inst/examples/monetdblite.R

In arkdb: Archive and Unarchive Databases Using Flat Files

# Provide an error handler for connecting to monetdblite if locked
# by another session
# @importFrom MonetDBLite MonetDBLite
monetdblite_connect <- function(dbname, ignore_lock = TRUE) {

  ## Path must exist, but db must not yet exist
  dir <- dirname(dbname)
  if (!dir.exists(dir)) {
    dir.create(dir, FALSE, TRUE)
  }

  if (requireNamespace("MonetDBLite", quietly = TRUE)) {
    MonetDBLite <- getExportedValue("MonetDBLite", "MonetDBLite")
  }

  db <- tryCatch(
    {
      if (ignore_lock) unlink(file.path(dbname, ".gdk_lock"))
      DBI::dbConnect(MonetDBLite(), dbname = dbname)
    },
    error = function(e) {
      if (grepl("Database lock", e)) {
        stop(paste(
          "Local arkdb database is locked by another R session.\n",
          "Try closing that session first or set the ARKDB_HOME\n",
          "environmental variable to a new location.\n"
        ),
        call. = FALSE
        )
      } else {
        stop(e)
      }
    },
    finally = NULL
  )
  db
}