Make the jobq closeable and document it.

projects/jobq/README.md

@@ -2,6 +2,37 @@
 
 Abusing sqlite3 as a job queue.
 
+## API
+
+**Note** - this API currently does not support multiplexing queues within a single state store.
+As files are ultimately the performance bottleneck, using multiple files PROBABLY serves you better anyway.
+But investigation here is needed.
+
+### jobq.JobQueue(path)
+Construct and return a fully migrated and connected job queue.
+The queue is closable, and usable as a context manager.
+
+### jobq.JobQueue.create(payload, new_state=None)
+Create a job with the given payload and optional state.
+
+### jobq.JobQueue.get(job_id)
+Read a job back by ID from the queue.
+
+### jobq.JobQueue.poll(query, new_state)
+Poll the queue for a single job matching the given query, atomically advancing it to the new state and returning it as if from `get()`.
+Note that poll selects the OLDEST MATCHING JOB FIRST, thus providing a global round-robin scheduler on jobs, optimizing for progress not throughput.
+
+### jobq.JobQueue.cas_state(job_id, old_state, new_state)
+Atomically update the state of a single job from an old state to a new state.
+Note that this operation NEED NOT SUCCEED, as the job MAY be concurrently modified.
+Job queue algorithms should either be lock-free or use state to implement markers/locks with timeout based recovery.
+
+### jobq.JobQueue.append_event(job_id, event)
+Append a user-defined event to the given job's event log.
+
+### jobq.JobQueue.delete(job_id)
+Purge a given job by ID from the system.
+
 ## Benchmarks
 
 Benchmarks are extremely steady.

projects/jobq/src/python/jobq/__init__.py

@@ -180,6 +180,18 @@ class JobQueue(object):
             self._queries = with_migrations("sqlite3", self._queries, db)
             run_migrations(self._queries, db)
 
+    def __enter__(self, *args, **kwargs):
+        pass
+
+    def __exit__(self, *args, **kwargs):
+        self.close()
+
+    def close(self):
+        if self._db:
+            self._db.commit()
+            self._db.close()
+            self._db = None
+
     def query(self, query, limit=None):
         with self._db as db:
             query = compile_query(query)