From c96ffe52c07f019b5ef656698772cf6cc163d609 Mon Sep 17 00:00:00 2001
From: Jan Lindemann <jan@janware.com>
Date: Tue, 29 Oct 2019 11:25:03 +0100
Subject: [PATCH] Add Process and Signals support

Signed-off-by: Jan Lindemann <jan@janware.com>
---
 tools/python/jwutils/Process.py          | 68 ++++++++++++++++++++++++
 tools/python/jwutils/Signals.py          | 34 ++++++++++++
 tools/python/jwutils/asyncio/Makefile    |  4 ++
 tools/python/jwutils/asyncio/Process.py  | 20 +++++++
 tools/python/jwutils/asyncio/Signals.py  | 10 ++++
 tools/python/jwutils/asyncio/__init__.py |  3 ++
 6 files changed, 139 insertions(+)
 create mode 100644 tools/python/jwutils/Process.py
 create mode 100644 tools/python/jwutils/Signals.py
 create mode 100644 tools/python/jwutils/asyncio/Makefile
 create mode 100644 tools/python/jwutils/asyncio/Process.py
 create mode 100644 tools/python/jwutils/asyncio/Signals.py
 create mode 100644 tools/python/jwutils/asyncio/__init__.py

diff --git a/tools/python/jwutils/Process.py b/tools/python/jwutils/Process.py
new file mode 100644
index 0000000..faf0084
--- /dev/null
+++ b/tools/python/jwutils/Process.py
@@ -0,0 +1,68 @@
+from abc import ABC, abstractmethod
+from enum import Enum, Flag, auto
+
+def _sigchld_handler(signum, process):
+    if not signum == signal.SIGCHLD:
+        return
+    Process.propagate_signal(signum)
+
+class Process(ABC): # export
+
+    __processes                   = []
+
+    class State(Enum):
+        Running                   = auto()
+        Shutdown                  = auto()
+        Done                      = auto()
+
+    class Flags(Flag):
+        FailOnExitWithoutShutdown = auto()
+
+    def __init__(self):
+        self.__state = Running
+        self.__flags = Flags.FailOnExitWithoutShutdown
+        if len(self.__processes) == 0:
+            self._signals().add_handler(signals.SIGCHLD, _sigchld_handler)
+        self.__processes.add(self)
+
+    @classmethod
+    def propagate_signal(cls, signum):
+        for p in cls.__processes:
+            p.__signal(signum)
+
+    def signal(self, signum):
+        if signum == signals.SIGCHLD:
+            self.exited()
+
+    @abstractmethod
+    def _pid(self):
+        pass
+
+    @classmethod
+    @abstractmethod
+    def signals(cls):
+        pass
+
+    # to be reimplemented
+    def _request_shutdown(self):
+        pass
+
+    # to be reimplemented
+    def name(self):
+        return str(self._pid())
+
+    def request_shutdown(self):
+        if not self.__state == Shutdown:
+            self.__state = Shutdown
+            self._request_shutdown()
+
+    def exited(self):
+        if self.__state == Process.State.Running:
+            slog(ERR, 'process "{}" exited unexpectedly'.format(process.name()))
+            if __flags & Process.Flags.FailOnExitWithoutShutdown:
+                slog(ERR, 'exiting')
+                exit(1)
+        self.__state = Process.State.Done
+        self.__processes.erase(self)
+        if len(self.__processes) == 0:
+            self._signals().remove_handler(signals.SIGCHLD) # FIXME: broken logic
diff --git a/tools/python/jwutils/Signals.py b/tools/python/jwutils/Signals.py
new file mode 100644
index 0000000..52d7819
--- /dev/null
+++ b/tools/python/jwutils/Signals.py
@@ -0,0 +1,34 @@
+from abc import ABC, abstractmethod
+
+_handled_signals = {}
+
+def _signal_handler(signal, frame):
+    if not signal in _handled_signals.keys():
+        return
+    for h in _handled_signals[signal]:
+        h.func(signal, *h.args)
+
+class Signals:
+
+    class Handler:
+        def __init__(self, func, args):
+            self.func = func
+            self.args = args
+
+    def __init(self):
+        pass
+
+    @classmethod
+    @abstractmethod
+    def _add_handler(self, signal, handler):
+        raise Exception("_add_handler() is not reimplemented")
+
+    @classmethod
+    def add_handler(cls, signals, handler, *args):
+        for signal in signals:
+            h = Signals.Handler(handler, args)
+            if not signal in _handled_signals.keys():
+                _handled_signals[signal] = [h]
+                cls._add_signal_handler(signal, _signal_handler)
+            else:
+                _handled_signals[signal].add(h)
diff --git a/tools/python/jwutils/asyncio/Makefile b/tools/python/jwutils/asyncio/Makefile
new file mode 100644
index 0000000..59b3ac1
--- /dev/null
+++ b/tools/python/jwutils/asyncio/Makefile
@@ -0,0 +1,4 @@
+TOPDIR = ../../../..
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/py-mod.mk
diff --git a/tools/python/jwutils/asyncio/Process.py b/tools/python/jwutils/asyncio/Process.py
new file mode 100644
index 0000000..d654da8
--- /dev/null
+++ b/tools/python/jwutils/asyncio/Process.py
@@ -0,0 +1,20 @@
+from abc import abstractmethod
+
+from ..Process import Process as ProcessBase
+from .Signals import Signals
+
+class Process(ProcessBase): # export
+
+    __signals = Signals()
+
+    def __init__(self, aio):
+        super().__init()
+        self.aio = aio
+
+    @classmethod
+    @abstractmethod
+    def signals(cls):
+        return cls.__signals
+
+    def wait(self):
+        return self.aio.wait()
diff --git a/tools/python/jwutils/asyncio/Signals.py b/tools/python/jwutils/asyncio/Signals.py
new file mode 100644
index 0000000..b6b43ac
--- /dev/null
+++ b/tools/python/jwutils/asyncio/Signals.py
@@ -0,0 +1,10 @@
+import asyncio
+from ..Signals import Signals as SignalsBase
+
+class Signals(SignalsBase):
+
+    # reimplemented from Signals
+    @classmethod
+    def _add_handler(cls, signal, handler):
+        loop = asyncio.get_running_loop()
+        loop.add_signal_handler(signal, handler, None) # None = *args
diff --git a/tools/python/jwutils/asyncio/__init__.py b/tools/python/jwutils/asyncio/__init__.py
new file mode 100644
index 0000000..fcdc905
--- /dev/null
+++ b/tools/python/jwutils/asyncio/__init__.py
@@ -0,0 +1,3 @@
+# >> -------------------------- generated by python-tools.sh >>
+from jwutils.asyncio.Process import Process
+# << -------------------------- generated by python-tools.sh <<