Introduce framework for checking/installing packages

- Uses PackageKit dameon, Glib library wrapping packagekit DBUS API and
  Python bindings for the Glib library.

- Implement a decorator to wrap views requiring packages.

- Framework allows for parallel operations.  However, doing parallel
  operations hangs because of what appears to be PackageKit backend
  limitations.

INSTALL

@@ -7,7 +7,7 @@
     $ sudo apt-get install libjs-jquery libjs-modernizr \
     libjs-bootstrap make pandoc python3 python3-cherrypy3 \
     python3-coverage python3-django python3-bootstrapform \
-    python3-setuptools
+    python3-gi python3-setuptools gir1.2-packagekitglib-1.0
 
 2. Install Plinth:
 

plinth/forms.py

@@ -0,0 +1,33 @@
+#
+# This file is part of Plinth.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+"""
+Plinth framework forms
+"""
+
+from django import forms
+
+
+class PackageInstallForm(forms.Form):
+    """Prompt for installation of a package.
+
+    XXX: Don't store the package list in a hidden input as it can be
+    modified on the client side.  Use session store to store and retrieve
+    the package list.  It has to be form specific so that multiple
+    instances of forms don't clash with each other.
+    """
+    package_names = forms.CharField(widget=forms.HiddenInput)

plinth/package.py

@@ -0,0 +1,184 @@
+#
+# This file is part of Plinth.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+"""
+Framework for installing and updating distribution packages
+"""
+
+import functools
+from gi.repository import PackageKitGlib as packagekit
+import logging
+import threading
+
+import plinth
+
+
+logger = logging.getLogger(__name__)
+transactions = {}
+packages_resolved = {}
+
+
+class Transaction(object):
+    """Information about an ongoing transaction."""
+
+    def __init__(self, package_names):
+        """Initialize transaction object.
+
+        Set most values to None until they are sent as progress update.
+        """
+        self.package_names = package_names
+
+        # Progress
+        self.allow_cancel = None
+        self.percentage = None
+        self.status = None
+        self.status_string = None
+        self.flags = None
+        self.package = None
+        self.package_id = None
+        self.item_progress = None
+        self.role = None
+        self.caller_active = None
+        self.download_size_remaining = None
+
+    def get_id(self):
+        """Return a identifier to use as a key in a map of transactions."""
+        return frozenset(self.package_names)
+
+    def __str__(self):
+        """Return the string representation of the object"""
+        return ('Transaction(packages={0}, allow_cancel={1}, status={2}, '
+                ' percentage={3}, package={4}, item_progress={5})').format(
+                    self.package_names, self.allow_cancel, self.status_string,
+                    self.percentage, self.package, self.item_progress)
+
+    def start_install(self):
+        """Start a PackageKit transaction to install given list of packages.
+
+        This operation is non-blocking at it spawns a new thread.
+        """
+        thread = threading.Thread(target=self._install)
+        thread.start()
+
+    def _install(self):
+        """Run a PackageKit transaction to install given packages."""
+        package_ids = [packages_resolved[package_name].get_id()
+                       for package_name in self.package_names]
+        client = packagekit.Client()
+        client.set_interactive(False)
+        client.install_packages(packagekit.TransactionFlagEnum.ONLY_TRUSTED,
+                                package_ids + [None], None,
+                                self.progress_callback, self)
+
+    def progress_callback(self, progress, progress_type, user_data):
+        """Process progress updates on package resolve operation"""
+        if progress_type == packagekit.ProgressType.PERCENTAGE:
+            self.percentage = progress.props.percentage
+        elif progress_type == packagekit.ProgressType.PACKAGE:
+            self.package = progress.props.package
+        elif progress_type == packagekit.ProgressType.ALLOW_CANCEL:
+            self.allow_cancel = progress.props.allow_cancel
+        elif progress_type == packagekit.ProgressType.PACKAGE_ID:
+            self.package_id = progress.props.package_id
+        elif progress_type == packagekit.ProgressType.ITEM_PROGRESS:
+            self.item_progress = progress.props.item_progress
+        elif progress_type == packagekit.ProgressType.STATUS:
+            self.status = progress.props.status
+            self.status_string = \
+                packagekit.StatusEnum.to_string(progress.props.status)
+            if self.status == packagekit.StatusEnum.FINISHED:
+                self.finish()
+        elif progress_type == packagekit.ProgressType.TRANSACTION_FLAGS:
+            self.flags = progress.props.transaction_flags
+        elif progress_type == packagekit.ProgressType.ROLE:
+            self.role = progress.props.role
+        elif progress_type == packagekit.ProgressType.CALLER_ACTIVE:
+            self.caller_active = progress.props.caller_active
+        elif progress_type == packagekit.ProgressType.DOWNLOAD_SIZE_REMAINING:
+            self.download_size_remaining = \
+                progress.props.download_size_remaining
+        else:
+            logger.info('Unhandle packagekit progress callback - %s, %s',
+                        progress, progress_type)
+
+    def finish(self):
+        """Perform clean up operations on the transaction.
+
+        Remove self from global transactions list.
+        """
+        del transactions[self.get_id()]
+
+
+def required(*package_names):
+    """Decorate a view to check and install required packages."""
+
+    def wrapper2(func):
+        """Return a function to check and install packages."""
+
+        @functools.wraps(func)
+        def wrapper(request, *args, **kwargs):
+            """Check and install packages required by a view."""
+            if not is_installing(package_names) and \
+               check_installed(package_names):
+                return func(request, *args, **kwargs)
+
+            view = plinth.views.PackageInstallView.as_view()
+            return view(request, package_names=package_names, *args, **kwargs)
+
+        return wrapper
+
+    return wrapper2
+
+
+def check_installed(package_names):
+    """Return a boolean installed status of package.
+
+    This operation is blocking and waits until the check is finished.
+    """
+    def _callback(progress, progress_type, user_data):
+        """Process progress updates on package resolve operation."""
+        pass
+
+    client = packagekit.Client()
+    response = client.resolve(packagekit.FilterEnum.INSTALLED,
+                              package_names + (None, ), None,
+                              _callback, None)
+
+    installed_package_names = []
+    for package in response.get_package_array():
+        if package.get_info() == packagekit.InfoEnum.INSTALLED:
+            installed_package_names.append(package.get_name())
+
+        packages_resolved[package.get_name()] = package
+
+    return set(installed_package_names) == set(package_names)
+
+
+def is_installing(package_names):
+    """Return whether a set of packages are currently being installed."""
+    return frozenset(package_names) in transactions
+
+
+def start_install(package_names):
+    """Start a PackageKit transaction to install given list of packages.
+
+    This operation is non-blocking at it spawns a new thread.
+    """
+    transaction = Transaction(package_names)
+    transactions[frozenset(package_names)] = transaction
+
+    transaction.start_install()

plinth/templates/package_install.html

@@ -0,0 +1,82 @@
+{% extends "base.html" %}
+{% comment %}
+#
+# This file is part of Plinth.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+{% endcomment %}
+
+{% load bootstrap %}
+
+
+{% block page_head %}
+
+  {% if is_installing %}
+    <meta http-equiv="refresh" content="3" />
+  {% endif %}
+
+{% endblock %}
+
+
+{% block content %}
+
+  <h2>Installation</h2>
+
+  {% if not is_installing %}
+
+    <p>This feature requires addtional packages to be installed.  Do you
+      wish to install them?</p>
+
+    <table class="table">
+      <thead>
+        <tr><th>Package</th><th>Summary</th></tr>
+      </thead>
+      <tbody>
+        {% for package in packages %}
+          <tr>
+            <td>{{ package.get_name }}</td>
+            <td>{{ package.get_summary }}</td>
+          </tr>
+        {% endfor %}
+      </tbody>
+    </table>
+
+    <form action="" method="post">
+      {% csrf_token %}
+
+      {{ form|bootstrap }}
+
+      <input type="submit" class="btn btn-md btn-primary" value="Install" />
+    </form>
+
+  {% else %}
+
+    {% for key, transaction in transactions.items %}
+      <div>Installing {{ transaction.package_names|join:", " }}:
+        {{ transaction.status_string }}
+      </div>
+      <div class="progress">
+        <div class="progress-bar progress-bar-striped active"
+             role="progressbar" aria-valuemin="0" aria-valuemax="100"
+             aria-valuenow="{{ transaction.percentage }}"
+             style="width: {{ transaction.percentage }}%">
+          <span class="sr-only">{{ transaction.percentage }}% complete</span>
+        </div>
+      </div>
+    {% endfor %}
+
+  {% endif %}
+
+{% endblock %}

plinth/views.py

@@ -19,13 +19,61 @@
 Main Plinth views
 """
 
+from django.core.exceptions import ImproperlyConfigured
 from django.core.urlresolvers import reverse
 from django.http.response import HttpResponseRedirect
+from django.views.generic.edit import FormView
+
+from plinth import package as package_module
+from plinth.forms import PackageInstallForm
 
 
 def index(request):
-    """Serve the main index page"""
+    """Serve the main index page."""
     if request.user.is_authenticated():
         return HttpResponseRedirect(reverse('apps:index'))
 
     return HttpResponseRedirect(reverse('help:about'))
+
+
+class PackageInstallView(FormView):
+    """View to prompt and install packages."""
+    template_name = 'package_install.html'
+    form_class = PackageInstallForm
+
+    def get_context_data(self, **kwargs):
+        """Return the context data rendering the template."""
+        context = super(PackageInstallView, self).get_context_data(**kwargs)
+        if 'packages_names' not in context:
+            context['package_names'] = self.kwargs.get('package_names', [])
+
+        # Package details must have been resolved before building the form
+        context['packages'] = [package_module.packages_resolved[package_name]
+                               for package_name in context['package_names']]
+        context['is_installing'] = \
+            package_module.is_installing(context['package_names'])
+        context['transactions'] = package_module.transactions
+
+        return context
+
+    def get_initial(self):
+        """Return the initial data to be filled in the form."""
+        initial = super(PackageInstallView, self).get_initial()
+        try:
+            initial['package_names'] = ','.join(self.kwargs['package_names'])
+        except KeyError:
+            raise ImproperlyConfigured('Argument package_names must be '
+                                       'provided to PackageInstallView')
+
+        return initial
+
+    def form_valid(self, form):
+        """Handle successful validation of the form.
+
+        Start the package installation and show this view again.
+        """
+        package_names = form.cleaned_data['package_names'].split(',')
+        package_module.start_install(package_names)
+
+        return self.render_to_response(
+            self.get_context_data(package_names=package_names))

setup.py

@@ -114,7 +114,8 @@ setuptools.setup(
     install_requires=[
         'cherrypy >= 3.0',
         'django >= 1.7.0',
-        'django-bootstrap-form'
+        'django-bootstrap-form',
+        'pygobject'
     ],
     tests_require=['coverage >= 3.7'],
     include_package_data=True,