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Make GWBITMASK fixed size

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Originally GWBITMASK was capable of extending itself dynamically,
a functionality that in practice was never used, and that, in fact,
was broken.

As GWBITMASK is used for a single purpose inside MaxScale, its size
is now fixed at 256 bits, which is sufficient for 256 threads. Its
fixed size removes a few potential error situations that now then
do not need to be dealt with. And in principle is also more
performant.

In a separate change, bitmask_free will be renamed to bitmask_finish,
as contrary to free-functions in general, the function does not free
the argument, but only its data. The implementation will be empty,
but the function left in place for symmetry reasons (alloc/free,
init/finish).
This commit is contained in:
Johan Wikman
2016-08-15 22:59:39 +03:00
parent 1f10b6337e
commit ed96e2c54a
3 changed files with 62 additions and 132 deletions
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18
server/include/gwbitmask.h
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@ -27,27 +27,25 @@
* @endverbatim
*/
/* Both these numbers MUST be exact multiples of 8 */
#define BIT_LENGTH_INITIAL 256 /**< Initial number of bits in the bitmask */
#define BIT_LENGTH_INC 256 /**< Number of bits to add on each increment */
/* This number MUST an be exact multiple of 8 */
#define MXS_BITMASK_LENGTH 256 /**< Number of bits in the bitmask */
#define MXS_BITMASK_SIZE (MXS_BITMASK_LENGTH / 8) /**< Number of bytes in the bitmask */
/**
* The bitmask structure used to store an arbitrary large bitmask
* The bitmask structure used to store a fixed size bitmask
*/
typedef struct
{
SPINLOCK lock; /**< Lock to protect the bitmask */
unsigned char *bits; /**< Pointer to the bits themselves */
int length; /**< The number of bits in the bitmask */
int size; /**< The number of bytes in the bitmask */
SPINLOCK lock; /**< Lock to protect the bitmask */
unsigned char bits[MXS_BITMASK_SIZE]; /**< The bits themselves */
} GWBITMASK;
#define GWBITMASK_INIT {SPINLOCK_INIT}
extern void bitmask_init(GWBITMASK *);
extern void bitmask_free(GWBITMASK *);
extern void bitmask_set(GWBITMASK *, int);
extern int bitmask_set(GWBITMASK *, int);
extern int bitmask_clear(GWBITMASK *, int);
extern int bitmask_clear_without_spinlock(GWBITMASK *, int);
extern int bitmask_isset(GWBITMASK *, int);