fixed a serious design flaw in Mojo::Message and made long poll much …

…easier

Changes

@@ -4,6 +4,8 @@ This file documents the revision history for Perl extension Mojolicious.
         - Added EXPERIMENTAL support for --mode and --home options to all
           Mojolicious commands.
         - Added while and until methods for Mojo::DOM collections. (vti)
+        - Fixed a serious design flaw in Mojo::Message and made long poll
+          much easier.
         - Fixed a bug where Mojo::IOLoop connections could be closed too
           early.
         - Fixed HTTPS support for CGI environments.

lib/Mojo/Content.pm

@@ -12,7 +12,7 @@ use Mojo::Headers;
 
 use constant CHUNK_SIZE => $ENV{MOJO_CHUNK_SIZE} || 262144;
 
-__PACKAGE__->attr([qw/body_cb filter/]);
+__PACKAGE__->attr([qw/filter read_cb/]);
 __PACKAGE__->attr([qw/buffer filter_buffer/] => sub { Mojo::ByteStream->new }
 );
 __PACKAGE__->attr(headers => sub { Mojo::Headers->new });
@@ -70,32 +70,21 @@ sub build_headers {
     return $headers;
 }
 
+sub finish { shift->{_eof} = 1 }
+
 sub generate_body_chunk {
     my ($self, $offset) = @_;
 
-    # Shortcut
-    return '' unless $self->body_cb;
-
-    # Remove written
+    # Buffer
     my $buffer = $self->buffer;
-    my $written = $offset - ($buffer->raw_size - $buffer->size);
-    $buffer->remove($written);
-
-    # Fill buffer
-    if (!$self->{_eof} && $buffer->size < CHUNK_SIZE) {
-
-        # Generate
-        my $chunk = $self->body_cb->($self, $buffer->raw_size);
 
-        # EOF
-        if (defined $chunk && !length $chunk) { $self->{_eof} = 1 }
-
-        # Buffer chunk
-        else { $buffer->add_chunk($chunk) }
+    # Callback
+    if (!$buffer->size && (my $cb = delete $self->{_drain})) {
+        $self->$cb($offset);
     }
 
     # Get chunk
-    my $chunk = $buffer->to_string;
+    my $chunk = $buffer->empty;
 
     # Pause or EOF
     return $self->{_eof} ? '' : undef unless length $chunk;
@@ -198,7 +187,7 @@ sub parse {
     else { $self->buffer($fbuffer) }
 
     # Custom body parser
-    if (my $cb = $self->body_cb) {
+    if (my $cb = $self->read_cb) {
 
         # Chunked or relaxed content
         if ($self->is_chunked || $self->relaxed) {
@@ -276,6 +265,32 @@ sub raw_body_size {
     return $length - $header_length;
 }
 
+sub write {
+    my ($self, $chunk, $cb) = @_;
+
+    # Dynamic content
+    $self->read_cb(sub { });
+
+    # Buffer
+    $self->buffer->add_chunk($chunk);
+
+    # Drain callback
+    $self->{_drain} = $cb if $cb;
+}
+
+sub write_chunk {
+    my ($self, $chunk, $cb) = @_;
+
+    # Filter
+    $self->filter(Mojo::Filter::Chunked->new) unless $self->filter;
+
+    # Chunked transfer encoding
+    $self->headers->transfer_encoding('chunked') unless $self->is_chunked;
+
+    # Write
+    $self->write(defined $chunk ? $self->filter->build($chunk) : '', $cb);
+}
+
 sub _build_headers {
     my $self = shift;
 
@@ -327,22 +342,6 @@ in RFC 2616.
 
 L<Mojo::Content> implements the following attributes.
 
-=head2 C<body_cb>
-
-    my $cb = $content->body_cb;
-
-    $counter = 1;
-    $content = $content->body_cb(sub {
-        my $self  = shift;
-        my $chunk = '';
-        $chunk    = "hello world!" if $counter == 1;
-        $chunk    = "hello world2!\n\n" if $counter == 2;
-        $counter++;
-        return $chunk;
-    });
-
-Content generator callback.
-
 =head2 C<buffer>
 
     my $buffer = $content->buffer;
@@ -371,6 +370,18 @@ Input buffer for filtering.
 
 The headers.
 
+=head2 C<read_cb>
+
+    my $cb   = $content->read_cb;
+    $content = $content->read_cb(sub {...});
+
+Content parser callback.
+
+    $content = $content->read_cb(sub {
+        my ($self, $chunk) = @_;
+        print $chunk;
+    });
+
 =head2 C<relaxed>
 
     my $relaxed = $content->relaxed;
@@ -413,11 +424,17 @@ Render whole body.
 
 Render all headers.
 
+=head2 C<finish>
+
+    $content->finish;
+
+Finish dynamic content generation.
+
 =head2 C<generate_body_chunk>
 
     my $chunk = $content->generate_body_chunk(0);
 
-Generate content from C<body_cb>.
+Generate dynamic content.
 
 =head2 C<get_body_chunk>
 
@@ -505,6 +522,22 @@ Parse and stop after headers.
 
 Raw size of body in bytes.
 
+=head2 C<write>
+
+    $content->write('Hello!');
+    $content->write('Hello!', sub {...});
+
+Write dynamic content, the optional drain callback will be invoked once all
+data has been written.
+
+=head2 C<write_chunk>
+
+    $content->write_chunk('Hello!');
+    $content->write_chunk('Hello!', sub {...});
+
+Write chunked content, the optional drain callback will be invoked once all
+data has been written.
+
 =head1 SEE ALSO
 
 L<Mojolicious>, L<Mojolicious::Guides>, L<http://mojolicious.org>.

lib/Mojo/Content/MultiPart.pm

@@ -90,7 +90,7 @@ sub get_body_chunk {
     my ($self, $offset) = @_;
 
     # Body generator
-    return $self->generate_body_chunk($offset) if $self->body_cb;
+    return $self->generate_body_chunk($offset) if $self->read_cb;
 
     # Multipart
     my $boundary        = $self->build_boundary;
@@ -138,7 +138,7 @@ sub parse {
     $self->SUPER::parse(@_);
 
     # Custom body parser
-    return $self if $self->body_cb;
+    return $self if $self->read_cb;
 
     # Upgrade state
     $self->{_state} = 'multipart_preamble'

lib/Mojo/Content/Single.pm

@@ -27,7 +27,7 @@ sub get_body_chunk {
     my ($self, $offset) = @_;
 
     # Body generator
-    return $self->generate_body_chunk($offset) if $self->body_cb;
+    return $self->generate_body_chunk($offset) if $self->read_cb;
 
     # Normal content
     return $self->asset->get_chunk($offset);
@@ -40,7 +40,7 @@ sub parse {
     $self->SUPER::parse(@_);
 
     # Still parsing headers or using a custom body parser
-    return $self if ($self->{_state} || '') eq 'headers' || $self->body_cb;
+    return $self if ($self->{_state} || '') eq 'headers' || $self->read_cb;
 
     # Headers
     my $headers = $self->headers;

lib/Mojo/HelloWorld.pm

@@ -5,7 +5,6 @@ use warnings;
 
 use base 'Mojo';
 
-use Mojo::Filter::Chunked;
 use Mojo::JSON;
 
 # How is education supposed to make me feel smarter? Besides,
@@ -49,16 +48,14 @@ sub _chunked_params {
     }
 
     # Callback
-    my $counter = 0;
-    my $chunked = Mojo::Filter::Chunked->new;
-    $tx->res->body(
-        sub {
-            my $self = shift;
-            my $chunk = $chunks->[$counter] || '';
-            $counter++;
-            return $chunked->build($chunk);
-        }
-    );
+    my $cb;
+    $cb = sub {
+        my $self = shift;
+        my $chunk = shift @$chunks || '';
+        $self->write_chunk($chunk, $chunk ? $cb : undef);
+        $self->finish unless $chunk;
+    };
+    $cb->($tx->res);
 }
 
 sub _diag {