diff options
Diffstat (limited to 'libraries/libldap_r/tpool.c')
| -rw-r--r-- | libraries/libldap_r/tpool.c | 1032 |
1 files changed, 1032 insertions, 0 deletions
diff --git a/libraries/libldap_r/tpool.c b/libraries/libldap_r/tpool.c new file mode 100644 index 0000000..17cee3b --- /dev/null +++ b/libraries/libldap_r/tpool.c @@ -0,0 +1,1032 @@ +/* $OpenLDAP$ */ +/* This work is part of OpenLDAP Software <http://www.openldap.org/>. + * + * Copyright 1998-2021 The OpenLDAP Foundation. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted only as authorized by the OpenLDAP + * Public License. + * + * A copy of this license is available in file LICENSE in the + * top-level directory of the distribution or, alternatively, at + * <http://www.OpenLDAP.org/license.html>. + */ + +#include "portable.h" + +#include <stdio.h> + +#include <ac/signal.h> +#include <ac/stdarg.h> +#include <ac/stdlib.h> +#include <ac/string.h> +#include <ac/time.h> +#include <ac/errno.h> + +#include "ldap-int.h" +#include "ldap_pvt_thread.h" /* Get the thread interface */ +#include "ldap_queue.h" +#define LDAP_THREAD_POOL_IMPLEMENTATION +#include "ldap_thr_debug.h" /* May rename symbols defined below */ + +#ifndef LDAP_THREAD_HAVE_TPOOL + +/* Thread-specific key with data and optional free function */ +typedef struct ldap_int_tpool_key_s { + void *ltk_key; + void *ltk_data; + ldap_pvt_thread_pool_keyfree_t *ltk_free; +} ldap_int_tpool_key_t; + +/* Max number of thread-specific keys we store per thread. + * We don't expect to use many... + */ +#define MAXKEYS 32 + +/* Max number of threads */ +#define LDAP_MAXTHR 1024 /* must be a power of 2 */ + +/* (Theoretical) max number of pending requests */ +#define MAX_PENDING (INT_MAX/2) /* INT_MAX - (room to avoid overflow) */ + +/* pool->ltp_pause values */ +enum { NOT_PAUSED = 0, WANT_PAUSE = 1, PAUSED = 2 }; + +/* Context: thread ID and thread-specific key/data pairs */ +typedef struct ldap_int_thread_userctx_s { + ldap_pvt_thread_t ltu_id; + ldap_int_tpool_key_t ltu_key[MAXKEYS]; +} ldap_int_thread_userctx_t; + + +/* Simple {thread ID -> context} hash table; key=ctx->ltu_id. + * Protected by ldap_pvt_thread_pool_mutex except during pauses, + * when it is read-only (used by pool_purgekey and pool_context). + * Protected by tpool->ltp_mutex during pauses. + */ +static struct { + ldap_int_thread_userctx_t *ctx; + /* ctx is valid when not NULL or DELETED_THREAD_CTX */ +# define DELETED_THREAD_CTX (&ldap_int_main_thrctx + 1) /* dummy addr */ +} thread_keys[LDAP_MAXTHR]; + +#define TID_HASH(tid, hash) do { \ + unsigned const char *ptr_ = (unsigned const char *)&(tid); \ + unsigned i_; \ + for (i_ = 0, (hash) = ptr_[0]; ++i_ < sizeof(tid);) \ + (hash) += ((hash) << 5) ^ ptr_[i_]; \ +} while(0) + + +/* Task for a thread to perform */ +typedef struct ldap_int_thread_task_s { + union { + LDAP_STAILQ_ENTRY(ldap_int_thread_task_s) q; + LDAP_SLIST_ENTRY(ldap_int_thread_task_s) l; + } ltt_next; + ldap_pvt_thread_start_t *ltt_start_routine; + void *ltt_arg; +} ldap_int_thread_task_t; + +typedef LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ldap_int_tpool_plist_t; + +struct ldap_int_thread_pool_s { + LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next; + + /* protect members below, and protect thread_keys[] during pauses */ + ldap_pvt_thread_mutex_t ltp_mutex; + + /* not paused and something to do for pool_<wrapper/pause/destroy>() */ + ldap_pvt_thread_cond_t ltp_cond; + + /* ltp_active_count <= 1 && ltp_pause */ + ldap_pvt_thread_cond_t ltp_pcond; + + /* ltp_pause == 0 ? <p_pending_list : &empty_pending_list, + * maintaned to reduce work for pool_wrapper() + */ + ldap_int_tpool_plist_t *ltp_work_list; + + /* pending tasks, and unused task objects */ + ldap_int_tpool_plist_t ltp_pending_list; + LDAP_SLIST_HEAD(tcl, ldap_int_thread_task_s) ltp_free_list; + + /* The pool is finishing, waiting for its threads to close. + * They close when ltp_pending_list is done. pool_submit() + * rejects new tasks. ltp_max_pending = -(its old value). + */ + int ltp_finishing; + + /* Some active task needs to be the sole active task. + * Atomic variable so ldap_pvt_thread_pool_pausing() can read it. + * Note: Pauses adjust ltp_<open_count/vary_open_count/work_list>, + * so pool_<submit/wrapper>() mostly can avoid testing ltp_pause. + */ + volatile sig_atomic_t ltp_pause; + + /* Max number of threads in pool, or 0 for default (LDAP_MAXTHR) */ + int ltp_max_count; + + /* Max pending + paused + idle tasks, negated when ltp_finishing */ + int ltp_max_pending; + + int ltp_pending_count; /* Pending + paused + idle tasks */ + int ltp_active_count; /* Active, not paused/idle tasks */ + int ltp_open_count; /* Number of threads, negated when ltp_pause */ + int ltp_starting; /* Currenlty starting threads */ + + /* >0 if paused or we may open a thread, <0 if we should close a thread. + * Updated when ltp_<finishing/pause/max_count/open_count> change. + * Maintained to reduce the time ltp_mutex must be locked in + * ldap_pvt_thread_pool_<submit/wrapper>(). + */ + int ltp_vary_open_count; +# define SET_VARY_OPEN_COUNT(pool) \ + ((pool)->ltp_vary_open_count = \ + (pool)->ltp_pause ? 1 : \ + (pool)->ltp_finishing ? -1 : \ + ((pool)->ltp_max_count ? (pool)->ltp_max_count : LDAP_MAXTHR) \ + - (pool)->ltp_open_count) +}; + +static ldap_int_tpool_plist_t empty_pending_list = + LDAP_STAILQ_HEAD_INITIALIZER(empty_pending_list); + +static int ldap_int_has_thread_pool = 0; +static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s) + ldap_int_thread_pool_list = + LDAP_STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list); + +static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex; + +static void *ldap_int_thread_pool_wrapper( void *pool ); + +static ldap_pvt_thread_key_t ldap_tpool_key; + +/* Context of the main thread */ +static ldap_int_thread_userctx_t ldap_int_main_thrctx; + +int +ldap_int_thread_pool_startup ( void ) +{ + ldap_int_main_thrctx.ltu_id = ldap_pvt_thread_self(); + ldap_pvt_thread_key_create( &ldap_tpool_key ); + return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex); +} + +int +ldap_int_thread_pool_shutdown ( void ) +{ + struct ldap_int_thread_pool_s *pool; + + while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) { + (ldap_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */ + } + ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex); + ldap_pvt_thread_key_destroy( ldap_tpool_key ); + return(0); +} + + +/* Create a thread pool */ +int +ldap_pvt_thread_pool_init ( + ldap_pvt_thread_pool_t *tpool, + int max_threads, + int max_pending ) +{ + ldap_pvt_thread_pool_t pool; + int rc; + + /* multiple pools are currently not supported (ITS#4943) */ + assert(!ldap_int_has_thread_pool); + + if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR)) + max_threads = 0; + if (! (1 <= max_pending && max_pending <= MAX_PENDING)) + max_pending = MAX_PENDING; + + *tpool = NULL; + pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1, + sizeof(struct ldap_int_thread_pool_s)); + + if (pool == NULL) return(-1); + + rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex); + if (rc != 0) { +fail1: + LDAP_FREE(pool); + return(rc); + } + rc = ldap_pvt_thread_cond_init(&pool->ltp_cond); + if (rc != 0) { +fail2: + ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex); + goto fail1; + } + rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond); + if (rc != 0) { + ldap_pvt_thread_cond_destroy(&pool->ltp_cond); + goto fail2; + } + + ldap_int_has_thread_pool = 1; + + pool->ltp_max_count = max_threads; + SET_VARY_OPEN_COUNT(pool); + pool->ltp_max_pending = max_pending; + + LDAP_STAILQ_INIT(&pool->ltp_pending_list); + pool->ltp_work_list = &pool->ltp_pending_list; + LDAP_SLIST_INIT(&pool->ltp_free_list); + + ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex); + LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next); + ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex); + + /* Start no threads just yet. That can break if the process forks + * later, as slapd does in order to daemonize. On at least POSIX, + * only the forking thread would survive in the child. Yet fork() + * can't unlock/clean up other threads' locks and data structures, + * unless pthread_atfork() handlers have been set up to do so. + */ + + *tpool = pool; + return(0); +} + + +/* Submit a task to be performed by the thread pool */ +int +ldap_pvt_thread_pool_submit ( + ldap_pvt_thread_pool_t *tpool, + ldap_pvt_thread_start_t *start_routine, void *arg ) +{ + struct ldap_int_thread_pool_s *pool; + ldap_int_thread_task_t *task; + ldap_pvt_thread_t thr; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) + return(-1); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + if (pool->ltp_pending_count >= pool->ltp_max_pending) + goto failed; + + task = LDAP_SLIST_FIRST(&pool->ltp_free_list); + if (task) { + LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l); + } else { + task = (ldap_int_thread_task_t *) LDAP_MALLOC(sizeof(*task)); + if (task == NULL) + goto failed; + } + + task->ltt_start_routine = start_routine; + task->ltt_arg = arg; + + pool->ltp_pending_count++; + LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, task, ltt_next.q); + + /* true if ltp_pause != 0 or we should open (create) a thread */ + if (pool->ltp_vary_open_count > 0 && + pool->ltp_open_count < pool->ltp_active_count+pool->ltp_pending_count) + { + if (pool->ltp_pause) + goto done; + + pool->ltp_starting++; + pool->ltp_open_count++; + SET_VARY_OPEN_COUNT(pool); + + if (0 != ldap_pvt_thread_create( + &thr, 1, ldap_int_thread_pool_wrapper, pool)) + { + /* couldn't create thread. back out of + * ltp_open_count and check for even worse things. + */ + pool->ltp_starting--; + pool->ltp_open_count--; + SET_VARY_OPEN_COUNT(pool); + + if (pool->ltp_open_count == 0) { + /* no open threads at all?!? + */ + ldap_int_thread_task_t *ptr; + + /* let pool_destroy know there are no more threads */ + ldap_pvt_thread_cond_signal(&pool->ltp_cond); + + LDAP_STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltt_next.q) + if (ptr == task) break; + if (ptr == task) { + /* no open threads, task not handled, so + * back out of ltp_pending_count, free the task, + * report the error. + */ + pool->ltp_pending_count--; + LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, task, + ldap_int_thread_task_s, ltt_next.q); + LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task, + ltt_next.l); + goto failed; + } + } + /* there is another open thread, so this + * task will be handled eventually. + */ + } + } + ldap_pvt_thread_cond_signal(&pool->ltp_cond); + + done: + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return(0); + + failed: + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return(-1); +} + +static void * +no_task( void *ctx, void *arg ) +{ + return NULL; +} + +/* Cancel a pending task that was previously submitted. + * Return 1 if the task was successfully cancelled, 0 if + * not found, -1 for invalid parameters + */ +int +ldap_pvt_thread_pool_retract ( + ldap_pvt_thread_pool_t *tpool, + ldap_pvt_thread_start_t *start_routine, void *arg ) +{ + struct ldap_int_thread_pool_s *pool; + ldap_int_thread_task_t *task; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) + return(-1); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + LDAP_STAILQ_FOREACH(task, &pool->ltp_pending_list, ltt_next.q) + if (task->ltt_start_routine == start_routine && + task->ltt_arg == arg) { + /* Could LDAP_STAILQ_REMOVE the task, but that + * walks ltp_pending_list again to find it. + */ + task->ltt_start_routine = no_task; + task->ltt_arg = NULL; + break; + } + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return task != NULL; +} + +/* Set max #threads. value <= 0 means max supported #threads (LDAP_MAXTHR) */ +int +ldap_pvt_thread_pool_maxthreads( + ldap_pvt_thread_pool_t *tpool, + int max_threads ) +{ + struct ldap_int_thread_pool_s *pool; + + if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR)) + max_threads = 0; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) + return(-1); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + pool->ltp_max_count = max_threads; + SET_VARY_OPEN_COUNT(pool); + + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return(0); +} + +/* Inspect the pool */ +int +ldap_pvt_thread_pool_query( + ldap_pvt_thread_pool_t *tpool, + ldap_pvt_thread_pool_param_t param, + void *value ) +{ + struct ldap_int_thread_pool_s *pool; + int count = -1; + + if ( tpool == NULL || value == NULL ) { + return -1; + } + + pool = *tpool; + + if ( pool == NULL ) { + return 0; + } + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + switch ( param ) { + case LDAP_PVT_THREAD_POOL_PARAM_MAX: + count = pool->ltp_max_count; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING: + count = pool->ltp_max_pending; + if (count < 0) + count = -count; + if (count == MAX_PENDING) + count = 0; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_OPEN: + count = pool->ltp_open_count; + if (count < 0) + count = -count; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_STARTING: + count = pool->ltp_starting; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE: + count = pool->ltp_active_count; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_PAUSING: + count = (pool->ltp_pause != 0); + break; + + case LDAP_PVT_THREAD_POOL_PARAM_PENDING: + count = pool->ltp_pending_count; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD: + count = pool->ltp_pending_count + pool->ltp_active_count; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX: + break; + + case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX: + break; + + case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX: + break; + + case LDAP_PVT_THREAD_POOL_PARAM_STATE: + *((char **)value) = + pool->ltp_pause ? "pausing" : + !pool->ltp_finishing ? "running" : + pool->ltp_pending_count ? "finishing" : "stopping"; + break; + + case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN: + break; + } + ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex ); + + if ( count > -1 ) { + *((int *)value) = count; + } + + return ( count == -1 ? -1 : 0 ); +} + +/* + * true if pool is pausing; does not lock any mutex to check. + * 0 if not pause, 1 if pause, -1 if error or no pool. + */ +int +ldap_pvt_thread_pool_pausing( ldap_pvt_thread_pool_t *tpool ) +{ + int rc = -1; + struct ldap_int_thread_pool_s *pool; + + if ( tpool != NULL && (pool = *tpool) != NULL ) { + rc = (pool->ltp_pause != 0); + } + + return rc; +} + +/* + * wrapper for ldap_pvt_thread_pool_query(), left around + * for backwards compatibility + */ +int +ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool ) +{ + int rc, count; + + rc = ldap_pvt_thread_pool_query( tpool, + LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count ); + + if ( rc == 0 ) { + return count; + } + + return rc; +} + +/* Destroy the pool after making its threads finish */ +int +ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending ) +{ + struct ldap_int_thread_pool_s *pool, *pptr; + ldap_int_thread_task_t *task; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) return(-1); + + ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex); + LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next) + if (pptr == pool) break; + if (pptr == pool) + LDAP_STAILQ_REMOVE(&ldap_int_thread_pool_list, pool, + ldap_int_thread_pool_s, ltp_next); + ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex); + + if (pool != pptr) return(-1); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + pool->ltp_finishing = 1; + SET_VARY_OPEN_COUNT(pool); + if (pool->ltp_max_pending > 0) + pool->ltp_max_pending = -pool->ltp_max_pending; + + if (!run_pending) { + while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL) { + LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q); + LDAP_FREE(task); + } + pool->ltp_pending_count = 0; + } + + while (pool->ltp_open_count) { + if (!pool->ltp_pause) + ldap_pvt_thread_cond_broadcast(&pool->ltp_cond); + ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex); + } + + while ((task = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL) + { + LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l); + LDAP_FREE(task); + } + + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + ldap_pvt_thread_cond_destroy(&pool->ltp_pcond); + ldap_pvt_thread_cond_destroy(&pool->ltp_cond); + ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex); + LDAP_FREE(pool); + *tpool = NULL; + ldap_int_has_thread_pool = 0; + return(0); +} + +/* Thread loop. Accept and handle submitted tasks. */ +static void * +ldap_int_thread_pool_wrapper ( + void *xpool ) +{ + struct ldap_int_thread_pool_s *pool = xpool; + ldap_int_thread_task_t *task; + ldap_int_tpool_plist_t *work_list; + ldap_int_thread_userctx_t ctx, *kctx; + unsigned i, keyslot, hash; + + assert(pool != NULL); + + for ( i=0; i<MAXKEYS; i++ ) { + ctx.ltu_key[i].ltk_key = NULL; + } + + ctx.ltu_id = ldap_pvt_thread_self(); + TID_HASH(ctx.ltu_id, hash); + + ldap_pvt_thread_key_setdata( ldap_tpool_key, &ctx ); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + /* thread_keys[] is read-only when paused */ + while (pool->ltp_pause) + ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex); + + /* find a key slot to give this thread ID and store a + * pointer to our keys there; start at the thread ID + * itself (mod LDAP_MAXTHR) and look for an empty slot. + */ + ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex); + for (keyslot = hash & (LDAP_MAXTHR-1); + (kctx = thread_keys[keyslot].ctx) && kctx != DELETED_THREAD_CTX; + keyslot = (keyslot+1) & (LDAP_MAXTHR-1)); + thread_keys[keyslot].ctx = &ctx; + ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex); + + pool->ltp_starting--; + pool->ltp_active_count++; + + for (;;) { + work_list = pool->ltp_work_list; /* help the compiler a bit */ + task = LDAP_STAILQ_FIRST(work_list); + if (task == NULL) { /* paused or no pending tasks */ + if (--(pool->ltp_active_count) < 2) { + /* Notify pool_pause it is the sole active thread. */ + ldap_pvt_thread_cond_signal(&pool->ltp_pcond); + } + + do { + if (pool->ltp_vary_open_count < 0) { + /* Not paused, and either finishing or too many + * threads running (can happen if ltp_max_count + * was reduced). Let this thread die. + */ + goto done; + } + + /* We could check an idle timer here, and let the + * thread die if it has been inactive for a while. + * Only die if there are other open threads (i.e., + * always have at least one thread open). + * The check should be like this: + * if (pool->ltp_open_count>1 && pool->ltp_starting==0) + * check timer, wait if ltp_pause, leave thread; + * + * Just use pthread_cond_timedwait() if we want to + * check idle time. + */ + ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex); + + work_list = pool->ltp_work_list; + task = LDAP_STAILQ_FIRST(work_list); + } while (task == NULL); + + pool->ltp_active_count++; + } + + LDAP_STAILQ_REMOVE_HEAD(work_list, ltt_next.q); + pool->ltp_pending_count--; + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + + task->ltt_start_routine(&ctx, task->ltt_arg); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task, ltt_next.l); + } + done: + + assert(!pool->ltp_pause); /* thread_keys writable, ltp_open_count >= 0 */ + + /* The ltp_mutex lock protects ctx->ltu_key from pool_purgekey() + * during this call, since it prevents new pauses. */ + ldap_pvt_thread_pool_context_reset(&ctx); + + ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex); + thread_keys[keyslot].ctx = DELETED_THREAD_CTX; + ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex); + + pool->ltp_open_count--; + SET_VARY_OPEN_COUNT(pool); + /* let pool_destroy know we're all done */ + if (pool->ltp_open_count == 0) + ldap_pvt_thread_cond_signal(&pool->ltp_cond); + + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + + ldap_pvt_thread_exit(NULL); + return(NULL); +} + +/* Arguments > ltp_pause to handle_pause(,PAUSE_ARG()). arg=PAUSE_ARG + * ensures (arg-ltp_pause) sets GO_* at need and keeps DO_PAUSE/GO_*. + */ +#define GO_IDLE 8 +#define GO_UNIDLE 16 +#define CHECK_PAUSE 32 /* if ltp_pause: GO_IDLE; wait; GO_UNIDLE */ +#define DO_PAUSE 64 /* CHECK_PAUSE; pause the pool */ +#define PAUSE_ARG(a) \ + ((a) | ((a) & (GO_IDLE|GO_UNIDLE) ? GO_IDLE-1 : CHECK_PAUSE)) + +static int +handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type ) +{ + struct ldap_int_thread_pool_s *pool; + int ret = 0, pause, max_ltp_pause; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) + return(0); + + if (pause_type == CHECK_PAUSE && !pool->ltp_pause) + return(0); + + /* Let pool_unidle() ignore requests for new pauses */ + max_ltp_pause = pause_type==PAUSE_ARG(GO_UNIDLE) ? WANT_PAUSE : NOT_PAUSED; + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + pause = pool->ltp_pause; /* NOT_PAUSED, WANT_PAUSE or PAUSED */ + + /* If ltp_pause and not GO_IDLE|GO_UNIDLE: Set GO_IDLE,GO_UNIDLE */ + pause_type -= pause; + + if (pause_type & GO_IDLE) { + pool->ltp_pending_count++; + pool->ltp_active_count--; + if (pause && pool->ltp_active_count < 2) { + /* Tell the task waiting to DO_PAUSE it can proceed */ + ldap_pvt_thread_cond_signal(&pool->ltp_pcond); + } + } + + if (pause_type & GO_UNIDLE) { + /* Wait out pause if any, then cancel GO_IDLE */ + if (pause > max_ltp_pause) { + ret = 1; + do { + ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex); + } while (pool->ltp_pause > max_ltp_pause); + } + pool->ltp_pending_count--; + pool->ltp_active_count++; + } + + if (pause_type & DO_PAUSE) { + /* Tell everyone else to pause or finish, then await that */ + ret = 0; + assert(!pool->ltp_pause); + pool->ltp_pause = WANT_PAUSE; + /* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test, + * and do not finish threads in ldap_pvt_thread_pool_wrapper() */ + pool->ltp_open_count = -pool->ltp_open_count; + SET_VARY_OPEN_COUNT(pool); + /* Hide pending tasks from ldap_pvt_thread_pool_wrapper() */ + pool->ltp_work_list = &empty_pending_list; + /* Wait for this task to become the sole active task */ + while (pool->ltp_active_count > 1) { + ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex); + } + assert(pool->ltp_pause == WANT_PAUSE); + pool->ltp_pause = PAUSED; + } + + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return(ret); +} + +/* Consider this task idle: It will not block pool_pause() in other tasks. */ +void +ldap_pvt_thread_pool_idle( ldap_pvt_thread_pool_t *tpool ) +{ + handle_pause(tpool, PAUSE_ARG(GO_IDLE)); +} + +/* Cancel pool_idle(). If the pool is paused, wait it out first. */ +void +ldap_pvt_thread_pool_unidle( ldap_pvt_thread_pool_t *tpool ) +{ + handle_pause(tpool, PAUSE_ARG(GO_UNIDLE)); +} + +/* + * If a pause was requested, wait for it. If several threads + * are waiting to pause, let through one or more pauses. + * The calling task must be active, not idle. + * Return 1 if we waited, 0 if not, -1 at parameter error. + */ +int +ldap_pvt_thread_pool_pausecheck( ldap_pvt_thread_pool_t *tpool ) +{ + return handle_pause(tpool, PAUSE_ARG(CHECK_PAUSE)); +} + +/* + * Pause the pool. The calling task must be active, not idle. + * Return when all other tasks are paused or idle. + */ +int +ldap_pvt_thread_pool_pause( ldap_pvt_thread_pool_t *tpool ) +{ + return handle_pause(tpool, PAUSE_ARG(DO_PAUSE)); +} + +/* End a pause */ +int +ldap_pvt_thread_pool_resume ( + ldap_pvt_thread_pool_t *tpool ) +{ + struct ldap_int_thread_pool_s *pool; + + if (tpool == NULL) + return(-1); + + pool = *tpool; + + if (pool == NULL) + return(0); + + ldap_pvt_thread_mutex_lock(&pool->ltp_mutex); + + assert(pool->ltp_pause == PAUSED); + pool->ltp_pause = 0; + if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */ + pool->ltp_open_count = -pool->ltp_open_count; + SET_VARY_OPEN_COUNT(pool); + pool->ltp_work_list = &pool->ltp_pending_list; + + ldap_pvt_thread_cond_broadcast(&pool->ltp_cond); + + ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex); + return(0); +} + +/* + * Get the key's data and optionally free function in the given context. + */ +int ldap_pvt_thread_pool_getkey( + void *xctx, + void *key, + void **data, + ldap_pvt_thread_pool_keyfree_t **kfree ) +{ + ldap_int_thread_userctx_t *ctx = xctx; + int i; + + if ( !ctx || !key || !data ) return EINVAL; + + for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) { + if ( ctx->ltu_key[i].ltk_key == key ) { + *data = ctx->ltu_key[i].ltk_data; + if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free; + return 0; + } + } + return ENOENT; +} + +static void +clear_key_idx( ldap_int_thread_userctx_t *ctx, int i ) +{ + for ( ; i < MAXKEYS-1 && ctx->ltu_key[i+1].ltk_key; i++ ) + ctx->ltu_key[i] = ctx->ltu_key[i+1]; + ctx->ltu_key[i].ltk_key = NULL; +} + +/* + * Set or remove data for the key in the given context. + * key can be any unique pointer. + * kfree() is an optional function to free the data (but not the key): + * pool_context_reset() and pool_purgekey() call kfree(key, data), + * but pool_setkey() does not. For pool_setkey() it is the caller's + * responsibility to free any existing data with the same key. + * kfree() must not call functions taking a tpool argument. + */ +int ldap_pvt_thread_pool_setkey( + void *xctx, + void *key, + void *data, + ldap_pvt_thread_pool_keyfree_t *kfree, + void **olddatap, + ldap_pvt_thread_pool_keyfree_t **oldkfreep ) +{ + ldap_int_thread_userctx_t *ctx = xctx; + int i, found; + + if ( !ctx || !key ) return EINVAL; + + for ( i=found=0; i<MAXKEYS; i++ ) { + if ( ctx->ltu_key[i].ltk_key == key ) { + found = 1; + break; + } else if ( !ctx->ltu_key[i].ltk_key ) { + break; + } + } + + if ( olddatap ) { + if ( found ) { + *olddatap = ctx->ltu_key[i].ltk_data; + } else { + *olddatap = NULL; + } + } + + if ( oldkfreep ) { + if ( found ) { + *oldkfreep = ctx->ltu_key[i].ltk_free; + } else { + *oldkfreep = 0; + } + } + + if ( data || kfree ) { + if ( i>=MAXKEYS ) + return ENOMEM; + ctx->ltu_key[i].ltk_key = key; + ctx->ltu_key[i].ltk_data = data; + ctx->ltu_key[i].ltk_free = kfree; + } else if ( found ) { + clear_key_idx( ctx, i ); + } + + return 0; +} + +/* Free all elements with this key, no matter which thread they're in. + * May only be called while the pool is paused. + */ +void ldap_pvt_thread_pool_purgekey( void *key ) +{ + int i, j; + ldap_int_thread_userctx_t *ctx; + + assert ( key != NULL ); + + for ( i=0; i<LDAP_MAXTHR; i++ ) { + ctx = thread_keys[i].ctx; + if ( ctx && ctx != DELETED_THREAD_CTX ) { + for ( j=0; j<MAXKEYS && ctx->ltu_key[j].ltk_key; j++ ) { + if ( ctx->ltu_key[j].ltk_key == key ) { + if (ctx->ltu_key[j].ltk_free) + ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key, + ctx->ltu_key[j].ltk_data ); + clear_key_idx( ctx, j ); + break; + } + } + } + } +} + +/* + * Find the context of the current thread. + * This is necessary if the caller does not have access to the + * thread context handle (for example, a slapd plugin calling + * slapi_search_internal()). No doubt it is more efficient + * for the application to keep track of the thread context + * handles itself. + */ +void *ldap_pvt_thread_pool_context( ) +{ + void *ctx = NULL; + + ldap_pvt_thread_key_getdata( ldap_tpool_key, &ctx ); + return ctx ? ctx : (void *) &ldap_int_main_thrctx; +} + +/* + * Free the context's keys. + * Must not call functions taking a tpool argument (because this + * thread already holds ltp_mutex when called from pool_wrapper()). + */ +void ldap_pvt_thread_pool_context_reset( void *vctx ) +{ + ldap_int_thread_userctx_t *ctx = vctx; + int i; + + for ( i=MAXKEYS-1; i>=0; i--) { + if ( !ctx->ltu_key[i].ltk_key ) + continue; + if ( ctx->ltu_key[i].ltk_free ) + ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key, + ctx->ltu_key[i].ltk_data ); + ctx->ltu_key[i].ltk_key = NULL; + } +} + +ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx ) +{ + ldap_int_thread_userctx_t *ctx = vctx; + + return ctx->ltu_id; +} +#endif /* LDAP_THREAD_HAVE_TPOOL */ |