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Simplify the winRead and winWrite VFS functions to reduce the number of system calls.

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FossilOrigin-Name: 10ce846759f6f22e70bb9b67bea7a0c2b8a156fe
This commit is contained in:
mistachkin
2012-03-30 12:27:55 +00:00
parent 46b721a294
commit 05340e3257
3 changed files with 31 additions and 16 deletions
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33
src/os_win.c
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@@ -1958,6 +1958,9 @@ static int winClose(sqlite3_file *id){
}
#endif
OSTRACE(("CLOSE %d %s\n", pFile->h, rc ? "ok" : "failed"));
if( rc ){
pFile->h = NULL;
}
OpenCounter(-1);
return rc ? SQLITE_OK
: winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
@@ -1975,6 +1978,7 @@ static int winRead(
int amt, /* Number of bytes to read */
sqlite3_int64 offset /* Begin reading at this offset */
){
OVERLAPPED overlapped; /* The offset for ReadFile. */
winFile *pFile = (winFile*)id; /* file handle */
DWORD nRead; /* Number of bytes actually read from file */
int nRetry = 0; /* Number of retrys */
@@ -1983,10 +1987,11 @@ static int winRead(
SimulateIOError(return SQLITE_IOERR_READ);
OSTRACE(("READ %d lock=%d\n", pFile->h, pFile->locktype));
if( seekWinFile(pFile, offset) ){
return SQLITE_FULL;
}
while( !osReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
memset(&overlapped, 0, sizeof(OVERLAPPED));
overlapped.Offset = (LONG)(offset & 0xffffffff);
overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
while( !osReadFile(pFile->h, pBuf, amt, &nRead, &overlapped) &&
osGetLastError()!=ERROR_HANDLE_EOF ){
DWORD lastErrno;
if( retryIoerr(&nRetry, &lastErrno) ) continue;
pFile->lastErrno = lastErrno;
@@ -2013,7 +2018,7 @@ static int winWrite(
int amt, /* Number of bytes to write */
sqlite3_int64 offset /* Offset into the file to begin writing at */
){
int rc; /* True if error has occured, else false */
int rc = 0; /* True if error has occured, else false */
winFile *pFile = (winFile*)id; /* File handle */
int nRetry = 0; /* Number of retries */
@@ -2024,19 +2029,29 @@ static int winWrite(
OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));
rc = seekWinFile(pFile, offset);
if( rc==0 ){
{
OVERLAPPED overlapped; /* The offset for WriteFile. */
u8 *aRem = (u8 *)pBuf; /* Data yet to be written */
int nRem = amt; /* Number of bytes yet to be written */
DWORD nWrite; /* Bytes written by each WriteFile() call */
DWORD lastErrno = NO_ERROR; /* Value returned by GetLastError() */
memset(&overlapped, 0, sizeof(OVERLAPPED));
overlapped.Offset = (LONG)(offset & 0xffffffff);
overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
while( nRem>0 ){
if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, 0) ){
if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, &overlapped) ){
if( retryIoerr(&nRetry, &lastErrno) ) continue;
break;
}
if( nWrite<=0 ) break;
if( nWrite<=0 ){
lastErrno = osGetLastError();
break;
}
offset += nWrite;
overlapped.Offset = (LONG)(offset & 0xffffffff);
overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
aRem += nWrite;
nRem -= nWrite;
}