RandomFieldsUtils (version 1.2.5)

FileExists: Files

Description

The function FileExists checks whether a file or a lock-file exists

The function LockRemove removes a lock-file

Usage

FileExists(file, printlevel=RFoptions()$basic$printlevel)
   LockFile(file, printlevel=RFoptions()$basic$printlevel)
   LockRemove(file)
   WaitOthers(file, i, cores, ideal.processes=ceiling(cores * 1.25),
                       max.processes=ceiling(cores * 1.5),
                       distance=5, time=5, path="./")

Arguments

file

name of the data file

printlevel

if PrintLevel<=1 no messages are displayed

i

integer; current value of process, usually the number of a loop index

cores

the number of cores on the machine

ideal.processes,max.processes,distance

integer. See Details

time

in minutes a process waits until it rechecks its environment

path

the current path of file

Value

FileExists returns

1

if file already exists

2

if file.lock already exists

3

if file.lock was tried to be created, but another process inferred and got priority

0

otherwise, file and file.lock did not exist and file.lock has been created

Details

FileExists checks whether file or file.lock exists. If none of them exists file.lock is created and hostname and PID are written into file.lock. This is useful if several processes use the same directory. Further, it is checked whether another process has tried to create the same file in the same instance. In this case FileExists returns for at least one of the processes that file.lock has already been created.

LockFile is the same as FileExists except that it does not check whether file already exists.

WaitOthers waits for others if more than ideal.processes processes have their value is less than i or if more than cores processes have their value is less than i-distance. It also waits if there are alreay max.processes are active. Note that WaitOthers write a file with ending ‘.wait’, which is also deleted be LockRemove.

Examples

# NOT RUN {
## the next command checks whether the file 'data.rda'
## or the file 'data.rda.lock' exists. If so, a positive
## value is returned. If not, the file 'data.rda.lock'
## is created and the value 0 returned.
FileExists("data.rda")

## the next command deletes the file 'data.rda.lock'
LockRemove("data.rda")
# }