Attached patch handles -some- of this; the initial concern about aggregate convergent trees.
Still under consideration is how to handle divergent trees, and also how to handle simple sequencing.
I've added a long blob of notes in the documentation under a "KNOWN ISSUES" section, so we can at least release this and continue considering design.
--
Paul Evans
=== modified file 'lib/Future.pm'
--- lib/Future.pm 2014-06-08 21:57:09 +0000
+++ lib/Future.pm 2014-06-26 18:23:14 +0000
@@ -1335,7 +1335,8 @@
Returns a new C<Future> instance that will indicate it is ready once all of
the sub future objects given to it indicate that they are ready, either by
-success or failure. Its result will a list of its component futures.
+success, failure or cancellation. Its result will a list of its component
+futures.
When given an empty list this constructor returns a new immediately-done
future.
@@ -1369,7 +1370,6 @@
weaken( my $weakself = $self );
my $sub_on_ready = sub {
- return if $_[0]->{cancelled};
return unless $weakself;
$pending--;
@@ -1392,7 +1392,9 @@
the sub future objects given to it indicate that they are ready, either by
success or failure. Any remaining component futures that are not yet ready
will be cancelled. Its result will be the result of the first component future
-that was ready; either success or failure.
+that was ready; either success or failure. Any component futures that are
+cancelled are ignored, apart from the final component left; at which point the
+result will be a failure.
When given an empty list this constructor returns an immediately-failed
future.
@@ -1435,27 +1437,36 @@
return $self;
}
+ my $pending = 0;
+
weaken( my $weakself = $self );
my $sub_on_ready = sub {
- return if $_[0]->{cancelled};
return unless $weakself;
-
- foreach my $sub ( @subs ) {
- $sub->{ready} or $sub->cancel;
+ return if $weakself->{result} or $weakself->{failure}; # don't recurse on child ->cancel
+
+ return if --$pending and $_[0]->{cancelled};
+
+ if( $_[0]->{cancelled} ) {
+ $weakself->{failure} = [ "All component futures were cancelled" ];
}
-
- if( $_[0]->{failure} ) {
+ elsif( $_[0]->{failure} ) {
$weakself->{failure} = [ $_[0]->failure ];
}
else {
$weakself->{result} = [ $_[0]->get ];
}
+
+ foreach my $sub ( @subs ) {
+ $sub->{ready} or $sub->cancel;
+ }
+
$weakself->_mark_ready;
};
foreach my $sub ( @subs ) {
# No need to test $sub->{ready} since we know none of them are
$sub->on_ready( $sub_on_ready );
+ $pending++;
}
return $self;
@@ -1467,7 +1478,8 @@
sub future objects given to it indicate that they have completed successfully,
or when any of them indicates that they have failed. If any sub future fails,
then this will fail immediately, and the remaining subs not yet ready will be
-cancelled.
+cancelled. Any component futures that are cancelled will cause an immediate
+failure of the result.
If successful, its result will be a concatenated list of the results of all
its component futures, in corresponding order. If it fails, its failure will
@@ -1522,14 +1534,21 @@
weaken( my $weakself = $self );
my $sub_on_ready = sub {
- return if $_[0]->{cancelled};
return unless $weakself;
+ return if $weakself->{result} or $weakself->{failure}; # don't recurse on child ->cancel
- if( my @failure = $_[0]->failure ) {
+ if( $_[0]->{cancelled} ) {
+ $weakself->{failure} = [ "All component futures were cancelled" ];
foreach my $sub ( @subs ) {
$sub->cancel if !$sub->{ready};
}
+ $weakself->_mark_ready;
+ }
+ elsif( my @failure = $_[0]->failure ) {
$weakself->{failure} = \@failure;
+ foreach my $sub ( @subs ) {
+ $sub->cancel if !$sub->{ready};
+ }
$weakself->_mark_ready;
}
else {
@@ -1554,7 +1573,9 @@
the sub future objects given to it indicate that they have completed
successfully, or when all of them indicate that they have failed. If any sub
future succeeds, then this will succeed immediately, and the remaining subs
-not yet ready will be cancelled.
+not yet ready will be cancelled. Any component futures that are cancelled are
+ignored, apart from the final component left; at which point the result will
+be a failure.
If successful, its result will be that of the first component future that
succeeded. If it fails, its failure will be that of the last component future
@@ -1618,22 +1639,26 @@
weaken( my $weakself = $self );
my $sub_on_ready = sub {
- return if $_[0]->{cancelled};
return unless $weakself;
-
- $pending--;
-
- if( my @failure = $_[0]->failure ) {
+ return if $weakself->{result} or $weakself->{failure}; # don't recurse on child ->cancel
+
+ return if --$pending and $_[0]->{cancelled};
+
+ if( $_[0]->{cancelled} ) {
+ $weakself->{failure} = [ "All component futures were cancelled" ];
+ $weakself->_mark_ready;
+ }
+ elsif( my @failure = $_[0]->failure ) {
$pending and return;
$weakself->{failure} = \@failure;
$weakself->_mark_ready;
}
else {
- foreach my $sub ( @subs ) {
- $sub->cancel if !$sub->{ready};
- }
$weakself->{result} = [ $_[0]->get ];
+ foreach my $sub ( @subs ) {
+ $sub->cancel if !$sub->{ready};
+ }
$weakself->_mark_ready;
}
};
=== modified file 't/10wait_all.t'
--- t/10wait_all.t 2014-03-26 15:09:41 +0000
+++ t/10wait_all.t 2014-06-26 18:23:14 +0000
@@ -129,6 +129,26 @@
is( $c2, undef, '$future->cancel ignores ready subs' );
}
+# cancelled dependents
+{
+ my $f1 = Future->new;
+ my $f2 = Future->new;
+
+ my $future = Future->wait_all( $f1, $f2 );
+
+ $f1->done( "result" );
+ $f2->cancel;
+
+ ok( $future->is_ready, '$future of cancelled sub is ready after final cancellation' );
+
+ is_deeply( [ $future->done_futures ],
+ [ $f1 ],
+ '->done_futures with cancellation' );
+ is_deeply( [ $future->cancelled_futures ],
+ [ $f2 ],
+ '->cancelled_futures with cancellation' );
+}
+
# wait_all on none
{
my $f = Future->wait_all( () );
=== modified file 't/11wait_any.t'
--- t/11wait_any.t 2014-03-26 15:09:41 +0000
+++ t/11wait_any.t 2014-06-26 18:23:14 +0000
@@ -108,6 +108,38 @@
is( $c1, 1, '$future->cancel marks subs cancelled' );
}
+# cancelled dependents
+{
+ my $f1 = Future->new;
+ my $f2 = Future->new;
+
+ my $future = Future->wait_any( $f1, $f2 );
+
+ $f1->cancel;
+
+ ok( !$future->is_ready, '$future not yet ready after first cancellation' );
+
+ $f2->done( "result" );
+
+ ok( $future->is_ready, '$future is ready' );
+
+ is_deeply( [ $future->done_futures ],
+ [ $f2 ],
+ '->done_futures with cancellation' );
+ is_deeply( [ $future->cancelled_futures ],
+ [ $f1 ],
+ '->cancelled_futures with cancellation' );
+
+ my $f3 = Future->new;
+ $future = Future->wait_any( $f3 );
+
+ $f3->cancel;
+
+ ok( $future->is_ready, '$future is ready after final cancellation' );
+
+ like( scalar $future->failure, qr/ cancelled/, 'Failure mentions cancelled' );
+}
+
# wait_any on none
{
my $f = Future->wait_any( () );
=== modified file 't/12needs_all.t'
--- t/12needs_all.t 2014-03-26 15:09:41 +0000
+++ t/12needs_all.t 2014-06-26 18:23:14 +0000
@@ -122,6 +122,20 @@
is( $c2, undef, '$future->cancel ignores ready subs' );
}
+# cancelled dependents
+{
+ my $f1 = Future->new;
+ my $f2 = Future->new;
+
+ my $future = Future->needs_all( $f1, $f2 );
+
+ $f1->cancel;
+
+ ok( $future->is_ready, '$future of cancelled sub is ready after first cancellation' );
+
+ like( scalar $future->failure, qr/ cancelled/, 'Failure mentions cancelled' );
+}
+
# needs_all on none
{
my $f = Future->needs_all( () );
=== modified file 't/13needs_any.t'
--- t/13needs_any.t 2014-03-26 15:09:41 +0000
+++ t/13needs_any.t 2014-06-26 18:23:14 +0000
@@ -157,6 +157,36 @@
is( $c2, undef, '$future->cancel ignores ready subs' );
}
+# cancelled dependents
+{
+ my $f1 = Future->new;
+ my $f2 = Future->new;
+
+ my $future = Future->needs_any( $f1, $f2 );
+
+ $f1->cancel;
+
+ ok( !$future->is_ready, '$future not yet ready after first cancellation' );
+
+ $f2->done( "result" );
+
+ is_deeply( [ $future->done_futures ],
+ [ $f2 ],
+ '->done_futures with cancellation' );
+ is_deeply( [ $future->cancelled_futures ],
+ [ $f1 ],
+ '->cancelled_futures with cancellation' );
+
+ my $f3 = Future->new;
+ $future = Future->needs_any( $f3 );
+
+ $f3->cancel;
+
+ ok( $future->is_ready, '$future is ready after final cancellation' );
+
+ like( scalar $future->failure, qr/ cancelled/, 'Failure mentions cancelled' );
+}
+
# needs_any on none
{
my $f = Future->needs_any( () );
