# Example 826 — The heartbeat stopped and the status stayed green `the_heartbeat_stopped_and_the_status_stayed_green.eml` - The service status board has shown green for the whole shift, and every status it displayed was the one the service reported. What a stopped report displays as is computed below. ## EML ```eml # Self-authored for the EML case corpus (no external origin). The service status # board has shown green for the whole shift, and every status it displayed was # the one the service reported. What a stopped report displays as is computed # below. # # The health reporting is built carefully. The service pushes a heartbeat every # ten seconds carrying its own self-check; the board shows the last status # received; a status of anything but healthy turns the tile red; and the board # is on the wall where everyone can see it. # # The board shows the LAST heartbeat's status, and a stopped heartbeat sends # nothing to replace it. 10 => heartbeat_interval_seconds 47 => minutes_since_the_last_heartbeat 6 => heartbeats_expected_per_minute 0 => heartbeats_received_since 0 => tiles_that_turn_red_on_a_missing_heartbeat minutes_since_the_last_heartbeat * heartbeats_expected_per_minute => heartbeats_expected_but_absent minutes_since_the_last_heartbeat * 60 => seconds_the_status_has_been_stale "heartbeat interval : " + str(heartbeat_interval_seconds) + " seconds" ^0 "minutes since the last beat : " + str(minutes_since_the_last_heartbeat) ^0 " heartbeats expected since : " + str(heartbeats_expected_but_absent) ^0 " heartbeats received since : " + str(heartbeats_received_since) ^0 "seconds the status has been stale : " + str(seconds_the_status_has_been_stale) ^0 "board status : green (last received)" ^0 "tiles that go red on absence : " + str(tiles_that_turn_red_on_a_missing_heartbeat) ^0 "" ^0 # ---- what the board verified ---- "the status board" ^0 " source : a heartbeat the service pushes every ten" ^0 " seconds, carrying its own self-check" ^0 " shows : the last status received" ^0 " on a non-healthy status : the tile turns red" ^0 " visibility : on the wall" ^0 " non-healthy statuses received : 0" ^0 " verdict : HEALTHY" ^0 "" ^0 " turning red on a reported fault is the part done right" ^0 " here, and it is why a sick service that still reports" ^0 " would show red" ^0 "" ^0 # ---- what a stopped heartbeat displays as ---- "the beats that never arrived" ^0 " expected in the last 47 minutes : " ^0 " " + str(heartbeats_expected_but_absent) ^0 " received : " + str(heartbeats_received_since) ^0 " what the board does with no new status : keeps the" ^0 " last one" ^0 " what the last one was : green" ^0 " so absence displays as : the last health, held" ^0 " indefinitely" ^0 "" ^0 # ---- what the service was actually doing ---- "the service behind the green tile" ^0 " state : dead for " + str(minutes_since_the_last_heartbeat) + " minutes" ^0 " what a dead service reports : nothing" ^0 " what nothing turns the tile : green, still" ^0 " the transition to red on silence : never defined" ^0 " is any displayed status wrong : no; each was really" ^0 " reported, once" ^0 " is the current display a current fact : no" ^0 "" ^0 # ---- null control ---- # The same board, with a tile that turns red when no heartbeat has arrived for # more than three intervals. 0 => nc_red_tiles_when_absence_holds_green 1 => nc_red_tiles_when_absence_turns_red 282 => nc_missing_beats_it_would_notice "null control - absence turns the tile red" ^0 " red tiles, absence holds green : " ^0 " " + str(nc_red_tiles_when_absence_holds_green) ^0 " red tiles, absence turns red : " ^0 " " + str(nc_red_tiles_when_absence_turns_red) ^0 " missing beats it would notice : " ^0 " " + str(nc_missing_beats_it_would_notice) ^0 " no heartbeat changed; the board stopped treating no" ^0 " news as good news" ^0 "" ^0 # ---- the rule ---- "what a green status board guarantees" ^0 " the last status the service reported was healthy :" ^0 " exactly, and a reported fault would turn it red" ^0 " the service is healthy : not addressed; the board shows" ^0 " the last heartbeat's status, and a stopped heartbeat is" ^0 " absence, not health - " + str(heartbeats_expected_but_absent) + " expected beats, 0 received," ^0 " still green" ^0 "" ^0 "a display of the last report is a fact about the past, and health is a fact" ^0 "about now; the two coincide only while the reports keep coming, and the moment" ^0 "they stop is the moment the display means the least" ^0 "" ^0 "The board shows the last pushed status and reddens on a reported fault - green" ^0 "all shift. It holds the last status when beats stop, so " + str(minutes_since_the_last_heartbeat) + " minutes of silence -" ^0 "" + str(heartbeats_expected_but_absent) + " expected beats, none received - display as green, under " + str(tiles_that_turn_red_on_a_missing_heartbeat) + " tiles that" ^0 "redden on absence." ^0 ``` ## Python (deterministic transpilation) ```python heartbeat_interval_seconds = 10 minutes_since_the_last_heartbeat = 47 heartbeats_expected_per_minute = 6 heartbeats_received_since = 0 tiles_that_turn_red_on_a_missing_heartbeat = 0 heartbeats_expected_but_absent = minutes_since_the_last_heartbeat * heartbeats_expected_per_minute seconds_the_status_has_been_stale = minutes_since_the_last_heartbeat * 60 print("heartbeat interval : " + str(heartbeat_interval_seconds) + " seconds") print("minutes since the last beat : " + str(minutes_since_the_last_heartbeat)) print(" heartbeats expected since : " + str(heartbeats_expected_but_absent)) print(" heartbeats received since : " + str(heartbeats_received_since)) print("seconds the status has been stale : " + str(seconds_the_status_has_been_stale)) print("board status : green (last received)") print("tiles that go red on absence : " + str(tiles_that_turn_red_on_a_missing_heartbeat)) print("") print("the status board") print(" source : a heartbeat the service pushes every ten") print(" seconds, carrying its own self-check") print(" shows : the last status received") print(" on a non-healthy status : the tile turns red") print(" visibility : on the wall") print(" non-healthy statuses received : 0") print(" verdict : HEALTHY") print("") print(" turning red on a reported fault is the part done right") print(" here, and it is why a sick service that still reports") print(" would show red") print("") print("the beats that never arrived") print(" expected in the last 47 minutes : ") print(" " + str(heartbeats_expected_but_absent)) print(" received : " + str(heartbeats_received_since)) print(" what the board does with no new status : keeps the") print(" last one") print(" what the last one was : green") print(" so absence displays as : the last health, held") print(" indefinitely") print("") print("the service behind the green tile") print(" state : dead for " + str(minutes_since_the_last_heartbeat) + " minutes") print(" what a dead service reports : nothing") print(" what nothing turns the tile : green, still") print(" the transition to red on silence : never defined") print(" is any displayed status wrong : no; each was really") print(" reported, once") print(" is the current display a current fact : no") print("") nc_red_tiles_when_absence_holds_green = 0 nc_red_tiles_when_absence_turns_red = 1 nc_missing_beats_it_would_notice = 282 print("null control - absence turns the tile red") print(" red tiles, absence holds green : ") print(" " + str(nc_red_tiles_when_absence_holds_green)) print(" red tiles, absence turns red : ") print(" " + str(nc_red_tiles_when_absence_turns_red)) print(" missing beats it would notice : ") print(" " + str(nc_missing_beats_it_would_notice)) print(" no heartbeat changed; the board stopped treating no") print(" news as good news") print("") print("what a green status board guarantees") print(" the last status the service reported was healthy :") print(" exactly, and a reported fault would turn it red") print(" the service is healthy : not addressed; the board shows") print(" the last heartbeat's status, and a stopped heartbeat is") print(" absence, not health - " + str(heartbeats_expected_but_absent) + " expected beats, 0 received,") print(" still green") print("") print("a display of the last report is a fact about the past, and health is a fact") print("about now; the two coincide only while the reports keep coming, and the moment") print("they stop is the moment the display means the least") print("") print("The board shows the last pushed status and reddens on a reported fault - green") print("all shift. It holds the last status when beats stop, so " + str(minutes_since_the_last_heartbeat) + " minutes of silence -") print("" + str(heartbeats_expected_but_absent) + " expected beats, none received - display as green, under " + str(tiles_that_turn_red_on_a_missing_heartbeat) + " tiles that") print("redden on absence.") ``` ## stdout (executed) ```text heartbeat interval : 10 seconds minutes since the last beat : 47 heartbeats expected since : 282 heartbeats received since : 0 seconds the status has been stale : 2820 board status : green (last received) tiles that go red on absence : 0 the status board source : a heartbeat the service pushes every ten seconds, carrying its own self-check shows : the last status received on a non-healthy status : the tile turns red visibility : on the wall non-healthy statuses received : 0 verdict : HEALTHY turning red on a reported fault is the part done right here, and it is why a sick service that still reports would show red the beats that never arrived expected in the last 47 minutes : 282 received : 0 what the board does with no new status : keeps the last one what the last one was : green so absence displays as : the last health, held indefinitely the service behind the green tile state : dead for 47 minutes what a dead service reports : nothing what nothing turns the tile : green, still the transition to red on silence : never defined is any displayed status wrong : no; each was really reported, once is the current display a current fact : no null control - absence turns the tile red red tiles, absence holds green : 0 red tiles, absence turns red : 1 missing beats it would notice : 282 no heartbeat changed; the board stopped treating no news as good news what a green status board guarantees the last status the service reported was healthy : exactly, and a reported fault would turn it red the service is healthy : not addressed; the board shows the last heartbeat's status, and a stopped heartbeat is absence, not health - 282 expected beats, 0 received, still green a display of the last report is a fact about the past, and health is a fact about now; the two coincide only while the reports keep coming, and the moment they stop is the moment the display means the least The board shows the last pushed status and reddens on a reported fault - green all shift. It holds the last status when beats stop, so 47 minutes of silence - 282 expected beats, none received - display as green, under 0 tiles that redden on absence. ``` ## Round-trip `ok: true` — round-trip fixpoint reached (python1 == python2) ## Trace event types eml:run:start · eml:assign · eml:output · eml:run:done