From 9dbf4a8c5a4a2a204873276acb28f97cca0a029a Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Thu, 30 May 2019 22:35:56 +0100
Subject: [PATCH] Turn commits

---
 syndicate/mini/core.py     | 41 +++++++++++++++++++++++++++++---------
 syndicate/mini/protocol.py |  3 +++
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/syndicate/mini/core.py b/syndicate/mini/core.py
index c0d8156..23cd98d 100644
--- a/syndicate/mini/core.py
+++ b/syndicate/mini/core.py
@@ -88,6 +88,8 @@ class Connection(object):
     def __init__(self, scope):
         self.endpoints = {}
         self.scope = scope
+        self.commitNeeded = False
+        self.worklist = []
 
     def _each_endpoint(self):
         return list(self.endpoints.values())
@@ -104,15 +106,16 @@ class Connection(object):
 
     def _update_endpoint(self, ep):
         self.endpoints[ep.id] = ep
-        self._send(self._encode(protocol.Assert(ep.id, ep.assertion)))
+        self._send(self._encode(protocol.Assert(ep.id, ep.assertion)), commitNeeded = True)
 
     def _clear_endpoint(self, ep):
         if ep.id in self.endpoints:
             del self.endpoints[ep.id]
-            self._send(self._encode(protocol.Clear(ep.id)))
+            self._send(self._encode(protocol.Clear(ep.id)), commitNeeded = True)
 
     def send(self, message):
-        self._send(self._encode(protocol.Message(message)))
+        self._send(self._encode(protocol.Message(message)), commitNeeded = True)
+        self._commit_if_needed()
 
     def _on_disconnected(self):
         for ep in self._each_endpoint():
@@ -123,14 +126,30 @@ class Connection(object):
         self._send(self._encode(protocol.Connect(self.scope)))
         for ep in self._each_endpoint():
             self._update_endpoint(ep)
+        self._commit_work()
 
     def _lookup(self, endpointId):
         return self.endpoints.get(endpointId, _dummy_endpoint)
 
+    def _push_work(self, thunk):
+        self.worklist.append(thunk)
+
+    def _commit_work(self):
+        for thunk in self.worklist:
+            thunk()
+        self.worklist.clear()
+        self._commit_if_needed()
+
+    def _commit_if_needed(self):
+        if self.commitNeeded:
+            self._send(self._encode(protocol.Commit()))
+            self.commitNeeded = False
+
     def _on_event(self, v):
-        if protocol.Add.isClassOf(v): return self._lookup(v[0])._add(v[1])
-        if protocol.Del.isClassOf(v): return self._lookup(v[0])._del(v[1])
-        if protocol.Msg.isClassOf(v): return self._lookup(v[0])._msg(v[1])
+        if protocol.Add.isClassOf(v): return self._push_work(lambda: self._lookup(v[0])._add(v[1]))
+        if protocol.Del.isClassOf(v): return self._push_work(lambda: self._lookup(v[0])._del(v[1]))
+        if protocol.Msg.isClassOf(v): return self._push_work(lambda: self._lookup(v[0])._msg(v[1]))
+        if protocol.Commit.isClassOf(v): return self._commit_work()
         if protocol.Err.isClassOf(v): return self._on_error(v[0])
         if protocol.Ping.isClassOf(v): self._send(self._encode(protocol.Pong()))
 
@@ -138,7 +157,7 @@ class Connection(object):
         log.error('%s: error from server: %r' % (self.__class__.__qualname__, detail))
         self._disconnect()
 
-    def _send(self, bs):
+    def _send(self, bs, commitNeeded = False):
         raise Exception('subclassresponsibility')
 
     def _disconnect(self):
@@ -165,9 +184,11 @@ class _StreamConnection(Connection, asyncio.Protocol):
             if v is None: break
             self._on_event(v)
 
-    def _send(self, bs):
+    def _send(self, bs, commitNeeded = False):
         if self.transport:
             self.transport.write(bs)
+            if commitNeeded:
+                self.commitNeeded = True
 
     def _disconnect(self):
         if self.stop_signal:
@@ -223,12 +244,14 @@ class WebsocketConnection(Connection):
         self.loop = None
         self.ws = None
 
-    def _send(self, bs):
+    def _send(self, bs, commitNeeded = False):
         if self.loop:
             def _do_send():
                 if self.ws:
                     self.loop.create_task(self.ws.send(bs))
             self.loop.call_soon_threadsafe(_do_send)
+            if commitNeeded:
+                self.commitNeeded = True
 
     def _disconnect(self):
         if self.loop:
diff --git a/syndicate/mini/protocol.py b/syndicate/mini/protocol.py
index d809c1f..2a2cc9a 100644
--- a/syndicate/mini/protocol.py
+++ b/syndicate/mini/protocol.py
@@ -5,6 +5,9 @@ from preserves import Record, Symbol
 Connect = Record.makeConstructor('Connect', 'scope')
 Peer = Record.makeConstructor('Peer', 'scope')
 
+## Bidirectional
+Commit = Record.makeConstructor('Commit', '')
+
 ## Client -> Server
 Assert = Record.makeConstructor('Assert', 'endpointName assertion')
 Clear = Record.makeConstructor('Clear', 'endpointName')