hydra/src/script/hydra-send-stats
Nikola Knezevic f79810bac1 Improve handling of Perl's block eval errors
Taken from `Perl::Critic`:

A common idiom in perl for dealing with possible errors is to use `eval`
followed by a check of `$@`/`$EVAL_ERROR`:

    eval {
        ...
    };
    if ($EVAL_ERROR) {
        ...
    }

There's a problem with this: the value of `$EVAL_ERROR` (`$@`) can change
between the end of the `eval` and the `if` statement. The issue are object
destructors:

    package Foo;

    ...

    sub DESTROY {
        ...
        eval { ... };
        ...
    }

    package main;

    eval {
        my $foo = Foo->new();
        ...
    };
    if ($EVAL_ERROR) {
        ...
    }

Assuming there are no other references to `$foo` created, when the
`eval` block in `main` is exited, `Foo::DESTROY()` will be invoked,
regardless of whether the `eval` finished normally or not. If the `eval`
in `main` fails, but the `eval` in `Foo::DESTROY()` succeeds, then
`$EVAL_ERROR` will be empty by the time that the `if` is executed.
Additional issues arise if you depend upon the exact contents of
`$EVAL_ERROR` and both `eval`s fail, because the messages from both will
be concatenated.

Even if there isn't an `eval` directly in the `DESTROY()` method code,
it may invoke code that does use `eval` or otherwise affects
`$EVAL_ERROR`.

The solution is to ensure that, upon normal exit, an `eval` returns a
true value and to test that value:

    # Constructors are no problem.
    my $object = eval { Class->new() };

    # To cover the possiblity that an operation may correctly return a
    # false value, end the block with "1":
    if ( eval { something(); 1 } ) {
        ...
    }

    eval {
        ...
        1;
    }
        or do {
            # Error handling here
        };

Unfortunately, you can't use the `defined` function to test the result;
`eval` returns an empty string on failure.

Various modules have been written to take some of the pain out of
properly localizing and checking `$@`/`$EVAL_ERROR`. For example:

    use Try::Tiny;
    try {
        ...
    } catch {
        # Error handling here;
        # The exception is in $_/$ARG, not $@/$EVAL_ERROR.
    };  # Note semicolon.

"But we don't use DESTROY() anywhere in our code!" you say. That may be
the case, but do any of the third-party modules you use have them? What
about any you may use in the future or updated versions of the ones you
already use?
2020-05-26 11:19:43 +02:00

77 lines
2.7 KiB
Perl
Executable File

#! /usr/bin/env perl
use strict;
use utf8;
use Net::Statsd;
use File::Slurp;
use JSON;
STDERR->autoflush(1);
binmode STDERR, ":encoding(utf8)";
sub gauge {
my ($name, $val) = @_;
die unless defined $val;
Net::Statsd::gauge($name, $val);
}
sub sendQueueRunnerStats {
my $s = `hydra-queue-runner --status`;
die "cannot get queue runner stats\n" if $? != 0;
my $json = decode_json($s) or die "cannot decode queue runner status";
gauge("hydra.queue.up", $json->{status} eq "up" ? 1 : 0);
return if $json->{status} ne "up";
gauge("hydra.queue.steps.active", $json->{nrActiveSteps});
gauge("hydra.queue.steps.building", $json->{nrStepsBuilding});
gauge("hydra.queue.steps.copying_to", $json->{nrStepsCopyingTo});
gauge("hydra.queue.steps.copying_from", $json->{nrStepsCopyingFrom});
gauge("hydra.queue.steps.waiting", $json->{nrStepsWaiting});
gauge("hydra.queue.steps.runnable", $json->{nrRunnableSteps});
gauge("hydra.queue.steps.unfinished", $json->{nrUnfinishedSteps});
gauge("hydra.queue.steps.finished", $json->{nrStepsDone});
gauge("hydra.queue.steps.retries", $json->{nrRetries});
gauge("hydra.queue.steps.unsupported", $json->{nrUnsupportedSteps});
gauge("hydra.queue.steps.max_retries", $json->{maxNrRetries});
if ($json->{nrStepsDone}) {
gauge("hydra.queue.steps.avg_total_time", $json->{avgStepTime});
gauge("hydra.queue.steps.avg_build_time", $json->{avgStepBuildTime});
}
foreach my $machine (keys %{$json->{machineTypes}}) {
my $machineType = $machine =~ s/:|,/_/r;
gauge("hydra.queue.$machineType.runnable", $json->{machineTypes}->{$machine}->{runnable});
gauge("hydra.queue.$machineType.running", $json->{machineTypes}->{$machine}->{running});
}
gauge("hydra.queue.builds.read", $json->{nrBuildsRead});
gauge("hydra.queue.builds.unfinished", $json->{nrQueuedBuilds});
gauge("hydra.queue.builds.finished", $json->{nrBuildsDone});
gauge("hydra.queue.checks", $json->{nrQueueWakeups});
gauge("hydra.queue.bytes_sent", $json->{bytesSent});
gauge("hydra.queue.bytes_received", $json->{bytesReceived});
gauge("hydra.queue.machines.total", scalar(grep { $_->{enabled} } (values %{$json->{machines}})));
gauge("hydra.queue.machines.in_use", scalar(grep { $_->{currentJobs} > 0 } (values %{$json->{machines}})));
}
while (1) {
eval {
sendQueueRunnerStats();
1;
} or do { warn "$@"; }
my $meminfo = read_file("/proc/meminfo", err_mode => 'quiet') // "";
$meminfo =~ m/Dirty:\s*(\d+) kB/;
if (defined $1) {
my $dirty = $1 / (1024.0 * 1024.0);
gauge("hydra.mem.dirty", $dirty);
}
sleep(30);
}