Speed up dependency graph construction

DESCRIPTION

@@ -12,7 +12,7 @@ Description: Pipeline tools coordinate the pieces of computationally
   The methodology in this package
   borrows from GNU 'Make' (2015, ISBN:978-9881443519)
   and 'drake' (2018, <doi:10.21105/joss.00550>).
-Version: 1.7.0.9001
+Version: 1.7.0.9002
 License: MIT + file LICENSE
 URL: https://docs.ropensci.org/targets/, https://github.com/ropensci/targets
 BugReports: https://github.com/ropensci/targets/issues

NEWS.md

@@ -1,6 +1,7 @@
-# targets 1.7.0.9001 (development)
+# targets 1.7.0.9002 (development)
 
 * Use `bslib` in `tar_watch()`.
+* Speed up `target_upstream_edges()` and `pipeline_upstream_edges()` by avoiding data frames until the last minute (17% speedup for certain kinds of large pipelines).
 
 # targets 1.7.0
 

R/class_pipeline.R

@@ -106,9 +106,15 @@ pipeline_targets_only_edges <- function(edges) {
 
 pipeline_upstream_edges <- function(pipeline, targets_only = TRUE) {
   edge_list <- map(pipeline$targets, ~target_upstream_edges(.x))
-  edges <- do.call(rbind, edge_list)
+  from <- map(edge_list, ~.x$from)
+  to <- map(edge_list, ~.x$to)
+  from <- unlist(from, recursive = FALSE, use.names = FALSE)
+  to <- unlist(to, recursive = FALSE, use.names = FALSE)
+  edges <- data_frame(from = from, to = to)
   edges <- if_any(targets_only, pipeline_targets_only_edges(edges), edges)
-  edges <- edges %|||% data_frame(from = character(0), to = character(0))
+  if (ncol(edges) < 2L) {
+    edges <- data_frame(from = character(0), to = character(0))
+  }
   rownames(edges) <- NULL
   edges
 }

R/class_target.R

@@ -140,7 +140,7 @@ target_upstream_edges <- function(target) {
   name <- target_get_name(target)
   from <- c(name, target$command$deps)
   to <- rep(name, length(from))
-  data_frame(from = from, to = to)
+  list(from = from, to = to)
 }
 
 target_update_queue <- function(target, scheduler) {

tests/testthat/test-class_target.R

@@ -117,7 +117,7 @@ tar_test("target_downstream_nonbranching()", {
 tar_test("target_upstream_edges()", {
   skip_cran()
   x <- target_init(name = "x", expr = quote(a + b))
-  e <- remove_loops(target_upstream_edges(x))
+  e <- remove_loops(as.data.frame(target_upstream_edges(x)))
   expect_true(is.data.frame(e))
   expect_equal(dim(e), c(3L, 2L))
   expect_equal(unique(e$to), "x")