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haproxy/include/haproxy/thread.h
Amaury Denoyelle 3891456d20 MINOR: thread: define cshared type 
Define a new type "struct cshared". This can be used as a tool to
manipulate a global counter with thread-safety ensured. Each thread
would declare its thread-local cshared type, which would point to a
global counter.

Each thread can then add/substract value to their owned thread-local
cshared instance via cshared_add(). If the difference exceed a
configured limit, either positively or negatively, the global counter is
updated and thread-local instance is reset to 0. Each thread can safely
read the global counter value using cshared_read().
2025-04-29 15:10:06 +02:00

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/*
* include/haproxy/thread.h
* definitions, macros and inline functions used by threads.
*
* Copyright (C) 2017 Christopher Faulet - cfaulet@haproxy.com
* Copyright (C) 2020 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_THREAD_H
#define _HAPROXY_THREAD_H
#include <haproxy/api.h>
#include <haproxy/thread-t.h>
#include <haproxy/tinfo.h>
/* Note: this file mainly contains 5 sections:
* - a small common part, which also corresponds to the common API
* - one used solely when USE_THREAD is *not* set
* - one used solely when USE_THREAD is set
* - one used solely when USE_THREAD is set WITHOUT debugging
* - one used solely when USE_THREAD is set WITH debugging
*
*/
/* Generic exports */
int parse_nbthread(const char *arg, char **err);
void ha_tkill(unsigned int thr, int sig);
void ha_tkillall(int sig);
void ha_thread_relax(void);
int thread_detect_binding_discrepancies(void);
int thread_detect_more_than_cpus(void);
int thread_map_to_groups();
int thread_resolve_group_mask(struct thread_set *ts, int defgrp, char **err);
void thread_detect_count(void);
int parse_thread_set(const char *arg, struct thread_set *ts, char **err);
const char *lock_label(enum lock_label label);
extern int thread_cpus_enabled_at_boot;
#ifndef USE_THREAD
/********************** THREADS DISABLED ************************/
/* Only way found to replace variables with constants that are optimized away
* at build time.
*/
enum { all_tgroups_mask = 1UL };
enum { tid_bit = 1UL };
enum { tid = 0 };
enum { tgid = 1 };
#define HA_SPIN_INIT(l) do { /* do nothing */ } while(0)
#define HA_SPIN_DESTROY(l) do { /* do nothing */ } while(0)
#define HA_SPIN_LOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_SPIN_TRYLOCK(lbl, l) ({ 0; })
#define HA_SPIN_UNLOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_INIT(l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_DESTROY(l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_WRLOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_TRYWRLOCK(lbl, l) ({ 0; })
#define HA_RWLOCK_WRUNLOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_RDLOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_TRYRDLOCK(lbl, l) ({ 0; })
#define HA_RWLOCK_RDUNLOCK(lbl, l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_SKLOCK(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_SKTOWR(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_WRTOSK(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_SKTORD(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_WRTORD(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_SKUNLOCK(lbl,l) do { /* do nothing */ } while(0)
#define HA_RWLOCK_TRYSKLOCK(lbl,l) ({ 0; })
#define HA_RWLOCK_TRYRDTOSK(lbl,l) ({ 0; })
#define HA_RWLOCK_TRYRDTOWR(lbl,l) ({ 0; })
#define ha_sigmask(how, set, oldset) sigprocmask(how, set, oldset)
/* Sets the current thread to a valid one described by <thr>, or to any thread
* and any group if NULL (e.g. for use during boot where they're not totally
* initialized).
*/
static inline void ha_set_thread(const struct thread_info *thr)
{
if (thr) {
ti = thr;
tg = ti->tg;
th_ctx = &ha_thread_ctx[ti->tid];
} else {
ti = &ha_thread_info[0];
tg = &ha_tgroup_info[0];
th_ctx = &ha_thread_ctx[0];
}
}
static inline void thread_idle_now()
{
tg_ctx->threads_idle |= ti->ltid_bit;
}
static inline void thread_idle_end()
{
tg_ctx->threads_idle &= ~ti->ltid_bit;
}
static inline void thread_harmless_now()
{
tg_ctx->threads_harmless |= ti->ltid_bit;
}
static inline int is_thread_harmless()
{
return !!(tg_ctx->threads_harmless & ti->ltid_bit);
}
static inline void thread_harmless_end()
{
tg_ctx->threads_harmless &= ~ti->ltid_bit;
}
static inline void thread_harmless_end_sig()
{
tg_ctx->threads_harmless &= ~ti->ltid_bit;
}
static inline void thread_isolate()
{
}
static inline void thread_isolate_full()
{
}
static inline void thread_release()
{
}
static inline unsigned long thread_isolated()
{
return 1;
}
static inline void setup_extra_threads(void *(*handler)(void *))
{
}
static inline void wait_for_threads_completion()
{
}
static inline void set_thread_cpu_affinity()
{
}
static inline unsigned long long ha_get_pthread_id(unsigned int thr)
{
return 0;
}
static inline void cshared_init(struct cshared *ctr, uint64_t *var, int lim)
{
ctr->global = var;
ctr->diff = 0;
ctr->lim = 0;
}
static inline void cshared_add(struct cshared *ctr, int diff)
{
ctr->global += diff;
}
static inline uint64_t cshared_read(struct cshared *ctr)
{
return *ctr->global;
}
#else /* !USE_THREAD */
/********************** THREADS ENABLED ************************/
#define PLOCK_LORW_INLINE_WAIT
#include <import/plock.h>
void thread_harmless_till_end(void);
void thread_isolate(void);
void thread_isolate_full(void);
void thread_release(void);
void ha_spin_init(HA_SPINLOCK_T *l);
void ha_rwlock_init(HA_RWLOCK_T *l);
void setup_extra_threads(void *(*handler)(void *));
void wait_for_threads_completion();
void set_thread_cpu_affinity();
unsigned long long ha_get_pthread_id(unsigned int thr);
extern volatile unsigned long all_tgroups_mask;
extern volatile unsigned int rdv_requests;
extern volatile unsigned int isolated_thread;
extern THREAD_LOCAL unsigned int tid; /* The thread id */
extern THREAD_LOCAL unsigned int tgid; /* The thread group id (starts at 1) */
#define ha_sigmask(how, set, oldset) pthread_sigmask(how, set, oldset)
/* Sets the current thread to a valid one described by <thr>, or to any thread
* and any group if NULL (e.g. for use during boot where they're not totally
* initialized).
*/
static inline void ha_set_thread(const struct thread_info *thr)
{
if (thr) {
BUG_ON(!thr->ltid_bit);
BUG_ON(!thr->tg);
BUG_ON(!thr->tgid);
ti = thr;
tg = thr->tg;
tid = thr->tid;
tgid = thr->tgid;
th_ctx = &ha_thread_ctx[tid];
tg_ctx = &ha_tgroup_ctx[tgid-1];
} else {
tgid = 1;
tid = 0;
ti = &ha_thread_info[0];
tg = &ha_tgroup_info[0];
th_ctx = &ha_thread_ctx[0];
tg_ctx = &ha_tgroup_ctx[0];
}
}
/* Marks the thread as idle, which means that not only it's not doing anything
* dangerous, but in addition it has not started anything sensitive either.
* This essentially means that the thread currently is in the poller, thus
* outside of any execution block. Needs to be terminated using
* thread_idle_end(). This is needed to release a concurrent call to
* thread_isolate_full().
*/
static inline void thread_idle_now()
{
HA_ATOMIC_OR(&tg_ctx->threads_idle, ti->ltid_bit);
}
/* Ends the harmless period started by thread_idle_now(), i.e. the thread is
* about to restart engaging in sensitive operations. This must not be done on
* a thread marked harmless, as it could cause a deadlock between another
* thread waiting for idle again and thread_harmless_end() in this thread.
*
* The right sequence is thus:
* thread_idle_now();
* thread_harmless_now();
* poll();
* thread_harmless_end();
* thread_idle_end();
*/
static inline void thread_idle_end()
{
HA_ATOMIC_AND(&tg_ctx->threads_idle, ~ti->ltid_bit);
}
/* Marks the thread as harmless. Note: this must be true, i.e. the thread must
* not be touching any unprotected shared resource during this period. Usually
* this is called before poll(), but it may also be placed around very slow
* calls (eg: some crypto operations). Needs to be terminated using
* thread_harmless_end().
*/
static inline void thread_harmless_now()
{
HA_ATOMIC_OR(&tg_ctx->threads_harmless, ti->ltid_bit);
}
/* Returns non-zero if the current thread is already harmless */
static inline int is_thread_harmless()
{
return !!(HA_ATOMIC_LOAD(&tg_ctx->threads_harmless) & ti->ltid_bit);
}
/* Ends the harmless period started by thread_harmless_now(). Usually this is
* placed after the poll() call. If it is discovered that a job was running and
* is relying on the thread still being harmless, the thread waits for the
* other one to finish.
*/
static inline void thread_harmless_end()
{
while (1) {
HA_ATOMIC_AND(&tg_ctx->threads_harmless, ~ti->ltid_bit);
if (likely(_HA_ATOMIC_LOAD(&rdv_requests) == 0))
break;
thread_harmless_till_end();
}
}
/* Ends the harmless period started by thread_harmless_now(), but without
* waiting for isolated requests. This is meant to be used from signal handlers
* which might be called recursively while a thread already requested an
* isolation that must be ignored. It must not be used past a checkpoint where
* another thread could return and see the current thread as harmless before
* this call (or this could validate an isolation request by accident).
*/
static inline void thread_harmless_end_sig()
{
HA_ATOMIC_AND(&tg_ctx->threads_harmless, ~ti->ltid_bit);
}
/* an isolated thread has its ID in isolated_thread */
static inline unsigned long thread_isolated()
{
return _HA_ATOMIC_LOAD(&isolated_thread) == tid;
}
/* locking levels, for history and debugging */
#define _LK_UN 0
#define _LK_RD 1
#define _LK_SK 2
#define _LK_WR 3
#if (DEBUG_THREAD < 1) && !defined(DEBUG_FULL)
#define _lock_wait(_LK_, lbl, expr) do { (void)(expr); } while (0)
#define _lock_cond(_LK_, lbl, expr) ({ typeof(expr) _expr = (expr); _expr; })
#else
#define _lock_wait(_LK_, lbl, expr) do { \
(void)(expr); \
th_ctx->lock_history = (th_ctx->lock_history << 8) + ((lbl + 1) << 2) + _LK_; \
} while (0)
#define _lock_cond(_LK_, lbl, expr) ({ \
typeof(expr) _expr = (expr); \
if (!_expr) \
th_ctx->lock_history = (th_ctx->lock_history << 8) + ((lbl + 1) << 2) + _LK_; \
_expr; \
})
#endif
/* Init a shared counter <ctr> which references global value <var>. Update are
* performed each time the shared counter exceed <lim>, either on the positive
* or negative value.
*/
static inline void cshared_init(struct cshared *ctr, uint64_t *var, int lim)
{
ctr->global = var;
ctr->diff = 0;
ctr->lim = lim;
}
/* Add <diff>, which may be positive or negative, to <ctr> shared counter. */
static inline void cshared_add(struct cshared *ctr, int diff)
{
ctr->diff += diff;
if (ctr->diff <= -(ctr->lim) || ctr->diff >= ctr->lim) {
HA_ATOMIC_ADD(ctr->global, ctr->diff);
ctr->diff = 0;
}
}
/* Atomically get current global value from <ctr> shared counter. */
static inline uint64_t cshared_read(struct cshared *ctr)
{
return HA_ATOMIC_LOAD(ctr->global);
}
#if (DEBUG_THREAD < 2) && !defined(DEBUG_FULL)
/* Thread debugging is DISABLED, these are the regular locking functions */
#define HA_SPIN_INIT(l) ({ (*l) = 0; })
#define HA_SPIN_DESTROY(l) ({ (*l) = 0; })
#define HA_SPIN_LOCK(lbl, l) _lock_wait(_LK_SK, lbl, pl_take_s(l))
#define HA_SPIN_TRYLOCK(lbl, l) _lock_cond(_LK_SK, lbl, !pl_try_s(l))
#define HA_SPIN_UNLOCK(lbl, l) _lock_wait(_LK_UN, lbl, pl_drop_s(l))
#define HA_RWLOCK_INIT(l) ({ (*l) = 0; })
#define HA_RWLOCK_DESTROY(l) ({ (*l) = 0; })
#define HA_RWLOCK_WRLOCK(lbl,l) _lock_wait(_LK_WR, lbl, pl_take_w(l))
#define HA_RWLOCK_TRYWRLOCK(lbl,l) _lock_cond(_LK_WR, lbl, !pl_try_w(l))
#define HA_RWLOCK_WRUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_w(l))
#define HA_RWLOCK_RDLOCK(lbl,l) _lock_wait(_LK_RD, lbl, pl_take_r(l))
#define HA_RWLOCK_TRYRDLOCK(lbl,l) _lock_cond(_LK_RD, lbl, (!pl_try_r(l)))
#define HA_RWLOCK_RDUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_r(l))
/* rwlock upgrades via seek locks */
#define HA_RWLOCK_SKLOCK(lbl,l) _lock_wait(_LK_SK, lbl, pl_take_s(l)) /* N --> S */
#define HA_RWLOCK_SKTOWR(lbl,l) _lock_wait(_LK_WR, lbl, pl_stow(l)) /* S --> W */
#define HA_RWLOCK_WRTOSK(lbl,l) _lock_wait(_LK_SK, lbl, pl_wtos(l)) /* W --> S */
#define HA_RWLOCK_SKTORD(lbl,l) _lock_wait(_LK_RD, lbl, pl_stor(l)) /* S --> R */
#define HA_RWLOCK_WRTORD(lbl,l) _lock_wait(_LK_RD, lbl, pl_wtor(l)) /* W --> R */
#define HA_RWLOCK_SKUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, pl_drop_s(l)) /* S --> N */
#define HA_RWLOCK_TRYSKLOCK(lbl,l) _lock_cond(_LK_SK, lbl, !pl_try_s(l)) /* N -?> S */
#define HA_RWLOCK_TRYRDTOSK(lbl,l) _lock_cond(_LK_SK, lbl, !pl_try_rtos(l)) /* R -?> S */
#define HA_RWLOCK_TRYRDTOWR(lbl, l) _lock_cond(_LK_WR, lbl, !pl_try_rtow(l)) /* R -?> W */
#else /* (DEBUG_THREAD < 2) && !defined(DEBUG_FULL) */
/* Thread debugging is ENABLED, these are the instrumented functions */
#define __SPIN_INIT(l) ({ (*l) = 0; })
#define __SPIN_DESTROY(l) ({ (*l) = 0; })
#define __SPIN_LOCK(l) pl_take_s(l)
#define __SPIN_TRYLOCK(l) (!pl_try_s(l))
#define __SPIN_UNLOCK(l) pl_drop_s(l)
#define __RWLOCK_INIT(l) ({ (*l) = 0; })
#define __RWLOCK_DESTROY(l) ({ (*l) = 0; })
#define __RWLOCK_WRLOCK(l) pl_take_w(l)
#define __RWLOCK_TRYWRLOCK(l) (!pl_try_w(l))
#define __RWLOCK_WRUNLOCK(l) pl_drop_w(l)
#define __RWLOCK_RDLOCK(l) pl_take_r(l)
#define __RWLOCK_TRYRDLOCK(l) (!pl_try_r(l))
#define __RWLOCK_RDUNLOCK(l) pl_drop_r(l)
/* rwlock upgrades via seek locks */
#define __RWLOCK_SKLOCK(l) pl_take_s(l) /* N --> S */
#define __RWLOCK_SKTOWR(l) pl_stow(l) /* S --> W */
#define __RWLOCK_WRTOSK(l) pl_wtos(l) /* W --> S */
#define __RWLOCK_SKTORD(l) pl_stor(l) /* S --> R */
#define __RWLOCK_WRTORD(l) pl_wtor(l) /* W --> R */
#define __RWLOCK_SKUNLOCK(l) pl_drop_s(l) /* S --> N */
#define __RWLOCK_TRYSKLOCK(l) (!pl_try_s(l)) /* N -?> S */
#define __RWLOCK_TRYRDTOSK(l) (!pl_try_rtos(l)) /* R -?> S */
#define __RWLOCK_TRYRDTOWR(l) (!pl_try_rtow(l)) /* R -?> W */
#define HA_SPIN_INIT(l) __spin_init(l)
#define HA_SPIN_DESTROY(l) __spin_destroy(l)
#define HA_SPIN_LOCK(lbl, l) _lock_wait(_LK_SK, lbl, __spin_lock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_SPIN_TRYLOCK(lbl, l) _lock_cond(_LK_SK, lbl, __spin_trylock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_SPIN_UNLOCK(lbl, l) _lock_wait(_LK_UN, lbl, __spin_unlock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_INIT(l) __ha_rwlock_init((l))
#define HA_RWLOCK_DESTROY(l) __ha_rwlock_destroy((l))
#define HA_RWLOCK_WRLOCK(lbl,l) _lock_wait(_LK_WR, lbl, __ha_rwlock_wrlock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_TRYWRLOCK(lbl,l) _lock_cond(_LK_WR, lbl, __ha_rwlock_trywrlock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_WRUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_wrunlock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_RDLOCK(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_rdlock(lbl, l))
#define HA_RWLOCK_TRYRDLOCK(lbl,l) _lock_cond(_LK_RD, lbl, __ha_rwlock_tryrdlock(lbl, l))
#define HA_RWLOCK_RDUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_rdunlock(lbl, l))
#define HA_RWLOCK_SKLOCK(lbl,l) _lock_wait(_LK_SK, lbl, __ha_rwlock_sklock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_SKTOWR(lbl,l) _lock_wait(_LK_WR, lbl, __ha_rwlock_sktowr(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_WRTOSK(lbl,l) _lock_wait(_LK_SK, lbl, __ha_rwlock_wrtosk(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_SKTORD(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_sktord(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_WRTORD(lbl,l) _lock_wait(_LK_RD, lbl, __ha_rwlock_wrtord(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_SKUNLOCK(lbl,l) _lock_wait(_LK_UN, lbl, __ha_rwlock_skunlock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_TRYSKLOCK(lbl,l) _lock_cond(_LK_SK, lbl, __ha_rwlock_trysklock(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_TRYRDTOSK(lbl,l) _lock_cond(_LK_RD, lbl, __ha_rwlock_tryrdtosk(lbl, l, __func__, __FILE__, __LINE__))
#define HA_RWLOCK_TRYRDTOWR(lbl,l) _lock_cond(_LK_WR, lbl, __ha_rwlock_tryrdtowr(lbl, l, __func__, __FILE__, __LINE__))
/* Following functions are used to collect some stats about locks. We wrap
* pthread functions to known how much time we wait in a lock. */
void show_lock_stats();
void __ha_rwlock_init(struct ha_rwlock *l);
void __ha_rwlock_destroy(struct ha_rwlock *l);
void __ha_rwlock_wrlock(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
int __ha_rwlock_trywrlock(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_wrunlock(enum lock_label lbl,struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_rdlock(enum lock_label lbl,struct ha_rwlock *l);
int __ha_rwlock_tryrdlock(enum lock_label lbl,struct ha_rwlock *l);
void __ha_rwlock_rdunlock(enum lock_label lbl,struct ha_rwlock *l);
void __ha_rwlock_wrtord(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_wrtosk(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_sklock(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_sktowr(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_sktord(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __ha_rwlock_skunlock(enum lock_label lbl,struct ha_rwlock *l,
const char *func, const char *file, int line);
int __ha_rwlock_trysklock(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
int __ha_rwlock_tryrdtosk(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
int __ha_rwlock_tryrdtowr(enum lock_label lbl, struct ha_rwlock *l,
const char *func, const char *file, int line);
void __spin_init(struct ha_spinlock *l);
void __spin_destroy(struct ha_spinlock *l);
void __spin_lock(enum lock_label lbl, struct ha_spinlock *l,
const char *func, const char *file, int line);
int __spin_trylock(enum lock_label lbl, struct ha_spinlock *l,
const char *func, const char *file, int line);
void __spin_unlock(enum lock_label lbl, struct ha_spinlock *l,
const char *func, const char *file, int line);
#endif /* DEBUG_THREAD */
#endif /* USE_THREAD */
#endif /* _HAPROXY_THREAD_H */
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