/* Copyright (C) 2005-2013 Shugo Maeda <shugo@ruby-lang.org> and Charlie Savage <cfis@savagexi.com>
   Please see the LICENSE file for copyright and distribution information */

#include "rp_stack.h"

#define INITIAL_STACK_SIZE 8

void
prof_frame_pause(prof_frame_t *frame, double current_measurement)
{
    if (frame && prof_frame_is_unpaused(frame))
        frame->pause_time = current_measurement;
}

void
prof_frame_unpause(prof_frame_t *frame, double current_measurement)
{
    if (frame && prof_frame_is_paused(frame)) {
        frame->dead_time += (current_measurement - frame->pause_time);
        frame->pause_time = -1;
    }
}


/* Creates a stack of prof_frame_t to keep track
   of timings for active methods. */
prof_stack_t *
prof_stack_create()
{
    prof_stack_t *stack = ALLOC(prof_stack_t);
    stack->start = ALLOC_N(prof_frame_t, INITIAL_STACK_SIZE);
    stack->ptr = stack->start;
    stack->end = stack->start + INITIAL_STACK_SIZE;

    return stack;
}

void
prof_stack_free(prof_stack_t *stack)
{
    xfree(stack->start);
    xfree(stack);
}

prof_frame_t *
prof_stack_push(prof_stack_t *stack, double measurement)
{
  prof_frame_t* result = NULL;

  /* Is there space on the stack?  If not, double
     its size. */
  if (stack->ptr == stack->end  )   
  {
    size_t len = stack->ptr - stack->start;
    size_t new_capacity = (stack->end - stack->start) * 2;
    REALLOC_N(stack->start, prof_frame_t, new_capacity);
    /* Memory just got moved, reset pointers */
    stack->ptr = stack->start + len;
    stack->end = stack->start + new_capacity;
  }

  // Setup returned stack pointer to be valid
  result = stack->ptr;
  result->child_time = 0;
  result->switch_time = 0;
  result->wait_time = 0;
  result->dead_time = 0;
  result->depth = (int)(stack->ptr - stack->start); // shortening of 64 bit into 32
  result->start_time = measurement;

  // Increment the stack ptr for next time
  stack->ptr++;

  // Return the result
  return result;
}

prof_frame_t *
prof_stack_pop(prof_stack_t *stack, double measurement)
{
  prof_frame_t *frame = NULL;
  prof_frame_t* parent_frame = NULL;
  prof_call_info_t *call_info;

  double total_time;
  double self_time;

  /* Frame can be null.  This can happen if RubProf.start is called from
     a method that exits.  And it can happen if an exception is raised
     in code that is being profiled and the stack unwinds (RubyProf is
     not notified of that by the ruby runtime. */
  if (stack->ptr == stack->start)
    return NULL;
  
  frame = --stack->ptr;

  /* Calculate the total time this method took */
  prof_frame_unpause(frame, measurement);
  total_time = measurement - frame->start_time - frame->dead_time;
  self_time = total_time - frame->child_time - frame->wait_time;

  /* Update information about the current method */
  call_info = frame->call_info;
  call_info->called++;
  call_info->total_time += total_time;
  call_info->self_time += self_time;
  call_info->wait_time += frame->wait_time;

  parent_frame = prof_stack_peek(stack);
  if (parent_frame)
  {
      parent_frame->child_time += total_time;
      parent_frame->dead_time += frame->dead_time;

      call_info->line = parent_frame->line;
  }

  return frame;
}

prof_frame_t *
prof_stack_peek(prof_stack_t *stack)
{
    if (stack->ptr == stack->start)
      return NULL;
    else
      return stack->ptr - 1;
}