Merge lp:~al-maisan/launchpad/qualify-subquery-507562 into lp:launchpad/db-devel

[Muharem Hrnjadovic]

[Muharem Hrnjadovic (al-maisan)]

Hello there!

The selection of candidate jobs for idle builders in the build farm uses a
general query part that may select too many candidates.
Thus, all build farm job type classes get a chance to add sub-queries that
further refine or narrow down the set of selected candidate jobs.

However, these sub-queries need to be put into context so that they apply only
to the jobs beloging to the job class that contributed the sub-query.

That is what the branch at hand does.

Please note that all _findBuildCandidate() tests (we have a pretty extensive
test coverage of the build farm candidate job selection) pass.

Test to run:

    bin/test -vv -t build

No "make lint" errors or warnings.

[Julian Edwards (julian-edwards)]

Approved with the readability improvement we discussed in person.

Cheers
J

review: Approve (code)

=== modified file 'lib/lp/buildmaster/model/builder.py'
--- lib/lp/buildmaster/model/builder.py	2010-01-14 07:10:33 +0000
+++ lib/lp/buildmaster/model/builder.py	2010-01-14 20:22:10 +0000
@@ -425,6 +425,14 @@
 
         :return: A candidate job.
         """
+        def qualify_subquery(job_type, sub_query):
+            """Put the sub-query into a job type context."""
+            qualified_query = """
+                ((BuildQueue.job_type != %s) OR (%%s))
+            """ % sqlvalues(job_type)
+            qualified_query %= sub_query
+            return qualified_query
+
         logger = self._getSlaveScannerLogger()
         candidate = None
 
@@ -447,7 +455,7 @@
         extra_tables = set()
         extra_queries = []
         job_classes = specific_job_classes()
-        for job_class in job_classes.values():
+        for job_type, job_class in job_classes.iteritems():
             tables, query = job_class.addCandidateSelectionCriteria(
                 self.processor, self.virtualized)
             if query == '':
@@ -459,7 +467,8 @@
             # lower case in order to avoid duplicates in the FROM clause.
             query_tables = query_tables.union(
                 set(table.lower() for table in tables))
-            extra_queries.append(query)
+            # The sub-query should only apply to jobs of the right type.
+            extra_queries.append(qualify_subquery(job_type, query))
         general_query = general_query % ', '.join(query_tables)
         query = ' AND '.join([general_query] + extra_queries) + order_clause