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Attempt to detect when two or more threads try to use the same database at

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the same time and return an SQLITE_MISUSE error.  Also return this error
if an attempt is made to use a closed database. (CVS 558)

FossilOrigin-Name: a05fabd2df1cb38c555a7b2f31b0ca687db500c2
This commit is contained in:
drh
2002-05-10 05:44:55 +00:00
parent d5feede1ff
commit 247be43d60
9 changed files with 119 additions and 22 deletions
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48
src/main.c
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@@ -14,7 +14,7 @@
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.69 2002/04/12 10:08:59 drh Exp $
** $Id: main.c,v 1.70 2002/05/10 05:44:56 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
@@ -332,6 +332,7 @@ sqlite *sqlite_open(const char *zFilename, int mode, char **pzErrMsg){
sqliteRegisterBuildinFunctions(db);
db->onError = OE_Default;
db->priorNewRowid = 0;
db->magic = SQLITE_MAGIC_BUSY;
/* Open the backend database driver */
rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
@@ -359,6 +360,7 @@ sqlite *sqlite_open(const char *zFilename, int mode, char **pzErrMsg){
sqliteFree(*pzErrMsg);
*pzErrMsg = 0;
}
db->magic = SQLITE_MAGIC_OPEN;
return db;
no_mem_on_open:
@@ -433,6 +435,8 @@ int sqlite_changes(sqlite *db){
*/
void sqlite_close(sqlite *db){
HashElem *i;
if( sqliteSafetyOn(db) ){ return; }
db->magic = SQLITE_MAGIC_CLOSED;
sqliteBtreeClose(db->pBe);
clearHashTable(db, 0);
if( db->pBeTemp ){
@@ -526,10 +530,12 @@ int sqlite_exec(
Parse sParse;
if( pzErrMsg ) *pzErrMsg = 0;
if( sqliteSafetyOn(db) ){ return SQLITE_MISUSE; }
if( (db->flags & SQLITE_Initialized)==0 ){
int rc = sqliteInit(db, pzErrMsg);
if( rc!=SQLITE_OK ){
sqliteStrRealloc(pzErrMsg);
sqliteSafetyOff(db);
return rc;
}
}
@@ -554,9 +560,49 @@ int sqlite_exec(
clearHashTable(db, 1);
}
db->recursionDepth--;
if( sqliteSafetyOff(db) ){ sParse.rc = SQLITE_MISUSE; }
return sParse.rc;
}
/*
** Change the magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
** when this routine is called.
**
** This routine is a attempt to detect if two threads attempt
** to use the same sqlite* pointer at the same time. There is a
** race condition so it is possible that the error is not detected.
** But usually the problem will be seen. The result will be an
** error which can be used to debugging the application that is
** using SQLite incorrectly.
*/
int sqliteSafetyOn(sqlite *db){
if( db->magic==SQLITE_MAGIC_OPEN ){
db->magic = SQLITE_MAGIC_BUSY;
return 0;
}else{
db->magic = SQLITE_MAGIC_ERROR;
db->flags |= SQLITE_Interrupt;
return 1;
}
}
/*
** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
** when this routine is called.
*/
int sqliteSafetyOff(sqlite *db){
if( db->magic==SQLITE_MAGIC_BUSY ){
db->magic = SQLITE_MAGIC_OPEN;
return 0;
}else{
db->magic = SQLITE_MAGIC_ERROR;
db->flags |= SQLITE_Interrupt;
return 1;
}
}
/*
** This routine implements a busy callback that sleeps and tries
** again until a timeout value is reached. The timeout value is