Paste: Served simple mmap counter

! This also includes the non-served version as MAIN:
! See also http://paste.factorcode.org/paste?id=1529

! ( scratchpad ) start-mmap-count-server
! ( scratchpad ) 1234 local-server ascii [
!                    "2" print flush readln
!                ] with-client print
! 1

USING: accessors alien.c-types arrays command-line io
io.encodings.ascii io.encodings.binary io.files io.files.temp
io.mmap io.servers.connection kernel math math.order
math.parser memoize namespaces sequences specialized-arrays
system threads ;

IN: mmap-count

SPECIALIZED-ARRAY: int

SYMBOLS: mmap-count-array mmap-count-server ;

CONSTANT: num-counters 10

MEMO: mmap-count-path ( -- path ) "counts" temp-file ;

: ensure-counts-file ( -- )
    mmap-count-path exists? [
        num-counters <int-array>
        mmap-count-path binary set-file-contents
    ] unless ;

: (count-at) ( i -- count )
    mmap-count-array get nth ;

: (increment-counter) ( i -- )
    mmap-count-array get
    [ 1 + ] change-nth ;

: counter-in-bounds? ( i -- ? )
    0 num-counters 1 - between? ;

: (handle-mmap-count-client) ( -- )
    readln string>number dup dup
    [ counter-in-bounds? and ] when*
    [ dup (increment-counter) (count-at) number>string ]
    [ drop
      "Specify a counter in the range [0,"
      num-counters 1 - number>string "]" 3array "" join
    ] if
    print flush ;

: <mmap-count-server> ( -- threaded-server )
    ascii <threaded-server> "mmap-count-server" >>name
    1234 local-server >>insecure [ (handle-mmap-count-client) ] >>handler ;

: start-mmap-count-server ( -- )
    ensure-counts-file <mmap-count-server> mmap-count-server set
    [
        mmap-count-path int [
            mmap-count-array set
            mmap-count-server get start-server
        ] with-mapped-array
    ] in-thread ;

: check-args ( -- )
    command-line get
    [ length 1 = ] [ first string>number ] bi and
    [ "Usage: mmap-count <n>" print 1 exit ] unless ;

: increment-and-respond ( i -- )
    mmap-count-path int [
        [ [ 1 + ] change-nth ]
        [ nth number>string print ] 2bi
    ] with-mapped-array ;

: exit-out-of-bounds ( i -- )
    number>string write " not in counter range [0," num-counters 1 -
    number>string "]" 3array "" join print 1 exit ;

: handle-command-line ( -- )
    check-args command-line get first string>number
    dup counter-in-bounds?
    [ ensure-counts-file increment-and-respond ] [ exit-out-of-bounds ] if ;

MAIN: handle-command-line