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WL#3230 concurrent hash

Browse Source 
Backport from 6.0.14 to 5.6.0

Original code from Sergei Golubchik
This commit is contained in:
Marc Alff
2009-11-17 19:31:40 -07:00
parent 7b9fd341a0
commit 244eced1a7
11 changed files with 1713 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
configure.in
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@ -2114,7 +2114,7 @@ AC_CHECK_FUNCS(alarm bcmp bfill bmove bsearch bzero \
pthread_setprio_np pthread_setschedparam pthread_sigmask readlink \
realpath rename rint rwlock_init setupterm \
shmget shmat shmdt shmctl sigaction sigemptyset sigaddset \
sighold sigset sigthreadmask port_create sleep \
sighold sigset sigthreadmask port_create sleep thr_yield \
snprintf socket stpcpy strcasecmp strerror strsignal strnlen strpbrk strstr \
strtol strtoll strtoul strtoull tell tempnam thr_setconcurrency vidattr \
posix_fallocate backtrace backtrace_symbols backtrace_symbols_fd)

2
include/Makefile.am
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@ -30,7 +30,7 @@ pkginclude_HEADERS = $(HEADERS_ABI) my_dbug.h m_string.h my_sys.h \
m_ctype.h my_attribute.h $(HEADERS_GEN_CONFIGURE) \
$(HEADERS_GEN_MAKE) probes_mysql.h probes_mysql_nodtrace.h
noinst_HEADERS = config-win.h config-netware.h my_bit.h \
noinst_HEADERS = config-win.h config-netware.h lf.h my_bit.h \
heap.h my_bitmap.h my_uctype.h \
myisam.h myisampack.h myisammrg.h ft_global.h\
mysys_err.h my_base.h help_start.h help_end.h \

268
include/lf.h Normal file
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@ -0,0 +1,268 @@
/* Copyright (C) 2007-2008 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef _lf_h
#define _lf_h
#include <my_atomic.h>
C_MODE_START
/*
Helpers to define both func() and _func(), where
func() is a _func() protected by my_atomic_rwlock_wrlock()
*/
#define lock_wrap(f, t, proto_args, args, lock) \
t _ ## f proto_args; \
static inline t f proto_args \
{ \
t ret; \
my_atomic_rwlock_wrlock(lock); \
ret= _ ## f args; \
my_atomic_rwlock_wrunlock(lock); \
return ret; \
}
#define lock_wrap_void(f, proto_args, args, lock) \
void _ ## f proto_args; \
static inline void f proto_args \
{ \
my_atomic_rwlock_wrlock(lock); \
_ ## f args; \
my_atomic_rwlock_wrunlock(lock); \
}
#define nolock_wrap(f, t, proto_args, args) \
t _ ## f proto_args; \
static inline t f proto_args \
{ \
return _ ## f args; \
}
#define nolock_wrap_void(f, proto_args, args) \
void _ ## f proto_args; \
static inline void f proto_args \
{ \
_ ## f args; \
}
/*
wait-free dynamic array, see lf_dynarray.c
4 levels of 256 elements each mean 4311810304 elements in an array - it
should be enough for a while
*/
#define LF_DYNARRAY_LEVEL_LENGTH 256
#define LF_DYNARRAY_LEVELS 4
typedef struct {
void * volatile level[LF_DYNARRAY_LEVELS];
uint size_of_element;
my_atomic_rwlock_t lock;
} LF_DYNARRAY;
typedef int (*lf_dynarray_func)(void *, void *);
void lf_dynarray_init(LF_DYNARRAY *array, uint element_size);
void lf_dynarray_destroy(LF_DYNARRAY *array);
nolock_wrap(lf_dynarray_value, void *,
(LF_DYNARRAY *array, uint idx),
(array, idx))
lock_wrap(lf_dynarray_lvalue, void *,
(LF_DYNARRAY *array, uint idx),
(array, idx),
&array->lock)
nolock_wrap(lf_dynarray_iterate, int,
(LF_DYNARRAY *array, lf_dynarray_func func, void *arg),
(array, func, arg))
/*
pin manager for memory allocator, lf_alloc-pin.c
*/
#define LF_PINBOX_PINS 4
#define LF_PURGATORY_SIZE 10
typedef void lf_pinbox_free_func(void *, void *, void*);
typedef struct {
LF_DYNARRAY pinarray;
lf_pinbox_free_func *free_func;
void *free_func_arg;
uint free_ptr_offset;
uint32 volatile pinstack_top_ver; /* this is a versioned pointer */
uint32 volatile pins_in_array; /* number of elements in array */
} LF_PINBOX;
typedef struct {
void * volatile pin[LF_PINBOX_PINS];
LF_PINBOX *pinbox;
void **stack_ends_here;
void *purgatory;
uint32 purgatory_count;
uint32 volatile link;
/* we want sizeof(LF_PINS) to be 64 to avoid false sharing */
#if SIZEOF_INT*2+SIZEOF_CHARP*(LF_PINBOX_PINS+3) != 64
char pad[64-sizeof(uint32)*2-sizeof(void*)*(LF_PINBOX_PINS+3)];
#endif
} LF_PINS;
/*
shortcut macros to do an atomic_wrlock on a structure that uses pins
(e.g. lf_hash).
*/
#define lf_rwlock_by_pins(PINS) \
my_atomic_rwlock_wrlock(&(PINS)->pinbox->pinarray.lock)
#define lf_rwunlock_by_pins(PINS) \
my_atomic_rwlock_wrunlock(&(PINS)->pinbox->pinarray.lock)
/*
compile-time assert, to require "no less than N" pins
it's enough if it'll fail on at least one compiler, so
we'll enable it on GCC only, which supports zero-length arrays.
*/
#if defined(__GNUC__) && defined(MY_LF_EXTRA_DEBUG)
#define LF_REQUIRE_PINS(N) \
static const char require_pins[LF_PINBOX_PINS-N] \
__attribute__ ((unused)); \
static const int LF_NUM_PINS_IN_THIS_FILE= N;
#define _lf_pin(PINS, PIN, ADDR) \
( \
assert(PIN < LF_NUM_PINS_IN_THIS_FILE), \
my_atomic_storeptr(&(PINS)->pin[PIN], (ADDR)) \
)
#else
#define LF_REQUIRE_PINS(N)
#define _lf_pin(PINS, PIN, ADDR) my_atomic_storeptr(&(PINS)->pin[PIN], (ADDR))
#endif
#define _lf_unpin(PINS, PIN) _lf_pin(PINS, PIN, NULL)
#define lf_pin(PINS, PIN, ADDR) \
do { \
lf_rwlock_by_pins(PINS); \
_lf_pin(PINS, PIN, ADDR); \
lf_rwunlock_by_pins(PINS); \
} while (0)
#define lf_unpin(PINS, PIN) lf_pin(PINS, PIN, NULL)
#define _lf_assert_pin(PINS, PIN) assert((PINS)->pin[PIN] != 0)
#define _lf_assert_unpin(PINS, PIN) assert((PINS)->pin[PIN] == 0)
void lf_pinbox_init(LF_PINBOX *pinbox, uint free_ptr_offset,
lf_pinbox_free_func *free_func, void * free_func_arg);
void lf_pinbox_destroy(LF_PINBOX *pinbox);
lock_wrap(lf_pinbox_get_pins, LF_PINS *,
(LF_PINBOX *pinbox),
(pinbox),
&pinbox->pinarray.lock)
lock_wrap_void(lf_pinbox_put_pins,
(LF_PINS *pins),
(pins),
&pins->pinbox->pinarray.lock)
lock_wrap_void(lf_pinbox_free,
(LF_PINS *pins, void *addr),
(pins, addr),
&pins->pinbox->pinarray.lock)
/*
memory allocator, lf_alloc-pin.c
*/
typedef struct st_lf_allocator {
LF_PINBOX pinbox;
uchar * volatile top;
uint element_size;
uint32 volatile mallocs;
void (*constructor)(uchar *); /* called, when an object is malloc()'ed */
void (*destructor)(uchar *); /* called, when an object is free()'d */
} LF_ALLOCATOR;
void lf_alloc_init(LF_ALLOCATOR *allocator, uint size, uint free_ptr_offset);
void lf_alloc_destroy(LF_ALLOCATOR *allocator);
uint lf_alloc_pool_count(LF_ALLOCATOR *allocator);
/*
shortcut macros to access underlying pinbox functions from an LF_ALLOCATOR
see _lf_pinbox_get_pins() and _lf_pinbox_put_pins()
*/
#define _lf_alloc_free(PINS, PTR) _lf_pinbox_free((PINS), (PTR))
#define lf_alloc_free(PINS, PTR) lf_pinbox_free((PINS), (PTR))
#define _lf_alloc_get_pins(A) _lf_pinbox_get_pins(&(A)->pinbox)
#define lf_alloc_get_pins(A) lf_pinbox_get_pins(&(A)->pinbox)
#define _lf_alloc_put_pins(PINS) _lf_pinbox_put_pins(PINS)
#define lf_alloc_put_pins(PINS) lf_pinbox_put_pins(PINS)
#define lf_alloc_direct_free(ALLOC, ADDR) my_free((uchar*)(ADDR), MYF(0))
lock_wrap(lf_alloc_new, void *,
(LF_PINS *pins),
(pins),
&pins->pinbox->pinarray.lock)
C_MODE_END
/*
extendible hash, lf_hash.c
*/
#include <hash.h>
C_MODE_START
#define LF_HASH_UNIQUE 1
/* lf_hash overhead per element (that is, sizeof(LF_SLIST) */
extern const int LF_HASH_OVERHEAD;
typedef struct {
LF_DYNARRAY array; /* hash itself */
LF_ALLOCATOR alloc; /* allocator for elements */
my_hash_get_key get_key; /* see HASH */
CHARSET_INFO *charset; /* see HASH */
uint key_offset, key_length; /* see HASH */
uint element_size; /* size of memcpy'ed area on insert */
uint flags; /* LF_HASH_UNIQUE, etc */
int32 volatile size; /* size of array */
int32 volatile count; /* number of elements in the hash */
} LF_HASH;
void lf_hash_init(LF_HASH *hash, uint element_size, uint flags,
uint key_offset, uint key_length, my_hash_get_key get_key,
CHARSET_INFO *charset);
void lf_hash_destroy(LF_HASH *hash);
int lf_hash_insert(LF_HASH *hash, LF_PINS *pins, const void *data);
void *lf_hash_search(LF_HASH *hash, LF_PINS *pins, const void *key, uint keylen);
int lf_hash_delete(LF_HASH *hash, LF_PINS *pins, const void *key, uint keylen);
/*
shortcut macros to access underlying pinbox functions from an LF_HASH
see _lf_pinbox_get_pins() and _lf_pinbox_put_pins()
*/
#define _lf_hash_get_pins(HASH) _lf_alloc_get_pins(&(HASH)->alloc)
#define lf_hash_get_pins(HASH) lf_alloc_get_pins(&(HASH)->alloc)
#define _lf_hash_put_pins(PINS) _lf_pinbox_put_pins(PINS)
#define lf_hash_put_pins(PINS) lf_pinbox_put_pins(PINS)
#define lf_hash_search_unpin(PINS) lf_unpin((PINS), 2)
/*
cleanup
*/
#undef lock_wrap_void
#undef lock_wrap
#undef nolock_wrap_void
#undef nolock_wrap
C_MODE_END
#endif

13
include/my_pthread.h
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@ -152,6 +152,7 @@ int pthread_join(pthread_t thread, void **value_ptr);
#define pthread_detach_this_thread()
#define pthread_condattr_init(A)
#define pthread_condattr_destroy(A)
#define pthread_yield() SwitchToThread()
#define my_pthread_getprio(thread_id) pthread_dummy(0)
@ -385,6 +386,17 @@ void my_pthread_attr_getstacksize(pthread_attr_t *attrib, size_t *size);
int my_pthread_mutex_trylock(pthread_mutex_t *mutex);
#endif
#if !defined(HAVE_PTHREAD_YIELD_ONE_ARG) && !defined(HAVE_PTHREAD_YIELD_ZERO_ARG)
/* no pthread_yield() available */
#ifdef HAVE_SCHED_YIELD
#define pthread_yield() sched_yield()
#elif defined(HAVE_PTHREAD_YIELD_NP) /* can be Mac OS X */
#define pthread_yield() pthread_yield_np()
#elif defined(HAVE_THR_YIELD)
#define pthread_yield() thr_yield()
#endif
#endif
/*
The defines set_timespec and set_timespec_nsec should be used
for calculating an absolute time at which
@ -663,6 +675,7 @@ struct st_my_thread_var
my_bool init;
struct st_my_thread_var *next,**prev;
void *opt_info;
void *stack_ends_here;
#ifndef DBUG_OFF
void *dbug;
char name[THREAD_NAME_SIZE+1];

3
mysys/Makefile.am
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@ -30,7 +30,8 @@ libmysys_a_SOURCES = my_init.c my_getwd.c mf_getdate.c my_mmap.c \
mf_tempdir.c my_lock.c mf_brkhant.c my_alarm.c \
my_malloc.c my_realloc.c my_once.c mulalloc.c \
my_alloc.c safemalloc.c my_new.cc \
my_vle.c my_atomic.c \
my_vle.c my_atomic.c lf_hash.c \
lf_dynarray.c lf_alloc-pin.c \
my_fopen.c my_fstream.c my_getsystime.c \
my_error.c errors.c my_div.c my_messnc.c \
mf_format.c mf_same.c mf_dirname.c mf_fn_ext.c \

534
mysys/lf_alloc-pin.c Normal file
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@ -0,0 +1,534 @@
/* QQ: TODO multi-pinbox */
/* Copyright (C) 2006-2008 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
wait-free concurrent allocator based on pinning addresses
It works as follows: every thread (strictly speaking - every CPU, but
it's too difficult to do) has a small array of pointers. They're called
"pins". Before using an object its address must be stored in this array
(pinned). When an object is no longer necessary its address must be
removed from this array (unpinned). When a thread wants to free() an
object it scans all pins of all threads to see if somebody has this
object pinned. If yes - the object is not freed (but stored in a
"purgatory"). To reduce the cost of a single free() pins are not scanned
on every free() but only added to (thread-local) purgatory. On every
LF_PURGATORY_SIZE free() purgatory is scanned and all unpinned objects
are freed.
Pins are used to solve ABA problem. To use pins one must obey
a pinning protocol:
1. Let's assume that PTR is a shared pointer to an object. Shared means
that any thread may modify it anytime to point to a different object
and free the old object. Later the freed object may be potentially
allocated by another thread. If we're unlucky that other thread may
set PTR to point to this object again. This is ABA problem.
2. Create a local pointer LOCAL_PTR.
3. Pin the PTR in a loop:
do
{
LOCAL_PTR= PTR;
pin(PTR, PIN_NUMBER);
} while (LOCAL_PTR != PTR)
4. It is guaranteed that after the loop has ended, LOCAL_PTR
points to an object (or NULL, if PTR may be NULL), that
will never be freed. It is not guaranteed though
that LOCAL_PTR == PTR (as PTR can change any time)
5. When done working with the object, remove the pin:
unpin(PIN_NUMBER)
6. When copying pins (as in the list traversing loop:
pin(CUR, 1);
while ()
{
do // standard
{ // pinning
NEXT=CUR->next; // loop
pin(NEXT, 0); // see #3
} while (NEXT != CUR->next); // above
...
...
CUR=NEXT;
pin(CUR, 1); // copy pin[0] to pin[1]
}
which keeps CUR address constantly pinned), note than pins may be
copied only upwards (!!!), that is pin[N] to pin[M], M > N.
7. Don't keep the object pinned longer than necessary - the number of
pins you have is limited (and small), keeping an object pinned
prevents its reuse and cause unnecessary mallocs.
Explanations:
3. The loop is important. The following can occur:
thread1> LOCAL_PTR= PTR
thread2> free(PTR); PTR=0;
thread1> pin(PTR, PIN_NUMBER);
now thread1 cannot access LOCAL_PTR, even if it's pinned,
because it points to a freed memory. That is, it *must*
verify that it has indeed pinned PTR, the shared pointer.
6. When a thread wants to free some LOCAL_PTR, and it scans
all lists of pins to see whether it's pinned, it does it
upwards, from low pin numbers to high. Thus another thread
must copy an address from one pin to another in the same
direction - upwards, otherwise the scanning thread may
miss it.
Implementation details:
Pins are given away from a "pinbox". Pinbox is stack-based allocator.
It used dynarray for storing pins, new elements are allocated by dynarray
as necessary, old are pushed in the stack for reuse. ABA is solved by
versioning a pointer - because we use an array, a pointer to pins is 16 bit,
upper 16 bits are used for a version.
It is assumed that pins belong to a THD and are not transferable
between THD's (LF_PINS::stack_ends_here being a primary reason
for this limitation).
*/
#include <my_global.h>
#include <my_sys.h>
#include <lf.h>
#define LF_PINBOX_MAX_PINS 65536
static void _lf_pinbox_real_free(LF_PINS *pins);
/*
Initialize a pinbox. Normally called from lf_alloc_init.
See the latter for details.
*/
void lf_pinbox_init(LF_PINBOX *pinbox, uint free_ptr_offset,
lf_pinbox_free_func *free_func, void *free_func_arg)
{
DBUG_ASSERT(free_ptr_offset % sizeof(void *) == 0);
compile_time_assert(sizeof(LF_PINS) == 64);
lf_dynarray_init(&pinbox->pinarray, sizeof(LF_PINS));
pinbox->pinstack_top_ver= 0;
pinbox->pins_in_array= 0;
pinbox->free_ptr_offset= free_ptr_offset;
pinbox->free_func= free_func;
pinbox->free_func_arg= free_func_arg;
}
void lf_pinbox_destroy(LF_PINBOX *pinbox)
{
lf_dynarray_destroy(&pinbox->pinarray);
}
/*
Get pins from a pinbox. Usually called via lf_alloc_get_pins() or
lf_hash_get_pins().
SYNOPSYS
pinbox -
DESCRIPTION
get a new LF_PINS structure from a stack of unused pins,
or allocate a new one out of dynarray.
NOTE
It is assumed that pins belong to a thread and are not transferable
between threads.
*/
LF_PINS *_lf_pinbox_get_pins(LF_PINBOX *pinbox)
{
uint32 pins, next, top_ver;
LF_PINS *el;
/*
We have an array of max. 64k elements.
The highest index currently allocated is pinbox->pins_in_array.
Freed elements are in a lifo stack, pinstack_top_ver.
pinstack_top_ver is 32 bits; 16 low bits are the index in the
array, to the first element of the list. 16 high bits are a version
(every time the 16 low bits are updated, the 16 high bits are
incremented). Versioniong prevents the ABA problem.
*/
top_ver= pinbox->pinstack_top_ver;
do
{
if (!(pins= top_ver % LF_PINBOX_MAX_PINS))
{
/* the stack of free elements is empty */
pins= my_atomic_add32((int32 volatile*) &pinbox->pins_in_array, 1)+1;
if (unlikely(pins >= LF_PINBOX_MAX_PINS))
return 0;
/*
note that the first allocated element has index 1 (pins==1).
index 0 is reserved to mean "NULL pointer"
*/
el= (LF_PINS *)_lf_dynarray_lvalue(&pinbox->pinarray, pins);
if (unlikely(!el))
return 0;
break;
}
el= (LF_PINS *)_lf_dynarray_value(&pinbox->pinarray, pins);
next= el->link;
} while (!my_atomic_cas32((int32 volatile*) &pinbox->pinstack_top_ver,
(int32*) &top_ver,
top_ver-pins+next+LF_PINBOX_MAX_PINS));
/*
set el->link to the index of el in the dynarray (el->link has two usages:
- if element is allocated, it's its own index
- if element is free, it's its next element in the free stack
*/
el->link= pins;
el->purgatory_count= 0;
el->pinbox= pinbox;
el->stack_ends_here= & my_thread_var->stack_ends_here;
return el;
}
/*
Put pins back to a pinbox. Usually called via lf_alloc_put_pins() or
lf_hash_put_pins().
DESCRIPTION
empty the purgatory (XXX deadlock warning below!),
push LF_PINS structure to a stack
*/
void _lf_pinbox_put_pins(LF_PINS *pins)
{
LF_PINBOX *pinbox= pins->pinbox;
uint32 top_ver, nr;
nr= pins->link;
#ifdef MY_LF_EXTRA_DEBUG
{
int i;
for (i= 0; i < LF_PINBOX_PINS; i++)
DBUG_ASSERT(pins->pin[i] == 0);
}
#endif
/*
XXX this will deadlock if other threads will wait for
the caller to do something after _lf_pinbox_put_pins(),
and they would have pinned addresses that the caller wants to free.
Thus: only free pins when all work is done and nobody can wait for you!!!
*/
while (pins->purgatory_count)
{
_lf_pinbox_real_free(pins);
if (pins->purgatory_count)
{
my_atomic_rwlock_wrunlock(&pins->pinbox->pinarray.lock);
pthread_yield();
my_atomic_rwlock_wrlock(&pins->pinbox->pinarray.lock);
}
}
top_ver= pinbox->pinstack_top_ver;
do
{
pins->link= top_ver % LF_PINBOX_MAX_PINS;
} while (!my_atomic_cas32((int32 volatile*) &pinbox->pinstack_top_ver,
(int32*) &top_ver,
top_ver-pins->link+nr+LF_PINBOX_MAX_PINS));
return;
}
static int ptr_cmp(void **a, void **b)
{
return *a < *b ? -1 : *a == *b ? 0 : 1;
}
#define add_to_purgatory(PINS, ADDR) \
do \
{ \
*(void **)((char *)(ADDR)+(PINS)->pinbox->free_ptr_offset)= \
(PINS)->purgatory; \
(PINS)->purgatory= (ADDR); \
(PINS)->purgatory_count++; \
} while (0)
/*
Free an object allocated via pinbox allocator
DESCRIPTION
add an object to purgatory. if necessary, call _lf_pinbox_real_free()
to actually free something.
*/
void _lf_pinbox_free(LF_PINS *pins, void *addr)
{
add_to_purgatory(pins, addr);
if (pins->purgatory_count % LF_PURGATORY_SIZE)
_lf_pinbox_real_free(pins);
}
struct st_harvester {
void **granary;
int npins;
};
/*
callback for _lf_dynarray_iterate:
scan all pins of all threads and accumulate all pins
*/
static int harvest_pins(LF_PINS *el, struct st_harvester *hv)
{
int i;
LF_PINS *el_end= el+min(hv->npins, LF_DYNARRAY_LEVEL_LENGTH);
for (; el < el_end; el++)
{
for (i= 0; i < LF_PINBOX_PINS; i++)
{
void *p= el->pin[i];
if (p)
*hv->granary++= p;
}
}
/*
hv->npins may become negative below, but it means that
we're on the last dynarray page and harvest_pins() won't be
called again. We don't bother to make hv->npins() correct
(that is 0) in this case.
*/
hv->npins-= LF_DYNARRAY_LEVEL_LENGTH;
return 0;
}
/*
callback for _lf_dynarray_iterate:
scan all pins of all threads and see if addr is present there
*/
static int match_pins(LF_PINS *el, void *addr)
{
int i;
LF_PINS *el_end= el+LF_DYNARRAY_LEVEL_LENGTH;
for (; el < el_end; el++)
for (i= 0; i < LF_PINBOX_PINS; i++)
if (el->pin[i] == addr)
return 1;
return 0;
}
#if STACK_DIRECTION < 0
#define available_stack_size(CUR,END) (long) ((char*)(CUR) - (char*)(END))
#else
#define available_stack_size(CUR,END) (long) ((char*)(END) - (char*)(CUR))
#endif
#define next_node(P, X) (*((uchar * volatile *)(((uchar *)(X)) + (P)->free_ptr_offset)))
#define anext_node(X) next_node(&allocator->pinbox, (X))
/*
Scan the purgatory and free everything that can be freed
*/
static void _lf_pinbox_real_free(LF_PINS *pins)
{
int npins, alloca_size;
void *list, **addr;
void *first, *last= NULL;
LF_PINBOX *pinbox= pins->pinbox;
LINT_INIT(first);
npins= pinbox->pins_in_array+1;
#ifdef HAVE_ALLOCA
alloca_size= sizeof(void *)*LF_PINBOX_PINS*npins;
/* create a sorted list of pinned addresses, to speed up searches */
if (available_stack_size(&pinbox, *pins->stack_ends_here) > alloca_size)
{
struct st_harvester hv;
addr= (void **) alloca(alloca_size);
hv.granary= addr;
hv.npins= npins;
/* scan the dynarray and accumulate all pinned addresses */
_lf_dynarray_iterate(&pinbox->pinarray,
(lf_dynarray_func)harvest_pins, &hv);
npins= hv.granary-addr;
/* and sort them */
if (npins)
qsort(addr, npins, sizeof(void *), (qsort_cmp)ptr_cmp);
}
else
#endif
addr= 0;
list= pins->purgatory;
pins->purgatory= 0;
pins->purgatory_count= 0;
while (list)
{
void *cur= list;
list= *(void **)((char *)cur+pinbox->free_ptr_offset);
if (npins)
{
if (addr) /* use binary search */
{
void **a, **b, **c;
for (a= addr, b= addr+npins-1, c= a+(b-a)/2; (b-a) > 1; c= a+(b-a)/2)
if (cur == *c)
a= b= c;
else if (cur > *c)
a= c;
else
b= c;
if (cur == *a || cur == *b)
goto found;
}
else /* no alloca - no cookie. linear search here */
{
if (_lf_dynarray_iterate(&pinbox->pinarray,
(lf_dynarray_func)match_pins, cur))
goto found;
}
}
/* not pinned - freeing */
if (last)
last= next_node(pinbox, last)= (uchar *)cur;
else
first= last= (uchar *)cur;
continue;
found:
/* pinned - keeping */
add_to_purgatory(pins, cur);
}
if (last)
pinbox->free_func(first, last, pinbox->free_func_arg);
}
/* lock-free memory allocator for fixed-size objects */
LF_REQUIRE_PINS(1)
/*
callback for _lf_pinbox_real_free to free a list of unpinned objects -
add it back to the allocator stack
DESCRIPTION
'first' and 'last' are the ends of the linked list of nodes:
first->el->el->....->el->last. Use first==last to free only one element.
*/
static void alloc_free(uchar *first,
uchar volatile *last,
LF_ALLOCATOR *allocator)
{
/*
we need a union here to access type-punned pointer reliably.
otherwise gcc -fstrict-aliasing will not see 'tmp' changed in the loop
*/
union { uchar * node; void *ptr; } tmp;
tmp.node= allocator->top;
do
{
anext_node(last)= tmp.node;
} while (!my_atomic_casptr((void **)(char *)&allocator->top,
(void **)&tmp.ptr, first) && LF_BACKOFF);
}
/*
initialize lock-free allocator
SYNOPSYS
allocator -
size a size of an object to allocate
free_ptr_offset an offset inside the object to a sizeof(void *)
memory that is guaranteed to be unused after
the object is put in the purgatory. Unused by ANY
thread, not only the purgatory owner.
This memory will be used to link waiting-to-be-freed
objects in a purgatory list.
*/
void lf_alloc_init(LF_ALLOCATOR *allocator, uint size, uint free_ptr_offset)
{
lf_pinbox_init(&allocator->pinbox, free_ptr_offset,
(lf_pinbox_free_func *)alloc_free, allocator);
allocator->top= 0;
allocator->mallocs= 0;
allocator->element_size= size;
allocator->constructor= 0;
allocator->destructor= 0;
DBUG_ASSERT(size >= sizeof(void*) + free_ptr_offset);
}
/*
destroy the allocator, free everything that's in it
NOTE
As every other init/destroy function here and elsewhere it
is not thread safe. No, this function is no different, ensure
that no thread needs the allocator before destroying it.
We are not responsible for any damage that may be caused by
accessing the allocator when it is being or has been destroyed.
Oh yes, and don't put your cat in a microwave.
*/
void lf_alloc_destroy(LF_ALLOCATOR *allocator)
{
uchar *node= allocator->top;
while (node)
{
uchar *tmp= anext_node(node);
if (allocator->destructor)
allocator->destructor(node);
my_free((void *)node, MYF(0));
node= tmp;
}
lf_pinbox_destroy(&allocator->pinbox);
allocator->top= 0;
}
/*
Allocate and return an new object.
DESCRIPTION
Pop an unused object from the stack or malloc it is the stack is empty.
pin[0] is used, it's removed on return.
*/
void *_lf_alloc_new(LF_PINS *pins)
{
LF_ALLOCATOR *allocator= (LF_ALLOCATOR *)(pins->pinbox->free_func_arg);
uchar *node;
for (;;)
{
do
{
node= allocator->top;
_lf_pin(pins, 0, node);
} while (node != allocator->top && LF_BACKOFF);
if (!node)
{
node= (void *)my_malloc(allocator->element_size, MYF(MY_WME));
if (allocator->constructor)
allocator->constructor(node);
#ifdef MY_LF_EXTRA_DEBUG
if (likely(node != 0))
my_atomic_add32(&allocator->mallocs, 1);
#endif
break;
}
if (my_atomic_casptr((void **)(char *)&allocator->top,
(void *)&node, anext_node(node)))
break;
}
_lf_unpin(pins, 0);
return node;
}
/*
count the number of objects in a pool.
NOTE
This is NOT thread-safe !!!
*/
uint lf_alloc_pool_count(LF_ALLOCATOR *allocator)
{
uint i;
uchar *node;
for (node= allocator->top, i= 0; node; node= anext_node(node), i++)
/* no op */;
return i;
}

207
mysys/lf_dynarray.c Normal file
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/* Copyright (C) 2006 MySQL AB
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Analog of DYNAMIC_ARRAY that never reallocs
(so no pointer into the array may ever become invalid).
Memory is allocated in non-contiguous chunks.
This data structure is not space efficient for sparse arrays.
Every element is aligned to sizeof(element) boundary
(to avoid false sharing if element is big enough).
LF_DYNARRAY is a recursive structure. On the zero level
LF_DYNARRAY::level[0] it's an array of LF_DYNARRAY_LEVEL_LENGTH elements,
on the first level it's an array of LF_DYNARRAY_LEVEL_LENGTH pointers
to arrays of elements, on the second level it's an array of pointers
to arrays of pointers to arrays of elements. And so on.
With four levels the number of elements is limited to 4311810304
(but as in all functions index is uint, the real limit is 2^32-1)
Actually, it's wait-free, not lock-free ;-)
*/
#include <my_global.h>
#include <m_string.h>
#include <my_sys.h>
#include <lf.h>
void lf_dynarray_init(LF_DYNARRAY *array, uint element_size)
{
bzero(array, sizeof(*array));
array->size_of_element= element_size;
my_atomic_rwlock_init(&array->lock);
}
static void recursive_free(void **alloc, int level)
{
if (!alloc)
return;
if (level)
{
int i;
for (i= 0; i < LF_DYNARRAY_LEVEL_LENGTH; i++)
recursive_free(alloc[i], level-1);
my_free((void *)alloc, MYF(0));
}
else
my_free(alloc[-1], MYF(0));
}
void lf_dynarray_destroy(LF_DYNARRAY *array)
{
int i;
for (i= 0; i < LF_DYNARRAY_LEVELS; i++)
recursive_free(array->level[i], i);
my_atomic_rwlock_destroy(&array->lock);
}
static const ulong dynarray_idxes_in_prev_levels[LF_DYNARRAY_LEVELS]=
{
0, /* +1 here to to avoid -1's below */
LF_DYNARRAY_LEVEL_LENGTH,
LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH +
LF_DYNARRAY_LEVEL_LENGTH,
LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH *
LF_DYNARRAY_LEVEL_LENGTH + LF_DYNARRAY_LEVEL_LENGTH *
LF_DYNARRAY_LEVEL_LENGTH + LF_DYNARRAY_LEVEL_LENGTH
};
static const ulong dynarray_idxes_in_prev_level[LF_DYNARRAY_LEVELS]=
{
0, /* +1 here to to avoid -1's below */
LF_DYNARRAY_LEVEL_LENGTH,
LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH,
LF_DYNARRAY_LEVEL_LENGTH * LF_DYNARRAY_LEVEL_LENGTH *
LF_DYNARRAY_LEVEL_LENGTH,
};
/*
Returns a valid lvalue pointer to the element number 'idx'.
Allocates memory if necessary.
*/
void *_lf_dynarray_lvalue(LF_DYNARRAY *array, uint idx)
{
void * ptr, * volatile * ptr_ptr= 0;
int i;
for (i= LF_DYNARRAY_LEVELS-1; idx < dynarray_idxes_in_prev_levels[i]; i--)
/* no-op */;
ptr_ptr= &array->level[i];
idx-= dynarray_idxes_in_prev_levels[i];
for (; i > 0; i--)
{
if (!(ptr= *ptr_ptr))
{
void *alloc= my_malloc(LF_DYNARRAY_LEVEL_LENGTH * sizeof(void *),
MYF(MY_WME|MY_ZEROFILL));
if (unlikely(!alloc))
return(NULL);
if (my_atomic_casptr(ptr_ptr, &ptr, alloc))
ptr= alloc;
else
my_free(alloc, MYF(0));
}
ptr_ptr= ((void **)ptr) + idx / dynarray_idxes_in_prev_level[i];
idx%= dynarray_idxes_in_prev_level[i];
}
if (!(ptr= *ptr_ptr))
{
uchar *alloc, *data;
alloc= my_malloc(LF_DYNARRAY_LEVEL_LENGTH * array->size_of_element +
max(array->size_of_element, sizeof(void *)),
MYF(MY_WME|MY_ZEROFILL));
if (unlikely(!alloc))
return(NULL);
/* reserve the space for free() address */
data= alloc + sizeof(void *);
{ /* alignment */
intptr mod= ((intptr)data) % array->size_of_element;
if (mod)
data+= array->size_of_element - mod;
}
((void **)data)[-1]= alloc; /* free() will need the original pointer */
if (my_atomic_casptr(ptr_ptr, &ptr, data))
ptr= data;
else
my_free(alloc, MYF(0));
}
return ((uchar*)ptr) + array->size_of_element * idx;
}
/*
Returns a pointer to the element number 'idx'
or NULL if an element does not exists
*/
void *_lf_dynarray_value(LF_DYNARRAY *array, uint idx)
{
void * ptr, * volatile * ptr_ptr= 0;
int i;
for (i= LF_DYNARRAY_LEVELS-1; idx < dynarray_idxes_in_prev_levels[i]; i--)
/* no-op */;
ptr_ptr= &array->level[i];
idx-= dynarray_idxes_in_prev_levels[i];
for (; i > 0; i--)
{
if (!(ptr= *ptr_ptr))
return(NULL);
ptr_ptr= ((void **)ptr) + idx / dynarray_idxes_in_prev_level[i];
idx %= dynarray_idxes_in_prev_level[i];
}
if (!(ptr= *ptr_ptr))
return(NULL);
return ((uchar*)ptr) + array->size_of_element * idx;
}
static int recursive_iterate(LF_DYNARRAY *array, void *ptr, int level,
lf_dynarray_func func, void *arg)
{
int res, i;
if (!ptr)
return 0;
if (!level)
return func(ptr, arg);
for (i= 0; i < LF_DYNARRAY_LEVEL_LENGTH; i++)
if ((res= recursive_iterate(array, ((void **)ptr)[i], level-1, func, arg)))
return res;
return 0;
}
/*
Calls func(array, arg) on every array of LF_DYNARRAY_LEVEL_LENGTH elements
in lf_dynarray.
DESCRIPTION
lf_dynarray consists of a set of arrays, LF_DYNARRAY_LEVEL_LENGTH elements
each. _lf_dynarray_iterate() calls user-supplied function on every array
from the set. It is the fastest way to scan the array, faster than
for (i=0; i < N; i++) { func(_lf_dynarray_value(dynarray, i)); }
NOTE
if func() returns non-zero, the scan is aborted
*/
int _lf_dynarray_iterate(LF_DYNARRAY *array, lf_dynarray_func func, void *arg)
{
int i, res;
for (i= 0; i < LF_DYNARRAY_LEVELS; i++)
if ((res= recursive_iterate(array, array->level[i], i, func, arg)))
return res;
return 0;
}

505
mysys/lf_hash.c Normal file
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/* Copyright (C) 2006-2008 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
extensible hash
TODO
try to get rid of dummy nodes ?
for non-unique hash, count only _distinct_ values
(but how to do it in lf_hash_delete ?)
*/
#include <my_global.h>
#include <m_string.h>
#include <my_sys.h>
#include <my_bit.h>
#include <lf.h>
LF_REQUIRE_PINS(3)
/* An element of the list */
typedef struct {
intptr volatile link; /* a pointer to the next element in a listand a flag */
uint32 hashnr; /* reversed hash number, for sorting */
const uchar *key;
size_t keylen;
/*
data is stored here, directly after the keylen.
thus the pointer to data is (void*)(slist_element_ptr+1)
*/
} LF_SLIST;
const int LF_HASH_OVERHEAD= sizeof(LF_SLIST);
/*
a structure to pass the context (pointers two the three successive elements
in a list) from lfind to linsert/ldelete
*/
typedef struct {
intptr volatile *prev;
LF_SLIST *curr, *next;
} CURSOR;
/*
the last bit in LF_SLIST::link is a "deleted" flag.
the helper macros below convert it to a pure pointer or a pure flag
*/
#define PTR(V) (LF_SLIST *)((V) & (~(intptr)1))
#define DELETED(V) ((V) & 1)
/*
DESCRIPTION
Search for hashnr/key/keylen in the list starting from 'head' and
position the cursor. The list is ORDER BY hashnr, key
RETURN
0 - not found
1 - found
NOTE
cursor is positioned in either case
pins[0..2] are used, they are NOT removed on return
*/
static int lfind(LF_SLIST * volatile *head, CHARSET_INFO *cs, uint32 hashnr,
const uchar *key, uint keylen, CURSOR *cursor, LF_PINS *pins)
{
uint32 cur_hashnr;
const uchar *cur_key;
uint cur_keylen;
intptr link;
retry:
cursor->prev= (intptr *)head;
do { /* PTR() isn't necessary below, head is a dummy node */
cursor->curr= (LF_SLIST *)(*cursor->prev);
_lf_pin(pins, 1, cursor->curr);
} while (*cursor->prev != (intptr)cursor->curr && LF_BACKOFF);
for (;;)
{
if (unlikely(!cursor->curr))
return 0; /* end of the list */
do {
/* QQ: XXX or goto retry ? */
link= cursor->curr->link;
cursor->next= PTR(link);
_lf_pin(pins, 0, cursor->next);
} while (link != cursor->curr->link && LF_BACKOFF);
cur_hashnr= cursor->curr->hashnr;
cur_key= cursor->curr->key;
cur_keylen= cursor->curr->keylen;
if (*cursor->prev != (intptr)cursor->curr)
{
(void)LF_BACKOFF;
goto retry;
}
if (!DELETED(link))
{
if (cur_hashnr >= hashnr)
{
int r= 1;
if (cur_hashnr > hashnr ||
(r= my_strnncoll(cs, (uchar*) cur_key, cur_keylen, (uchar*) key,
keylen)) >= 0)
return !r;
}
cursor->prev= &(cursor->curr->link);
_lf_pin(pins, 2, cursor->curr);
}
else
{
/*
we found a deleted node - be nice, help the other thread
and remove this deleted node
*/
if (my_atomic_casptr((void **)cursor->prev,
(void **)&cursor->curr, cursor->next))
_lf_alloc_free(pins, cursor->curr);
else
{
(void)LF_BACKOFF;
goto retry;
}
}
cursor->curr= cursor->next;
_lf_pin(pins, 1, cursor->curr);
}
}
/*
DESCRIPTION
insert a 'node' in the list that starts from 'head' in the correct
position (as found by lfind)
RETURN
0 - inserted
not 0 - a pointer to a duplicate (not pinned and thus unusable)
NOTE
it uses pins[0..2], on return all pins are removed.
if there're nodes with the same key value, a new node is added before them.
*/
static LF_SLIST *linsert(LF_SLIST * volatile *head, CHARSET_INFO *cs,
LF_SLIST *node, LF_PINS *pins, uint flags)
{
CURSOR cursor;
int res;
for (;;)
{
if (lfind(head, cs, node->hashnr, node->key, node->keylen,
&cursor, pins) &&
(flags & LF_HASH_UNIQUE))
{
res= 0; /* duplicate found */
break;
}
else
{
node->link= (intptr)cursor.curr;
DBUG_ASSERT(node->link != (intptr)node); /* no circular references */
DBUG_ASSERT(cursor.prev != &node->link); /* no circular references */
if (my_atomic_casptr((void **)cursor.prev, (void **)&cursor.curr, node))
{
res= 1; /* inserted ok */
break;
}
}
}
_lf_unpin(pins, 0);
_lf_unpin(pins, 1);
_lf_unpin(pins, 2);
/*
Note that cursor.curr is not pinned here and the pointer is unreliable,
the object may dissapear anytime. But if it points to a dummy node, the
pointer is safe, because dummy nodes are never freed - initialize_bucket()
uses this fact.
*/
return res ? 0 : cursor.curr;
}
/*
DESCRIPTION
deletes a node as identified by hashnr/keey/keylen from the list
that starts from 'head'
RETURN
0 - ok
1 - not found
NOTE
it uses pins[0..2], on return all pins are removed.
*/
static int ldelete(LF_SLIST * volatile *head, CHARSET_INFO *cs, uint32 hashnr,
const uchar *key, uint keylen, LF_PINS *pins)
{
CURSOR cursor;
int res;
for (;;)
{
if (!lfind(head, cs, hashnr, key, keylen, &cursor, pins))
{
res= 1; /* not found */
break;
}
else
{
/* mark the node deleted */
if (my_atomic_casptr((void **)&(cursor.curr->link),
(void **)&cursor.next,
(void *)(((intptr)cursor.next) | 1)))
{
/* and remove it from the list */
if (my_atomic_casptr((void **)cursor.prev,
(void **)&cursor.curr, cursor.next))
_lf_alloc_free(pins, cursor.curr);
else
{
/*
somebody already "helped" us and removed the node ?
Let's check if we need to help that someone too!
(to ensure the number of "set DELETED flag" actions
is equal to the number of "remove from the list" actions)
*/
lfind(head, cs, hashnr, key, keylen, &cursor, pins);
}
res= 0;
break;
}
}
}
_lf_unpin(pins, 0);
_lf_unpin(pins, 1);
_lf_unpin(pins, 2);
return res;
}
/*
DESCRIPTION
searches for a node as identified by hashnr/keey/keylen in the list
that starts from 'head'
RETURN
0 - not found
node - found
NOTE
it uses pins[0..2], on return the pin[2] keeps the node found
all other pins are removed.
*/
static LF_SLIST *lsearch(LF_SLIST * volatile *head, CHARSET_INFO *cs,
uint32 hashnr, const uchar *key, uint keylen,
LF_PINS *pins)
{
CURSOR cursor;
int res= lfind(head, cs, hashnr, key, keylen, &cursor, pins);
if (res)
_lf_pin(pins, 2, cursor.curr);
_lf_unpin(pins, 0);
_lf_unpin(pins, 1);
return res ? cursor.curr : 0;
}
static inline const uchar* hash_key(const LF_HASH *hash,
const uchar *record, size_t *length)
{
if (hash->get_key)
return (*hash->get_key)(record, length, 0);
*length= hash->key_length;
return record + hash->key_offset;
}
/*
Compute the hash key value from the raw key.
@note, that the hash value is limited to 2^31, because we need one
bit to distinguish between normal and dummy nodes.
*/
static inline uint calc_hash(LF_HASH *hash, const uchar *key, uint keylen)
{
ulong nr1= 1, nr2= 4;
hash->charset->coll->hash_sort(hash->charset, (uchar*) key, keylen,
&nr1, &nr2);
return nr1 & INT_MAX32;
}
#define MAX_LOAD 1.0 /* average number of elements in a bucket */
static int initialize_bucket(LF_HASH *, LF_SLIST * volatile*, uint, LF_PINS *);
/*
Initializes lf_hash, the arguments are compatible with hash_init
@note element_size sets both the size of allocated memory block for
lf_alloc and a size of memcpy'ed block size in lf_hash_insert. Typically
they are the same, indeed. But LF_HASH::element_size can be decreased
after lf_hash_init, and then lf_alloc will allocate larger block that
lf_hash_insert will copy over. It is desireable if part of the element
is expensive to initialize - for example if there is a mutex or
DYNAMIC_ARRAY. In this case they should be initialize in the
LF_ALLOCATOR::constructor, and lf_hash_insert should not overwrite them.
See wt_init() for example.
*/
void lf_hash_init(LF_HASH *hash, uint element_size, uint flags,
uint key_offset, uint key_length, my_hash_get_key get_key,
CHARSET_INFO *charset)
{
lf_alloc_init(&hash->alloc, sizeof(LF_SLIST)+element_size,
offsetof(LF_SLIST, key));
lf_dynarray_init(&hash->array, sizeof(LF_SLIST *));
hash->size= 1;
hash->count= 0;
hash->element_size= element_size;
hash->flags= flags;
hash->charset= charset ? charset : &my_charset_bin;
hash->key_offset= key_offset;
hash->key_length= key_length;
hash->get_key= get_key;
DBUG_ASSERT(get_key ? !key_offset && !key_length : key_length);
}
void lf_hash_destroy(LF_HASH *hash)
{
LF_SLIST *el, **head= (LF_SLIST **)_lf_dynarray_value(&hash->array, 0);
if (unlikely(!head))
return;
el= *head;
while (el)
{
intptr next= el->link;
if (el->hashnr & 1)
lf_alloc_direct_free(&hash->alloc, el); /* normal node */
else
my_free((void *)el, MYF(0)); /* dummy node */
el= (LF_SLIST *)next;
}
lf_alloc_destroy(&hash->alloc);
lf_dynarray_destroy(&hash->array);
}
/*
DESCRIPTION
inserts a new element to a hash. it will have a _copy_ of
data, not a pointer to it.
RETURN
0 - inserted
1 - didn't (unique key conflict)
-1 - out of memory
NOTE
see linsert() for pin usage notes
*/
int lf_hash_insert(LF_HASH *hash, LF_PINS *pins, const void *data)
{
int csize, bucket, hashnr;
LF_SLIST *node, * volatile *el;
lf_rwlock_by_pins(pins);
node= (LF_SLIST *)_lf_alloc_new(pins);
if (unlikely(!node))
return -1;
memcpy(node+1, data, hash->element_size);
node->key= hash_key(hash, (uchar *)(node+1), &node->keylen);
hashnr= calc_hash(hash, node->key, node->keylen);
bucket= hashnr % hash->size;
el= _lf_dynarray_lvalue(&hash->array, bucket);
if (unlikely(!el))
return -1;
if (*el == NULL && unlikely(initialize_bucket(hash, el, bucket, pins)))
return -1;
node->hashnr= my_reverse_bits(hashnr) | 1; /* normal node */
if (linsert(el, hash->charset, node, pins, hash->flags))
{
_lf_alloc_free(pins, node);
lf_rwunlock_by_pins(pins);
return 1;
}
csize= hash->size;
if ((my_atomic_add32(&hash->count, 1)+1.0) / csize > MAX_LOAD)
my_atomic_cas32(&hash->size, &csize, csize*2);
lf_rwunlock_by_pins(pins);
return 0;
}
/*
DESCRIPTION
deletes an element with the given key from the hash (if a hash is
not unique and there're many elements with this key - the "first"
matching element is deleted)
RETURN
0 - deleted
1 - didn't (not found)
-1 - out of memory
NOTE
see ldelete() for pin usage notes
*/
int lf_hash_delete(LF_HASH *hash, LF_PINS *pins, const void *key, uint keylen)
{
LF_SLIST * volatile *el;
uint bucket, hashnr= calc_hash(hash, (uchar *)key, keylen);
bucket= hashnr % hash->size;
lf_rwlock_by_pins(pins);
el= _lf_dynarray_lvalue(&hash->array, bucket);
if (unlikely(!el))
return -1;
/*
note that we still need to initialize_bucket here,
we cannot return "node not found", because an old bucket of that
node may've been split and the node was assigned to a new bucket
that was never accessed before and thus is not initialized.
*/
if (*el == NULL && unlikely(initialize_bucket(hash, el, bucket, pins)))
return -1;
if (ldelete(el, hash->charset, my_reverse_bits(hashnr) | 1,
(uchar *)key, keylen, pins))
{
lf_rwunlock_by_pins(pins);
return 1;
}
my_atomic_add32(&hash->count, -1);
lf_rwunlock_by_pins(pins);
return 0;
}
/*
RETURN
a pointer to an element with the given key (if a hash is not unique and
there're many elements with this key - the "first" matching element)
NULL if nothing is found
MY_ERRPTR if OOM
NOTE
see lsearch() for pin usage notes
*/
void *lf_hash_search(LF_HASH *hash, LF_PINS *pins, const void *key, uint keylen)
{
LF_SLIST * volatile *el, *found;
uint bucket, hashnr= calc_hash(hash, (uchar *)key, keylen);
bucket= hashnr % hash->size;
lf_rwlock_by_pins(pins);
el= _lf_dynarray_lvalue(&hash->array, bucket);
if (unlikely(!el))
return MY_ERRPTR;
if (*el == NULL && unlikely(initialize_bucket(hash, el, bucket, pins)))
return MY_ERRPTR;
found= lsearch(el, hash->charset, my_reverse_bits(hashnr) | 1,
(uchar *)key, keylen, pins);
lf_rwunlock_by_pins(pins);
return found ? found+1 : 0;
}
static const uchar *dummy_key= (uchar*)"";
/*
RETURN
0 - ok
-1 - out of memory
*/
static int initialize_bucket(LF_HASH *hash, LF_SLIST * volatile *node,
uint bucket, LF_PINS *pins)
{
uint parent= my_clear_highest_bit(bucket);
LF_SLIST *dummy= (LF_SLIST *)my_malloc(sizeof(LF_SLIST), MYF(MY_WME));
LF_SLIST **tmp= 0, *cur;
LF_SLIST * volatile *el= _lf_dynarray_lvalue(&hash->array, parent);
if (unlikely(!el || !dummy))
return -1;
if (*el == NULL && bucket &&
unlikely(initialize_bucket(hash, el, parent, pins)))
return -1;
dummy->hashnr= my_reverse_bits(bucket) | 0; /* dummy node */
dummy->key= dummy_key;
dummy->keylen= 0;
if ((cur= linsert(el, hash->charset, dummy, pins, LF_HASH_UNIQUE)))
{
my_free((void *)dummy, MYF(0));
dummy= cur;
}
my_atomic_casptr((void **)node, (void **)&tmp, dummy);
/*
note that if the CAS above failed (after linsert() succeeded),
it would mean that some other thread has executed linsert() for
the same dummy node, its linsert() failed, it picked up our
dummy node (in "dummy= cur") and executed the same CAS as above.
Which means that even if CAS above failed we don't need to retry,
and we should not free(dummy) - there's no memory leak here
*/
return 0;
}

3
mysys/my_thr_init.c
View File

@ -284,6 +284,9 @@ my_bool my_thread_init(void)
pthread_cond_init(&tmp->suspend, NULL);
tmp->init= 1;
tmp->stack_ends_here= (char*)&tmp +
STACK_DIRECTION * (long)my_thread_stack_size;
pthread_mutex_lock(&THR_LOCK_threads);
tmp->id= ++thread_id;
++THR_thread_count;

2
unittest/mysys/Makefile.am
View File

@ -23,7 +23,7 @@ LDADD = $(top_builddir)/unittest/mytap/libmytap.a \
$(top_builddir)/dbug/libdbug.a \
$(top_builddir)/strings/libmystrings.a
noinst_PROGRAMS = bitmap-t base64-t my_vsnprintf-t
noinst_PROGRAMS = bitmap-t base64-t lf-t my_vsnprintf-t
if NEED_THREAD
# my_atomic-t is used to check thread functions, so it is safe to

178
unittest/mysys/lf-t.c Normal file
View File

@ -0,0 +1,178 @@
/* Copyright (C) 2008-2008 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/**
@file
Unit tests for lock-free algorithms of mysys
*/
#include "thr_template.c"
#include <lf.h>
int32 inserts= 0, N;
LF_ALLOCATOR lf_allocator;
LF_HASH lf_hash;
/*
pin allocator - alloc and release an element in a loop
*/
pthread_handler_t test_lf_pinbox(void *arg)
{
int m= *(int *)arg;
int32 x= 0;
LF_PINS *pins;
my_thread_init();
pins= lf_pinbox_get_pins(&lf_allocator.pinbox);
for (x= ((int)(intptr)(&m)); m ; m--)
{
lf_pinbox_put_pins(pins);
pins= lf_pinbox_get_pins(&lf_allocator.pinbox);
}
lf_pinbox_put_pins(pins);
pthread_mutex_lock(&mutex);
if (!--running_threads) pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
my_thread_end();
return 0;
}
/*
thread local data area, allocated using lf_alloc.
union is required to enforce the minimum required element size (sizeof(ptr))
*/
typedef union {
int32 data;
void *not_used;
} TLA;
pthread_handler_t test_lf_alloc(void *arg)
{
int m= (*(int *)arg)/2;
int32 x,y= 0;
LF_PINS *pins;
my_thread_init();
pins= lf_alloc_get_pins(&lf_allocator);
for (x= ((int)(intptr)(&m)); m ; m--)
{
TLA *node1, *node2;
x= (x*m+0x87654321) & INT_MAX32;
node1= (TLA *)lf_alloc_new(pins);
node1->data= x;
y+= node1->data;
node1->data= 0;
node2= (TLA *)lf_alloc_new(pins);
node2->data= x;
y-= node2->data;
node2->data= 0;
lf_alloc_free(pins, node1);
lf_alloc_free(pins, node2);
}
lf_alloc_put_pins(pins);
pthread_mutex_lock(&mutex);
bad+= y;
if (--N == 0)
{
diag("%d mallocs, %d pins in stack",
lf_allocator.mallocs, lf_allocator.pinbox.pins_in_array);
#ifdef MY_LF_EXTRA_DEBUG
bad|= lf_allocator.mallocs - lf_alloc_pool_count(&lf_allocator);
#endif
}
if (!--running_threads) pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
my_thread_end();
return 0;
}
#define N_TLH 1000
pthread_handler_t test_lf_hash(void *arg)
{
int m= (*(int *)arg)/(2*N_TLH);
int32 x,y,z,sum= 0, ins= 0;
LF_PINS *pins;
my_thread_init();
pins= lf_hash_get_pins(&lf_hash);
for (x= ((int)(intptr)(&m)); m ; m--)
{
int i;
y= x;
for (i= 0; i < N_TLH; i++)
{
x= (x*(m+i)+0x87654321) & INT_MAX32;
z= (x<0) ? -x : x;
if (lf_hash_insert(&lf_hash, pins, &z))
{
sum+= z;
ins++;
}
}
for (i= 0; i < N_TLH; i++)
{
y= (y*(m+i)+0x87654321) & INT_MAX32;
z= (y<0) ? -y : y;
if (lf_hash_delete(&lf_hash, pins, (uchar *)&z, sizeof(z)))
sum-= z;
}
}
lf_hash_put_pins(pins);
pthread_mutex_lock(&mutex);
bad+= sum;
inserts+= ins;
if (--N == 0)
{
diag("%d mallocs, %d pins in stack, %d hash size, %d inserts",
lf_hash.alloc.mallocs, lf_hash.alloc.pinbox.pins_in_array,
lf_hash.size, inserts);
bad|= lf_hash.count;
}
if (!--running_threads) pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
my_thread_end();
return 0;
}
void do_tests()
{
plan(4);
lf_alloc_init(&lf_allocator, sizeof(TLA), offsetof(TLA, not_used));
lf_hash_init(&lf_hash, sizeof(int), LF_HASH_UNIQUE, 0, sizeof(int), 0,
&my_charset_bin);
bad= my_atomic_initialize();
ok(!bad, "my_atomic_initialize() returned %d", bad);
test_concurrently("lf_pinbox", test_lf_pinbox, N= THREADS, CYCLES);
test_concurrently("lf_alloc", test_lf_alloc, N= THREADS, CYCLES);
test_concurrently("lf_hash", test_lf_hash, N= THREADS, CYCLES/10);
lf_hash_destroy(&lf_hash);
lf_alloc_destroy(&lf_allocator);
}