build_site() fails if http user dir cache is present but empty.

[fwimp]

This is a very strange one, and I'm not precisely sure how my installation got into this state. For context I am using windows, so can't confirm that this is reproducible on OSX/Linux.

However in the case where the http cache at tools::R_user_dir("pkgdown", "cache"), "http") is present but contains no data, build_site() fails.

The root cause of this failure is in the function cran_link().

see build-home-index.R@L192

It seems that httr2 is reading the cache as present, and trying to load data from it, however given that there is no data, the underlying readRDS() call fails.

Whilst at its root this is possibly overall an httr2 issue more than a pkgdown issue, it'd be useful to either have mitigation for a corrupted httr2 cache hit, or at least a warning to the user to try deleting the http cache file.

Deleting the http cache file fixes the error and the build succeeds.

Steps to reproduce

1. Open the cache file *.rds located at the directory specified by tools::R_user_dir("pkgdown", "cache"), "http") in a text editor.
2. Delete all data in the file and save.
3. Run build_site() as usual.

Full stack traces

Console output

── Building home ───────────────────────────────────────────────────────────────
Reading LICENSE.md
Error: 
! in callr subprocess.
Caused by error in `readRDS(path)`:
! error reading from connection
ℹ See `$stdout` and `$stderr` for standard output and error.
Type .Last.error to see the more details.

Full stack trace (from .Last.error)

Reading LICENSE.md
Error: 
! in callr subprocess.
Caused by error in `readRDS(path)`:
! error reading from connection
ℹ See `$stdout` and `$stderr` for standard output and error.
Type .Last.error to see the more details.
> .Last.error
<callr_error/rlib_error_3_0/rlib_error/error>
Error: 
! in callr subprocess.
Caused by error in `readRDS(path)`:
! error reading from connection
ℹ See `$stdout` and `$stderr` for standard output and error.
---
Backtrace:
1. pkgdown::build_site()
4. pkgdown:::build_site_external(pkg = pkg, examples = examples, run_dont_run = run_dont_run, …
5. callr::r(function(..., cli_colors, hyperlinks, pkgdown_internet) { …
6. callr:::get_result(output = out, options)
7. callr:::throw(callr_remote_error(remerr, output), parent = fix_msg(remerr[[3]]))
---
Subprocess backtrace:
 1. pkgdown::build_site(...)
 2. pkgdown:::build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, …
 3. pkgdown::build_home(pkg, override = override, preview = FALSE)
 4. pkgdown::build_home_index(pkg, quiet = quiet)
 5. pkgdown:::data_home(pkg)
 8. pkgdown:::print_yaml(list(pagetitle = title, sidebar = data_home_sidebar(pkg, …
 9. base::structure(x, class = "print_yaml")
 10. pkgdown:::data_home_sidebar(pkg, call = call)
 11. pkgdown:::data_home_sidebar_links(pkg)
12. pkgdown:::cran_link(pkg$package)
13. httr2::req_perform(req)
14. httr2:::cache_pre_fetch(req)
15. httr2:::resp_cache_info(cache_get(req))
16. httr2:::resp_cache_expires(resp, control)
17. control %||% resp_cache_control(resp)
18. httr2:::resp_cache_control(resp)
19. httr2::resp_header(resp, "Cache-Control")
20. httr2:::check_response(resp)
21. httr2:::is_response(resp)
22. httr2:::cache_get(req)
23. base::readRDS(path)
24. base::.handleSimpleError(function (e) …
25. global h(simpleError(msg, call))

[hadley]

Do you have the latest httr2 installed?

[jayhesselberth]

The dev version has pkgdown::clean_cache() to address this issue, which is also fixed in the new httr2 release.

[fwimp]

Ahh, I'd installed httr2 a few weeks ago, and hadn't seen 1.0.2 come out last week. Installing that fixes the problem at its root.

Also missed #2696 which mentioned this same issue.

Thank you both!

[fwimp]

@hadley Weirdly, this is still happening occasionally on httr2 version 1.0.2! It is inconsistent though as a re-run shortly after fixed the problem.

Not precisely sure where this should go as it's not quite a pkgdown issue, but figured it was best to still document the issue as I saw it.

── Building home ───────────────────────────────────────────────────────────────
Writing authors.html
Reading pkg_dev_notes.md
Writing pkg_dev_notes.html
Reading LICENSE.md
Writing LICENSE.html
Error: 
! in callr subprocess.
Caused by error in `readRDS(path)`:
! error reading from connection
ℹ See `$stdout` and `$stderr` for standard output and error.
Type .Last.error to see the more details.

Backtrace

> .Last.error
<callr_error/rlib_error_3_0/rlib_error/error>
Error: 
! in callr subprocess.
Caused by error in `readRDS(path)`:
! error reading from connection
ℹ See `$stdout` and `$stderr` for standard output and error.
---
Backtrace:
1. pkgdown::build_site()
2. pkgdown:::build_site_external(pkg = pkg, examples = examples, run_dont_run = run_dont_run, …
3. callr::r(function(..., cli_colors, hyperlinks, pkgdown_internet) { …
4. callr:::get_result(output = out, options)
5. callr:::throw(callr_remote_error(remerr, output), parent = fix_msg(remerr[[3]]))
---
Subprocess backtrace:
 1. pkgdown::build_site(...)
 2. pkgdown:::build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, …
 3. pkgdown::build_home(pkg, override = override, preview = FALSE)
 4. pkgdown::build_home_index(pkg, quiet = quiet)
 5. pkgdown:::data_home(pkg)
 6. pkgdown:::print_yaml(list(pagetitle = title, sidebar = data_home_sidebar(pkg, …
 7. base::structure(x, class = "print_yaml")
 8. pkgdown:::data_home_sidebar(pkg, call = call)
 9. pkgdown:::data_home_sidebar_links(pkg)
10. pkgdown:::cran_link(pkg$package)
11. httr2::req_perform(req)
12. httr2:::cache_pre_fetch(req)
13. httr2:::resp_cache_info(cache_get(req))
14. httr2:::resp_cache_expires(resp, control)
15. control %||% resp_cache_control(resp)
16. httr2:::resp_cache_control(resp)
17. httr2::resp_header(resp, "Cache-Control")
18. httr2:::check_response(resp)
19. httr2:::is_response(resp)
20. httr2:::cache_get(req)
21. base::readRDS(path)
22. base::.handleSimpleError(function (e) …
23. global h(simpleError(msg, call))

[jayhesselberth]

@fwimp

Try cleaning your cache, then re-build.

# install.pakcages("pak")
pak::pak("r-lib/pkgdown")
pkgdown::clean_cache()
pkgdown::build_site()

[fwimp]

Ah alas I had already fixed it by deleting that same cache manually, otherwise I would have tested this route.

Not entirely sure why this continues to happen, should probably shift to an httr2 issue if it happens further.

Thank you!

[francisbarton]

Cache clearance also fixed the same issue for me

[hadley]

This bug is definitively fixed in httr2 1.0.3.