SQLAlchemy objects can't be used from multiple threads - so when starting
threads for builds, pass the ComponentBuild id rather than the object.
(Note that despite the comment that the threads were sharing a session,
they weren't - what was passed to the thread was a scoped_session that
acts as a separate thread-local session per-thread.)
BUILD_COMPONENT_DB_SESSION_LOCK - a threading.Lock() object that was used
in a few places - but not nearly enough places to effectively lock usage
of a shared session - is removed.
Using a memory database causes tests/test_build to intermittently
fail, because using the same pysqlite3 connection object from multiple
threads - as was done so that the threads shared the same memory database
- is not, in the end, thread safe. One thread will stomp on the transaction
state of other threads, resulting in errors from starting a new transaction
when another is already in progress, or trying to commit a transaction
that is not in progress.
To avoid a significant speed penalty, the session-scope fixture sets up
a database in the pytest temporary directory, which will typically be on
tmpfs. Time to complete all tests:
memory backend: 38 seconds
file on tmpfs: 40 seconds
file on nvme ssd with btrfs: 137 seconds
MBSSQLAlchemy, which attempted to make the memory backend work, is removed.
Session hooks are installed on the Session class rather than on the
scoped_session instance - this works better when we're changing from
one database to another at test setup time.
Since ComponentBuildTrace(s) get created with db_session.commit() call,
is is not possible to commit more items in bulk if they already have been flushed.
Current unit-tests' setup can be significantly sped up if items can be quickly
flushed on the fly and bulk-commited only once at the end. Moreover in general it
seems more appropriate/safer to handle this in before_flush as any implicit
or accidental flush could cause new build traces not to be created at all. As flush
is implicitly called before every commit anyway, this change shouldn't pose any harm.
In MBS, there are two cases to send a message when a module build moves
to a new state. One is to create a new module build, with
ModuleBuild.create particularly, when user submit a module build.
Another one is to transition a module build to a new state with
ModuleBuild.transition. This commit handles these two cases in a little
different ways.
For the former, existing code is refactored by moving the publish call
outside ModuleBuild.create.
For the latter, message is sent in a hook of SQLAlchemy ORM event
after_commit rather than immediately inside the ModuleBuild.transition.
Both of these changes ensure the message is sent after the changes are
committed into database successfully. Then, the backend can have
confidence that the database has the module build data when receive a
message.
Signed-off-by: Chenxiong Qi <cqi@redhat.com>
This also includes `from __future__ import absolute_import`
in every file so that the imports are consistent in Python 2 and 3.
The Python 2 tests fail without this.
