Add dependencies and script for generating API documentation.

Signed-off-by: Daira Emma Hopwood <daira@jacaranda.org>

.flake8

@@ -1,4 +1,14 @@
 [flake8]
 exclude = .git, __pycache__
-ignore = E302
+
+# Justifications for each ignored error or warning:
+# * E302: always requiring two blank lines rather than one between top-level items is too annoying and nitpicky.
+# * E402: we want imports for tests to go between the main code and the tests.
+# * W503, W504: these give false positives for the style of avoiding \ at the end of each line by using parens.
+#
+# References:
+# - https://flake8.pycqa.org/en/latest/user/error-codes.html
+# - https://pycodestyle.pycqa.org/en/latest/intro.html#error-codes
+ignore = E302, E402, W503, W504
+
 max-line-length = 120

.github/workflows/tests.yml

@@ -0,0 +1,23 @@
+name: tests
+
+on: pull_request
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install gnome-keyring
+        run: sudo apt-get install gnome-keyring
+
+      - name: Install poetry
+        run: pip install --user poetry
+
+      - name: Install dependencies
+        run: poetry install --no-root
+
+      - name: Run tests
+        # -p '[a-z]*.py' avoids running tests from __init__.py files twice.
+        run: poetry run python -m unittest discover -s simtfl -t . -p '[a-z]*.py' --verbose --buffer

README.md

@@ -23,30 +23,25 @@ Note the caveats: *experimental*, *simulator*, *research*, *potential*.
 
        poetry run demo
 
-## Programming patterns
+## Documentation
 
-The code makes use of the [simpy](https://simpy.readthedocs.io/en/latest/)
-discrete event simulation library. This means that functions representing
-processes are implemented as generators, so that the library can simulate
-timeouts and asynchronous communication (typically faster than real time).
+Design documentation is under the `doc/` directory:
 
-We use the convention of putting "(process)" in the doc comment of these
-functions. They either must use the `yield` construct, *or* return the
-result of calling another "(process)" function (not both).
+* [Programming patterns for use of simpy](doc/patterns.md).
 
-Objects that implement processes typically hold the `simpy.Environment` in
-an instance variable `self.env`.
-
-To wait for another process `f()` before continuing, use `yield from f()`.
-(If it is the last thing to do in a function with no other `yield`
-statements, `return f()` can be used as an optimization.)
-
-A "(process)" function that does nothing should `return skip()`, using
-`simtfl.util.skip`.
+You can also generate API documentation by running `./gendoc.sh`.
+The starting point for the generated documentation is <apidoc/simtfl.html>.
 
 ## Contributing
 
-Please check `poetry run flake8` before submitting a PR.
+Please use `./check.sh` before submitting a PR. This currently runs `flake8`
+and the unit tests locally.
+
+You can use `./check.sh -k <substring>` to run `flake8` and then only tests
+with names matching the given substring. This will not suppress output to
+stdout or stderr (but `./check.sh -bk <substring>` will).
+
+To see other options for running unit tests, use `poetry run python -m unittest -h`.
 
 ## License
 

check.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+set -eu
+cd -P -- "$(dirname -- "$(command -v -- "$0")")"
+
+echo Running flake8...
+poetry run flake8
+
+echo
+echo Running unit tests...
+args="${*:---buffer}"
+poetry run python -m unittest discover -s simtfl -t . -p '[a-z]*.py' --verbose ${args}

doc/patterns.md

@@ -0,0 +1,20 @@
+# Programming patterns
+
+The code makes use of the [simpy](https://simpy.readthedocs.io/en/latest/)
+discrete event simulation library. This means that functions representing
+processes are implemented as generators, so that the library can simulate
+timeouts and asynchronous communication (typically faster than real time).
+
+We use the convention of putting "(process)" in the doc comment of these
+functions. They either must use the `yield` construct, *or* return the
+result of calling another "(process)" function (not both).
+
+Objects that implement processes typically hold the `simpy.Environment` in
+an instance variable `self.env`.
+
+To wait for another process `f()` before continuing, use `yield from f()`.
+(If it is the last thing to do in a function with no other `yield`
+statements, `return f()` can be used as an optimization.)
+
+A "(process)" function that does nothing should `return skip()`, using
+`simtfl.util.skip`.

gendoc.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -eu
+
+poetry run pdoc simtfl -o apidoc --no-include-undocumented -d markdown

poetry.lock

@@ -17,6 +17,94 @@ mccabe = ">=0.7.0,<0.8.0"
 pycodestyle = ">=2.11.0,<2.12.0"
 pyflakes = ">=3.1.0,<3.2.0"
 
+[[package]]
+name = "jinja2"
+version = "3.1.2"
+description = "A very fast and expressive template engine."
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
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+    {file = "Jinja2-3.1.2.tar.gz", hash = "sha256:31351a702a408a9e7595a8fc6150fc3f43bb6bf7e319770cbc0db9df9437e852"},
+]
+
+[package.dependencies]
+MarkupSafe = ">=2.0"
+
+[package.extras]
+i18n = ["Babel (>=2.7)"]
+
+[[package]]
+name = "markupsafe"
+version = "2.1.3"
+description = "Safely add untrusted strings to HTML/XML markup."
+category = "dev"
+optional = false
+python-versions = ">=3.7"
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+]
+
 [[package]]
 name = "mccabe"
 version = "0.7.0"
@@ -29,16 +117,36 @@ files = [
     {file = "mccabe-0.7.0.tar.gz", hash = "sha256:348e0240c33b60bbdf4e523192ef919f28cb2c3d7d5c7794f74009290f236325"},
 ]
 
+[[package]]
+name = "pdoc"
+version = "14.1.0"
+description = "API Documentation for Python Projects"
+category = "dev"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "pdoc-14.1.0-py3-none-any.whl", hash = "sha256:e8869dffe21296b3bd5545b28e7f07cae0656082aca43f8915323187e541b126"},
+    {file = "pdoc-14.1.0.tar.gz", hash = "sha256:3a0bd921a05c39a82b1505089eb6dc99d857b71b856aa60d1aca4d9086d0e18c"},
+]
+
+[package.dependencies]
+Jinja2 = ">=2.11.0"
+MarkupSafe = "*"
+pygments = ">=2.12.0"
+
+[package.extras]
+dev = ["black", "hypothesis", "mypy", "pygments (>=2.14.0)", "pytest", "pytest-cov", "pytest-timeout", "ruff", "tox", "types-pygments"]
+
 [[package]]
 name = "pycodestyle"
-version = "2.11.0"
+version = "2.11.1"
 description = "Python style guide checker"
 category = "dev"
 optional = false
 python-versions = ">=3.8"
 files = [
-    {file = "pycodestyle-2.11.0-py2.py3-none-any.whl", hash = "sha256:5d1013ba8dc7895b548be5afb05740ca82454fd899971563d2ef625d090326f8"},
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 ]
 
 [[package]]
@@ -53,6 +161,21 @@ files = [
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 ]
 
+[[package]]
+name = "pygments"
+version = "2.16.1"
+description = "Pygments is a syntax highlighting package written in Python."
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "Pygments-2.16.1-py3-none-any.whl", hash = "sha256:13fc09fa63bc8d8671a6d247e1eb303c4b343eaee81d861f3404db2935653692"},
+    {file = "Pygments-2.16.1.tar.gz", hash = "sha256:1daff0494820c69bc8941e407aa20f577374ee88364ee10a98fdbe0aece96e29"},
+]
+
+[package.extras]
+plugins = ["importlib-metadata"]
+
 [[package]]
 name = "simpy"
 version = "4.0.2"
@@ -68,4 +191,4 @@ files = [
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.10"
-content-hash = "c164f34aba3ecbda9fc9942d6e2bfad3eb11491c433ee46bdf0262fd8147209f"
+content-hash = "d9f1f22d9f90f2ad4d00ec2785eee468e847dc1c8c4015615febe6094edf3e62"

pyproject.toml

@@ -12,6 +12,7 @@ simpy = "^4"
 
 [tool.poetry.dev-dependencies]
 flake8 = "^6"
+pdoc = "^14"
 
 [tool.poetry.scripts]
 demo = "simtfl.demo:run"

simtfl/__init__.py

@@ -0,0 +1,7 @@
+"""
+This is an experimental simulator for research into a potential [Trailing Finality
+Layer](https://electriccoin.co/blog/the-trailing-finality-layer-a-stepping-stone-to-proof-of-stake-in-zcash/)
+for Zcash.
+
+See the [README](../README.md) for more information.
+"""

simtfl/demo.py

@@ -58,14 +58,9 @@ def run():
     """
     Runs the demo.
     """
-    env = Environment()
-    network = Network(env, delay=4)
+    network = Network(Environment(), delay=4)
     for i in range(10):
-        network.add_node(PongNode(i, env, network))
+        network.add_node(PongNode())
 
-    network.add_node(PingNode(10, env, network))
-
-    for i in range(network.num_nodes()):
-        env.process(network.start_node(i))
-
-    env.run()
+    network.add_node(PingNode())
+    network.run_all()

simtfl/message.py

@@ -1,12 +1,15 @@
+"""
+Base classes for messages.
+"""
+
+from dataclasses import dataclass
+from typing import Any
+
+
+@dataclass(frozen=True)
 class PayloadMessage:
     """
     A message with an arbitrary payload.
     """
-    def __init__(self, payload):
-        """
-        Constructs a `PayloadMessage` with the given payload.
-        """
-        self.payload = payload
-
-    def __str__(self):
-        return f"{self.__class__.__name__}({self.payload})"
+    payload: Any
+    """The payload."""

simtfl/network.py

@@ -1,3 +1,7 @@
+"""
+Framework for message passing in a network of nodes.
+"""
+
 from .util import skip
 
 
@@ -30,16 +34,34 @@ class Network:
         """
         Adds a node with the next available ident.
         """
+        ident = self.num_nodes()
         self.nodes.append(node)
+        node.initialize(ident, self.env, self)
 
     def start_node(self, ident):
         """
         (process) Start the node with the given ident.
         """
         node = self.node(ident)
-        print(f"T{self.env.now:5d}: starting  {node}")
+        print(f"T{self.env.now:5d}: starting  {ident:2d}: {node}")
         return node.run()
 
+    def start_processes(self):
+        """
+        Start a process for each node.
+        """
+        print()
+        for i in range(self.num_nodes()):
+            self.env.process(self.start_node(i))
+
+    def run_all(self, *args, **kwargs):
+        """
+        Convenience method to start a process for each node, then start
+        the simulation. Takes the same arguments as `simpy.Environment.run`.
+        """
+        self.start_processes()
+        self.env.run(*args, **kwargs)
+
     def send(self, sender, target, message, delay=None):
         """
         (process) Sends a message to the node with ident `target`, from the node

simtfl/node.py

@@ -1,42 +1,57 @@
-from .util import skip
+"""
+Base classes for node implementations.
+"""
+
 from collections import deque
 
+from .util import skip
+
 
 class PassiveNode:
     """
-    A node that sends no messages and does nothing with received messages.
-    This class is intended to be subclassed.
+    A node that processes messages concurrently. By default it sends no
+    messages and does nothing with received messages. This class is
+    intended to be subclassed.
+
+    Inherit from this class directly if all messages are to be processed
+    concurrently without blocking. If messages are to be processed
+    sequentially, it may be easier to inherit from `SequentialNode`.
+
+    Note that the simulation is deterministic regardless of which option
+    is selected.
     """
-    def __init__(self, ident, env, network):
+    def initialize(self, ident, env, network):
         """
-        Constructs a PassiveNode with the given simpy Environment and network.
+        Initializes a PassiveNode with the given ident, simpy Environment,
+        and network. Nodes are initialized when they are added to a network.
         """
         self.ident = ident
         self.env = env
         self.network = network
 
     def __str__(self):
-        return f"{self.ident:2d}: {self.__class__.__name__}"
+        return f"{self.__class__.__name__}"
 
     def send(self, target, message):
         """
         (process) This method can be overridden to intercept messages being sent
-        by this node. It should typically call `self.network.send`.
+        by this node. The implementation in this class calls `self.network.send`.
         """
         return self.network.send(self.ident, target, message)
 
     def receive(self, sender, message):
         """
         (process) This method can be overridden to intercept messages being received
-        by this node. It should typically call `self.handle`.
+        by this node. The implementation in this class calls `self.handle`.
         """
         return self.handle(sender, message)
 
-    def handle(self, message, sender):
+    def handle(self, sender, message):
         """
         (process) Handles a message by doing nothing. Note that the handling of
         each message, and the `run` method, are in separate simpy processes. That
-        is, yielding here will not block other incoming messages.
+        is, yielding here will not block other incoming messages for a direct
+        subclass of `PassiveNode`.
         """
         return skip()
 
@@ -49,13 +64,15 @@ class PassiveNode:
 
 class SequentialNode(PassiveNode):
     """
-    A node that processes messages sequentially.
+    A node that processes messages sequentially. By default it sends no
+    messages and does nothing with received messages. This class is
+    intended to be subclassed.
     """
-    def __init__(self, ident, env, network):
+    def initialize(self, ident, env, network):
         """
-        Constructs a SequentialNode with the given simpy Environment and network.
+        Initializes a SequentialNode with the given simpy Environment and network.
         """
-        super().__init__(ident, env, network)
+        super().initialize(ident, env, network)
         self._mailbox = deque()
         self._wakeup = env.event()
 
@@ -70,6 +87,16 @@ class SequentialNode(PassiveNode):
             pass
         return skip()
 
+    def handle(self, sender, message):
+        """
+        (process) Handles a message by doing nothing. Messages are handled
+        sequentially; that is, handling of the next message will be blocked
+        on this process.
+        """
+        # This is the same implementation as `PassiveNode`, but the documentation
+        # is different.
+        return skip()
+
     def run(self):
         """
         (process) Repeatedly handle incoming messages.
@@ -87,3 +114,63 @@ class SequentialNode(PassiveNode):
             # concurrency.
             self._wakeup = self.env.event()
             yield self._wakeup
+
+
+__all__ = ['PassiveNode', 'SequentialNode']
+
+from simpy import Environment
+import unittest
+
+from .message import PayloadMessage
+from .network import Network
+
+
+class PassiveReceiverTestNode(PassiveNode):
+    def __init__(self):
+        super().__init__()
+        self.received = deque()
+
+    def handle(self, sender, message):
+        self.received.append((sender, message, self.env.now))
+        yield self.env.timeout(3)
+
+
+class SequentialReceiverTestNode(SequentialNode):
+    def __init__(self):
+        super().__init__()
+        self.received = deque()
+
+    def handle(self, sender, message):
+        self.received.append((sender, message, self.env.now))
+        yield self.env.timeout(3)
+
+
+class SenderTestNode(PassiveNode):
+    def run(self):
+        for i in range(3):
+            yield from self.send(0, PayloadMessage(i))
+            yield self.env.timeout(1)
+
+
+class TestFramework(unittest.TestCase):
+    def _test_node(self, receiver_node, expected):
+        network = Network(Environment())
+        network.add_node(receiver_node)
+        network.add_node(SenderTestNode())
+        network.run_all()
+
+        self.assertEqual(list(network.node(0).received), expected)
+
+    def test_passive_node(self):
+        self._test_node(PassiveReceiverTestNode(), [
+            (1, PayloadMessage(0), 1),
+            (1, PayloadMessage(1), 2),
+            (1, PayloadMessage(2), 3),
+        ])
+
+    def test_sequential_node(self):
+        self._test_node(SequentialReceiverTestNode(), [
+            (1, PayloadMessage(0), 1),
+            (1, PayloadMessage(1), 4),
+            (1, PayloadMessage(2), 7),
+        ])

simtfl/util.py

@@ -2,6 +2,7 @@
 Utilities.
 """
 
+
 def skip():
     """
     (process) Does nothing.