Add distributed counter example

examples/distributed_counter_example.py

@@ -0,0 +1,78 @@
+from flask_boiler.context import Context as CTX
+from flask_boiler.schema import Schema
+from flask_boiler.fields import Integer
+from flask_boiler.domain_model import DomainModel
+from flask_boiler.view_mediator_dav import ViewMediatorDAV
+from flask_boiler.view_model import ViewModel
+
+
+class ShardSchema(Schema):
+
+    count = Integer()
+
+
+class Shard(DomainModel):
+
+    class Meta:
+        schema_cls = ShardSchema
+        collection_id = "CounterAShards"
+
+
+class CounterViewSchema(Schema):
+
+    total_count = Integer(dump_only=True)
+
+
+class CounterView(ViewModel):
+
+    class Meta:
+        schema_cls = CounterViewSchema
+
+    def __init__(self, *args, **kwargs):
+        doc_ref = CTX.db.collection("counters").document("counter_0")
+        super().__init__(*args, doc_ref=doc_ref, **kwargs)
+        self.shards = dict()
+
+    @property
+    def total_count(self):
+        return sum(v.count for _, v in self.shards.items())
+
+    def set_shard(self, sid, shard):
+        self.shards[sid] = shard
+
+    def get_vm_update_callback(self, dm_cls, *args, **kwargs) :
+
+        if dm_cls == Shard:
+            def callback(vm: CounterView, dm: Shard):
+                vm.set_shard(dm.doc_id, dm)
+            return callback
+        else:
+            return super().get_vm_update_callback(dm_cls, *args, **kwargs)
+
+
+class CounterMediator(ViewMediatorDAV):
+
+    def __init__(self, shard_size, *args, **kwargs):
+        super().__init__(*args, view_model_cls=CounterView, **kwargs)
+        self.shard_size = shard_size
+        self.view_model = None
+
+    @classmethod
+    def notify(cls, obj):
+        obj.save()
+
+    def start(self):
+
+        struct = dict()
+
+        for i in range(self.shard_size):
+            doc_id = str(i)
+            shard = Shard.new(doc_id=doc_id, )
+            shard.save()
+            struct[shard.doc_id] = (Shard, doc_id)
+
+        self.view_model = self.view_model_cls.get(
+            f_notify=self.notify,
+            struct_d=struct,
+            once=False)
+

tests/test_examples.py

@@ -1,2 +1,48 @@
+from google.cloud.firestore import Increment
+
 from examples.meeting_room.tests.test_view_model import *
 from examples.meeting_room.tests.test_dav import *
+
+from examples import distributed_counter_example as dc
+from .fixtures import CTX
+
+
+def test_start(CTX):
+    """
+    TODO: add teardown steps to delete documents generated in firestore
+
+    :param CTX:
+    :return:
+    """
+
+    mediator = dc.CounterMediator(
+        mutation_cls=None,
+        shard_size=2
+    )
+
+    mediator.start()
+
+    time.sleep(3)
+
+    doc_ref = CTX.db.collection("counters").document("counter_0")
+
+    assert doc_ref.get().to_dict() == {
+        "doc_ref": "counters/counter_0",
+        "obj_type": "CounterView",
+        "totalCount": 0
+    }
+
+    CTX.db.collection("Shard").document("0").set(
+        document_data={
+            "count": Increment(1),
+        },
+        merge=True
+    )
+
+    time.sleep(1)
+
+    assert doc_ref.get().to_dict() == {
+        "doc_ref": "counters/counter_0",
+        "obj_type": "CounterView",
+        "totalCount": 1
+    }