Implement Workflow.random_uuid() and Workflow.new_random().

Author: firdaus

README.md

@@ -24,8 +24,8 @@ version is targeted to be released in ~~September of 2019~~ January 2020.
 - [ ] Timers
 - [x] Sleep
 - [ ] Loggers
-- [ ] newRandom
-- [ ] UUID
+- [x] newRandom
+- [x] UUID
 - [ ] Workflow Versioning
 
 2.0

cadence/decision_loop.py

@@ -4,6 +4,8 @@
 import contextvars
 import datetime
 import json
+import uuid
+import random
 import logging
 import threading
 from asyncio.base_futures import CancelledError
@@ -420,6 +422,16 @@ def handle_timer_canceled(self, event: HistoryEvent):
     def set_current_run_id(self, run_id: str):
         self.current_run_id = run_id
 
+    def random_uuid(self) -> uuid.UUID:
+        return uuid.uuid3(uuid.UUID(self.current_run_id), str(self.decider.get_and_increment_next_id()))
+    
+    def new_random(self) -> random.Random:
+        random_uuid = self.random_uuid()
+        lsb = random_uuid.bytes[:8]
+        generator = random.Random()
+        generator.seed(lsb, version=2)
+        return generator
+
 
 @dataclass
 class ReplayDecider:

cadence/tests/test_random.py

@@ -1,4 +1,5 @@
 import random
+import uuid
 
 
 def test_python_random_determinism():
@@ -9,3 +10,7 @@ def test_python_random_determinism():
     assert generator.randint(0, 100) == 41
     assert generator.randint(0, 100) == 16
     assert generator.randint(0, 100) == 11
+
+
+def test_python_uuid3_determinism():
+    assert uuid.uuid3(uuid.UUID("8d3149e9-71d3-4ad3-9216-bfbf0473b7c6"), "25") == uuid.UUID('db602869-db61-341b-9e01-81393de6c9b0')

cadence/tests/test_workflow_random.py

@@ -0,0 +1,73 @@
+import pytest
+
+from cadence.workerfactory import WorkerFactory
+from cadence.workflow import workflow_method, Workflow, WorkflowClient
+
+TASK_LIST = "TestWorkflowRandom"
+DOMAIN = "sample"
+
+checkpoint_values = {}
+
+
+def record_value(key, v):
+    values = checkpoint_values.setdefault(key, [])
+    values.append(v)
+
+
+class TestRandomWorkflow:
+    @workflow_method(task_list=TASK_LIST)
+    async def get_greetings(self) -> list:
+        raise NotImplementedError
+
+
+class TestRandomWorkflowImpl(TestRandomWorkflow):
+
+    def __init__(self):
+        pass
+
+    async def get_greetings(self) -> None:
+        record_value("uuid-checkpoint-1", Workflow.random_uuid())
+        Workflow.sleep(1)
+        record_value("uuid-checkpoint-2", Workflow.random_uuid())
+        Workflow.sleep(1)
+        record_value("uuid-checkpoint-3", Workflow.random_uuid())
+        Workflow.sleep(1)
+
+        random = Workflow.new_random()
+        record_value("random-checkpoint-1", random.randint(0, 2 ** 64))
+        record_value("random-checkpoint-2", random.randint(0, 2 ** 64))
+        Workflow.sleep(1)
+
+        random = Workflow.new_random()
+        record_value("random-checkpoint-3", random.randint(0, 2 ** 64))
+        record_value("random-checkpoint-4", random.randint(0, 2 ** 64))
+        Workflow.sleep(1)
+
+        random = Workflow.new_random()
+        record_value("random-checkpoint-5", random.randint(0, 2 ** 64))
+        record_value("random-checkpoint-6", random.randint(0, 2 ** 64))
+        Workflow.sleep(1)
+
+
+@pytest.mark.repeat(3)
+def test_workflow_random():
+    checkpoint_values.clear()
+    factory = WorkerFactory("localhost", 7933, DOMAIN)
+    worker = factory.new_worker(TASK_LIST)
+    worker.register_workflow_implementation_type(TestRandomWorkflowImpl)
+    factory.start()
+
+    client = WorkflowClient.new_client(domain=DOMAIN)
+    workflow: TestRandomWorkflow = client.new_workflow_stub(TestRandomWorkflow)
+    workflow.get_greetings()
+
+    # Verify that the value is always the same at each checkpoint
+    for checkpoint, values in checkpoint_values.items():
+        assert all(v == values[0] for v in values)
+
+    # Verify that each checkpoint produced a unique value
+    values = [v[0] for k, v in checkpoint_values.items()]
+    assert len(set(values)) == 9
+
+    print("Stopping workers")
+    worker.stop()

cadence/workflow.py

@@ -2,6 +2,8 @@
 import datetime
 import inspect
 import json
+import random
+import uuid
 from dataclasses import dataclass, field
 from typing import Callable, List, Type, Dict, Tuple
 from uuid import uuid4
@@ -49,6 +51,17 @@ def now() -> datetime.datetime:
         now_in_ms = task.decider.decision_context.current_time_millis()
         return datetime.datetime.fromtimestamp(now_in_ms / 1000)
 
+    @staticmethod
+    def random_uuid() -> uuid.UUID:
+        from cadence.decision_loop import ITask
+        task: ITask = ITask.current()
+        return task.decider.decision_context.random_uuid()
+
+    @staticmethod
+    def new_random() -> random.Random:
+        from cadence.decision_loop import ITask
+        task: ITask = ITask.current()
+        return task.decider.decision_context.new_random()
 
 class WorkflowStub:
     pass