[R-package] manage Dataset and Booster handles as R external pointers (…

…fixes #3016) (#4265)

* started converting handles

* more changes

* sort of working for Dataset

* yay all the tests are passing for Dataset handle changes

* working for other handle types

* remove debugging logging

* remove unnecessary spaces

* fix null logic

* more NULL

* updates

* Apply suggestions from code review

Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* consolidate steps

Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

R-package/R/lgb.Booster.R

@@ -37,7 +37,7 @@ Booster <- R6::R6Class(
 
       # Create parameters and handle
       params <- append(params, list(...))
-      handle <- lgb.null.handle()
+      handle <- NULL
 
       # Attempts to create a handle for the dataset
       try({
@@ -52,11 +52,10 @@ Booster <- R6::R6Class(
           params <- modifyList(params, train_set$get_params())
           params_str <- lgb.params2str(params = params)
           # Store booster handle
-          .Call(
+          handle <- .Call(
             LGBM_BoosterCreate_R
             , train_set_handle
             , params_str
-            , handle
           )
 
           # Create private booster information
@@ -88,10 +87,9 @@ Booster <- R6::R6Class(
           }
 
           # Create booster from model
-          .Call(
+          handle <- .Call(
             LGBM_BoosterCreateFromModelfile_R
             , modelfile
-            , handle
           )
 
         } else if (!is.null(model_str)) {
@@ -102,10 +100,9 @@ Booster <- R6::R6Class(
           }
 
           # Create booster from model
-          .Call(
+          handle <- .Call(
             LGBM_BoosterLoadModelFromString_R
             , model_str
-            , handle
           )
 
         } else {

R-package/R/lgb.Dataset.R

@@ -192,41 +192,38 @@ Dataset <- R6::R6Class(
       if (!is.null(private$reference)) {
         ref_handle <- private$reference$.__enclos_env__$private$get_handle()
       }
-      handle <- lgb.null.handle()
 
       # Not subsetting
       if (is.null(private$used_indices)) {
 
         # Are we using a data file?
         if (is.character(private$raw_data)) {
 
-          .Call(
+          handle <- .Call(
             LGBM_DatasetCreateFromFile_R
             , private$raw_data
             , params_str
             , ref_handle
-            , handle
           )
 
         } else if (is.matrix(private$raw_data)) {
 
           # Are we using a matrix?
-          .Call(
+          handle <- .Call(
             LGBM_DatasetCreateFromMat_R
             , private$raw_data
             , nrow(private$raw_data)
             , ncol(private$raw_data)
             , params_str
             , ref_handle
-            , handle
           )
 
         } else if (methods::is(private$raw_data, "dgCMatrix")) {
           if (length(private$raw_data@p) > 2147483647L) {
             stop("Cannot support large CSC matrix")
           }
           # Are we using a dgCMatrix (sparsed matrix column compressed)
-          .Call(
+          handle <- .Call(
             LGBM_DatasetCreateFromCSC_R
             , private$raw_data@p
             , private$raw_data@i
@@ -236,7 +233,6 @@ Dataset <- R6::R6Class(
             , nrow(private$raw_data)
             , params_str
             , ref_handle
-            , handle
           )
 
         } else {
@@ -257,13 +253,12 @@ Dataset <- R6::R6Class(
         }
 
         # Construct subset
-        .Call(
+        handle <- .Call(
           LGBM_DatasetGetSubset_R
           , ref_handle
           , c(private$used_indices) # Adding c() fixes issue in R v3.5
           , length(private$used_indices)
           , params_str
-          , handle
         )
 
       }

R-package/R/lgb.Predictor.R

@@ -30,17 +30,15 @@ Predictor <- R6::R6Class(
     initialize = function(modelfile, ...) {
       params <- list(...)
       private$params <- lgb.params2str(params = params)
-      # Create new lgb handle
-      handle <- lgb.null.handle()
+      handle <- NULL
 
       # Check if handle is a character
       if (is.character(modelfile)) {
 
         # Create handle on it
-        .Call(
+        handle <- .Call(
           LGBM_BoosterCreateFromModelfile_R
           , modelfile
-          , handle
         )
         private$need_free_handle <- TRUE
 

R-package/R/utils.R

@@ -6,16 +6,13 @@ lgb.is.Dataset <- function(x) {
   return(lgb.check.r6.class(object = x, name = "lgb.Dataset"))
 }
 
-lgb.null.handle <- function() {
-  if (.Machine$sizeof.pointer == 8L) {
-    return(NA_real_)
-  } else {
-    return(NA_integer_)
-  }
-}
-
 lgb.is.null.handle <- function(x) {
-  return(is.null(x) || is.na(x))
+  if (is.null(x)) {
+    return(TRUE)
+  }
+  return(
+    isTRUE(.Call(LGBM_HandleIsNull_R, x))
+  )
 }
 
 # [description] Get the most recent error stored on the C++ side and raise it