Import and export targets to and from drake caches

[wlandau]

Summary

This PR implements serious methods in the decorated storr API to import and export targets to and from drake caches.

Note: importing targets does not import history. Importing history is an all-or-nothing action managed directly with txtq (requires txtq >= 0.1.9002).

library(drake)
# You can import and export targets to and from decorated storrs.
plan1 <- drake_plan(w = "w", x = "x")
plan2 <- drake_plan(a = "a", x = "x2")
cache1 <- new_cache("cache1")
cache2 <- new_cache("cache2")
make(plan1, cache = cache1)
#> target w
#> target x
make(plan2, cache = cache2)
#> target a
#> target x
cache1$import(cache2, a)
cache1$get("a")
#> [1] "a"
cache1$get("x")
#> [1] "x"
cache1$import(cache2)
cache1$get("x")
#> [1] "x2"
# With txtq >= 0.1.6.9002 (on GitHub)
# you can import history from one cache into another.
# Regular import() does not do this.
drake_history(cache = cache1)
#> # A tibble: 2 x 8
#>   target current built             exists hash      command    seed runtime
#>   <chr>  <lgl>   <chr>             <lgl>  <chr>     <chr>     <int>   <dbl>
#> 1 w      TRUE    2019-09-28 21:43… TRUE   5a88927b… "\"w\""  1.98e9   0.001
#> 2 x      FALSE   2019-09-28 21:43… TRUE   7a3f077a… "\"x\""  1.06e9   0.001
cache1$history$import(cache2$history)
drake_history(cache = cache1)
#> # A tibble: 4 x 8
#>   target current built             exists hash      command    seed runtime
#>   <chr>  <lgl>   <chr>             <lgl>  <chr>     <chr>     <int>   <dbl>
#> 1 a      TRUE    2019-09-28 21:43… TRUE   8568aa40… "\"a\""  1.67e9   0    
#> 2 w      TRUE    2019-09-28 21:43… TRUE   5a88927b… "\"w\""  1.98e9   0.001
#> 3 x      FALSE   2019-09-28 21:43… TRUE   7a3f077a… "\"x\""  1.06e9   0.001
#> 4 x      TRUE    2019-09-28 21:43… TRUE   531cde55… "\"x2\…  1.06e9   0

^{Created on 2019-09-28 by the reprex package (v0.3.0)}

Related GitHub issues and pull requests

• Ref: Import drake caches into other drake caches #1015

Checklist

• I understand and agree to drake's code of conduct.
• I have listed any substantial changes in the development news.
• I have added testthat unit tests to tests/testthat for any new functionality.
• This pull request is not a draft.

[wlandau]

cc @billdenney and @noamross

[codecov-io]

Codecov Report

Merging #1021 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #1021   +/-   ##
======================================
  Coverage     100%    100%           
======================================
  Files          46      46           
  Lines        6494    6536   +42     
======================================
+ Hits         6494    6536   +42

Impacted Files	Coverage Δ
R/cache.R	100% <ø> (ø)	⬆️
R/utils.R	100% <100%> (ø)	⬆️
R/decorate_storr.R	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 30e49a8...b856d60. Read the comment docs.