In clear(), remove keys in bulk instead of one by one.

[wlandau]

clear() removes keys one by one, which is slower than it could be for RDS storrs.

storr/R/storr.R

Line 207 in 0c64f1e

invisible(length(vlapply(self$list(namespace), self$del, namespace)))

library(storr)
init_storr <- function() {
  s <- storr_rds(tempfile())
  keys <- as.character(seq_len(1e4))
  values <- rep(TRUE, length(keys))
  s$mset(keys, values)
  s
}

s <- init_storr()
system.time(s$clear())
#>    user  system elapsed 
#>   0.244   0.866   1.111

s <- init_storr()
system.time(unlink(file.path(s$path, "keys", s$default_namespace), recursive = TRUE))
#>    user  system elapsed 
#>       0       0       0

^{Created on 2020-03-11 by the reprex package (v0.3.0)}

@richfitz, would you be open to driver-specific clear() methods so we can do whatever is fastest for the situation?

[richfitz]

Yes, absolutely. Mdel might be the best method name? Work has been all encompassing sorry with covonavirus this year

[richfitz]

Have a look at

system.time(s$del(s$list()))

this is still quite slow. In the special case of dropping a whole namespace we can do better. So if the driver has a clear method that takes a namespace, then the storr object should use it, otherwise it should delete