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post-review fixes

Browse Source 
include/atomic/generic-msvc.h:
  prevent possible compiler warnings
include/lf.h:
  comments, better definition for LF_HASH_OVERHEAD
include/maria.h:
  define MARIA_CANNOT_ROLLBACK here
include/my_pthread.h:
  avoid possible name clash
include/waiting_threads.h:
  comments, const, move WT_RESOURCE to waiting_threads.c
mysql-test/suite/maria/r/maria_notembedded.result:
  new test
mysql-test/suite/maria/t/maria_notembedded.test:
  new test - 5-way deadlock
mysys/lf_hash.c:
  better definition for LF_HASH_OVERHEAD
mysys/my_static.c:
  comment
mysys/my_thr_init.c:
  casts
mysys/waiting_threads.c:
  comments, asserts, etc
server-tools/instance-manager/parse.cc:
  fix my_init_dynamic_array() to follow new calling conventions
sql/mysqld.cc:
  call wt_init after set_proper_floating_point_mode
sql/sql_class.h:
  comment
storage/maria/ha_maria.cc:
  move MARIA_CANNOT_ROLLBACK to a common header
storage/maria/ma_commit.c:
  comment
storage/maria/ma_write.c:
  comments, check for HA_ERR_FOUND_DUPP_KEY
storage/maria/trnman.c:
  comments, assert
storage/maria/trnman.h:
  comments
storage/maria/unittest/trnman-t.c:
  be paranoid
unittest/mysys/lf-t.c:
  comments
unittest/mysys/waiting_threads-t.c:
  comments, safety, memory leak
This commit is contained in:
Sergei Golubchik
2009-01-15 22:27:36 +01:00
parent e01f6c8971
commit 9c96fde120
27 changed files with 553 additions and 349 deletions
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122
include/waiting_threads.h
View File

@@ -1,4 +1,4 @@
/* Copyright (C) 2008 MySQL AB
/* 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
@@ -24,16 +24,18 @@
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 {
int (*compare)(void *a, void *b);
const void *(*make_key)(WT_RESOURCE_ID *id, uint *len);
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;
WT_RESOURCE_TYPE *type;
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
@@ -43,93 +45,17 @@ extern uint32 wt_wait_stats[WT_WAIT_STATS+1];
extern uint32 wt_cycle_stats[2][WT_CYCLE_STATS+1];
extern uint32 wt_success_stats;
/*
'lock' protects 'owners', 'state', and 'waiter_count'
'id' is read-only
a resource is picked up from a hash in a lock-free manner
it's returned pinned, so it cannot be freed at once
but it may be freed right after the pin is removed
to free a resource it should be
1. have no owners
2. have no waiters
two ways to access a resource:
1. find it in a hash
- it's returned pinned.
a) take a lock in exclusive mode
b) check the state, it should be ACTIVE
c) unpin
2. by a direct reference
- could only used if a resource cannot be freed
e.g. accessing a resource by thd->waiting_for is safe,
a resource cannot be freed as there's a thread waiting for it
*/
typedef struct st_wt_resource {
WT_RESOURCE_ID id;
uint waiter_count;
enum { ACTIVE, FREE } state;
#ifndef DBUG_OFF
pthread_mutex_t *mutex;
#endif
/*
before the 'lock' all elements are mutable, after (and including) -
immutable in the sense that lf_hash_insert() won't memcpy() over them.
See wt_init().
*/
#ifdef WT_RWLOCKS_USE_MUTEXES
/*
we need a special rwlock-like 'lock' to allow readers bypass
waiting writers, otherwise readers can deadlock. For example:
A waits on resource x, owned by B, B waits on resource y, owned
by A, we have a cycle (A->x->B->y->A)
Both A and B start deadlock detection:
A locks x B locks y
A goes deeper B goes deeper
A locks y B locks x
with mutexes it would deadlock. With rwlocks it won't, as long
as both A and B are taking read locks (and they do).
But other threads may take write locks. Assume there's
C who wants to start waiting on x, and D who wants to start
waiting on y.
A read-locks x B read-locks y
A goes deeper B goes deeper
=> C write-locks x (to add a new edge) D write-locks y
.. C is blocked D is blocked
A read-locks y B read-locks x
Now, if a read lock can bypass a pending wrote lock request, we're fine.
If it can not, we have a deadlock.
writer starvation is technically possible, but unlikely, because
the contention is expected to be low.
*/
struct {
pthread_cond_t cond;
pthread_mutex_t mutex;
uint readers: 16;
uint pending_writers: 15;
uint write_locked: 1;
} lock;
#else
rw_lock_t lock;
#endif
pthread_cond_t cond;
DYNAMIC_ARRAY owners;
} WT_RESOURCE;
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
automatically (not to protect this array but to protect its
own - caller's - data structures, and we'll get it for free.
If not, we'll need to add a mutex
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;
/*
@@ -141,8 +67,10 @@ typedef struct st_wt_thd {
LF_PINS *pins;
/* pointers to values */
ulong *timeout_short, *deadlock_search_depth_short;
ulong *timeout_long, *deadlock_search_depth_long;
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
@@ -169,13 +97,13 @@ typedef struct st_wt_thd {
*/
ulong volatile weight;
/*
'killed' is indirectly protected by waiting_for->lock -
a killed thread needs to clear its 'waiting_for', and thus needs a lock.
'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 volatile killed;
my_bool killed;
#ifndef DBUG_OFF
const char *name;
#endif
@@ -189,13 +117,13 @@ typedef struct st_wt_thd {
void wt_init(void);
void wt_end(void);
void wt_thd_lazy_init(WT_THD *, ulong *, ulong *, ulong *, ulong *);
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 *, WT_RESOURCE_ID *);
int wt_thd_will_wait_for(WT_THD *, WT_THD *, const WT_RESOURCE_ID *);
int wt_thd_cond_timedwait(WT_THD *, pthread_mutex_t *);
void wt_thd_release(WT_THD *, WT_RESOURCE_ID *);
void wt_thd_release(WT_THD *, const WT_RESOURCE_ID *);
#define wt_thd_release_all(THD) wt_thd_release((THD), 0)
int wt_resource_id_memcmp(void *, void *);
int wt_resource_id_memcmp(const void *, const void *);
C_MODE_END