/****************************************************************************
 * sched/pthread/pthread_create.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdbool.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <debug.h>
#include <assert.h>
#include <errno.h>

#include <nuttx/queue.h>
#include <nuttx/sched.h>
#include <nuttx/arch.h>
#include <nuttx/semaphore.h>
#include <nuttx/kmalloc.h>
#include <nuttx/pthread.h>

#include "sched/sched.h"
#include "group/group.h"
#include "clock/clock.h"
#include "pthread/pthread.h"
#include "tls/tls.h"

/****************************************************************************
 * Public Data
 ****************************************************************************/

/* Default pthread attributes (see include/nuttx/pthread.h).  When configured
 * to build separate kernel- and user-address spaces, this global is
 * duplicated in each address spaced.  This copy can only be shared within
 * the kernel address space.
 */

const pthread_attr_t g_default_pthread_attr = PTHREAD_ATTR_INITIALIZER;

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: pthread_tcb_setup
 *
 * Description:
 *   This function sets up parameters in the Task Control Block (TCB) in
 *   preparation for starting a new thread.
 *
 *   pthread_tcb_setup() is called from nxtask_init() and nxtask_start() to
 *   create a new task (with arguments cloned via strdup) or pthread_create()
 *   which has one argument passed by value (distinguished by the pthread
 *   boolean argument).
 *
 * Input Parameters:
 *   tcb        - Address of the new task's TCB
 *   trampoline - User space pthread startup function
 *   arg        - The argument to provide to the pthread on startup.
 *
 * Returned Value:
 *  None
 *
 ****************************************************************************/

static inline void pthread_tcb_setup(FAR struct pthread_tcb_s *ptcb,
                                     FAR struct tcb_s *parent,
                                     pthread_trampoline_t trampoline,
                                     pthread_addr_t arg)
{
#if CONFIG_TASK_NAME_SIZE > 0
  /* Copy the pthread name into the TCB */

  strlcpy(ptcb->cmn.name, parent->name, CONFIG_TASK_NAME_SIZE);
#endif /* CONFIG_TASK_NAME_SIZE */

  /* For pthreads, args are strictly pass-by-value; that actual
   * type wrapped by pthread_addr_t is unknown.
   */

  ptcb->trampoline = trampoline;
  ptcb->arg        = arg;
}

/****************************************************************************
 * Name:  pthread_start
 *
 * Description:
 *   This function is the low level entry point into the pthread
 *
 * Input Parameters:
 * None
 *
 ****************************************************************************/

static void pthread_start(void)
{
  FAR struct pthread_tcb_s *ptcb = (FAR struct pthread_tcb_s *)this_task();

  /* The priority of this thread may have been boosted to avoid priority
   * inversion problems.  If that is the case, then drop to the correct
   * execution priority.
   */

  if (ptcb->cmn.sched_priority > ptcb->cmn.init_priority)
    {
      DEBUGVERIFY(nxsched_set_priority(&ptcb->cmn, ptcb->cmn.init_priority));
    }

  /* Pass control to the thread entry point. In the kernel build this has to
   * be handled differently if we are starting a user-space pthread; we have
   * to switch to user-mode before calling into the pthread.
   */

  DEBUGASSERT(ptcb->trampoline != NULL && ptcb->cmn.entry.pthread != NULL);

#ifdef CONFIG_BUILD_FLAT
  ptcb->trampoline(ptcb->cmn.entry.pthread, ptcb->arg);
#else
  up_pthread_start(ptcb->trampoline, ptcb->cmn.entry.pthread, ptcb->arg);
#endif

  /* The thread has returned (should never happen) */

  DEBUGPANIC();
  pthread_exit(NULL);
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name:  nx_pthread_create
 *
 * Description:
 *   This function creates and activates a new thread with specified
 *   attributes.
 *
 * Input Parameters:
 *    trampoline - The user space startup function
 *    thread     - The pthread handle to be used
 *    attr       - It points to a pthread_attr_t structure whose contents are
 *                 used at thread creation time to determine attributes
 *                 for the new thread
 *    entry      - The new thread starts execution by invoking entry
 *    arg        - It is passed as the sole argument of entry
 *
 * Returned Value:
 *   OK (0) on success; a (non-negated) errno value on failure. The errno
 *   variable is not set.
 *
 ****************************************************************************/

int nx_pthread_create(pthread_trampoline_t trampoline, FAR pthread_t *thread,
                      FAR const pthread_attr_t *attr,
                      pthread_startroutine_t entry, pthread_addr_t arg)
{
  FAR struct pthread_tcb_s *ptcb;
  struct sched_param param;
  FAR struct tcb_s *parent;
  int policy;
  int errcode;
  pid_t pid;
  int ret;
  bool group_joined = false;

  DEBUGASSERT(trampoline != NULL);

  /* If attributes were not supplied, use the default attributes */

  if (!attr)
    {
      attr = &g_default_pthread_attr;
    }

  /* Allocate a TCB for the new task. */

  ptcb = (FAR struct pthread_tcb_s *)
            kmm_zalloc(sizeof(struct pthread_tcb_s));
  if (!ptcb)
    {
      serr("ERROR: Failed to allocate TCB\n");
      return ENOMEM;
    }

  /* Bind the parent's group to the new TCB (we have not yet joined the
   * group).
   */

  ret = group_bind(ptcb);
  if (ret < 0)
    {
      errcode = ENOMEM;
      goto errout_with_tcb;
    }

#ifdef CONFIG_ARCH_ADDRENV
  /* Share the address environment of the parent task group. */

  ret = addrenv_join(this_task(), (FAR struct tcb_s *)ptcb);
  if (ret < 0)
    {
      errcode = -ret;
      goto errout_with_tcb;
    }
#endif

  if (attr->detachstate == PTHREAD_CREATE_DETACHED)
    {
      ptcb->cmn.flags |= TCB_FLAG_DETACHED;
    }

  if (attr->stackaddr)
    {
      /* Use pre-allocated stack */

      ret = up_use_stack((FAR struct tcb_s *)ptcb, attr->stackaddr,
                         attr->stacksize);
    }
  else
    {
      /* Allocate the stack for the TCB */

      ret = up_create_stack((FAR struct tcb_s *)ptcb, attr->stacksize,
                            TCB_FLAG_TTYPE_PTHREAD);
    }

  if (ret != OK)
    {
      errcode = ENOMEM;
      goto errout_with_tcb;
    }

  /* Initialize thread local storage */

  ret = tls_init_info(&ptcb->cmn);
  if (ret != OK)
    {
      errcode = -ret;
      goto errout_with_tcb;
    }

  /* Should we use the priority and scheduler specified in the pthread
   * attributes?  Or should we use the current thread's priority and
   * scheduler?
   */

  if (attr->inheritsched == PTHREAD_INHERIT_SCHED)
    {
      /* Get the priority (and any other scheduling parameters) for this
       * thread.
       */

      ret = nxsched_get_param(0, &param);
      if (ret < 0)
        {
          errcode = -ret;
          goto errout_with_tcb;
        }

      /* Get the scheduler policy for this thread */

      policy = nxsched_get_scheduler(0);
      if (policy < 0)
        {
          errcode = -policy;
          goto errout_with_tcb;
        }
    }
  else
    {
      /* Use the scheduler policy and policy the attributes */

      policy                             = attr->policy;
      param.sched_priority               = attr->priority;

#ifdef CONFIG_SCHED_SPORADIC
      param.sched_ss_low_priority        = attr->low_priority;
      param.sched_ss_max_repl            = attr->max_repl;
      param.sched_ss_repl_period.tv_sec  = attr->repl_period.tv_sec;
      param.sched_ss_repl_period.tv_nsec = attr->repl_period.tv_nsec;
      param.sched_ss_init_budget.tv_sec  = attr->budget.tv_sec;
      param.sched_ss_init_budget.tv_nsec = attr->budget.tv_nsec;
#endif
    }

#ifdef CONFIG_SCHED_SPORADIC
  if (policy == SCHED_SPORADIC)
    {
      FAR struct sporadic_s *sporadic;
      sclock_t repl_ticks;
      sclock_t budget_ticks;

      /* Convert timespec values to system clock ticks */

      clock_time2ticks(&param.sched_ss_repl_period, &repl_ticks);
      clock_time2ticks(&param.sched_ss_init_budget, &budget_ticks);

      /* The replenishment period must be greater than or equal to the
       * budget period.
       */

      if (repl_ticks < budget_ticks)
        {
          errcode = EINVAL;
          goto errout_with_tcb;
        }

      /* Initialize the sporadic policy */

      ret = nxsched_initialize_sporadic(&ptcb->cmn);
      if (ret >= 0)
        {
          sporadic               = ptcb->cmn.sporadic;
          DEBUGASSERT(sporadic != NULL);

          /* Save the sporadic scheduling parameters */

          sporadic->hi_priority  = param.sched_priority;
          sporadic->low_priority = param.sched_ss_low_priority;
          sporadic->max_repl     = param.sched_ss_max_repl;
          sporadic->repl_period  = repl_ticks;
          sporadic->budget       = budget_ticks;

          /* And start the first replenishment interval */

          ret = nxsched_start_sporadic(&ptcb->cmn);
        }

      /* Handle any failures */

      if (ret < 0)
        {
          errcode = -ret;
          goto errout_with_tcb;
        }
    }
#endif

  /* Initialize the task control block */

  ret = pthread_setup_scheduler(ptcb, param.sched_priority, pthread_start,
                                entry);
  if (ret != OK)
    {
      errcode = EBUSY;
      goto errout_with_tcb;
    }

#if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
  /* Allocate the kernel stack */

  ret = up_addrenv_kstackalloc(&ptcb->cmn);
  if (ret < 0)
    {
      errcode = ENOMEM;
      goto errout_with_tcb;
    }
#endif

#ifdef CONFIG_SMP
  /* pthread_setup_scheduler() will set the affinity mask by inheriting the
   * setting from the parent task.  We need to override this setting
   * with the value from the pthread attributes unless that value is
   * zero:  Zero is the default value and simply means to inherit the
   * parent thread's affinity mask.
   */

  if (attr->affinity != 0)
    {
      ptcb->cmn.affinity = attr->affinity;
    }
#endif

  parent = this_task();
  DEBUGASSERT(parent != NULL);

  /* Configure the TCB for a pthread receiving on parameter
   * passed by value
   */

  pthread_tcb_setup(ptcb, parent, trampoline, arg);

  /* Join the parent's task group */

  ret = group_join(ptcb);
  if (ret < 0)
    {
      errcode = ENOMEM;
      goto errout_with_tcb;
    }

  group_joined = true;

  /* Set the appropriate scheduling policy in the TCB */

  ptcb->cmn.flags &= ~TCB_FLAG_POLICY_MASK;
  switch (policy)
    {
      default:
      case SCHED_FIFO:
        ptcb->cmn.flags    |= TCB_FLAG_SCHED_FIFO;
        break;

#if CONFIG_RR_INTERVAL > 0
      case SCHED_OTHER:
      case SCHED_RR:
        ptcb->cmn.flags    |= TCB_FLAG_SCHED_RR;
        ptcb->cmn.timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
        break;
#endif

#ifdef CONFIG_SCHED_SPORADIC
      case SCHED_SPORADIC:
        ptcb->cmn.flags    |= TCB_FLAG_SCHED_SPORADIC;
        break;
#endif
    }

#ifdef CONFIG_CANCELLATION_POINTS
  /* Set the deferred cancellation type */

  ptcb->cmn.flags |= TCB_FLAG_CANCEL_DEFERRED;
#endif

  /* Get the assigned pid before we start the task (who knows what
   * could happen to ptcb after this!).
   */

  pid = ptcb->cmn.pid;

  /* If the priority of the new pthread is lower than the priority of the
   * parent thread, then starting the pthread could result in both the
   * parent and the pthread to be blocked.  This is a recipe for priority
   * inversion issues.
   *
   * We avoid this here by boosting the priority of the (inactive) pthread
   * so it has the same priority as the parent thread.
   */

  if (ptcb->cmn.sched_priority < parent->sched_priority)
    {
      ret = nxsched_set_priority(&ptcb->cmn, parent->sched_priority);
      if (ret < 0)
        {
          ret = -ret;
        }
    }

  /* Then activate the task */

  sched_lock();
  if (ret == OK)
    {
      nxtask_activate((FAR struct tcb_s *)ptcb);

      /* Return the thread information to the caller */

      if (thread)
        {
          *thread = (pthread_t)pid;
        }

      sched_unlock();
    }
  else
    {
      sched_unlock();
      dq_rem((FAR dq_entry_t *)ptcb, &g_inactivetasks);

      errcode = EIO;
      goto errout_with_tcb;
    }

  return ret;

errout_with_tcb:

  /* Clear group binding */

  if (ptcb && !group_joined)
    {
      ptcb->cmn.group = NULL;
    }

  nxsched_release_tcb((FAR struct tcb_s *)ptcb, TCB_FLAG_TTYPE_PTHREAD);
  return errcode;
}