public virtual RC Unlock(LOCK locktype)
{
Debug.Assert(locktype <= LOCK.SHARED);
#if DEBUG
SysEx.OSTRACE("UNLOCK {0} to {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
var rc = RC.OK;
var type = this.Locktype;
if (type >= LOCK.EXCLUSIVE)
{
lockingStrategy.UnlockFile(this, SHARED_FIRST, SHARED_SIZE);
if (locktype == LOCK.SHARED && getReadLock() == 0)
{
// This should never happen. We should always be able to reacquire the read lock
rc = winLogError(RC.IOERR_UNLOCK, "winUnlock", Path);
}
}
if (type >= LOCK.RESERVED)
{
try { lockingStrategy.UnlockFile(this, RESERVED_BYTE, 1); }
catch (Exception) { }
}
if (locktype == LOCK.NO && type >= LOCK.SHARED)
{
unlockReadLock();
}
if (type >= LOCK.PENDING)
{
try { lockingStrategy.UnlockFile(this, PENDING_BYTE, 1); }
catch (Exception) { }
}
this.Locktype = locktype;
return(rc);
}
public virtual RC CheckReservedLock(ref int pResOut)
{
int rc;
if (Locktype >= LOCK.RESERVED)
{
rc = 1;
#if DEBUG
SysEx.OSTRACE("TEST WR-LOCK {0} {1} (local)", S.Name, rc);
#endif
}
else
{
try
{
lockingStrategy.LockFile(this, RESERVED_BYTE, 1);
lockingStrategy.UnlockFile(this, RESERVED_BYTE, 1);
rc = 1;
}
catch (IOException) { rc = 0; }
rc = 1 - rc;
#if DEBUG
SysEx.OSTRACE("TEST WR-LOCK {0} {1} (remote)", S.GetHashCode(), rc);
#endif
}
pResOut = rc;
return(RC.OK);
}
public virtual RC Read(byte[] buffer, int amount, long offset)
{
if (buffer == null)
{
buffer = new byte[amount];
}
#if DEBUG
SysEx.OSTRACE("READ {0} lock={1}", S.GetHashCode(), Locktype);
#endif
if (!S.CanRead)
{
return(RC.IOERR_READ);
}
if (seekWinFile(offset) != 0)
{
return(RC.FULL);
}
int nRead; // Number of bytes actually read from file
try { nRead = S.Read(buffer, 0, amount); }
catch (Exception) { LastErrno = (uint)Marshal.GetLastWin32Error(); return(winLogError(RC.IOERR_READ, "winRead", Path)); }
if (nRead < amount)
{
// Unread parts of the buffer must be zero-filled
Array.Clear(buffer, (int)nRead, (int)(amount - nRead));
return(RC.IOERR_SHORT_READ);
}
return(RC.OK);
}
public virtual RC Sync(SYNC flags)
{
// Check that one of SQLITE_SYNC_NORMAL or FULL was passed
Debug.Assert(((int)flags & 0x0F) == (int)SYNC.NORMAL || ((int)flags & 0x0F) == (int)SYNC.FULL);
SysEx.OSTRACE("SYNC {0} lock={1}", S.GetHashCode(), Locktype);
#if SQLITE_NO_SYNC
return(SQLITE.OK);
#else
S.Flush();
return(RC.OK);
#endif
}
public virtual RC Close()
{
Debug.Assert(Shm == null);
#if DEBUG
SysEx.OSTRACE("CLOSE {0} ({1})", S.GetHashCode(), S.Name);
#endif
bool rc;
int cnt = 0;
do
{
S.Close();
rc = true;
} while (!rc && ++cnt < MX_CLOSE_ATTEMPT);
return(rc ? RC.OK : winLogError(RC.IOERR_CLOSE, "winClose", Path));
}
public virtual RC Truncate(long size)
{
var rc = RC.OK;
#if DEBUG
SysEx.OSTRACE("TRUNCATE {0} {1,11}", S.Name, size);
#endif
// If the user has configured a chunk-size for this file, truncate the file so that it consists of an integer number of chunks (i.e. the
// actual file size after the operation may be larger than the requested size).
if (Chunk != 0)
{
size = ((size + Chunk - 1) / Chunk) * Chunk;
}
try { S.SetLength(size); rc = RC.OK; }
catch (IOException e) { LastErrno = (uint)Marshal.GetLastWin32Error(); rc = winLogError(RC.IOERR_TRUNCATE, "winTruncate2", Path); }
SysEx.OSTRACE("TRUNCATE {0} {1,%11} {2}", S.GetHashCode(), size, rc == RC.OK ? "ok" : "failed");
return(rc);
}
public virtual RC Write(byte[] buffer, int amount, long offset)
{
Debug.Assert(amount > 0);
#if DEBUG
SysEx.OSTRACE("WRITE {0} lock={1}", S.GetHashCode(), Locktype);
#endif
var rc = seekWinFile(offset);
long wrote = S.Position;
try
{
Debug.Assert(buffer.Length >= amount);
S.Write(buffer, 0, amount);
rc = 1;
wrote = S.Position - wrote;
}
catch (IOException) { return(RC.READONLY); }
if (rc == 0 || amount > (int)wrote)
{
LastErrno = (uint)Marshal.GetLastWin32Error();
return(LastErrno == ERROR_HANDLE_DISK_FULL || LastErrno == ERROR_DISK_FULL ? RC.FULL : winLogError(RC.IOERR_WRITE, "winWrite", Path));
}
return(RC.OK);
}
public virtual RC Lock(LOCK locktype)
{
#if DEBUG
SysEx.OSTRACE("LOCK {0} {1} was {2}({3})", S.GetHashCode(), locktype, this.Locktype, SharedLockByte);
#endif
// If there is already a lock of this type or more restrictive on the OsFile, do nothing. Don't use the end_lock: exit path, as sqlite3OsEnterMutex() hasn't been called yet.
if (this.Locktype >= locktype)
{
return(RC.OK);
}
// Make sure the locking sequence is correct
Debug.Assert(this.Locktype != LOCK.NO || locktype == LOCK.SHARED);
Debug.Assert(locktype != LOCK.PENDING);
Debug.Assert(locktype != LOCK.RESERVED || this.Locktype == LOCK.SHARED);
// Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or a SHARED lock. If we are acquiring a SHARED lock, the acquisition of
// the PENDING_LOCK byte is temporary.
uint error = 0;
var res = 1; // Result of a windows lock call
var gotPendingLock = false; // True if we acquired a PENDING lock this time
var newLocktype = this.Locktype;
if (this.Locktype == LOCK.NO || (locktype == LOCK.EXCLUSIVE && this.Locktype == LOCK.RESERVED))
{
res = 0;
var cnt = 3;
while (cnt-- > 0 && res == 0)
{
try { lockingStrategy.LockFile(this, PENDING_BYTE, 1); res = 1; }
catch (Exception)
{
// Try 3 times to get the pending lock. The pending lock might be held by another reader process who will release it momentarily.
#if DEBUG
SysEx.OSTRACE("could not get a PENDING lock. cnt={0}", cnt);
#endif
Thread.Sleep(1);
}
}
gotPendingLock = (res != 0);
if (0 == res)
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a shared lock
if (locktype == LOCK.SHARED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.NO);
res = getReadLock();
if (res != 0)
{
newLocktype = LOCK.SHARED;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a RESERVED lock
if (locktype == LOCK.RESERVED && res != 0)
{
Debug.Assert(this.Locktype == LOCK.SHARED);
try { lockingStrategy.LockFile(this, RESERVED_BYTE, 1); newLocktype = LOCK.RESERVED; res = 1; }
catch (Exception) { res = 0; error = (uint)Marshal.GetLastWin32Error(); }
if (res != 0)
{
newLocktype = LOCK.RESERVED;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
}
}
// Acquire a PENDING lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
newLocktype = LOCK.PENDING;
gotPendingLock = false;
}
// Acquire an EXCLUSIVE lock
if (locktype == LOCK.EXCLUSIVE && res != 0)
{
Debug.Assert(this.Locktype >= LOCK.SHARED);
res = unlockReadLock();
#if DEBUG
SysEx.OSTRACE("unreadlock = {0}", res);
#endif
try { lockingStrategy.LockFile(this, SHARED_FIRST, SHARED_SIZE); newLocktype = LOCK.EXCLUSIVE; res = 1; }
catch (Exception) { res = 0; }
if (res != 0)
{
newLocktype = LOCK.EXCLUSIVE;
}
else
{
error = (uint)Marshal.GetLastWin32Error();
#if DEBUG
SysEx.OSTRACE("error-code = {0}", error);
#endif
getReadLock();
}
}
// If we are holding a PENDING lock that ought to be released, then release it now.
if (gotPendingLock && locktype == LOCK.SHARED)
{
lockingStrategy.UnlockFile(this, PENDING_BYTE, 1);
}
// Update the state of the lock has held in the file descriptor then return the appropriate result code.
var rc = RC.OK;
if (res != 0)
{
rc = RC.OK;
}
else
{
#if DEBUG
SysEx.OSTRACE("LOCK FAILED {0} trying for {1} but got {2}", S.GetHashCode(), locktype, newLocktype);
#endif
LastErrno = error;
rc = RC.BUSY;
}
this.Locktype = newLocktype;
return(rc);
}
