with convention and be flush-left. Another
** big comment (similar to this one) will mark the point in the code where
** we transition back to normal indentation.
**
** The formatting of each case is important.  The makefile for SQLite
** generates two C files "opcodes.h" and "opcodes.c" by scanning this
** file looking for lines that begin with "case OP_".  The opcodes.h files
** will be filled with #defines that give unique integer values to each
** opcode and the opcodes.c file is filled with an array of strings where
** each string is the symbolic name for the corresponding opcode.  If the
** case statement is followed by a comment of the form "/# same as ... #/"
** that comment is used to determine the particular value of the opcode.
**
** Other keywords in the comment that follows each case are used to
** construct the OPFLG_INITIALIZER value that initializes opcodeProperty[].
** Keywords include: in1, in2, in3, out2_prerelease, out2, out3.  See
** the mkopcodeh.awk script for additional information.
**
** Documentation about VDBE opcodes is generated by scanning this file
** for lines of that contain "Opcode:".  That line and all subsequent
** comment lines are used in the generation of the opcode.html documentation
** file.
**
** SUMMARY:
**
**     Formatting is important to scripts that scan this file.
**     Do not deviate from the formatting style currently in use.
**
*****************************************************************************/

/* Opcode:  Goto * P2 * * *
**
** An unconditional jump to address P2.
** The next instruction executed will be 
** the one at index P2 from the beginning of
** the program.
*/
case OP_Goto: {             /* jump */
  CHECK_FOR_INTERRUPT;
  pc = pOp->p2 - 1;
  break;
}

/* Opcode:  Gosub P1 P2 * * *
**
** Write the current address onto register P1
** and then jump to address P2.
*/
case OP_Gosub: {            /* jump */
  assert( pOp->p1>0 );
  assert( pOp->p1<=p->nMem );
  pIn1 = &p->aMem[pOp->p1];
  assert( (pIn1->flags & MEM_Dyn)==0 );
  pIn1->flags = MEM_Int;
  pIn1->u.i = pc;
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = pOp->p2 - 1;
  break;
}

/* Opcode:  Return P1 * * * *
**
** Jump to the next instruction after the address in register P1.
*/
case OP_Return: {           /* in1 */
  assert( pIn1->flags & MEM_Int );
  pc = pIn1->u.i;
  break;
}

/* Opcode:  Yield P1 * * * *
**
** Swap the program counter with the value in register P1.
*/
case OP_Yield: {
  int pcDest;
  assert( pOp->p1>0 );
  assert( pOp->p1<=p->nMem );
  pIn1 = &p->aMem[pOp->p1];
  assert( (pIn1->flags & MEM_Dyn)==0 );
  pIn1->flags = MEM_Int;
  pcDest = pIn1->u.i;
  pIn1->u.i = pc;
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = pcDest;
  break;
}


/* Opcode:  Halt P1 P2 * P4 *
**
** Exit immediately.  All open cursors, Fifos, etc are closed
** automatically.
**
** P1 is the result code returned by sqlite3_exec(), sqlite3_reset(),
** or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
** For errors, it can be some other value.  If P1!=0 then P2 will determine
** whether or not to rollback the current transaction.  Do not rollback
** if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort,
** then back out all changes that have occurred during this execution of the
** VDBE, but do not rollback the transaction. 
**
** If P4 is not null then it is an error message string.
**
** There is an implied "Halt 0 0 0" instruction inserted at the very end of
** every program.  So a jump past the last instruction of the program
** is the same as executing Halt.
*/
case OP_Halt: {
  p->rc = pOp->p1;
  p->pc = pc;
  p->errorAction = pOp->p2;
  if( pOp->p4.z ){
    sqlite3SetString(&p->zErrMsg, db, "%s", pOp->p4.z);
  }
  rc = sqlite3VdbeHalt(p);
  assert( rc==SQLITE_BUSY || rc==SQLITE_OK );
  if( rc==SQLITE_BUSY ){
    p->rc = rc = SQLITE_BUSY;