How can I check if the connection is valid with the ROracle database?

[gabrieldev]

# database.R
# Database options
options(user_db = Sys.getenv("user_db"))
options(pass_db = Sys.getenv("pass_db"))
options(host_db = Sys.getenv("host_db"))
options(port_db = Sys.getenv("port_db"))
options(name_db = Sys.getenv("name_db"))

drv <- dbDriver(drvName = "Oracle")

# Function that connect on db
connection <- function() {

  connect.string <- paste("(DESCRIPTION=",
                          "(ADDRESS=(PROTOCOL=tcp)(HOST=", options()$host_db, ")(PORT=", options()$port_db, "))",
                          "(CONNECT_DATA=(SERVICE_NAME=", options()$name_db, ")))", sep = "")

  pool <- dbPool(drv, dbname = connect.string, user = options()$user_db, password = options()$pass_db,
                 minSize = 10,
                 maxSize = Inf,    # this could have been omitted since it's the default
                 idleTimeout = 3600000 ) # one hour)
  return(pool)
}


shiny::onStop(function(){
  print("call pool stop")
  poolClose(pool)
})

CheckDatabase <- function () {
  cons <- dbListConnections(drv)
  if (length(cons) > 0) {
    for (con in cons) {
      tryCatch({
        dbGetQuery(con, "SELECT idt FROM schema.table WHERE ROWNUM <= 4")
        break
      }, error=function(cond) {
        con <- connection()
        return (con)

      },warning = function(cond){
        con <- connection()
        return (con)

      })
    }


  } else {
    con <- connection()
  }
  return(con)
}

# server.R 
source('database.R')

con <- CheckDatabase()

df <- tbl(CheckDatabase(), sql('SELECT * FROM schema.table))

If I don't take a while to perform the query, or use the checkDatabase() function, it works until I'm inactive for a while, then I get the error.
After a certain time, about 10 minutes or less, when I go to make a query in the DB, I receive:

ORA-03114: not connected to ORACLE 

How can I validate the connection?
Because I already tried like this:
dbIsValid(con), but I get that it's an oracle database connection and it doesn't work, like this:

 unable to find an inherited method for function ‘dbIsValid’ for signature ‘"OraConnection"’