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Diffstat (limited to 'usr.bin/dig/lib/isc/task.c')
| -rw-r--r-- | usr.bin/dig/lib/isc/task.c | 1513 |
1 files changed, 1513 insertions, 0 deletions
diff --git a/usr.bin/dig/lib/isc/task.c b/usr.bin/dig/lib/isc/task.c new file mode 100644 index 00000000000..e9d5e92b3ae --- /dev/null +++ b/usr.bin/dig/lib/isc/task.c @@ -0,0 +1,1513 @@ +/* + * Copyright (C) Internet Systems Consortium, Inc. ("ISC") + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH + * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, + * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM + * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE + * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR + * PERFORMANCE OF THIS SOFTWARE. + */ + +/*! \file + * \author Principal Author: Bob Halley + */ + +/* + * XXXRTH Need to document the states a task can be in, and the rules + * for changing states. + */ + +#include <stdlib.h> +#include <isc/app.h> +#include <isc/event.h> +#include <isc/magic.h> +#include <isc/msgs.h> + +#include <string.h> +#include <isc/task.h> +#include <isc/util.h> + +#include "task_p.h" + +#ifdef ISC_TASK_TRACE +#define XTRACE(m) fprintf(stderr, "task %p thread %lu: %s\n", \ + task, 0, (m)) +#define XTTRACE(t, m) fprintf(stderr, "task %p thread %lu: %s\n", \ + (t), 0, (m)) +#define XTHREADTRACE(m) fprintf(stderr, "thread %lu: %s\n", \ + 0, (m)) +#else +#define XTRACE(m) +#define XTTRACE(t, m) +#define XTHREADTRACE(m) +#endif + +/*** + *** Types. + ***/ + +typedef enum { + task_state_idle, task_state_ready, task_state_running, + task_state_done +} task_state_t; + +#define TASK_MAGIC ISC_MAGIC('T', 'A', 'S', 'K') +#define VALID_TASK(t) ISC_MAGIC_VALID(t, TASK_MAGIC) + +typedef struct isc__task isc__task_t; +typedef struct isc__taskmgr isc__taskmgr_t; + +struct isc__task { + /* Not locked. */ + isc_task_t common; + isc__taskmgr_t * manager; + /* Locked by task lock. */ + task_state_t state; + unsigned int references; + isc_eventlist_t events; + isc_eventlist_t on_shutdown; + unsigned int nevents; + unsigned int quantum; + unsigned int flags; + isc_stdtime_t now; + char name[16]; + void * tag; + /* Locked by task manager lock. */ + LINK(isc__task_t) link; + LINK(isc__task_t) ready_link; + LINK(isc__task_t) ready_priority_link; +}; + +#define TASK_F_SHUTTINGDOWN 0x01 +#define TASK_F_PRIVILEGED 0x02 + +#define TASK_SHUTTINGDOWN(t) (((t)->flags & TASK_F_SHUTTINGDOWN) \ + != 0) + +#define TASK_MANAGER_MAGIC ISC_MAGIC('T', 'S', 'K', 'M') +#define VALID_MANAGER(m) ISC_MAGIC_VALID(m, TASK_MANAGER_MAGIC) + +typedef ISC_LIST(isc__task_t) isc__tasklist_t; + +struct isc__taskmgr { + /* Not locked. */ + isc_taskmgr_t common; + /* Locked by task manager lock. */ + unsigned int default_quantum; + LIST(isc__task_t) tasks; + isc__tasklist_t ready_tasks; + isc__tasklist_t ready_priority_tasks; + isc_taskmgrmode_t mode; + unsigned int tasks_running; + unsigned int tasks_ready; + isc_boolean_t pause_requested; + isc_boolean_t exclusive_requested; + isc_boolean_t exiting; + + /* + * Multiple threads can read/write 'excl' at the same time, so we need + * to protect the access. We can't use 'lock' since isc_task_detach() + * will try to acquire it. + */ + isc__task_t *excl; + unsigned int refs; +}; + +#define DEFAULT_TASKMGR_QUANTUM 10 +#define DEFAULT_DEFAULT_QUANTUM 5 +#define FINISHED(m) ((m)->exiting && EMPTY((m)->tasks)) + +static isc__taskmgr_t *taskmgr = NULL; + +/*% + * The following are intended for internal use (indicated by "isc__" + * prefix) but are not declared as static, allowing direct access from + * unit tests etc. + */ + +isc_result_t +isc__task_create(isc_taskmgr_t *manager0, unsigned int quantum, + isc_task_t **taskp); +void +isc__task_attach(isc_task_t *source0, isc_task_t **targetp); +void +isc__task_detach(isc_task_t **taskp); +void +isc__task_send(isc_task_t *task0, isc_event_t **eventp); +void +isc__task_sendanddetach(isc_task_t **taskp, isc_event_t **eventp); +unsigned int +isc__task_purgerange(isc_task_t *task0, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag); +unsigned int +isc__task_purge(isc_task_t *task, void *sender, isc_eventtype_t type, + void *tag); +isc_boolean_t +isc_task_purgeevent(isc_task_t *task0, isc_event_t *event); +unsigned int +isc__task_unsendrange(isc_task_t *task, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag, + isc_eventlist_t *events); +unsigned int +isc__task_unsend(isc_task_t *task, void *sender, isc_eventtype_t type, + void *tag, isc_eventlist_t *events); +isc_result_t +isc__task_onshutdown(isc_task_t *task0, isc_taskaction_t action, + void *arg); +void +isc__task_shutdown(isc_task_t *task0); +void +isc__task_destroy(isc_task_t **taskp); +void +isc__task_setname(isc_task_t *task0, const char *name, void *tag); +const char * +isc__task_getname(isc_task_t *task0); +void * +isc__task_gettag(isc_task_t *task0); +void +isc__task_getcurrenttime(isc_task_t *task0, isc_stdtime_t *t); +isc_result_t +isc__taskmgr_create(unsigned int workers, + unsigned int default_quantum, isc_taskmgr_t **managerp); +void +isc__taskmgr_destroy(isc_taskmgr_t **managerp); +void +isc_taskmgr_setexcltask(isc_taskmgr_t *mgr0, isc_task_t *task0); +isc_result_t +isc_taskmgr_excltask(isc_taskmgr_t *mgr0, isc_task_t **taskp); +isc_result_t +isc__task_beginexclusive(isc_task_t *task); +void +isc__task_endexclusive(isc_task_t *task0); +void +isc__task_setprivilege(isc_task_t *task0, isc_boolean_t priv); +isc_boolean_t +isc__task_privilege(isc_task_t *task0); +void +isc__taskmgr_setmode(isc_taskmgr_t *manager0, isc_taskmgrmode_t mode); +isc_taskmgrmode_t +isc__taskmgr_mode(isc_taskmgr_t *manager0); + +static inline isc_boolean_t +empty_readyq(isc__taskmgr_t *manager); + +static inline isc__task_t * +pop_readyq(isc__taskmgr_t *manager); + +static inline void +push_readyq(isc__taskmgr_t *manager, isc__task_t *task); + +static struct isc__taskmethods { + isc_taskmethods_t methods; + + /*% + * The following are defined just for avoiding unused static functions. + */ + void *purgeevent, *unsendrange, *getname, *gettag, *getcurrenttime; +} taskmethods = { + { + isc__task_attach, + isc__task_detach, + isc__task_destroy, + isc__task_send, + isc__task_sendanddetach, + isc__task_unsend, + isc__task_onshutdown, + isc__task_shutdown, + isc__task_setname, + isc__task_purge, + isc__task_purgerange, + isc__task_beginexclusive, + isc__task_endexclusive, + isc__task_setprivilege, + isc__task_privilege + }, + (void *)isc_task_purgeevent, + (void *)isc__task_unsendrange, + (void *)isc__task_getname, + (void *)isc__task_gettag, + (void *)isc__task_getcurrenttime +}; + +static isc_taskmgrmethods_t taskmgrmethods = { + isc__taskmgr_destroy, + isc__taskmgr_setmode, + isc__taskmgr_mode, + isc__task_create, + isc_taskmgr_setexcltask, + isc_taskmgr_excltask +}; + +/*** + *** Tasks. + ***/ + +static void +task_finished(isc__task_t *task) { + isc__taskmgr_t *manager = task->manager; + + REQUIRE(EMPTY(task->events)); + REQUIRE(task->nevents == 0); + REQUIRE(EMPTY(task->on_shutdown)); + REQUIRE(task->references == 0); + REQUIRE(task->state == task_state_done); + + XTRACE("task_finished"); + + UNLINK(manager->tasks, task, link); + + task->common.impmagic = 0; + task->common.magic = 0; + free(task); +} + +isc_result_t +isc__task_create(isc_taskmgr_t *manager0, unsigned int quantum, + isc_task_t **taskp) +{ + isc__taskmgr_t *manager = (isc__taskmgr_t *)manager0; + isc__task_t *task; + isc_boolean_t exiting; + + REQUIRE(VALID_MANAGER(manager)); + REQUIRE(taskp != NULL && *taskp == NULL); + + task = malloc(sizeof(*task)); + if (task == NULL) + return (ISC_R_NOMEMORY); + XTRACE("isc_task_create"); + task->manager = manager; + task->state = task_state_idle; + task->references = 1; + INIT_LIST(task->events); + INIT_LIST(task->on_shutdown); + task->nevents = 0; + task->quantum = quantum; + task->flags = 0; + task->now = 0; + memset(task->name, 0, sizeof(task->name)); + task->tag = NULL; + INIT_LINK(task, link); + INIT_LINK(task, ready_link); + INIT_LINK(task, ready_priority_link); + + exiting = ISC_FALSE; + if (!manager->exiting) { + if (task->quantum == 0) + task->quantum = manager->default_quantum; + APPEND(manager->tasks, task, link); + } else + exiting = ISC_TRUE; + + if (exiting) { + free(task); + return (ISC_R_SHUTTINGDOWN); + } + + task->common.methods = (isc_taskmethods_t *)&taskmethods; + task->common.magic = ISCAPI_TASK_MAGIC; + task->common.impmagic = TASK_MAGIC; + *taskp = (isc_task_t *)task; + + return (ISC_R_SUCCESS); +} + +void +isc__task_attach(isc_task_t *source0, isc_task_t **targetp) { + isc__task_t *source = (isc__task_t *)source0; + + /* + * Attach *targetp to source. + */ + + REQUIRE(VALID_TASK(source)); + REQUIRE(targetp != NULL && *targetp == NULL); + + XTTRACE(source, "isc_task_attach"); + + source->references++; + + *targetp = (isc_task_t *)source; +} + +static inline isc_boolean_t +task_shutdown(isc__task_t *task) { + isc_boolean_t was_idle = ISC_FALSE; + isc_event_t *event, *prev; + + /* + * Caller must be holding the task's lock. + */ + + XTRACE("task_shutdown"); + + if (! TASK_SHUTTINGDOWN(task)) { + XTRACE("shutting down"); + task->flags |= TASK_F_SHUTTINGDOWN; + if (task->state == task_state_idle) { + INSIST(EMPTY(task->events)); + task->state = task_state_ready; + was_idle = ISC_TRUE; + } + INSIST(task->state == task_state_ready || + task->state == task_state_running); + + /* + * Note that we post shutdown events LIFO. + */ + for (event = TAIL(task->on_shutdown); + event != NULL; + event = prev) { + prev = PREV(event, ev_link); + DEQUEUE(task->on_shutdown, event, ev_link); + ENQUEUE(task->events, event, ev_link); + task->nevents++; + } + } + + return (was_idle); +} + +/* + * Moves a task onto the appropriate run queue. + * + * Caller must NOT hold manager lock. + */ +static inline void +task_ready(isc__task_t *task) { + isc__taskmgr_t *manager = task->manager; + + REQUIRE(VALID_MANAGER(manager)); + REQUIRE(task->state == task_state_ready); + + XTRACE("task_ready"); + + push_readyq(manager, task); +} + +static inline isc_boolean_t +task_detach(isc__task_t *task) { + + /* + * Caller must be holding the task lock. + */ + + REQUIRE(task->references > 0); + + XTRACE("detach"); + + task->references--; + if (task->references == 0 && task->state == task_state_idle) { + INSIST(EMPTY(task->events)); + /* + * There are no references to this task, and no + * pending events. We could try to optimize and + * either initiate shutdown or clean up the task, + * depending on its state, but it's easier to just + * make the task ready and allow run() or the event + * loop to deal with shutting down and termination. + */ + task->state = task_state_ready; + return (ISC_TRUE); + } + + return (ISC_FALSE); +} + +void +isc__task_detach(isc_task_t **taskp) { + isc__task_t *task; + isc_boolean_t was_idle; + + /* + * Detach *taskp from its task. + */ + + REQUIRE(taskp != NULL); + task = (isc__task_t *)*taskp; + REQUIRE(VALID_TASK(task)); + + XTRACE("isc_task_detach"); + + was_idle = task_detach(task); + + if (was_idle) + task_ready(task); + + *taskp = NULL; +} + +static inline isc_boolean_t +task_send(isc__task_t *task, isc_event_t **eventp) { + isc_boolean_t was_idle = ISC_FALSE; + isc_event_t *event; + + /* + * Caller must be holding the task lock. + */ + + REQUIRE(eventp != NULL); + event = *eventp; + REQUIRE(event != NULL); + REQUIRE(event->ev_type > 0); + REQUIRE(task->state != task_state_done); + REQUIRE(!ISC_LINK_LINKED(event, ev_ratelink)); + + XTRACE("task_send"); + + if (task->state == task_state_idle) { + was_idle = ISC_TRUE; + INSIST(EMPTY(task->events)); + task->state = task_state_ready; + } + INSIST(task->state == task_state_ready || + task->state == task_state_running); + ENQUEUE(task->events, event, ev_link); + task->nevents++; + *eventp = NULL; + + return (was_idle); +} + +void +isc__task_send(isc_task_t *task0, isc_event_t **eventp) { + isc__task_t *task = (isc__task_t *)task0; + isc_boolean_t was_idle; + + /* + * Send '*event' to 'task'. + */ + + REQUIRE(VALID_TASK(task)); + + XTRACE("isc_task_send"); + + /* + * We're trying hard to hold locks for as short a time as possible. + * We're also trying to hold as few locks as possible. This is why + * some processing is deferred until after the lock is released. + */ + was_idle = task_send(task, eventp); + + if (was_idle) { + /* + * We need to add this task to the ready queue. + * + * We've waited until now to do it because making a task + * ready requires locking the manager. If we tried to do + * this while holding the task lock, we could deadlock. + * + * We've changed the state to ready, so no one else will + * be trying to add this task to the ready queue. The + * only way to leave the ready state is by executing the + * task. It thus doesn't matter if events are added, + * removed, or a shutdown is started in the interval + * between the time we released the task lock, and the time + * we add the task to the ready queue. + */ + task_ready(task); + } +} + +void +isc__task_sendanddetach(isc_task_t **taskp, isc_event_t **eventp) { + isc_boolean_t idle1, idle2; + isc__task_t *task; + + /* + * Send '*event' to '*taskp' and then detach '*taskp' from its + * task. + */ + + REQUIRE(taskp != NULL); + task = (isc__task_t *)*taskp; + REQUIRE(VALID_TASK(task)); + + XTRACE("isc_task_sendanddetach"); + + idle1 = task_send(task, eventp); + idle2 = task_detach(task); + + /* + * If idle1, then idle2 shouldn't be true as well since we're holding + * the task lock, and thus the task cannot switch from ready back to + * idle. + */ + INSIST(!(idle1 && idle2)); + + if (idle1 || idle2) + task_ready(task); + + *taskp = NULL; +} + +#define PURGE_OK(event) (((event)->ev_attributes & ISC_EVENTATTR_NOPURGE) == 0) + +static unsigned int +dequeue_events(isc__task_t *task, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag, + isc_eventlist_t *events, isc_boolean_t purging) +{ + isc_event_t *event, *next_event; + unsigned int count = 0; + + REQUIRE(VALID_TASK(task)); + REQUIRE(last >= first); + + XTRACE("dequeue_events"); + + /* + * Events matching 'sender', whose type is >= first and <= last, and + * whose tag is 'tag' will be dequeued. If 'purging', matching events + * which are marked as unpurgable will not be dequeued. + * + * sender == NULL means "any sender", and tag == NULL means "any tag". + */ + + for (event = HEAD(task->events); event != NULL; event = next_event) { + next_event = NEXT(event, ev_link); + if (event->ev_type >= first && event->ev_type <= last && + (sender == NULL || event->ev_sender == sender) && + (tag == NULL || event->ev_tag == tag) && + (!purging || PURGE_OK(event))) { + DEQUEUE(task->events, event, ev_link); + task->nevents--; + ENQUEUE(*events, event, ev_link); + count++; + } + } + + return (count); +} + +unsigned int +isc__task_purgerange(isc_task_t *task0, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag) +{ + isc__task_t *task = (isc__task_t *)task0; + unsigned int count; + isc_eventlist_t events; + isc_event_t *event, *next_event; + + /* + * Purge events from a task's event queue. + */ + + XTRACE("isc_task_purgerange"); + + ISC_LIST_INIT(events); + + count = dequeue_events(task, sender, first, last, tag, &events, + ISC_TRUE); + + for (event = HEAD(events); event != NULL; event = next_event) { + next_event = NEXT(event, ev_link); + ISC_LIST_UNLINK(events, event, ev_link); + isc_event_free(&event); + } + + /* + * Note that purging never changes the state of the task. + */ + + return (count); +} + +unsigned int +isc__task_purge(isc_task_t *task, void *sender, isc_eventtype_t type, + void *tag) +{ + /* + * Purge events from a task's event queue. + */ + + XTRACE("isc_task_purge"); + + return (isc__task_purgerange(task, sender, type, type, tag)); +} + +isc_boolean_t +isc_task_purgeevent(isc_task_t *task0, isc_event_t *event) { + isc__task_t *task = (isc__task_t *)task0; + isc_event_t *curr_event, *next_event; + + /* + * Purge 'event' from a task's event queue. + * + * XXXRTH: WARNING: This method may be removed before beta. + */ + + REQUIRE(VALID_TASK(task)); + + /* + * If 'event' is on the task's event queue, it will be purged, + * unless it is marked as unpurgeable. 'event' does not have to be + * on the task's event queue; in fact, it can even be an invalid + * pointer. Purging only occurs if the event is actually on the task's + * event queue. + * + * Purging never changes the state of the task. + */ + + for (curr_event = HEAD(task->events); + curr_event != NULL; + curr_event = next_event) { + next_event = NEXT(curr_event, ev_link); + if (curr_event == event && PURGE_OK(event)) { + DEQUEUE(task->events, curr_event, ev_link); + task->nevents--; + break; + } + } + + if (curr_event == NULL) + return (ISC_FALSE); + + isc_event_free(&curr_event); + + return (ISC_TRUE); +} + +unsigned int +isc__task_unsendrange(isc_task_t *task, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag, + isc_eventlist_t *events) +{ + /* + * Remove events from a task's event queue. + */ + + XTRACE("isc_task_unsendrange"); + + return (dequeue_events((isc__task_t *)task, sender, first, + last, tag, events, ISC_FALSE)); +} + +unsigned int +isc__task_unsend(isc_task_t *task, void *sender, isc_eventtype_t type, + void *tag, isc_eventlist_t *events) +{ + /* + * Remove events from a task's event queue. + */ + + XTRACE("isc_task_unsend"); + + return (dequeue_events((isc__task_t *)task, sender, type, + type, tag, events, ISC_FALSE)); +} + +isc_result_t +isc__task_onshutdown(isc_task_t *task0, isc_taskaction_t action, + void *arg) +{ + isc__task_t *task = (isc__task_t *)task0; + isc_boolean_t disallowed = ISC_FALSE; + isc_result_t result = ISC_R_SUCCESS; + isc_event_t *event; + + /* + * Send a shutdown event with action 'action' and argument 'arg' when + * 'task' is shutdown. + */ + + REQUIRE(VALID_TASK(task)); + REQUIRE(action != NULL); + + event = isc_event_allocate(NULL, + ISC_TASKEVENT_SHUTDOWN, + action, + arg, + sizeof(*event)); + if (event == NULL) + return (ISC_R_NOMEMORY); + + if (TASK_SHUTTINGDOWN(task)) { + disallowed = ISC_TRUE; + result = ISC_R_SHUTTINGDOWN; + } else + ENQUEUE(task->on_shutdown, event, ev_link); + + if (disallowed) + free(event); + + return (result); +} + +void +isc__task_shutdown(isc_task_t *task0) { + isc__task_t *task = (isc__task_t *)task0; + isc_boolean_t was_idle; + + /* + * Shutdown 'task'. + */ + + REQUIRE(VALID_TASK(task)); + + was_idle = task_shutdown(task); + + if (was_idle) + task_ready(task); +} + +void +isc__task_destroy(isc_task_t **taskp) { + + /* + * Destroy '*taskp'. + */ + + REQUIRE(taskp != NULL); + + isc_task_shutdown(*taskp); + isc_task_detach(taskp); +} + +void +isc__task_setname(isc_task_t *task0, const char *name, void *tag) { + isc__task_t *task = (isc__task_t *)task0; + + /* + * Name 'task'. + */ + + REQUIRE(VALID_TASK(task)); + + strlcpy(task->name, name, sizeof(task->name)); + task->tag = tag; +} + +const char * +isc__task_getname(isc_task_t *task0) { + isc__task_t *task = (isc__task_t *)task0; + + REQUIRE(VALID_TASK(task)); + + return (task->name); +} + +void * +isc__task_gettag(isc_task_t *task0) { + isc__task_t *task = (isc__task_t *)task0; + + REQUIRE(VALID_TASK(task)); + + return (task->tag); +} + +void +isc__task_getcurrenttime(isc_task_t *task0, isc_stdtime_t *t) { + isc__task_t *task = (isc__task_t *)task0; + + REQUIRE(VALID_TASK(task)); + REQUIRE(t != NULL); + + *t = task->now; +} + +/*** + *** Task Manager. + ***/ + +/* + * Return ISC_TRUE if the current ready list for the manager, which is + * either ready_tasks or the ready_priority_tasks, depending on whether + * the manager is currently in normal or privileged execution mode. + * + * Caller must hold the task manager lock. + */ +static inline isc_boolean_t +empty_readyq(isc__taskmgr_t *manager) { + isc__tasklist_t queue; + + if (manager->mode == isc_taskmgrmode_normal) + queue = manager->ready_tasks; + else + queue = manager->ready_priority_tasks; + + return (ISC_TF(EMPTY(queue))); +} + +/* + * Dequeue and return a pointer to the first task on the current ready + * list for the manager. + * If the task is privileged, dequeue it from the other ready list + * as well. + * + * Caller must hold the task manager lock. + */ +static inline isc__task_t * +pop_readyq(isc__taskmgr_t *manager) { + isc__task_t *task; + + if (manager->mode == isc_taskmgrmode_normal) + task = HEAD(manager->ready_tasks); + else + task = HEAD(manager->ready_priority_tasks); + + if (task != NULL) { + DEQUEUE(manager->ready_tasks, task, ready_link); + if (ISC_LINK_LINKED(task, ready_priority_link)) + DEQUEUE(manager->ready_priority_tasks, task, + ready_priority_link); + } + + return (task); +} + +/* + * Push 'task' onto the ready_tasks queue. If 'task' has the privilege + * flag set, then also push it onto the ready_priority_tasks queue. + * + * Caller must hold the task manager lock. + */ +static inline void +push_readyq(isc__taskmgr_t *manager, isc__task_t *task) { + ENQUEUE(manager->ready_tasks, task, ready_link); + if ((task->flags & TASK_F_PRIVILEGED) != 0) + ENQUEUE(manager->ready_priority_tasks, task, + ready_priority_link); + manager->tasks_ready++; +} + +static void +dispatch(isc__taskmgr_t *manager) { + isc__task_t *task; + unsigned int total_dispatch_count = 0; + isc__tasklist_t new_ready_tasks; + isc__tasklist_t new_priority_tasks; + unsigned int tasks_ready = 0; + + REQUIRE(VALID_MANAGER(manager)); + + ISC_LIST_INIT(new_ready_tasks); + ISC_LIST_INIT(new_priority_tasks); + + while (!FINISHED(manager)) { + if (total_dispatch_count >= DEFAULT_TASKMGR_QUANTUM || + empty_readyq(manager)) + break; + XTHREADTRACE("working"); + + task = pop_readyq(manager); + if (task != NULL) { + unsigned int dispatch_count = 0; + isc_boolean_t done = ISC_FALSE; + isc_boolean_t requeue = ISC_FALSE; + isc_boolean_t finished = ISC_FALSE; + isc_event_t *event; + + INSIST(VALID_TASK(task)); + + /* + * Note we only unlock the manager lock if we actually + * have a task to do. We must reacquire the manager + * lock before exiting the 'if (task != NULL)' block. + */ + manager->tasks_ready--; + manager->tasks_running++; + + INSIST(task->state == task_state_ready); + task->state = task_state_running; + XTRACE("running"); + isc_stdtime_get(&task->now); + do { + if (!EMPTY(task->events)) { + event = HEAD(task->events); + DEQUEUE(task->events, event, ev_link); + task->nevents--; + + /* + * Execute the event action. + */ + XTRACE("execute action"); + if (event->ev_action != NULL) { + (event->ev_action)( + (isc_task_t *)task, + event); + } + dispatch_count++; + total_dispatch_count++; + } + + if (task->references == 0 && + EMPTY(task->events) && + !TASK_SHUTTINGDOWN(task)) { + isc_boolean_t was_idle; + + /* + * There are no references and no + * pending events for this task, + * which means it will not become + * runnable again via an external + * action (such as sending an event + * or detaching). + * + * We initiate shutdown to prevent + * it from becoming a zombie. + * + * We do this here instead of in + * the "if EMPTY(task->events)" block + * below because: + * + * If we post no shutdown events, + * we want the task to finish. + * + * If we did post shutdown events, + * will still want the task's + * quantum to be applied. + */ + was_idle = task_shutdown(task); + INSIST(!was_idle); + } + + if (EMPTY(task->events)) { + /* + * Nothing else to do for this task + * right now. + */ + XTRACE("empty"); + if (task->references == 0 && + TASK_SHUTTINGDOWN(task)) { + /* + * The task is done. + */ + XTRACE("done"); + finished = ISC_TRUE; + task->state = task_state_done; + } else + task->state = task_state_idle; + done = ISC_TRUE; + } else if (dispatch_count >= task->quantum) { + /* + * Our quantum has expired, but + * there is more work to be done. + * We'll requeue it to the ready + * queue later. + * + * We don't check quantum until + * dispatching at least one event, + * so the minimum quantum is one. + */ + XTRACE("quantum"); + task->state = task_state_ready; + requeue = ISC_TRUE; + done = ISC_TRUE; + } + } while (!done); + + if (finished) + task_finished(task); + + manager->tasks_running--; + if (requeue) { + /* + * We know we're awake, so we don't have + * to wakeup any sleeping threads if the + * ready queue is empty before we requeue. + * + * A possible optimization if the queue is + * empty is to 'goto' the 'if (task != NULL)' + * block, avoiding the ENQUEUE of the task + * and the subsequent immediate DEQUEUE + * (since it is the only executable task). + * We don't do this because then we'd be + * skipping the exit_requested check. The + * cost of ENQUEUE is low anyway, especially + * when you consider that we'd have to do + * an extra EMPTY check to see if we could + * do the optimization. If the ready queue + * were usually nonempty, the 'optimization' + * might even hurt rather than help. + */ + ENQUEUE(new_ready_tasks, task, ready_link); + if ((task->flags & TASK_F_PRIVILEGED) != 0) + ENQUEUE(new_priority_tasks, task, + ready_priority_link); + tasks_ready++; + } + } + + } + + ISC_LIST_APPENDLIST(manager->ready_tasks, new_ready_tasks, ready_link); + ISC_LIST_APPENDLIST(manager->ready_priority_tasks, new_priority_tasks, + ready_priority_link); + manager->tasks_ready += tasks_ready; + if (empty_readyq(manager)) + manager->mode = isc_taskmgrmode_normal; + +} + +static void +manager_free(isc__taskmgr_t *manager) { + + manager->common.impmagic = 0; + manager->common.magic = 0; + free(manager); + + taskmgr = NULL; +} + +isc_result_t +isc__taskmgr_create(unsigned int workers, + unsigned int default_quantum, isc_taskmgr_t **managerp) +{ + isc_result_t result; + unsigned int i, started = 0; + isc__taskmgr_t *manager; + + /* + * Create a new task manager. + */ + + REQUIRE(workers > 0); + REQUIRE(managerp != NULL && *managerp == NULL); + + UNUSED(i); + UNUSED(started); + + if (taskmgr != NULL) { + if (taskmgr->refs == 0) + return (ISC_R_SHUTTINGDOWN); + taskmgr->refs++; + *managerp = (isc_taskmgr_t *)taskmgr; + return (ISC_R_SUCCESS); + } + + manager = malloc(sizeof(*manager)); + if (manager == NULL) + return (ISC_R_NOMEMORY); + manager->common.methods = &taskmgrmethods; + manager->common.impmagic = TASK_MANAGER_MAGIC; + manager->common.magic = ISCAPI_TASKMGR_MAGIC; + manager->mode = isc_taskmgrmode_normal; + + if (default_quantum == 0) + default_quantum = DEFAULT_DEFAULT_QUANTUM; + manager->default_quantum = default_quantum; + INIT_LIST(manager->tasks); + INIT_LIST(manager->ready_tasks); + INIT_LIST(manager->ready_priority_tasks); + manager->tasks_running = 0; + manager->tasks_ready = 0; + manager->exclusive_requested = ISC_FALSE; + manager->pause_requested = ISC_FALSE; + manager->exiting = ISC_FALSE; + manager->excl = NULL; + + manager->refs = 1; + taskmgr = manager; + + *managerp = (isc_taskmgr_t *)manager; + + return (ISC_R_SUCCESS); + + free(manager); + return (result); +} + +void +isc__taskmgr_destroy(isc_taskmgr_t **managerp) { + isc__taskmgr_t *manager; + isc__task_t *task; + unsigned int i; + + /* + * Destroy '*managerp'. + */ + + REQUIRE(managerp != NULL); + manager = (isc__taskmgr_t *)*managerp; + REQUIRE(VALID_MANAGER(manager)); + + UNUSED(i); + + manager->refs--; + if (manager->refs > 0) { + *managerp = NULL; + return; + } + + XTHREADTRACE("isc_taskmgr_destroy"); + /* + * Only one non-worker thread may ever call this routine. + * If a worker thread wants to initiate shutdown of the + * task manager, it should ask some non-worker thread to call + * isc_taskmgr_destroy(), e.g. by signalling a condition variable + * that the startup thread is sleeping on. + */ + + /* + * Detach the exclusive task before acquiring the manager lock + */ + if (manager->excl != NULL) + isc__task_detach((isc_task_t **) &manager->excl); + + /* + * Make sure we only get called once. + */ + INSIST(!manager->exiting); + manager->exiting = ISC_TRUE; + + /* + * If privileged mode was on, turn it off. + */ + manager->mode = isc_taskmgrmode_normal; + + /* + * Post shutdown event(s) to every task (if they haven't already been + * posted). + */ + for (task = HEAD(manager->tasks); + task != NULL; + task = NEXT(task, link)) { + if (task_shutdown(task)) + push_readyq(manager, task); + } + /* + * Dispatch the shutdown events. + */ + while (isc__taskmgr_ready((isc_taskmgr_t *)manager)) + (void)isc__taskmgr_dispatch((isc_taskmgr_t *)manager); + INSIST(ISC_LIST_EMPTY(manager->tasks)); + taskmgr = NULL; + + manager_free(manager); + + *managerp = NULL; +} + +void +isc__taskmgr_setmode(isc_taskmgr_t *manager0, isc_taskmgrmode_t mode) { + isc__taskmgr_t *manager = (isc__taskmgr_t *)manager0; + + manager->mode = mode; +} + +isc_taskmgrmode_t +isc__taskmgr_mode(isc_taskmgr_t *manager0) { + isc__taskmgr_t *manager = (isc__taskmgr_t *)manager0; + isc_taskmgrmode_t mode; + mode = manager->mode; + return (mode); +} + +isc_boolean_t +isc__taskmgr_ready(isc_taskmgr_t *manager0) { + isc__taskmgr_t *manager = (isc__taskmgr_t *)manager0; + isc_boolean_t is_ready; + + if (manager == NULL) + manager = taskmgr; + if (manager == NULL) + return (ISC_FALSE); + + is_ready = !empty_readyq(manager); + + return (is_ready); +} + +isc_result_t +isc__taskmgr_dispatch(isc_taskmgr_t *manager0) { + isc__taskmgr_t *manager = (isc__taskmgr_t *)manager0; + + if (manager == NULL) + manager = taskmgr; + if (manager == NULL) + return (ISC_R_NOTFOUND); + + dispatch(manager); + + return (ISC_R_SUCCESS); +} + +void +isc_taskmgr_setexcltask(isc_taskmgr_t *mgr0, isc_task_t *task0) { + isc__taskmgr_t *mgr = (isc__taskmgr_t *) mgr0; + isc__task_t *task = (isc__task_t *) task0; + + REQUIRE(VALID_MANAGER(mgr)); + REQUIRE(VALID_TASK(task)); + if (mgr->excl != NULL) + isc__task_detach((isc_task_t **) &mgr->excl); + isc__task_attach(task0, (isc_task_t **) &mgr->excl); +} + +isc_result_t +isc_taskmgr_excltask(isc_taskmgr_t *mgr0, isc_task_t **taskp) { + isc__taskmgr_t *mgr = (isc__taskmgr_t *) mgr0; + isc_result_t result = ISC_R_SUCCESS; + + REQUIRE(VALID_MANAGER(mgr)); + REQUIRE(taskp != NULL && *taskp == NULL); + + if (mgr->excl != NULL) + isc__task_attach((isc_task_t *) mgr->excl, taskp); + else + result = ISC_R_NOTFOUND; + + return (result); +} + +isc_result_t +isc__task_beginexclusive(isc_task_t *task0) { + UNUSED(task0); + return (ISC_R_SUCCESS); +} + +void +isc__task_endexclusive(isc_task_t *task0) { + UNUSED(task0); +} + +void +isc__task_setprivilege(isc_task_t *task0, isc_boolean_t priv) { + isc__task_t *task = (isc__task_t *)task0; + isc__taskmgr_t *manager = task->manager; + isc_boolean_t oldpriv; + + oldpriv = ISC_TF((task->flags & TASK_F_PRIVILEGED) != 0); + if (priv) + task->flags |= TASK_F_PRIVILEGED; + else + task->flags &= ~TASK_F_PRIVILEGED; + + if (priv == oldpriv) + return; + + if (priv && ISC_LINK_LINKED(task, ready_link)) + ENQUEUE(manager->ready_priority_tasks, task, + ready_priority_link); + else if (!priv && ISC_LINK_LINKED(task, ready_priority_link)) + DEQUEUE(manager->ready_priority_tasks, task, + ready_priority_link); +} + +isc_boolean_t +isc__task_privilege(isc_task_t *task0) { + isc__task_t *task = (isc__task_t *)task0; + isc_boolean_t priv; + + priv = ISC_TF((task->flags & TASK_F_PRIVILEGED) != 0); + return (priv); +} + +isc_result_t +isc__task_register(void) { + return (isc_task_register(isc__taskmgr_create)); +} + +isc_boolean_t +isc_task_exiting(isc_task_t *t) { + isc__task_t *task = (isc__task_t *)t; + + REQUIRE(VALID_TASK(task)); + return (TASK_SHUTTINGDOWN(task)); +} + + +static isc_taskmgrcreatefunc_t taskmgr_createfunc = NULL; + +isc_result_t +isc_task_register(isc_taskmgrcreatefunc_t createfunc) { + isc_result_t result = ISC_R_SUCCESS; + + if (taskmgr_createfunc == NULL) + taskmgr_createfunc = createfunc; + else + result = ISC_R_EXISTS; + + return (result); +} + +isc_result_t +isc_taskmgr_createinctx(isc_appctx_t *actx, + unsigned int workers, unsigned int default_quantum, + isc_taskmgr_t **managerp) +{ + isc_result_t result; + + REQUIRE(taskmgr_createfunc != NULL); + result = (*taskmgr_createfunc)(workers, default_quantum, + managerp); + + if (result == ISC_R_SUCCESS) + isc_appctx_settaskmgr(actx, *managerp); + + return (result); +} + +isc_result_t +isc_taskmgr_create(unsigned int workers, + unsigned int default_quantum, isc_taskmgr_t **managerp) +{ + return (isc__taskmgr_create(workers, default_quantum, managerp)); +} + +void +isc_taskmgr_destroy(isc_taskmgr_t **managerp) { + REQUIRE(managerp != NULL && ISCAPI_TASKMGR_VALID(*managerp)); + + isc__taskmgr_destroy(managerp); + + ENSURE(*managerp == NULL); +} + +void +isc_taskmgr_setmode(isc_taskmgr_t *manager, isc_taskmgrmode_t mode) { + REQUIRE(ISCAPI_TASKMGR_VALID(manager)); + + isc__taskmgr_setmode(manager, mode); +} + +isc_taskmgrmode_t +isc_taskmgr_mode(isc_taskmgr_t *manager) { + REQUIRE(ISCAPI_TASKMGR_VALID(manager)); + + return (isc__taskmgr_mode(manager)); +} + +isc_result_t +isc_task_create(isc_taskmgr_t *manager, unsigned int quantum, + isc_task_t **taskp) +{ + REQUIRE(ISCAPI_TASKMGR_VALID(manager)); + REQUIRE(taskp != NULL && *taskp == NULL); + + return (isc__task_create(manager, quantum, taskp)); +} + +void +isc_task_attach(isc_task_t *source, isc_task_t **targetp) { + REQUIRE(ISCAPI_TASK_VALID(source)); + REQUIRE(targetp != NULL && *targetp == NULL); + + isc__task_attach(source, targetp); + + ENSURE(*targetp == source); +} + +void +isc_task_detach(isc_task_t **taskp) { + REQUIRE(taskp != NULL && ISCAPI_TASK_VALID(*taskp)); + + isc__task_detach(taskp); + + ENSURE(*taskp == NULL); +} + +void +isc_task_send(isc_task_t *task, isc_event_t **eventp) { + REQUIRE(ISCAPI_TASK_VALID(task)); + REQUIRE(eventp != NULL && *eventp != NULL); + + isc__task_send(task, eventp); +} + +void +isc_task_sendanddetach(isc_task_t **taskp, isc_event_t **eventp) { + REQUIRE(taskp != NULL && ISCAPI_TASK_VALID(*taskp)); + REQUIRE(eventp != NULL && *eventp != NULL); + + isc__task_sendanddetach(taskp, eventp); + + ENSURE(*taskp == NULL); +} + +unsigned int +isc_task_unsend(isc_task_t *task, void *sender, isc_eventtype_t type, + void *tag, isc_eventlist_t *events) +{ + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_unsend(task, sender, type, tag, events)); +} + +isc_result_t +isc_task_onshutdown(isc_task_t *task, isc_taskaction_t action, void *arg) +{ + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_onshutdown(task, action, arg)); +} + +void +isc_task_shutdown(isc_task_t *task) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + isc__task_shutdown(task); +} + +void +isc_task_destroy(isc_task_t **taskp) { + isc__task_destroy(taskp); +} + +void +isc_task_setname(isc_task_t *task, const char *name, void *tag) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + isc__task_setname(task, name, tag); +} + +unsigned int +isc_task_purge(isc_task_t *task, void *sender, isc_eventtype_t type, void *tag) +{ + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_purge(task, sender, type, tag)); +} + +isc_result_t +isc_task_beginexclusive(isc_task_t *task) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_beginexclusive(task)); +} + +void +isc_task_endexclusive(isc_task_t *task) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + isc__task_endexclusive(task); +} + +void +isc_task_setprivilege(isc_task_t *task, isc_boolean_t priv) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + isc__task_setprivilege(task, priv); +} + +isc_boolean_t +isc_task_privilege(isc_task_t *task) { + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_privilege(task)); +} + +void +isc_task_getcurrenttime(isc_task_t *task, isc_stdtime_t *t) { + isc__task_getcurrenttime(task, t); +} + +/*% + * This is necessary for libisc's internal timer implementation. Other + * implementation might skip implementing this. + */ +unsigned int +isc_task_purgerange(isc_task_t *task, void *sender, isc_eventtype_t first, + isc_eventtype_t last, void *tag) +{ + REQUIRE(ISCAPI_TASK_VALID(task)); + + return (isc__task_purgerange(task, sender, first, last, tag)); +} |