vdbeapi.c

最新的sqlite3.6.2源代码

/*
** 2004 May 26
**
** 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 use to implement APIs that are part of the
** VDBE.
**
** $Id: vdbeapi.c,v 1.140 2008/08/21 12:19:44 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

#if 0 && defined(SQLITE_ENABLE_MEMORY_MANAGEMENT)
/*
** The following structure contains pointers to the end points of a
** doubly-linked list of all compiled SQL statements that may be holding
** buffers eligible for release when the sqlite3_release_memory() interface is
** invoked. Access to this list is protected by the SQLITE_MUTEX_STATIC_LRU2
** mutex.
**
** Statements are added to the end of this list when sqlite3_reset() is
** called. They are removed either when sqlite3_step() or sqlite3_finalize()
** is called. When statements are added to this list, the associated 
** register array (p->aMem[1..p->nMem]) may contain dynamic buffers that
** can be freed using sqlite3VdbeReleaseMemory().
**
** When statements are added or removed from this list, the mutex
** associated with the Vdbe being added or removed (Vdbe.db->mutex) is
** already held. The LRU2 mutex is then obtained, blocking if necessary,
** the linked-list pointers manipulated and the LRU2 mutex relinquished.
*/
struct StatementLruList {
  Vdbe *pFirst;
  Vdbe *pLast;
};
static struct StatementLruList sqlite3LruStatements;

/*
** Check that the list looks to be internally consistent. This is used
** as part of an assert() statement as follows:
**
**   assert( stmtLruCheck() );
*/
#ifndef NDEBUG
static int stmtLruCheck(){
  Vdbe *p;
  for(p=sqlite3LruStatements.pFirst; p; p=p->pLruNext){
    assert(p->pLruNext || p==sqlite3LruStatements.pLast);
    assert(!p->pLruNext || p->pLruNext->pLruPrev==p);
    assert(p->pLruPrev || p==sqlite3LruStatements.pFirst);
    assert(!p->pLruPrev || p->pLruPrev->pLruNext==p);
  }
  return 1;
}
#endif

/*
** Add vdbe p to the end of the statement lru list. It is assumed that
** p is not already part of the list when this is called. The lru list
** is protected by the SQLITE_MUTEX_STATIC_LRU mutex.
*/
static void stmtLruAdd(Vdbe *p){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));

  if( p->pLruPrev || p->pLruNext || sqlite3LruStatements.pFirst==p ){
    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
    return;
  }

  assert( stmtLruCheck() );

  if( !sqlite3LruStatements.pFirst ){
    assert( !sqlite3LruStatements.pLast );
    sqlite3LruStatements.pFirst = p;
    sqlite3LruStatements.pLast = p;
  }else{
    assert( !sqlite3LruStatements.pLast->pLruNext );
    p->pLruPrev = sqlite3LruStatements.pLast;
    sqlite3LruStatements.pLast->pLruNext = p;
    sqlite3LruStatements.pLast = p;
  }

  assert( stmtLruCheck() );

  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
}

/*
** Assuming the SQLITE_MUTEX_STATIC_LRU2 mutext is already held, remove
** statement p from the least-recently-used statement list. If the 
** statement is not currently part of the list, this call is a no-op.
*/
static void stmtLruRemoveNomutex(Vdbe *p){
  if( p->pLruPrev || p->pLruNext || p==sqlite3LruStatements.pFirst ){
    assert( stmtLruCheck() );
    if( p->pLruNext ){
      p->pLruNext->pLruPrev = p->pLruPrev;
    }else{
      sqlite3LruStatements.pLast = p->pLruPrev;
    }
    if( p->pLruPrev ){
      p->pLruPrev->pLruNext = p->pLruNext;
    }else{
      sqlite3LruStatements.pFirst = p->pLruNext;
    }
    p->pLruNext = 0;
    p->pLruPrev = 0;
    assert( stmtLruCheck() );
  }
}

/*
** Assuming the SQLITE_MUTEX_STATIC_LRU2 mutext is not held, remove
** statement p from the least-recently-used statement list. If the 
** statement is not currently part of the list, this call is a no-op.
*/
static void stmtLruRemove(Vdbe *p){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
  stmtLruRemoveNomutex(p);
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
}

/*
** Try to release n bytes of memory by freeing buffers associated 
** with the memory registers of currently unused vdbes.
*/
int sqlite3VdbeReleaseMemory(int n){
  Vdbe *p;
  Vdbe *pNext;
  int nFree = 0;

  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
  for(p=sqlite3LruStatements.pFirst; p && nFree<n; p=pNext){
    pNext = p->pLruNext;

    /* For each statement handle in the lru list, attempt to obtain the
    ** associated database mutex. If it cannot be obtained, continue
    ** to the next statement handle. It is not possible to block on
    ** the database mutex - that could cause deadlock.
    */
    if( SQLITE_OK==sqlite3_mutex_try(p->db->mutex) ){
      nFree += sqlite3VdbeReleaseBuffers(p);
      stmtLruRemoveNomutex(p);
      sqlite3_mutex_leave(p->db->mutex);
    }
  }
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));

  return nFree;
}

/*
** Call sqlite3Reprepare() on the statement. Remove it from the
** lru list before doing so, as Reprepare() will free all the
** memory register buffers anyway.
*/
int vdbeReprepare(Vdbe *p){
  stmtLruRemove(p);
  return sqlite3Reprepare(p);
}

#else       /* !SQLITE_ENABLE_MEMORY_MANAGEMENT */
  #define stmtLruRemove(x)
  #define stmtLruAdd(x)
  #define vdbeReprepare(x) sqlite3Reprepare(x)
#endif


/*
** Return TRUE (non-zero) of the statement supplied as an argument needs
** to be recompiled.  A statement needs to be recompiled whenever the
** execution environment changes in a way that would alter the program
** that sqlite3_prepare() generates.  For example, if new functions or
** collating sequences are registered or if an authorizer function is
** added or changed.
*/
int sqlite3_expired(sqlite3_stmt *pStmt){
  Vdbe *p = (Vdbe*)pStmt;
  return p==0 || p->expired;
}

/*
** The following routine destroys a virtual machine that is created by
** the sqlite3_compile() routine. The integer returned is an SQLITE_
** success/failure code that describes the result of executing the virtual
** machine.
**
** This routine sets the error code and string returned by
** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
*/
int sqlite3_finalize(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
#ifndef SQLITE_MUTEX_NOOP
    sqlite3_mutex *mutex = v->db->mutex;
#endif
    sqlite3_mutex_enter(mutex);
    stmtLruRemove(v);
    rc = sqlite3VdbeFinalize(v);
    sqlite3_mutex_leave(mutex);
  }
  return rc;
}

/*
** Terminate the current execution of an SQL statement and reset it
** back to its starting state so that it can be reused. A success code from
** the prior execution is returned.
**
** This routine sets the error code and string returned by
** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
*/
int sqlite3_reset(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3VdbeReset(v);
    stmtLruAdd(v);
    sqlite3VdbeMakeReady(v, -1, 0, 0, 0);
    assert( (rc & (v->db->errMask))==rc );
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}

/*
** Set all the parameters in the compiled SQL statement to NULL.
*/
int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
  int i;
  int rc = SQLITE_OK;
  Vdbe *p = (Vdbe*)pStmt;
#ifndef SQLITE_MUTEX_NOOP
  sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
#endif
  sqlite3_mutex_enter(mutex);
  for(i=0; i<p->nVar; i++){
    sqlite3VdbeMemRelease(&p->aVar[i]);
    p->aVar[i].flags = MEM_Null;
  }
  sqlite3_mutex_leave(mutex);
  return rc;
}


/**************************** sqlite3_value_  *******************************
** The following routines extract information from a Mem or sqlite3_value
** structure.
*/
const void *sqlite3_value_blob(sqlite3_value *pVal){
  Mem *p = (Mem*)pVal;
  if( p->flags & (MEM_Blob|MEM_Str) ){
    sqlite3VdbeMemExpandBlob(p);
    p->flags &= ~MEM_Str;
    p->flags |= MEM_Blob;
    return p->z;
  }else{
    return sqlite3_value_text(pVal);
  }
}
int sqlite3_value_bytes(sqlite3_value *pVal){
  return sqlite3ValueBytes(pVal, SQLITE_UTF8);
}
int sqlite3_value_bytes16(sqlite3_value *pVal){
  return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
}
double sqlite3_value_double(sqlite3_value *pVal){
  return sqlite3VdbeRealValue((Mem*)pVal);
}
int sqlite3_value_int(sqlite3_value *pVal){
  return sqlite3VdbeIntValue((Mem*)pVal);
}
sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
  return sqlite3VdbeIntValue((Mem*)pVal);
}
const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
  return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
}
#ifndef SQLITE_OMIT_UTF16
const void *sqlite3_value_text16(sqlite3_value* pVal){
  return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
}
const void *sqlite3_value_text16be(sqlite3_value *pVal){
  return sqlite3ValueText(pVal, SQLITE_UTF16BE);
}
const void *sqlite3_value_text16le(sqlite3_value *pVal){
  return sqlite3ValueText(pVal, SQLITE_UTF16LE);
}
#endif /* SQLITE_OMIT_UTF16 */
int sqlite3_value_type(sqlite3_value* pVal){
  return pVal->type;
}

/**************************** sqlite3_result_  *******************************
** The following routines are used by user-defined functions to specify
** the function result.
*/
void sqlite3_result_blob(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  void (*xDel)(void *)
){
  assert( n>=0 );
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, 0, xDel);
}
void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetDouble(&pCtx->s, rVal);
}
void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  pCtx->isError = SQLITE_ERROR;
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
}
#ifndef SQLITE_OMIT_UTF16
void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  pCtx->isError = SQLITE_ERROR;
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
}
#endif
void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal);
}
void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetInt64(&pCtx->s, iVal);
}
void sqlite3_result_null(sqlite3_context *pCtx){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetNull(&pCtx->s);
}
void sqlite3_result_text(
  sqlite3_context *pCtx, 
  const char *z, 
  int n,
  void (*xDel)(void *)
){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, xDel);
}
#ifndef SQLITE_OMIT_UTF16
void sqlite3_result_text16(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  void (*xDel)(void *)
){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16NATIVE, xDel);
}
void sqlite3_result_text16be(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  void (*xDel)(void *)
){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16BE, xDel);
}
void sqlite3_result_text16le(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  void (*xDel)(void *)
){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16LE, xDel);
}
#endif /* SQLITE_OMIT_UTF16 */
void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemCopy(&pCtx->s, pValue);
}
void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetZeroBlob(&pCtx->s, n);
}
void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
  pCtx->isError = errCode;
}

/* Force an SQLITE_TOOBIG error. */
void sqlite3_result_error_toobig(sqlite3_context *pCtx){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  pCtx->isError = SQLITE_TOOBIG;
  sqlite3VdbeMemSetStr(&pCtx->s, "string or blob too big", -1, 
                       SQLITE_UTF8, SQLITE_STATIC);
}

/* An SQLITE_NOMEM error. */
void sqlite3_result_error_nomem(sqlite3_context *pCtx){
  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  sqlite3VdbeMemSetNull(&pCtx->s);
  pCtx->isError = SQLITE_NOMEM;
  pCtx->s.db->mallocFailed = 1;
}

/*
** Execute the statement pStmt, either until a row of data is ready, the
** statement is completely executed or an error occurs.
**
** This routine implements the bulk of the logic behind the sqlite_step()
** API.  The only thing omitted is the automatic recompile if a 
** schema change has occurred.  That detail is handled by the
** outer sqlite3_step() wrapper procedure.
*/
static int sqlite3Step(Vdbe *p){
  sqlite3 *db;