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prevent multiple threads from removing and creating the fifo file
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1 # no need for shebang - this file is included from other scripts
2
3 LOOPSLEEP_DATE="$(which date)"
4 if [ -z "$LOOPSLEEP_DATE" ]
5     then
6     echo >&2 "$0: ERROR: Cannot find the command 'date' in the system path."
7     exit 1
8 fi
9
10 # -----------------------------------------------------------------------------
11 # use the date command as a high resolution timer
12
13 now_ms=
14 LOOPSLEEPMS_HIGHRES=1
15 test "$($LOOPSLEEP_DATE +%N)" = "%N" && LOOPSLEEPMS_HIGHRES=0
16 current_time_ms_from_date() {
17     if [ $LOOPSLEEPMS_HIGHRES -eq 0 ]
18     then
19         now_ms="$($LOOPSLEEP_DATE +'%s')000"
20     else
21         now_ms="$(( $( $LOOPSLEEP_DATE +'%s * 1000 + %-N / 1000000' ) ))"
22     fi
23 }
24
25 # -----------------------------------------------------------------------------
26 # use /proc/uptime as a high resolution timer
27
28 current_time_ms_from_date
29 current_time_ms_from_uptime_started="${now_ms}"
30 current_time_ms_from_uptime_first=0
31 current_time_ms_from_uptime() {
32     local up rest arr n
33
34     read up rest </proc/uptime
35     if [ $? -ne 0 ]
36         then
37         echo >&2 "$0: Cannot read /proc/uptime - falling back to current_time_ms_from_date()."
38         current_time_ms="current_time_ms_from_date"
39         current_time_ms_from_date
40         current_time_ms_accuracy=1
41         return
42     fi
43
44     arr=(${up//./ })
45
46     if [ ${#arr[1]} -lt 1 ]
47         then
48         n="${arr[0]}000"
49     elif [ ${#arr[1]} -lt 2 ]
50         then
51         n="${arr[0]}${arr[1]}00"
52     elif [ ${#arr[1]} -lt 3 ]
53         then
54         n="${arr[0]}${arr[1]}0"
55     else
56         n="${arr[0]}${arr[1]}"
57     fi
58
59     now_ms=$((current_time_ms_from_uptime_started - current_time_ms_from_uptime_first + n))
60
61     if [ "${now_ms}" -lt "${current_time_ms_from_uptime_started}" ]
62         then
63         echo >&2 "$0: Cannot use current_time_ms_from_uptime() - falling back to current_time_ms_from_date()."
64         current_time_ms="current_time_ms_from_date"
65         current_time_ms_from_date
66         current_time_ms_accuracy=1
67     fi
68 }
69 current_time_ms_from_uptime
70 current_time_ms_from_uptime_first="$((now_ms - current_time_ms_from_uptime_started))"
71 current_time_ms="current_time_ms_from_uptime"
72 current_time_ms_accuracy=10
73 if [ "${current_time_ms_from_uptime_first}" -eq 0 ]
74     then
75     echo >&2 "$0: Invalid setup for current_time_ms_from_uptime() - falling back to current_time_ms_from_date()."
76     current_time_ms="current_time_ms_from_date"
77     current_time_ms_accuracy=1
78 fi
79
80 # -----------------------------------------------------------------------------
81 # use read with timeout for sleep
82
83 mysleep="mysleep_read"
84
85 mysleep_fifo="${NETDATA_CACHE_DIR-/tmp}/.netdata_bash_sleep_timer_fifo"
86 [ ! -e "${mysleep_fifo}" ] && mkfifo "${mysleep_fifo}"
87 [ ! -e "${mysleep_fifo}" ] && mysleep="sleep"
88
89 mysleep_read() {
90     read -t "${1}" <>"${mysleep_fifo}"
91     ret=$?
92     if [ $ret -le 128 ]
93         then
94         echo >&2 "$0: Cannot use read for sleeping (return code ${ret})."
95         mysleep="sleep"
96         ${mysleep} "${1}"
97     fi
98 }
99
100
101 # -----------------------------------------------------------------------------
102 # this function is used to sleep a fraction of a second
103 # it calculates the difference between every time is called
104 # and tries to align the sleep time to give you exactly the
105 # loop you need.
106
107 LOOPSLEEPMS_LASTRUN=0
108 LOOPSLEEPMS_LASTSLEEP=0
109 LOOPSLEEPMS_LASTWORK=0
110
111 loopsleepms() {
112     local tellwork=0 t="$1" div s m now mstosleep
113
114     if [ "$t" = "tellwork" ]
115     then
116         tellwork=1
117         shift
118         t="$1"
119     fi
120     div="${2-100}"
121
122     # $t = the time in seconds to wait
123
124     # if high resolution is not supported
125     # just sleep the time requested, in seconds
126     if [ $LOOPSLEEPMS_HIGHRES -eq 0 ]
127     then
128         sleep $t
129         return
130     fi
131
132     # get the current time, in ms
133     # milliseconds since epoch (1-1-1970)
134     now="$(( $( $LOOPSLEEP_DATE +'%s * 1000 + %-N / 1000000' ) ))"
135
136     # calculate required sleep in ms
137     t=$((t * 1000 * div / 100))
138
139     # this is our first run
140     # just wait the requested time
141     test $LOOPSLEEPMS_LASTRUN -eq 0 && LOOPSLEEPMS_LASTRUN=$now
142
143     # calculate ms since last run
144     LOOPSLEEPMS_LASTWORK=$((now - LOOPSLEEPMS_LASTRUN - LOOPSLEEPMS_LASTSLEEP))
145     # echo "# last loop's work took $LOOPSLEEPMS_LASTWORK ms"
146
147     # calculate ms to sleep
148     mstosleep=$(( t - LOOPSLEEPMS_LASTWORK + current_time_ms_accuracy ))
149     # echo "# mstosleep is $mstosleep ms"
150
151     # if we are too slow, sleep some time
152     test $mstosleep -lt 200 && mstosleep=200
153
154     s=$((mstosleep / 1000))
155     m=$((mstosleep - (s * 1000)))
156
157     test $tellwork -eq 1 && echo >&2 " >>> PERFORMANCE >>> WORK TOOK $LOOPSLEEPMS_LASTWORK ms ( $((LOOPSLEEPMS_LASTWORK * 100 / 1000)).$((LOOPSLEEPMS_LASTWORK % 10))% cpu ) >>> SLEEPING $mstosleep ms"
158
159     # echo "# sleeping $s.$m"
160     # echo
161     ${mysleep} $s.$m
162
163     # keep the values we need
164     # for our next run
165     LOOPSLEEPMS_LASTRUN=$now
166     LOOPSLEEPMS_LASTSLEEP=$mstosleep
167 }