Deal with moved cache issues

If a user manually copies a complete Cache folder (including the db file and rasters folder), there are issues that must be addressed, depending on the Cache backend used. If using DBI (e.g., RSQLite or Postgres), the db table must be renamed. Run this function after a manual copy of a cache folder. See examples for one way to do that.

movedCache(
  new,
  old,
  drv = getDrv(getOption("reproducible.drv", NULL)),
  conn = getOption("reproducible.conn", NULL),
  verbose = getOption("reproducible.verbose")
)

Arguments

new

Either the path of the new cachePath where the cache was moved or copied to, or the new DB Table Name

old

Optional, if there is only one table in the new cache path. Either the path of the previous cachePath where the cache was moved or copied from, or the old DB Table Name

drv

if using a database backend, drv must be an object that inherits from DBIDriver e.g., from package RSQLite, e.g., SQLite

conn

an optional DBIConnection object, as returned by dbConnect().

verbose

Numeric, -1 silent (where possible), 0 being very quiet, 1 showing more messaging, 2 being more messaging, etc. Default is 1. Above 3 will output much more information about the internals of Caching, which may help diagnose Caching challenges. Can set globally with an option, e.g., options('reproducible.verbose' = 0) to reduce to minimal

Value

movedCache does not return anything; it is called for its side effects.

Details

When the backend database for a reproducinle cache is an SQL database, the files on disk cannot be copied manually to a new location because they contain internal tables. Because reproducible gives the main table a name based on the cachePath path, calls to Cache will attempt to call this internally if it detects a name mismatch.

Examples

data.table::setDTthreads(2)
tmpdir <- "tmpdir"
tmpCache <- "tmpCache"
tmpCacheDir <- normalizePath(file.path(tempdir(), tmpCache), mustWork = FALSE)
tmpdirPath <- normalizePath(file.path(tempdir(), tmpdir), mustWork = FALSE)
bb <- Cache(rnorm, 1, cachePath = tmpCacheDir)

# Copy all files from tmpCache to tmpdir
froms <- normalizePath(dir(tmpCacheDir, recursive = TRUE, full.names = TRUE),
  mustWork = FALSE
)
dir.create(file.path(tmpdirPath, "rasters"), recursive = TRUE, showWarnings = FALSE)
dir.create(file.path(tmpdirPath, "cacheOutputs"), recursive = TRUE, showWarnings = FALSE)
file.copy(
  from = froms, overwrite = TRUE,
  to = gsub(tmpCache, tmpdir, froms)
)
#> [1] TRUE TRUE

# Can use 'movedCache' to update the database table, though will generally
#   happen automatically, with message indicating so
movedCache(new = tmpdirPath, old = tmpCacheDir)
bb <- Cache(rnorm, 1, cachePath = tmpdirPath) # should recover the previous call
#>   ...(Object to retrieve (fn: rnorm, 422bae4ed2f770cc.rds))
#>      loaded cached result from previous rnorm call