debug-flow.R

require(R6)
# depends: {purrr}, {tibble}, {tidy} for graph conversion

Step = R6Class("Step", list(
  id = NA,
  stage = NA,
  state = NA,
  parent = NA,
  children = list(),
  open = TRUE,
  initialize = function(id, parent, stage = NA, state = NA){
    self$id = id
    self$parent = parent
    self$stage = stage
    self$state = state
  },
  add_child = function(id){ self$children = c(self$children, id) }
))

Process = R6Class("Process", list(
  graph = list(),
  tree = c(1),
  k = 1,
  initialize = function(){ self$graph[[1]] = Step$new(1, NA, 'root', NA) },
  add = function(stage = NA, state = NA){
    self$k = self$k + 1  # iterate to next ID
    parent = self$tree[length(self$tree)]
    self$graph[[parent]]$add_child(self$k) # fails
    self$graph[[self$k]] = Step$new(self$k, parent, stage, state)
    self$tree = c(self$tree, self$k)
    return(self$k)
  },
  close = function(){ self$tree = self$tree[-length(self$tree)] }
))

trace_nodes = function(x){
  purrr::map_df(x$graph, ~ tibble::tibble(id = .x$id, stage = .x$stage, state = .x$state))
}

trace_edges = function(x){
  tidyr::unnest(purrr::map_df(x$graph, ~ tibble::tibble(from = .x$id, to = .x$children)), to)
}

trace_to_graph = function(x){
  nodes = trace_nodes(x)
  edges = trace_edges(x)
  tidygraph::tbl_graph(nodes = nodes, edges = edges)
}


#-------------------------------------------------------------

# EXAMPLE USAGE

# requires {stringr}

test_fun = function(max_depth, min_children = 0){
  
  stage_name = sample(stringr::words,1)  # any unique identifier for the function
  state_val = head(iris,sample(150)[1])  # any state information you wish to log
  
  # the important bit
  trace$add(stage_name, list(state_val))  # registers the process
  on.exit(expr = trace$close())           # set callback to log exit
  
  if(max_depth == 0) return()
  n = max(min_children, sample(0:2 ,1))
  if(n > 0) for(i in 1:n) test_fun(max_depth-1)
}

# initialise the logger
trace = Process$new()

# simulate some sequences of function calls
test_fun(4, 3)
test_fun(3, 2)

# visualise the flow
require(ggraph)
require(tidygraph)

trace_nodes(trace)
g = trace_to_graph(trace)

g %>% activate(nodes) %>% mutate(state = purrr::map_dbl(state, object.size)) %>% 
  ggraph('tree') +
  geom_edge_elbow() +
  geom_node_label(aes(label = paste0(id, '. <', stage, '>\n\nsize: ', state)))