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Add comments to the changes of check-in (3200). (CVS 3202)

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FossilOrigin-Name: 697498d4e86a42d7063417a9549ad04aaf4db31c
This commit is contained in:
drh
2006-06-04 23:31:48 +00:00
parent 2871bd0cab
commit 59e63a6b30
3 changed files with 35 additions and 11 deletions
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32
src/os_win.c
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@@ -476,8 +476,18 @@ static BOOL winceLockFileEx(
#endif /* OS_WINCE */
/*
** Delete the named file
** Delete the named file.
**
** Note that windows does not allow a file to be deleted if some other
** process has it open. Sometimes a virus scanner or indexing program
** will open a journal file shortly after it is created in order to do
** whatever it is it does. While this other process is holding the
** file open, we will be unable to delete it. To work around this
** problem, we delay 100 milliseconds and try to delete again. Up
** to MX_DELETION_ATTEMPTs deletion attempts are run before giving
** up and returning an error.
*/
#define MX_DELETION_ATTEMPTS 3
int sqlite3WinDelete(const char *zFilename){
WCHAR *zWide = utf8ToUnicode(zFilename);
int cnt = 0;
@@ -485,7 +495,7 @@ int sqlite3WinDelete(const char *zFilename){
if( zWide ){
do{
rc = DeleteFileW(zWide);
}while( rc==0 && cnt++ < 3 && (Sleep(100), 1) );
}while( rc==0 && cnt++ < MX_DELETION_ATTEMPTS && (Sleep(100), 1) );
sqliteFree(zWide);
}else{
#if OS_WINCE
@@ -493,7 +503,7 @@ int sqlite3WinDelete(const char *zFilename){
#else
do{
rc = DeleteFileA(zFilename);
}while( rc==0 && cnt++ < 3 && (Sleep(100), 1) );
}while( rc==0 && cnt++ < MX_DELETION_ATTEMPTS && (Sleep(100), 1) );
#endif
}
TRACE2("DELETE \"%s\"\n", zFilename);
@@ -630,6 +640,12 @@ int sqlite3WinOpenReadWrite(
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
**
** Sometimes if we have just deleted a prior journal file, windows
** will fail to open a new one because there is a "pending delete".
** To work around this bug, we pause for 100 milliseconds and attempt
** a second open after the first one fails. The whole operation only
** fails if both open attempts are unsuccessful.
*/
int sqlite3WinOpenExclusive(const char *zFilename, OsFile **pId, int delFlag){
winFile f;
@@ -808,7 +824,15 @@ int sqlite3WinTempFileName(char *zBuf){
/*
** Close a file.
**
** It is reported that an attempt to close a handle might sometimes
** fail. This is a very unreasonable result, but windows is notorious
** for being unreasonable so I do not doubt that it might happen. If
** the close fails, we pause for 100 milliseconds and try again. As
** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
** giving up and returning an error.
*/
#define MX_CLOSE_ATTEMPT 3
static int winClose(OsFile **pId){
winFile *pFile;
int rc = 1;
@@ -817,7 +841,7 @@ static int winClose(OsFile **pId){
TRACE2("CLOSE %d\n", pFile->h);
do{
rc = CloseHandle(pFile->h);
}while( rc==0 && cnt++ < 3 && (Sleep(100), 1) );
}while( rc==0 && cnt++ < MX_CLOSE_ATTEMPT && (Sleep(100), 1) );
#if OS_WINCE
winceDestroyLock(pFile);
if( pFile->zDeleteOnClose ){