Add subscriptions

cylc/flow/network/schema.py

@@ -16,19 +16,20 @@
 
 """GraphQL API schema via Graphene implementation."""
 
-from graphene import (
-    Boolean, Field, Float, ID, InputObjectType, Int,
-    List, Mutation, ObjectType, Schema, String, Union
-)
-from graphene.types.generic import GenericScalar
-from graphene.utils.str_converters import to_snake_case
+import asyncio
+from typing import Callable, AsyncGenerator, Any
 
 from cylc.flow.task_state import TASK_STATUSES_ORDERED
 from cylc.flow.ws_data_mgr import (
     ID_DELIM, FAMILIES, FAMILY_PROXIES,
     JOBS, TASKS, TASK_PROXIES
 )
-
+from graphene import (
+    Boolean, Field, Float, ID, InputObjectType, Int,
+    List, Mutation, ObjectType, Schema, String, Union
+)
+from graphene.types.generic import GenericScalar
+from graphene.utils.str_converters import to_snake_case
 
 PROXY_NODES = 'proxy_nodes'
 
@@ -1182,4 +1183,104 @@ class Mutations(ObjectType):
         description=TaskActions._meta.description)
 
 
-schema = Schema(query=Queries, mutation=Mutations)
+# ** Subscription Related ** #
+
+def to_subscription(func: Callable, sleep_seconds: float = 5.) -> Callable:
+    """Wraps a function in a while-true-sleep, transforming
+    the function into an async-generator, used by the
+    websockets/subscriptions.
+
+    Args:
+        func (Callable): a callable.
+        sleep_seconds (float): asyncio sleep interval in seconds.
+    Returns:
+        Callable: a callable async-generator wrapping the original callable.
+    """
+    async def gen(*args: Any, **kwargs: Any) -> AsyncGenerator[Any, None]:
+        """
+        Args:
+            *args: Variable length argument list, varies as per schema.
+            **kwargs: Arbitrary keyword arguments, varies as per schema.
+        Returns:
+            AsyncGenerator[Any, None]: an async generator that will
+                yield values from resolvers.
+        """
+        while True:
+            yield await func(*args, **kwargs)
+            await asyncio.sleep(sleep_seconds)
+    return gen
+
+
+class Subscriptions(ObjectType):
+    """Defines the subscriptions available in the schema."""
+    class Meta:
+        description = """Multi-Workflow root level subscriptions."""
+    workflows = List(
+        Workflow,
+        description=Workflow._meta.description,
+        ids=List(ID, default_value=[]),
+        exids=List(ID, default_value=[]),
+        resolver=to_subscription(get_workflows))
+    job = Field(
+        Job,
+        description=Job._meta.description,
+        id=ID(required=True),
+        resolver=to_subscription(get_node_by_id))
+    jobs = List(
+        Job,
+        description=Job._meta.description,
+        args=all_jobs_args,
+        resolver=to_subscription(get_nodes_all))
+    task = Field(
+        Task,
+        description=Task._meta.description,
+        id=ID(required=True),
+        resolver=to_subscription(get_node_by_id))
+    tasks = List(
+        Task,
+        description=Task._meta.description,
+        args=all_def_args,
+        resolver=to_subscription(get_nodes_all))
+    task_proxy = Field(
+        TaskProxy,
+        description=TaskProxy._meta.description,
+        id=ID(required=True),
+        resolver=to_subscription(get_node_by_id))
+    task_proxies = List(
+        TaskProxy,
+        description=TaskProxy._meta.description,
+        args=all_proxy_args,
+        resolver=to_subscription(get_nodes_all))
+    family = Field(
+        Family,
+        description=Family._meta.description,
+        id=ID(required=True),
+        resolver=to_subscription(get_node_by_id))
+    families = List(
+        Family,
+        description=Family._meta.description,
+        args=all_def_args,
+        resolver=to_subscription(get_nodes_all))
+    family_proxy = Field(
+        FamilyProxy,
+        description=FamilyProxy._meta.description,
+        id=ID(required=True),
+        resolver=to_subscription(get_node_by_id))
+    family_proxies = List(
+        FamilyProxy,
+        description=FamilyProxy._meta.description,
+        args=all_proxy_args,
+        resolver=to_subscription(get_nodes_all))
+    edges = List(
+        Edge,
+        description=Edge._meta.description,
+        args=all_edge_args,
+        resolver=to_subscription(get_edges_all))
+    nodes_edges = Field(
+        NodesEdges,
+        description=NodesEdges._meta.description,
+        args=nodes_edges_args_all,
+        resolver=to_subscription(get_nodes_edges))
+
+
+schema = Schema(query=Queries, subscription=Subscriptions, mutation=Mutations)

cylc/flow/tests/network/test_schema.py

@@ -0,0 +1,35 @@
+# THIS FILE IS PART OF THE CYLC SUITE ENGINE.
+# Copyright (C) 2008-2019 NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Tests for cylc.flow.network.schema"""
+
+import asyncio
+from types import AsyncGeneratorType
+
+from cylc.flow.network.schema import to_subscription
+
+
+def test_to_subscription():
+    """Test to_subscription function."""
+    async def async_callable():
+        return []
+
+    assert asyncio.iscoroutine(async_callable())
+
+    async_generator = to_subscription(async_callable)
+
+    assert not asyncio.iscoroutine(async_generator())
+    assert isinstance(async_generator(), AsyncGeneratorType)