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#ifndef QUEUE_H
#define QUEUE_H
#include "my_global.h"
#include "my_base.h"
#include "my_pthread.h"
#include "my_sys.h"
#include "mysql/psi/mysql_thread.h"
#include "mysql/psi/psi.h"
#include <cstring>
#define UNUSED_SPACE 0xFF
/*
We will use N-1 to check whether buffer is full or not.
Comments
# Free Space
* Filled Space
H Head
T Tail
*/
template <typename Element_type>
class circular_buffer_queue
{
public:
uchar *buffer, *buffer_end;
//Total no of events currently in queue
ulong events;
ulong buffer_size;
mysql_mutex_t lock_queue;
mysql_mutex_t free_queue;
mysql_cond_t free_cond;
uchar *head, *tail;
PSI_file_key k1, k2;
PSI_cond_key c1;
ulong free_size()
{
if (head > tail)
return buffer_size - (head-tail)-1;
if (tail > head)
return tail-head-1;
return buffer_size - 1;
}
ulong used_buffer()
{
return buffer_size - free_size() -1;
}
circular_buffer_queue(){};
int init(ulong buffer_size)
{
if (!(buffer= (uchar*)my_malloc(PSI_INSTRUMENT_ME, buffer_size,
MYF(MY_THREAD_SPECIFIC|MY_WME))))
return 1;
this->buffer_size= buffer_size;
buffer_end= buffer + buffer_size;
head= tail= buffer;
mysql_mutex_init(k1, &lock_queue, MY_MUTEX_INIT_SLOW);
mysql_mutex_init(k2, &free_queue, MY_MUTEX_INIT_SLOW);
mysql_cond_init(c1, &free_cond, 0);
return 0;
}
void destroy()
{
my_free(buffer);
mysql_mutex_destroy(&lock_queue);
mysql_mutex_destroy(&free_queue);
mysql_cond_destroy(&free_cond);
}
/*
We want to write in continues memory.
*/
int enqueue(Element_type *elem)
{
uint32 length= elem->total_length;
if (free_size() < length)
return 1;
mysql_mutex_lock(&lock_queue);
head= elem->write(head, buffer, buffer_end);
mysql_mutex_unlock(&lock_queue);
return 0;
};
Element_type *dequeue()
{
if (used_buffer() > 0)
{
mysql_mutex_lock(&lock_queue);
Element_type *el= new Element_type(tail, buffer, buffer_end);
//We are not going to unlock mutex till we get explicit call of
//unlock_mutex by caller thread (that means sql thread has copied data
//into its buffer)
tail= el->tail;
return el;
}
return NULL;
}
int waited_enqueue(Element_type *elem)
{
mysql_mutex_lock(&free_queue);
while(free_size() < elem->total_length)
mysql_cond_wait(&free_cond, &free_queue);
mysql_mutex_unlock(&free_queue);
return enqueue(elem);
}
void lock_mutex()
{
mysql_mutex_lock(&lock_queue);
}
void unlock_mutex()
{
mysql_mutex_unlock(&lock_queue);
mysql_cond_broadcast(&free_cond);
}
void do_wait(uint32 size)
{
while(free_size() < size)
mysql_cond_wait(&free_cond, &free_queue);
}
};
#endif /* QUEUE_H */
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