toaster: bldcontrol models Add a cancelling state the BuildRequest

To accurately reflect the state of a build request we also need a
cancelling state. This is set when we've started a build and then for
whatever reason cancel it, cancelling is not instantaneous so we have
this state to indicate that a cancel is in progress.

Also add a state transition guard. As the state of a BuildRequest can
currently be modified by three processes; Toastergui,
Runbuilds/bldcontrol and the buildinofhelper we cannot say for sure
which process will be running at the time of cancellation so in order to
avoid one of these processes making an incorrect transition only allow
transitions of state to increase.

e.g. CREATED -> QUEUED -> INPROGRESS
And to ignore such requested changes such as
INPROGRESS -> CREATED

Signed-off-by: Michael Wood <michael.g.wood@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 45 insertions, 1 deletions

diff --git a/lib/toaster/bldcontrol/migrations/0003_add_cancelling_state.py b/lib/toaster/bldcontrol/migrations/0003_add_cancelling_state.py
new file mode 100644
index 0000000000..eec9216ca3
--- /dev/null
+++ b/lib/toaster/bldcontrol/migrations/0003_add_cancelling_state.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bldcontrol', '0002_auto_20160120_1250'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='buildrequest',
+            name='state',
+            field=models.IntegerField(default=0, choices=[(0, b'created'), (1, b'queued'), (2, b'in progress'), (3, b'completed'), (4, b'failed'), (5, b'deleted'), (6, b'cancelling'), (7, b'archive')]),
+        ),
+    ]
diff --git a/lib/toaster/bldcontrol/models.py b/lib/toaster/bldcontrol/models.py
index 9b2d0d0b24..cb49a58c45 100644
--- a/lib/toaster/bldcontrol/models.py
+++ b/lib/toaster/bldcontrol/models.py
@@ -4,6 +4,8 @@ from django.core.validators import MaxValueValidator, MinValueValidator
 from django.utils.encoding import force_bytes
 from orm.models import Project, ProjectLayer, ProjectVariable, ProjectTarget, Build, Layer_Version
 
+import logging
+logger = logging.getLogger("toaster")
 # a BuildEnvironment is the equivalent of the "build/" directory on the localhost
 class BuildEnvironment(models.Model):
     SERVER_STOPPED = 0
@@ -64,7 +66,8 @@ class BuildRequest(models.Model):
     REQ_COMPLETED = 3
     REQ_FAILED = 4
     REQ_DELETED = 5
-    REQ_ARCHIVE = 6
+    REQ_CANCELLING = 6
+    REQ_ARCHIVE = 7
 
     REQUEST_STATE = (
         (REQ_CREATED, "created"),
@@ -73,6 +76,7 @@ class BuildRequest(models.Model):
         (REQ_COMPLETED, "completed"),
         (REQ_FAILED, "failed"),
         (REQ_DELETED, "deleted"),
+        (REQ_CANCELLING, "cancelling"),
         (REQ_ARCHIVE, "archive"),
     )
 
@@ -85,6 +89,27 @@ class BuildRequest(models.Model):
     created     = models.DateTimeField(auto_now_add = True)
     updated     = models.DateTimeField(auto_now = True)
 
+    def __init__(self, *args, **kwargs):
+        super(BuildRequest, self).__init__(*args, **kwargs)
+        # Save the old state incase it's about to be modified
+        self.old_state = self.state
+
+    def save(self, *args, **kwargs):
+        # Check that the state we're trying to set is not going backwards
+        # e.g. from REQ_FAILED to REQ_INPROGRESS
+        if self.old_state != self.state and self.old_state > self.state:
+            logger.warn("Invalid state change requested: "
+                        "Cannot go from %s to %s - ignoring request" %
+                        (BuildRequest.REQUEST_STATE[self.old_state][1],
+                         BuildRequest.REQUEST_STATE[self.state][1])
+                       )
+            # Set property back to the old value
+            self.state = self.old_state
+            return
+
+        super(BuildRequest, self).save(*args, **kwargs)
+
+
     def get_duration(self):
         return (self.updated - self.created).total_seconds()