diff options
Diffstat (limited to 'include/waiting_threads.h')
| -rw-r--r-- | include/waiting_threads.h | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/include/waiting_threads.h b/include/waiting_threads.h new file mode 100644 index 00000000..5f708f42 --- /dev/null +++ b/include/waiting_threads.h @@ -0,0 +1,129 @@ +/* Copyright (C) 2008 MySQL AB, 2008-2009 Sun Microsystems, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; version 2 of the License. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ + +#ifndef _waiting_threads_h +#define _waiting_threads_h + +#include <my_sys.h> + +#include <lf.h> + +C_MODE_START + +typedef struct st_wt_resource_id WT_RESOURCE_ID; +typedef struct st_wt_resource WT_RESOURCE; + +typedef struct st_wt_resource_type { + my_bool (*compare)(const void *a, const void *b); + const void *(*make_key)(const WT_RESOURCE_ID *id, uint *len); /* not used */ +} WT_RESOURCE_TYPE; + +struct st_wt_resource_id { + ulonglong value; + const WT_RESOURCE_TYPE *type; +}; +/* the below differs from sizeof(WT_RESOURCE_ID) by the amount of padding */ +#define sizeof_WT_RESOURCE_ID (sizeof(ulonglong)+sizeof(void*)) + +#define WT_WAIT_STATS 24 +#define WT_CYCLE_STATS 32 +extern ulonglong wt_wait_table[WT_WAIT_STATS]; +extern uint32 wt_wait_stats[WT_WAIT_STATS+1]; +extern uint32 wt_cycle_stats[2][WT_CYCLE_STATS+1]; +extern uint32 wt_success_stats; + +typedef struct st_wt_thd { + /* + XXX + there's no protection (mutex) against concurrent access of the + dynarray below. it is assumed that a caller will have it anyway + (not to protect this array but to protect its own - caller's - + data structures), and we'll get it for free. A caller needs to + ensure that a blocker won't release a resource before a blocked + thread starts waiting, which is usually done with a mutex. + + If the above assumption is wrong, we'll need to add a mutex here. + */ + DYNAMIC_ARRAY my_resources; + /* + 'waiting_for' is modified under waiting_for->lock, and only by thd itself + 'waiting_for' is read lock-free (using pinning protocol), but a thd object + can read its own 'waiting_for' without any locks or tricks. + */ + WT_RESOURCE *waiting_for; + LF_PINS *pins; + + /* pointers to values */ + const ulong *timeout_short; + const ulong *deadlock_search_depth_short; + const ulong *timeout_long; + const ulong *deadlock_search_depth_long; + + /* + weight relates to the desirability of a transaction being killed if it's + part of a deadlock. In a deadlock situation transactions with lower weights + are killed first. + + Examples of using the weight to implement different selection strategies: + + 1. Latest + Keep all weights equal. + 2. Random + Assign weights at random. + (variant: modify a weight randomly before every lock request) + 3. Youngest + Set weight to -NOW() + 4. Minimum locks + count locks granted in your lock manager, store the value as a weight + 5. Minimum work + depends on the definition of "work". For example, store the number + of rows modifies in this transaction (or a length of REDO log for a + transaction) as a weight. + + It is only statistically relevant and is not protected by any locks. + */ + ulong volatile weight; + /* + 'killed' is indirectly protected by waiting_for->lock because + a killed thread needs to clear its 'waiting_for' and thus needs a lock. + That is a thread needs an exclusive lock to read 'killed' reliably. + But other threads may change 'killed' from 0 to 1, a shared + lock is enough for that. + */ + my_bool killed; +#ifndef DBUG_OFF + const char *name; +#endif +} WT_THD; + +#define WT_TIMEOUT ETIMEDOUT +#define WT_OK 0 +#define WT_DEADLOCK -1 +#define WT_DEPTH_EXCEEDED -2 +#define WT_FREE_TO_GO -3 + +void wt_init(void); +void wt_end(void); +void wt_thd_lazy_init(WT_THD *, const ulong *, const ulong *, const ulong *, const ulong *); +void wt_thd_destroy(WT_THD *); +int wt_thd_will_wait_for(WT_THD *, WT_THD *, const WT_RESOURCE_ID *); +int wt_thd_cond_timedwait(WT_THD *, mysql_mutex_t *); +void wt_thd_release(WT_THD *, const WT_RESOURCE_ID *); +#define wt_thd_release_all(THD) wt_thd_release((THD), 0) +my_bool wt_resource_id_memcmp(const void *, const void *); + +C_MODE_END + +#endif |