pylightning: Add the `sync` keyword to hooks and methods

This indicates that the method or hook will accepts a request
parameter, and will use that to return the result or raise an
exception instead of returning the return value. This allows the hook
or method to stash the incomplete request or pass it around, without
blocking the JSON-RPC interface.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

contrib/pylightning/lightning/plugin.py

@@ -113,7 +113,7 @@ class Plugin(object):
         if os.getenv('LIGHTNINGD_PLUGIN') and autopatch:
             monkey_patch(self, stdout=True, stderr=True)
 
-        self.add_method("getmanifest", self._getmanifest)
+        self.add_method("getmanifest", self._getmanifest, sync=True)
         self.rpc_filename = None
         self.lightning_dir = None
         self.rpc = None
@@ -121,7 +121,7 @@ class Plugin(object):
 
         self.write_lock = RLock()
 
-    def add_method(self, name, func):
+    def add_method(self, name, func, sync):
         """Add a plugin method to the dispatch table.
 
         The function will be expected at call time (see `_dispatch`)
@@ -149,6 +149,7 @@ class Plugin(object):
 
         # Register the function with the name
         method = Method(name, func, MethodType.RPCMETHOD)
+        method.asynchronous = not sync
         self.methods[name] = method
 
     def add_subscription(self, topic, func):
@@ -206,17 +207,17 @@ class Plugin(object):
         else:
             return self.options[name]['default']
 
-    def method(self, method_name, *args, **kwargs):
+    def method(self, method_name, *args, sync=True, **kwargs):
         """Decorator to add a plugin method to the dispatch table.
 
         Internally uses add_method.
         """
         def decorator(f):
-            self.add_method(method_name, f)
+            self.add_method(method_name, f, sync=sync)
             return f
         return decorator
 
-    def add_hook(self, name, func):
+    def add_hook(self, name, func, sync=True):
         """Register a hook that is called synchronously by lightningd on events
         """
         if name in self.methods:
@@ -224,15 +225,16 @@ class Plugin(object):
                 "Method {} was already registered".format(name, self.methods[name])
             )
         method = Method(name, func, MethodType.HOOK)
+        method.asynchronous = not sync
         self.methods[name] = method
 
-    def hook(self, method_name):
+    def hook(self, method_name, sync=True):
         """Decorator to add a plugin hook to the dispatch table.
 
         Internally uses add_hook.
         """
         def decorator(f):
-            self.add_hook(method_name, f)
+            self.add_hook(method_name, f, sync)
             return f
         return decorator