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haproxy/include/haproxy/stick_table.h
Christopher Faulet ad946a704d MINOR: stick-table: Always decrement ref count before killing a session 
Guarded functions to kill a sticky session, stksess_kill()
stksess_kill_if_expired(), may or may not decrement and test its reference
counter before really killing it. This depends on a parameter. If it is set
to non-zero value, the ref count is decremented and if it falls to zero, the
session is killed. Otherwise, if this parameter is equal to zero, the
session is killed, regardless the ref count value.

In the code, these functions are always called with a non-zero parameter and
the ref count is always decremented and tested. So, there is no reason to
still have a special case. Especially because it is not really easy to say
if it is supported or not. Does it mean it is possible to kill a sticky
session while it is still referenced somewhere ? probably not. So, does it
mean it is possible to kill a unreferenced session ? This case may be
problematic because the session is accessed outside of any lock and thus may
be released by another thread because it is unreferenced. Enlarging scope of
the lock to avoid any issue is possible but it is a bit of shame to do so
because there is no usage for now.

The best is to simplify the API and remove this case. Now, stksess_kill()
and stksess_kill_if_expired() functions always decrement and test the ref
count before killing a sticky session.
2024-06-26 15:05:06 +02:00

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/*
* include/haproxy/stick_table.h
* Functions for stick tables management.
*
* Copyright (C) 2009-2010 EXCELIANCE, Emeric Brun <ebrun@exceliance.fr>
* Copyright (C) 2010 Willy Tarreau <w@1wt.eu>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _HAPROXY_STICK_TABLE_H
#define _HAPROXY_STICK_TABLE_H
#include <haproxy/api.h>
#include <haproxy/dict-t.h>
#include <haproxy/errors.h>
#include <haproxy/freq_ctr.h>
#include <haproxy/sample-t.h>
#include <haproxy/stick_table-t.h>
#include <haproxy/thread.h>
#include <haproxy/ticks.h>
#include <haproxy/xxhash.h>
extern struct stktable *stktables_list;
extern struct pool_head *pool_head_stk_ctr;
extern struct stktable_type stktable_types[];
#define stktable_data_size(type) (sizeof(((union stktable_data*)0)->type))
#define stktable_data_cast(ptr, type) ((union stktable_data*)(ptr))->type
void stktable_store_name(struct stktable *t);
struct stktable *stktable_find_by_name(const char *name);
struct stksess *stksess_new(struct stktable *t, struct stktable_key *key);
void stksess_setkey(struct stktable *t, struct stksess *ts, struct stktable_key *key);
void stksess_free(struct stktable *t, struct stksess *ts);
int stksess_kill(struct stktable *t, struct stksess *ts);
int stktable_get_key_shard(struct stktable *t, const void *key, size_t len);
int stktable_init(struct stktable *t, char **err_msg);
void stktable_deinit(struct stktable *t);
int stktable_parse_type(char **args, int *idx, unsigned long *type, size_t *key_size, const char *file, int linenum);
int parse_stick_table(const char *file, int linenum, char **args,
struct stktable *t, char *id, char *nid, struct peers *peers);
struct stksess *stktable_get_entry(struct stktable *table, struct stktable_key *key);
struct stksess *stktable_set_entry(struct stktable *table, struct stksess *nts);
void stktable_requeue_exp(struct stktable *t, const struct stksess *ts);
void stktable_touch_with_exp(struct stktable *t, struct stksess *ts, int decrefcount, int expire, int decrefcnt);
void stktable_touch_remote(struct stktable *t, struct stksess *ts, int decrefcnt);
void stktable_touch_local(struct stktable *t, struct stksess *ts, int decrefccount);
struct stksess *stktable_lookup(struct stktable *t, struct stksess *ts);
struct stksess *stktable_lookup_key(struct stktable *t, struct stktable_key *key);
struct stksess *stktable_update_key(struct stktable *table, struct stktable_key *key);
struct stktable_key *smp_to_stkey(struct sample *smp, struct stktable *t);
struct stktable_key *stktable_fetch_key(struct stktable *t, struct proxy *px, struct session *sess,
struct stream *strm, unsigned int opt,
struct sample_expr *expr, struct sample *smp);
struct stkctr *smp_fetch_sc_stkctr(struct session *sess, struct stream *strm, const struct arg *args, const char *kw, struct stkctr *stkctr);
struct stkctr *smp_create_src_stkctr(struct session *sess, struct stream *strm, const struct arg *args, const char *kw, struct stkctr *stkctr);
int stktable_compatible_sample(struct sample_expr *expr, unsigned long table_type);
int stktable_register_data_store(int idx, const char *name, int std_type, int arg_type);
int stktable_get_data_type(char *name);
int stktable_trash_oldest(struct stktable *t, int to_batch);
int __stksess_kill(struct stktable *t, struct stksess *ts);
/************************* Composite address manipulation *********************
* Composite addresses are simply unsigned long data in which the higher bits
* represent a pointer, and the two lower bits are flags. There are several
* places where we just want to associate one or two flags to a pointer (eg,
* to type it), and these functions permit this. The pointer is necessarily a
* 32-bit aligned pointer, as its two lower bits will be cleared and replaced
* with the flags.
*****************************************************************************/
/* Masks the two lower bits of a composite address and converts it to a
* pointer. This is used to mix some bits with some aligned pointers to
* structs and to retrieve the original (32-bit aligned) pointer.
*/
static inline void *caddr_to_ptr(unsigned long caddr)
{
return (void *)(caddr & ~3UL);
}
/* Only retrieves the two lower bits of a composite address. This is used to mix
* some bits with some aligned pointers to structs and to retrieve the original
* data (2 bits).
*/
static inline unsigned int caddr_to_data(unsigned long caddr)
{
return (caddr & 3UL);
}
/* Combines the aligned pointer whose 2 lower bits will be masked with the bits
* from <data> to form a composite address. This is used to mix some bits with
* some aligned pointers to structs and to retrieve the original (32-bit aligned)
* pointer.
*/
static inline unsigned long caddr_from_ptr(void *ptr, unsigned int data)
{
return (((unsigned long)ptr) & ~3UL) + (data & 3);
}
/* sets the 2 bits of <data> in the <caddr> composite address */
static inline unsigned long caddr_set_flags(unsigned long caddr, unsigned int data)
{
return caddr | (data & 3);
}
/* clears the 2 bits of <data> in the <caddr> composite address */
static inline unsigned long caddr_clr_flags(unsigned long caddr, unsigned int data)
{
return caddr & ~(unsigned long)(data & 3);
}
/* return allocation size for standard data type <type> */
static inline int stktable_type_size(int type)
{
switch(type) {
case STD_T_SINT:
case STD_T_UINT:
return sizeof(int);
case STD_T_ULL:
return sizeof(unsigned long long);
case STD_T_FRQP:
return sizeof(struct freq_ctr);
case STD_T_DICT:
return sizeof(struct dict_entry *);
}
return 0;
}
int stktable_alloc_data_type(struct stktable *t, int type, const char *sa, const char *sa2);
/* return pointer for data type <type> in sticky session <ts> of table <t>, all
* of which must exist (otherwise use stktable_data_ptr() if unsure).
*/
static inline void *__stktable_data_ptr(struct stktable *t, struct stksess *ts, int type)
{
return (void *)ts + t->data_ofs[type];
}
/* return pointer for data type <type> in sticky session <ts> of table <t>, or
* NULL if either <ts> is NULL or the type is not stored.
*/
static inline void *stktable_data_ptr(struct stktable *t, struct stksess *ts, int type)
{
if (type >= STKTABLE_DATA_TYPES)
return NULL;
if (!t->data_ofs[type]) /* type not stored */
return NULL;
if (!ts)
return NULL;
return __stktable_data_ptr(t, ts, type);
}
/* return pointer on the element of index <idx> from the array data type <type>
* in sticky session <ts> of table <t>, or NULL if either <ts> is NULL
* or this element is not stored because this type is not stored or
* requested index is greater than the number of elements of the array.
* Note: this function is also usable on non array types, they are
* considered as array of size 1, so a call with <idx> at 0
* as the same behavior than 'stktable_data_ptr'.
*/
static inline void *stktable_data_ptr_idx(struct stktable *t, struct stksess *ts, int type, unsigned int idx)
{
if (type >= STKTABLE_DATA_TYPES)
return NULL;
if (!t->data_ofs[type]) /* type not stored */
return NULL;
if (!ts)
return NULL;
if (t->data_nbelem[type] <= idx)
return NULL;
return __stktable_data_ptr(t, ts, type) + idx*stktable_type_size(stktable_data_types[type].std_type);
}
/* return a shard number for key <key> of len <len> present in table <t>, for
* use with the tree indexing. The value will be from 0 to
* CONFIG_HAP_TBL_BUCKETS-1.
*/
static inline uint stktable_calc_shard_num(const struct stktable *t, const void *key, size_t len)
{
#if CONFIG_HAP_TBL_BUCKETS > 1
return XXH32(key, len, t->hash_seed) % CONFIG_HAP_TBL_BUCKETS;
#else
return 0;
#endif
}
/* kill an entry if it's expired and its ref_cnt is zero */
static inline int __stksess_kill_if_expired(struct stktable *t, struct stksess *ts)
{
if (t->expire != TICK_ETERNITY && tick_is_expired(ts->expire, now_ms))
return __stksess_kill(t, ts);
return 0;
}
/*
* Decrease the refcount of a stksess and relase it if the refcount falls to 0
* _AND_ if the session expired. Note,, the refcount is always decremented.
*
* This function locks the corresponding table shard to proceed. When this
* function is called, the caller must be sure it owns a reference on the
* stksess (refcount >= 1).
*/
static inline void stksess_kill_if_expired(struct stktable *t, struct stksess *ts)
{
uint shard;
size_t len;
if (t->expire != TICK_ETERNITY && tick_is_expired(ts->expire, now_ms)) {
if (t->type == SMP_T_STR)
len = strlen((const char *)ts->key.key);
else
len = t->key_size;
shard = stktable_calc_shard_num(t, ts->key.key, len);
/* make the compiler happy when shard is not used without threads */
ALREADY_CHECKED(shard);
HA_RWLOCK_WRLOCK(STK_TABLE_LOCK, &t->shards[shard].sh_lock);
if (!HA_ATOMIC_SUB_FETCH(&ts->ref_cnt, 1))
__stksess_kill_if_expired(t, ts);
HA_RWLOCK_WRUNLOCK(STK_TABLE_LOCK, &t->shards[shard].sh_lock);
}
else
HA_ATOMIC_SUB_FETCH(&ts->ref_cnt, 1);
}
/* sets the stick counter's entry pointer */
static inline void stkctr_set_entry(struct stkctr *stkctr, struct stksess *entry)
{
stkctr->entry = caddr_from_ptr(entry, 0);
}
/* returns the entry pointer from a stick counter */
static inline struct stksess *stkctr_entry(struct stkctr *stkctr)
{
return caddr_to_ptr(stkctr->entry);
}
/* returns the two flags from a stick counter */
static inline unsigned int stkctr_flags(struct stkctr *stkctr)
{
return caddr_to_data(stkctr->entry);
}
/* sets up to two flags at a time on a composite address */
static inline void stkctr_set_flags(struct stkctr *stkctr, unsigned int flags)
{
stkctr->entry = caddr_set_flags(stkctr->entry, flags);
}
/* returns the two flags from a stick counter */
static inline void stkctr_clr_flags(struct stkctr *stkctr, unsigned int flags)
{
stkctr->entry = caddr_clr_flags(stkctr->entry, flags);
}
/* Increase the number of cumulated HTTP requests in the tracked counter
* <stkctr>. It returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_inc_http_req_ctr(struct stkctr *stkctr)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_REQ_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_uint)++;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_REQ_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_HTTP_REQ_RATE].u, 1);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
/* Increase the number of cumulated failed HTTP requests in the tracked counter
* <stkctr>. It returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_inc_http_err_ctr(struct stkctr *stkctr)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_ERR_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_uint)++;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_ERR_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_HTTP_ERR_RATE].u, 1);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
/* Increase the number of cumulated failed HTTP responses in the tracked counter
* <stkctr>. It returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_inc_http_fail_ctr(struct stkctr *stkctr)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_FAIL_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_uint)++;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_HTTP_FAIL_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_HTTP_FAIL_RATE].u, 1);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
/* Increase the number of bytes received in the tracked counter <stkctr>. It
* returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_inc_bytes_in_ctr(struct stkctr *stkctr, unsigned long long bytes)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_BYTES_IN_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_ull) += bytes;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_BYTES_IN_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_BYTES_IN_RATE].u, bytes);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
/* Increase the number of bytes sent in the tracked counter <stkctr>. It
* returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_inc_bytes_out_ctr(struct stkctr *stkctr, unsigned long long bytes)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_BYTES_OUT_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_ull) += bytes;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_BYTES_OUT_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_BYTES_OUT_RATE].u, bytes);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
/* Add <inc> to the number of cumulated front glitches in the tracked counter
* <stkctr>. It returns 0 if the entry pointer does not exist and nothing is
* performed. Otherwise it returns 1.
*/
static inline int stkctr_add_glitch_ctr(struct stkctr *stkctr, uint inc)
{
struct stksess *ts;
void *ptr1, *ptr2;
ts = stkctr_entry(stkctr);
if (!ts)
return 0;
HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
ptr1 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_GLITCH_CNT);
if (ptr1)
stktable_data_cast(ptr1, std_t_uint) += inc;
ptr2 = stktable_data_ptr(stkctr->table, ts, STKTABLE_DT_GLITCH_RATE);
if (ptr2)
update_freq_ctr_period(&stktable_data_cast(ptr2, std_t_frqp),
stkctr->table->data_arg[STKTABLE_DT_GLITCH_RATE].u, inc);
HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
/* If data was modified, we need to touch to re-schedule sync */
if (ptr1 || ptr2)
stktable_touch_local(stkctr->table, ts, 0);
return 1;
}
#endif /* _HAPROXY_STICK_TABLE_H */
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