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Ring_buffer: make synchronization optional

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With this patch, the 'Ring_buffer' class can be made unsynchronized by
setting the 'Ring_buffer_unsynchronized' policy as third template
argument.

Fixes #922.
This commit is contained in:
Christian Prochaska 2013-10-14 22:49:20 +02:00 committed by Christian Helmuth
parent dc8fc1a33c
commit cf040e2833
1 changed files with 38 additions and 7 deletions
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45
os/include/os/ring_buffer.h
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@ -18,6 +18,36 @@
#include <base/exception.h>
#include <util/string.h>
struct Ring_buffer_unsynchronized
{
struct Sem
{
void down() { }
void up() { }
};
struct Lock
{
void lock() { }
void unlock() { }
};
struct Lock_guard
{
Lock_guard(Lock &lock) { }
};
};
struct Ring_buffer_synchronized
{
typedef Genode::Semaphore Sem;
typedef Genode::Lock Lock;
typedef Genode::Lock::Guard Lock_guard;
};
/**
* Ring buffer template
*
@ -30,17 +60,18 @@
* stored in the buffer. Hence, the ring buffer is suited
* for simple plain-data element types.
*/
template <typename ET, int QUEUE_SIZE>
template <typename ET, int QUEUE_SIZE,
typename SYNC_POLICY = Ring_buffer_synchronized>
class Ring_buffer
{
private:
int _head;
int _tail;
Genode::Semaphore _sem; /* element counter */
Genode::Lock _head_lock; /* synchronize add */
int _head;
int _tail;
typename SYNC_POLICY::Sem _sem; /* element counter */
typename SYNC_POLICY::Lock _head_lock; /* synchronize add */
ET _queue[QUEUE_SIZE];
ET _queue[QUEUE_SIZE];
public:
@ -60,7 +91,7 @@ class Ring_buffer
*/
void add(ET ev)
{
Genode::Lock::Guard lock_guard(_head_lock);
typename SYNC_POLICY::Lock_guard lock_guard(_head_lock);
if ((_head + 1)%QUEUE_SIZE != _tail) {
_queue[_head] = ev;