/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup genericproc
 * @{
 */

/**
 * @file
 * @brief	Task management.
 */

#include <main/uinit.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <proc/uarg.h>
#include <mm/as.h>
#include <mm/slab.h>
#include <atomic.h>
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <arch.h>
#include <panic.h>
#include <adt/btree.h>
#include <adt/list.h>
#include <ipc/ipc.h>
#include <security/cap.h>
#include <memstr.h>
#include <print.h>
#include <lib/elf.h>
#include <errno.h>
#include <func.h>
#include <syscall/copy.h>

#ifndef LOADED_PROG_STACK_PAGES_NO
#define LOADED_PROG_STACK_PAGES_NO 1
#endif

/** Spinlock protecting the tasks_btree B+tree. */
SPINLOCK_INITIALIZE(tasks_lock);

/** B+tree of active tasks.
 *
 * The task is guaranteed to exist after it was found in the tasks_btree as
 * long as:
 * @li the tasks_lock is held,
 * @li the task's lock is held when task's lock is acquired before releasing
 *     tasks_lock or
 * @li the task's refcount is greater than 0
 *
 */
btree_t tasks_btree;

static task_id_t task_counter = 0;

/** Initialize tasks
 *
 * Initialize kernel tasks support.
 *
 */
void task_init(void)
{
	TASK = NULL;
	btree_create(&tasks_btree);
}

/** Kill all tasks except the current task.
 *
 */
void task_done(void)
{
	task_t *t;
	do { /* Repeat until there are any tasks except TASK */
		
		/* Messing with task structures, avoid deadlock */
		ipl_t ipl = interrupts_disable();
		spinlock_lock(&tasks_lock);
		
		t = NULL;
		link_t *cur;
		for (cur = tasks_btree.leaf_head.next;
		    cur != &tasks_btree.leaf_head; cur = cur->next) {
			btree_node_t *node;
			
			node = list_get_instance(cur, btree_node_t, leaf_link);
			
			unsigned int i;
			for (i = 0; i < node->keys; i++) {
				if ((task_t *) node->value[i] != TASK) {
					t = (task_t *) node->value[i];
					break;
				}
			}
		}
		
		if (t != NULL) {
			task_id_t id = t->taskid;
			
			spinlock_unlock(&tasks_lock);
			interrupts_restore(ipl);
			
#ifdef CONFIG_DEBUG
			printf("Killing task %llu\n", id);
#endif			
			task_kill(id);
		} else {
			spinlock_unlock(&tasks_lock);
			interrupts_restore(ipl);
		}
		
	} while (t != NULL);
}

/** Create new task
 *
 * Create new task with no threads.
 *
 * @param as Task's address space.
 * @param name Symbolic name.
 *
 * @return New task's structure
 *
 */
task_t *task_create(as_t *as, char *name)
{
	ipl_t ipl;
	task_t *ta;
	int i;
	
	ta = (task_t *) malloc(sizeof(task_t), 0);

	task_create_arch(ta);

	spinlock_initialize(&ta->lock, "task_ta_lock");
	list_initialize(&ta->th_head);
	ta->as = as;
	ta->name = name;
	atomic_set(&ta->refcount, 0);
	atomic_set(&ta->lifecount, 0);
	ta->context = CONTEXT;

	ta->capabilities = 0;
	ta->cycles = 0;
	
	ipc_answerbox_init(&ta->answerbox);
	for (i = 0; i < IPC_MAX_PHONES; i++)
		ipc_phone_init(&ta->phones[i]);
	if ((ipc_phone_0) && (context_check(ipc_phone_0->task->context,
	    ta->context)))
		ipc_phone_connect(&ta->phones[0], ipc_phone_0);
	atomic_set(&ta->active_calls, 0);

	mutex_initialize(&ta->futexes_lock);
	btree_create(&ta->futexes);
	
	ipl = interrupts_disable();

	/*
	 * Increment address space reference count.
	 */
	atomic_inc(&as->refcount);

	spinlock_lock(&tasks_lock);
	ta->taskid = ++task_counter;
	btree_insert(&tasks_btree, (btree_key_t) ta->taskid, (void *) ta, NULL);
	spinlock_unlock(&tasks_lock);
	interrupts_restore(ipl);

	return ta;
}

/** Destroy task.
 *
 * @param t Task to be destroyed.
 */
void task_destroy(task_t *t)
{
	/*
	 * Remove the task from the task B+tree.
	 */
	spinlock_lock(&tasks_lock);
	btree_remove(&tasks_btree, t->taskid, NULL);
	spinlock_unlock(&tasks_lock);

	/*
	 * Perform architecture specific task destruction.
	 */
	task_destroy_arch(t);

	/*
	 * Free up dynamically allocated state.
	 */
	btree_destroy(&t->futexes);

	/*
	 * Drop our reference to the address space.
	 */
	if (atomic_predec(&t->as->refcount) == 0) 
		as_destroy(t->as);
	
	free(t);
	TASK = NULL;
}

/** Create new task with 1 thread and run it
 *
 * @param program_addr Address of program executable image.
 * @param name Program name. 
 *
 * @return Task of the running program or NULL on error.
 */
task_t *task_run_program(void *program_addr, char *name)
{
	as_t *as;
	as_area_t *a;
	int rc;
	thread_t *t;
	task_t *task;
	uspace_arg_t *kernel_uarg;

	as = as_create(0);
	ASSERT(as);

	rc = elf_load((elf_header_t *) program_addr, as);
	if (rc != EE_OK) {
		as_destroy(as);
		return NULL;
	} 
	
	kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
	kernel_uarg->uspace_entry =
	    (void *) ((elf_header_t *) program_addr)->e_entry;
	kernel_uarg->uspace_stack = (void *) USTACK_ADDRESS;
	kernel_uarg->uspace_thread_function = NULL;
	kernel_uarg->uspace_thread_arg = NULL;
	kernel_uarg->uspace_uarg = NULL;
	
	task = task_create(as, name);
	ASSERT(task);

	/*
	 * Create the data as_area.
	 */
	a = as_area_create(as, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE,
	    LOADED_PROG_STACK_PAGES_NO * PAGE_SIZE, USTACK_ADDRESS,
	    AS_AREA_ATTR_NONE, &anon_backend, NULL);

	/*
	 * Create the main thread.
	 */
	t = thread_create(uinit, kernel_uarg, task, THREAD_FLAG_USPACE,
	    "uinit", false);
	ASSERT(t);
	
	thread_ready(t);

	return task;
}

/** Syscall for reading task ID from userspace.
 *
 * @param uspace_task_id Userspace address of 8-byte buffer where to store
 * current task ID.
 *
 * @return 0 on success or an error code from @ref errno.h.
 */
unative_t sys_task_get_id(task_id_t *uspace_task_id)
{
	/*
	 * No need to acquire lock on TASK because taskid
	 * remains constant for the lifespan of the task.
	 */
	return (unative_t) copy_to_uspace(uspace_task_id, &TASK->taskid,
	    sizeof(TASK->taskid));
}

/** Find task structure corresponding to task ID.
 *
 * The tasks_lock must be already held by the caller of this function
 * and interrupts must be disabled.
 *
 * @param id Task ID.
 *
 * @return Task structure address or NULL if there is no such task ID.
 */
task_t *task_find_by_id(task_id_t id)
{
	btree_node_t *leaf;
	
	return (task_t *) btree_search(&tasks_btree, (btree_key_t) id, &leaf);
}

/** Get accounting data of given task.
 *
 * Note that task lock of 't' must be already held and
 * interrupts must be already disabled.
 *
 * @param t Pointer to thread.
 *
 */
uint64_t task_get_accounting(task_t *t)
{
	/* Accumulated value of task */
	uint64_t ret = t->cycles;
	
	/* Current values of threads */
	link_t *cur;
	for (cur = t->th_head.next; cur != &t->th_head; cur = cur->next) {
		thread_t *thr = list_get_instance(cur, thread_t, th_link);
		
		spinlock_lock(&thr->lock);
		/* Process only counted threads */
		if (!thr->uncounted) {
			if (thr == THREAD) {
				/* Update accounting of current thread */
				thread_update_accounting();
			} 
			ret += thr->cycles;
		}
		spinlock_unlock(&thr->lock);
	}
	
	return ret;
}

/** Kill task.
 *
 * This function is idempotent.
 * It signals all the task's threads to bail it out.
 *
 * @param id ID of the task to be killed.
 *
 * @return 0 on success or an error code from errno.h
 */
int task_kill(task_id_t id)
{
	ipl_t ipl;
	task_t *ta;
	link_t *cur;

	if (id == 1)
		return EPERM;
	
	ipl = interrupts_disable();
	spinlock_lock(&tasks_lock);
	if (!(ta = task_find_by_id(id))) {
		spinlock_unlock(&tasks_lock);
		interrupts_restore(ipl);
		return ENOENT;
	}
	spinlock_unlock(&tasks_lock);
	
	/*
	 * Interrupt all threads except ktaskclnp.
	 */
	spinlock_lock(&ta->lock);
	for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
		thread_t *thr;
		bool sleeping = false;
		
		thr = list_get_instance(cur, thread_t, th_link);
			
		spinlock_lock(&thr->lock);
		thr->interrupted = true;
		if (thr->state == Sleeping)
			sleeping = true;
		spinlock_unlock(&thr->lock);
		
		if (sleeping)
			waitq_interrupt_sleep(thr);
	}
	spinlock_unlock(&ta->lock);
	interrupts_restore(ipl);
	
	return 0;
}

/** Print task list */
void task_print_list(void)
{
	link_t *cur;
	ipl_t ipl;
	
	/* Messing with task structures, avoid deadlock */
	ipl = interrupts_disable();
	spinlock_lock(&tasks_lock);
	
	printf("taskid name       ctx address    as         cycles     threads "
	    "calls  callee\n");
	printf("------ ---------- --- ---------- ---------- ---------- ------- "
	    "------ ------>\n");

	for (cur = tasks_btree.leaf_head.next; cur != &tasks_btree.leaf_head;
	    cur = cur->next) {
		btree_node_t *node;
		unsigned int i;
		
		node = list_get_instance(cur, btree_node_t, leaf_link);
		for (i = 0; i < node->keys; i++) {
			task_t *t;
			int j;

			t = (task_t *) node->value[i];
		
			spinlock_lock(&t->lock);
			
			uint64_t cycles;
			char suffix;
			order(task_get_accounting(t), &cycles, &suffix);
			
			printf("%-6llu %-10s %-3ld %#10zx %#10zx %9llu%c %7zd "
			    "%6zd", t->taskid, t->name, t->context, t, t->as,
			    cycles, suffix, t->refcount,
			    atomic_get(&t->active_calls));
			for (j = 0; j < IPC_MAX_PHONES; j++) {
				if (t->phones[j].callee)
					printf(" %zd:%#zx", j,
					    t->phones[j].callee);
			}
			printf("\n");
			
			spinlock_unlock(&t->lock);
		}
	}

	spinlock_unlock(&tasks_lock);
	interrupts_restore(ipl);
}

/** @}
 */