haiku/headers/private/kernel/disk_device_manager/KDiskDeviceUtils.h

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// KDiskDeviceUtils.h
#ifndef _K_DISK_DEVICE_UTILS_H
#define _K_DISK_DEVICE_UTILS_H
#include <string.h>
#include <SupportDefs.h>
namespace BPrivate {
namespace DiskDevice {
// helper functions
// set_string
static inline
status_t
set_string(char *&location, const char *newValue)
{
// unset old value
if (location) {
free(location);
location = NULL;
}
// set new value
status_t error = B_OK;
if (newValue) {
location = strdup(newValue);
if (!location)
error = B_NO_MEMORY;
}
return error;
}
// locking
// AutoLockerStandardLocking
template<typename Lockable>
class AutoLockerStandardLocking {
public:
inline bool Lock(Lockable *lockable)
{
return lockable->Lock();
}
inline void Unlock(Lockable *lockable)
{
lockable->Unlock();
}
};
// AutoLockerReadLocking
template<typename Lockable>
class AutoLockerReadLocking {
public:
inline bool Lock(Lockable *lockable)
{
return lockable->ReadLock();
}
inline void Unlock(Lockable *lockable)
{
lockable->ReadUnlock();
}
};
// AutoLockerWriteLocking
template<typename Lockable>
class AutoLockerWriteLocking {
public:
inline bool Lock(Lockable *lockable)
{
return lockable->WriteLock();
}
inline void Unlock(Lockable *lockable)
{
lockable->WriteUnlock();
}
};
// AutoLocker
template<typename Lockable,
typename Locking = AutoLockerStandardLocking<Lockable> >
class AutoLocker {
private:
typedef AutoLocker<Lockable, Locking> ThisClass;
public:
inline AutoLocker(Lockable *lockable)
: fLockable(lockable),
fLocked(false)
{
_Lock();
}
inline AutoLocker(Lockable &lockable)
: fLockable(&lockable),
fLocked(false)
{
_Lock();
}
inline ~AutoLocker()
{
_Unlock();
}
inline AutoLocker<Lockable, Locking> &operator=(Lockable *lockable)
{
_Unlock();
fLockable = lockable;
_Lock();
}
inline AutoLocker<Lockable, Locking> &operator=(Lockable &lockable)
{
_Unlock();
fLockable = &lockable;
_Lock();
}
inline bool IsLocked() const { return fLocked; }
inline operator bool() const { return fLocked; }
private:
inline void _Lock()
{
if (fLockable)
fLocked = fLocking.Lock(fLockable);
}
inline void _Unlock()
{
if (fLockable && fLocked) {
fLocking.Unlock(fLockable);
fLocked = false;
}
}
private:
Lockable *fLockable;
bool fLocked;
Locking fLocking;
};
// instantiations
class KDiskDevice;
class KDiskDeviceManager;
typedef AutoLocker<KDiskDevice, AutoLockerReadLocking<KDiskDevice> >
DeviceReadLocker;
typedef AutoLocker<KDiskDevice, AutoLockerWriteLocking<KDiskDevice> >
DeviceWriteLocker;
typedef AutoLocker<KDiskDeviceManager > ManagerLocker;
} // namespace DiskDevice
} // namespace BPrivate
using BPrivate::DiskDevice::set_string;
using BPrivate::DiskDevice::AutoLocker;
using BPrivate::DiskDevice::DeviceReadLocker;
using BPrivate::DiskDevice::DeviceWriteLocker;
using BPrivate::DiskDevice::ManagerLocker;
#endif // _K_DISK_DEVICE_H