summaryrefslogtreecommitdiffstats
path: root/collectors/charts.d.plugin/loopsleepms.sh.inc
blob: bdc032b99d9caad062f2658c3edfbc85448bbebf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
# no need for shebang - this file is included from other scripts
# SPDX-License-Identifier: GPL-3.0-or-later

LOOPSLEEP_DATE="$(which date 2>/dev/null || command -v date 2>/dev/null)"
if [ -z "$LOOPSLEEP_DATE" ]
    then
    echo >&2 "$0: ERROR: Cannot find the command 'date' in the system path."
    exit 1
fi

# -----------------------------------------------------------------------------
# use the date command as a high resolution timer

now_ms=
LOOPSLEEPMS_HIGHRES=1
test "$($LOOPSLEEP_DATE +%N)" = "%N" && LOOPSLEEPMS_HIGHRES=0
test -z "$($LOOPSLEEP_DATE +%N)"     && LOOPSLEEPMS_HIGHRES=0
current_time_ms_from_date() {
    if [ $LOOPSLEEPMS_HIGHRES -eq 0 ]
    then
        now_ms="$($LOOPSLEEP_DATE +'%s')000"
    else
        now_ms="$(( $( $LOOPSLEEP_DATE +'%s * 1000 + %-N / 1000000' ) ))"
    fi
}

# -----------------------------------------------------------------------------
# use /proc/uptime as a high resolution timer

current_time_ms_from_date
current_time_ms_from_uptime_started="${now_ms}"
current_time_ms_from_uptime_last="${now_ms}"
current_time_ms_from_uptime_first=0
current_time_ms_from_uptime() {
    local up rest arr=() n

    read up rest </proc/uptime
    if [ $? -ne 0 ]
        then
        echo >&2 "$0: Cannot read /proc/uptime - falling back to current_time_ms_from_date()."
        current_time_ms="current_time_ms_from_date"
        current_time_ms_from_date
        current_time_ms_accuracy=1
        return
    fi

    arr=(${up//./ })

    if [ ${#arr[1]} -lt 1 ]
        then
        n="${arr[0]}000"
    elif [ ${#arr[1]} -lt 2 ]
        then
        n="${arr[0]}${arr[1]}00"
    elif [ ${#arr[1]} -lt 3 ]
        then
        n="${arr[0]}${arr[1]}0"
    else
        n="${arr[0]}${arr[1]}"
    fi

    now_ms=$((current_time_ms_from_uptime_started - current_time_ms_from_uptime_first + n))

    if [ "${now_ms}" -lt "${current_time_ms_from_uptime_last}" ]
        then
        echo >&2 "$0: Cannot use current_time_ms_from_uptime() - new time ${now_ms} is older than the last ${current_time_ms_from_uptime_last} - falling back to current_time_ms_from_date()."
        current_time_ms="current_time_ms_from_date"
        current_time_ms_from_date
        current_time_ms_accuracy=1
    fi

    current_time_ms_from_uptime_last="${now_ms}"
}
current_time_ms_from_uptime
current_time_ms_from_uptime_first="$((now_ms - current_time_ms_from_uptime_started))"
current_time_ms_from_uptime_last="${current_time_ms_from_uptime_first}"
current_time_ms="current_time_ms_from_uptime"
current_time_ms_accuracy=10
if [ "${current_time_ms_from_uptime_first}" -eq 0 ]
    then
    echo >&2 "$0: Invalid setup for current_time_ms_from_uptime() - falling back to current_time_ms_from_date()."
    current_time_ms="current_time_ms_from_date"
    current_time_ms_accuracy=1
fi

# -----------------------------------------------------------------------------
# use read with timeout for sleep

mysleep=""

mysleep_fifo="${NETDATA_CACHE_DIR-/tmp}/.netdata_bash_sleep_timer_fifo"
[ -f "${mysleep_fifo}" ] && rm "${mysleep_fifo}"
[ ! -p "${mysleep_fifo}" ] && mkfifo "${mysleep_fifo}"
[ -p "${mysleep_fifo}" ] && mysleep="mysleep_read"

mysleep_read() {
    read -t "${1}" <>"${mysleep_fifo}"
    ret=$?
    if [ $ret -le 128 ]
        then
        echo >&2 "$0: Cannot use read for sleeping (return code ${ret})."
        mysleep="sleep"
        ${mysleep} "${1}"
    fi
}

# -----------------------------------------------------------------------------
# use bash loadable module for sleep

mysleep_builtin() {
    builtin sleep "${1}"
    ret=$?
    if [ $ret -ne 0 ]
        then
        echo >&2 "$0: Cannot use builtin sleep for sleeping (return code ${ret})."
        mysleep="sleep"
        ${mysleep} "${1}"
    fi
}

if [ -z "${mysleep}" -a "$((BASH_VERSINFO[0] +0))" -ge 3 -a "${NETDATA_BASH_LOADABLES}" != "DISABLE" ]
    then
    # enable modules only for bash version 3+

    for bash_modules_path in ${BASH_LOADABLES_PATH//:/ } "$(pkg-config bash --variable=loadablesdir 2>/dev/null)" "/usr/lib/bash" "/lib/bash" "/lib64/bash" "/usr/local/lib/bash" "/usr/local/lib64/bash"
    do
        [ -z "${bash_modules_path}" -o ! -d "${bash_modules_path}" ] && continue

        # check for sleep
        for bash_module_sleep in "sleep" "sleep.so"
        do
            if [ -f "${bash_modules_path}/${bash_module_sleep}" ]
                then
                if enable -f "${bash_modules_path}/${bash_module_sleep}" sleep 2>/dev/null
                    then
                    mysleep="mysleep_builtin"
                    # echo >&2 "$0: Using bash loadable ${bash_modules_path}/${bash_module_sleep} for sleep"
                    break
                fi
            fi

        done

        [ ! -z "${mysleep}" ] && break
    done
fi

# -----------------------------------------------------------------------------
# fallback to external sleep

[ -z "${mysleep}" ] && mysleep="sleep"


# -----------------------------------------------------------------------------
# this function is used to sleep a fraction of a second
# it calculates the difference between every time is called
# and tries to align the sleep time to give you exactly the
# loop you need.

LOOPSLEEPMS_LASTRUN=0
LOOPSLEEPMS_NEXTRUN=0
LOOPSLEEPMS_LASTSLEEP=0
LOOPSLEEPMS_LASTWORK=0

loopsleepms() {
    local tellwork=0 t="${1}" div s m now mstosleep

    if [ "${t}" = "tellwork" ]
    then
        tellwork=1
        shift
        t="${1}"
    fi

    # $t = the time in seconds to wait

    # if high resolution is not supported
    # just sleep the time requested, in seconds
    if [ ${LOOPSLEEPMS_HIGHRES} -eq 0 ]
    then
        sleep ${t}
        return
    fi

    # get the current time, in ms in ${now_ms}
    ${current_time_ms}

    # calculate ms since last run
    [ ${LOOPSLEEPMS_LASTRUN} -gt 0 ] && \
        LOOPSLEEPMS_LASTWORK=$((now_ms - LOOPSLEEPMS_LASTRUN - LOOPSLEEPMS_LASTSLEEP + current_time_ms_accuracy))
    # echo "# last loop's work took $LOOPSLEEPMS_LASTWORK ms"
    
    # remember this run
    LOOPSLEEPMS_LASTRUN=${now_ms}

    # calculate the next run
    LOOPSLEEPMS_NEXTRUN=$(( ( now_ms - ( now_ms % ( t * 1000 ) ) ) + ( t * 1000 ) ))

    # calculate ms to sleep
    mstosleep=$(( LOOPSLEEPMS_NEXTRUN - now_ms + current_time_ms_accuracy ))
    # echo "# mstosleep is $mstosleep ms"

    # if we are too slow, sleep some time
    test ${mstosleep} -lt 200 && mstosleep=200

    s=$(( mstosleep / 1000 ))
    m=$(( mstosleep - (s * 1000) ))
    [ "${m}" -lt 100 ] && m="0${m}"
    [ "${m}" -lt 10  ] && m="0${m}"

    test $tellwork -eq 1 && echo >&2 " >>> PERFORMANCE >>> WORK TOOK ${LOOPSLEEPMS_LASTWORK} ms ( $((LOOPSLEEPMS_LASTWORK * 100 / 1000)).$((LOOPSLEEPMS_LASTWORK % 10))% cpu ) >>> SLEEPING ${mstosleep} ms"

    # echo "# sleeping ${s}.${m}"
    # echo
    ${mysleep} ${s}.${m}

    # keep the values we need
    # for our next run
    LOOPSLEEPMS_LASTSLEEP=$mstosleep
}

# test it
#while [ 1 ]
#do
#    r=$(( (RANDOM * 2000 / 32767) ))
#    s=$((r / 1000))
#    m=$((r - (s * 1000)))
#    [ "${m}" -lt 100 ] && m="0${m}"
#    [ "${m}" -lt 10  ] && m="0${m}"
#    echo "${r} = ${s}.${m}"
#
#    # the work
#    ${mysleep} ${s}.${m}
#
#    # the alignment loop
#    loopsleepms tellwork 1
#done