Solution to task 2

1 files changed, 87 insertions, 0 deletions

diff --git a/challenge-142/jo-37/perl/ch-2.pl b/challenge-142/jo-37/perl/ch-2.pl
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+++ b/challenge-142/jo-37/perl/ch-2.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use AnyEvent;
+use Coro;
+use Coro::AnyEvent;
+
+use experimental 'signatures';
+
+our ($tests, $examples, $verbose);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [-verbose] [I1 I2 ...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-verbose
+    enable trace output
+
+I1 I2 ...
+    nonnegative integers to be sorted
+
+EOS
+
+
+### Input and Output
+
+say "@{sleep_sort(\@ARGV)}";
+
+
+### Implementation
+
+# Coros, as cooperative threads, generally do not run in parallel, thus
+# no locking is required when accessing shared data.  Using a semaphore
+# for flow control: by waiting for the "ready" semaphore to become
+# available, the main thread allows the async coros to be scheduled and
+# regains control when all have finished with the same call.
+# Note: The sleep function is event-driven and will not block the
+# overall processing.
+sub sleep_sort ($arr) {
+    # Collect sorted result here:
+    my @sorted;
+    # Will be unlocked when all threads have finished:
+    my $ready = Coro::Semaphore->new(1 - @$arr);
+    # Create threads.
+    async {
+        my ($ready, $sorted, $time) = @_;
+        die "time machine not implemented" if $time < 0;
+        say "sleep for $time s" if $verbose;
+        Coro::AnyEvent::sleep $time;
+        say "woke up after $time s" if $verbose;
+        push @$sorted, $time;
+        $ready->up;
+    } $ready, \@sorted, $_ for @$arr;
+    # Start processing and wait for async threads.
+    $ready->down;
+
+    \@sorted;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples";
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+        is sleep_sort([3, 1, 2, 1]), [1, 1, 2, 3], 'simple test';
+
+        local $verbose;
+        is sleep_sort([2, (1) x 9999]),
+            array {item 9999 => 2; etc;}, 'check last element';
+    }
+
+    done_testing;
+    exit;
+}