[Rd] Different serialization of functions in interactive vs. batch mode

[Holger Hoefling]

Hi,

I posted this question to the regular help list, but it seems to be
this is probably a question that is better addressed on r-devel. Sorry
for the double posting.

I am using hash-values to cache certain results in R. This caching
also depends on the hash-value of the function that is being cached
(calculated using the digest package). I noticed that computations
that should already be cached are recomputed when switching from an
interactive session to a BATCH session. Therefore, I wrote a test
script

library(digest)
testfun <- function() {
    return(NULL)
}
testval <- "testval"
print(digest(testfun))
print(serialize(testfun, connection = NULL))

and executed it once using input-redirection from a file (testFile.R)
and once copying the code into an interactive R session. The
hash-values of the functions differ. As digest internally relies on
serialize, I also checked there and found that digest is not the
reason for the discrepancy. Instead, the serialized value of the
function already differs between the BATCH and inteactive sessions.

I was wondering if someone knows if
1. Is this a feature or a bug? It feels like a bug to me as all the
inputs are identical, I would expect that the output is identical as
well. Is there something I am overlooking?
2. Is there a way to get consistent hash-values for functions between
BATCH and interactive sessions.

The output from the BATCH and interactive runs are below (as well as
sessionInfo)

Thank you very much for your help!

Holger Hoefling

---------------------------------
BATCH run (via input redirection):

$ R --vanilla < testFile.R

R version 3.1.0 (2014-04-10) -- "Spring Dance"
Copyright (C) 2014 The R Foundation for Statistical Computing
Platform: x86_64-unknown-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(digest)
> testfun <- function() {
+     return(NULL)
+ }
> print(digest(testfun))
[1] "b03160b9250f0d5b5bcce42bd86d8e56"
> print(serialize(testfun, connection = NULL))
 [1] 58 0a 00 00 00 02 00 03 01 00 00 02 03 00 00 00 04 03 00 00 00 fd 00 00 00
[26] fe 00 00 00 06 00 00 00 01 00 04 00 09 00 00 00 01 7b 00 00 00 02 00 00 00
[51] 06 00 00 00 01 00 04 00 09 00 00 00 06 72 65 74 75 72 6e 00 00 00 02 00 00
[76] 00 fe 00 00 00 fe 00 00 00 fe
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
[1] C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] digest_0.6.4
>

----------------------------------------------
Interactive run:

$ R --vanilla

R version 3.1.0 (2014-04-10) -- "Spring Dance"
Copyright (C) 2014 The R Foundation for Statistical Computing
Platform: x86_64-unknown-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(digest)
> testfun <- function() {
+     return(NULL)
+ }
> print(digest(testfun))
[1] "fada482d2894088b079a8e56b7044862"
> print(serialize(testfun, connection = NULL))
  [1] 58 0a 00 00 00 02 00 03 01 00 00 02 03 00 00 00 06 03 00 00 04 02 00 00 00
 [26] 01 00 04 00 09 00 00 00 06 73 72 63 72 65 66 00 00 03 0d 00 00 00 08 00 00
 [51] 00 01 00 00 00 0c 00 00 00 03 00 00 00 01 00 00 00 0c 00 00 00 01 00 00 00
 [76] 01 00 00 00 03 00 00 04 02 00 00 00 01 00 04 00 09 00 00 00 07 73 72 63 66
[101] 69 6c 65 00 00 00 04 00 00 00 00 00 00 00 f2 00 00 04 02 00 00 00 01 00 04
[126] 00 09 00 00 00 05 6c 69 6e 65 73 00 00 00 10 00 00 00 01 00 04 00 09 00 00
[151] 00 2b 74 65 73 74 66 75 6e 20 3c 2d 20 66 75 6e 63 74 69 6f 6e 28 29 20 7b
[176] 0a 20 20 20 20 72 65 74 75 72 6e 28 4e 55 4c 4c 29 0a 7d 0a 00 00 04 02 00
[201] 00 00 01 00 04 00 09 00 00 00 08 66 69 6c 65 6e 61 6d 65 00 00 00 10 00 00
[226] 00 01 00 04 00 09 00 00 00 00 00 00 00 fe 00 00 00 fe 00 00 04 02 00 00 00
[251] 01 00 04 00 09 00 00 00 05 63 6c 61 73 73 00 00 00 10 00 00 00 02 00 04 00
[276] 09 00 00 00 0b 73 72 63 66 69 6c 65 63 6f 70 79 00 04 00 09 00 00 00 07 73
[301] 72 63 66 69 6c 65 00 00 00 fe 00 00 04 02 00 00 06 ff 00 00 00 10 00 00 00
[326] 01 00 04 00 09 00 00 00 06 73 72 63 72 65 66 00 00 00 fe 00 00 00 fe 00 00
[351] 00 fd 00 00 00 fe 00 00 02 06 00 00 04 02 00 00 01 ff 00 00 00 13 00 00 00
[376] 02 00 00 03 0d 00 00 00 08 00 00 00 01 00 00 00 17 00 00 00 01 00 00 00 17
[401] 00 00 00 17 00 00 00 17 00 00 00 01 00 00 00 01 00 00 04 02 00 00 02 ff 00
[426] 00 03 ff 00 00 04 02 00 00 06 ff 00 00 00 10 00 00 00 01 00 04 00 09 00 00
[451] 00 06 73 72 63 72 65 66 00 00 00 fe 00 00 03 0d 00 00 00 08 00 00 00 02 00
[476] 00 00 05 00 00 00 02 00 00 00 10 00 00 00 05 00 00 00 10 00 00 00 02 00 00
[501] 00 02 00 00 04 02 00 00 02 ff 00 00 03 ff 00 00 04 02 00 00 06 ff 00 00 00
[526] 10 00 00 00 01 00 04 00 09 00 00 00 06 73 72 63 72 65 66 00 00 00 fe 00 00
[551] 04 02 00 00 02 ff 00 00 03 ff 00 00 04 02 00 00 00 01 00 04 00 09 00 00 00
[576] 0b 77 68 6f 6c 65 53 72 63 72 65 66 00 00 03 0d 00 00 00 08 00 00 00 01 00
[601] 00 00 00 00 00 00 03 00 00 00 01 00 00 00 00 00 00 00 01 00 00 00 01 00 00
[626] 00 03 00 00 04 02 00 00 02 ff 00 00 03 ff 00 00 04 02 00 00 06 ff 00 00 00
[651] 10 00 00 00 01 00 04 00 09 00 00 00 06 73 72 63 72 65 66 00 00 00 fe 00 00
[676] 00 fe 00 00 00 01 00 04 00 09 00 00 00 01 7b 00 00 00 02 00 00 00 06 00 00
[701] 00 01 00 04 00 09 00 00 00 06 72 65 74 75 72 6e 00 00 00 02 00 00 00 fe 00
[726] 00 00 fe 00 00 00 fe
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
[1] C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] digest_0.6.4
>