scgi: support reusing a listen socket

This is useful when used in combination with e.g. systemd.

2 files changed, 32 insertions, 12 deletions

diff --git a/wsgitools/scgi/asynchronous.py b/wsgitools/scgi/asynchronous.py
index 75f1ff0..e1dbcc6 100644
--- a/wsgitools/scgi/asynchronous.py
+++ b/wsgitools/scgi/asynchronous.py
@@ -191,7 +191,7 @@ class SCGIServer(asyncore.dispatcher):
     multiple threads."""
     def __init__(self, wsgiapp, port, interface="localhost", error=sys.stderr,
                  maxrequestsize=None, maxpostsize=None, blocksize=None,
-                 config={}):
+                 config={}, reusesocket=None):
         """
         @param wsgiapp: is the wsgi application to be run.
         @type port: int
@@ -215,8 +215,16 @@ class SCGIServer(asyncore.dispatcher):
         @type config: {}
         @param config: the environ dictionary is updated using these values for
                 each request.
+        @type reusesocket: None or socket.socket
+        @param reusesocket: If a socket is passed, do not create a socket.
+                Instead use given socket as listen socket. The passed socket
+                must be set up for accepting tcp connections (i.e. AF_INET,
+                SOCK_STREAM with bind and listen called).
         """
-        asyncore.dispatcher.__init__(self)
+        if reusesocket is None:
+            asyncore.dispatcher.__init__(self)
+        else:
+            asyncore.dispatcher.__init__(self, reusesocket)
 
         self.wsgiapp = wsgiapp
         self.error = error
@@ -229,10 +237,11 @@ class SCGIServer(asyncore.dispatcher):
             self.conf["blocksize"] = blocksize
         self.conf["config"] = config
 
-        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.set_reuse_addr()
-        self.bind((interface, port))
-        self.listen(5)
+        if reusesocket is None:
+            self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.set_reuse_addr()
+            self.bind((interface, port))
+            self.listen(5)
 
     def handle_accept(self):
         """asyncore interface"""
diff --git a/wsgitools/scgi/forkpool.py b/wsgitools/scgi/forkpool.py
index b090a54..8ccd579 100644
--- a/wsgitools/scgi/forkpool.py
+++ b/wsgitools/scgi/forkpool.py
@@ -168,7 +168,8 @@ class SCGIServer:
             self.state = state
 
     def __init__(self, wsgiapp, port, interface="localhost", error=sys.stderr,
-                 minworkers=2, maxworkers=32, maxrequests=1000, config={}):
+                 minworkers=2, maxworkers=32, maxrequests=1000, config={},
+                 reusesocket=None):
         """
         @param wsgiapp: is the WSGI application to be run.
         @type port: int
@@ -188,6 +189,11 @@ class SCGIServer:
         @type config: {}
         @param config: the environ dictionary is updated using these values for
                 each request.
+        @type reusesocket: None or socket.socket
+        @param reusesocket: If a socket is passed, do not create a socket.
+                Instead use given socket as listen socket. The passed socket
+                must be set up for accepting tcp connections (i.e. AF_INET,
+                SOCK_STREAM with bind and listen called).
         """
         assert hasattr(error, "write")
         self.wsgiapp = wsgiapp
@@ -198,6 +204,7 @@ class SCGIServer:
         self.maxrequests = maxrequests
         self.config = config
         self.error = error
+        self.reusesocket = reusesocket
         self.server = None # becomes a socket
         # maps filedescriptors to WorkerStates
         self.workers = {}
@@ -218,10 +225,13 @@ class SCGIServer:
         """
         Serve the wsgi application.
         """
-        self.server = socket.socket()
-        self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        self.server.bind((self.interface, self.port))
-        self.server.listen(5)
+        if self.reusesocket is None:
+            self.server = socket.socket()
+            self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            self.server.bind((self.interface, self.port))
+            self.server.listen(5)
+        else:
+            self.server = self.reusesocket
         self.running = True
         while self.running:
             while (len(self.workers) < self.minworkers or # less than min
@@ -254,7 +264,8 @@ class SCGIServer:
                     pid, _ = os.waitpid(0, os.WNOHANG)
             except OSError:
                 pass
-        self.server.close()
+        if self.reusesocket is None:
+            self.server.close()
         self.server = None
         self.killworkers()