#598: support polling for platforms where we cannot rely on dbus to g…

…et notified of printer changes (ie: osx, or with env var to test) - don't even try the dbus approach on OSX by default, make the polling delay configurable, add some debug

git-svn-id: https://xpra.org/svn/Xpra/trunk@8871 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client/client_base.py

@@ -26,6 +26,13 @@
 from xpra.os_util import get_hex_uuid, get_machine_id, get_user_uuid, load_binary_file, SIGNAMES, strtobytes, bytestostr
 from xpra.util import typedict, updict, xor, repr_ellipsized, nonl, disconnect_is_an_error
 
+try:
+    import xpra.platform.printing
+    assert xpra.platform.printing
+    HAS_PRINTING = True
+except:
+    HAS_PRINTING = False
+
 EXIT_OK = 0
 EXIT_CONNECTION_LOST = 1
 EXIT_TIMEOUT = 2
@@ -350,6 +357,7 @@ def cleanup(self):
         if self._protocol:
             self._protocol.close()
             self._protocol = None
+        self.cleanup_printing()
 
     def glib_init(self):
         try:
@@ -538,14 +546,26 @@ def parse_printing_capabilities(self):
                 self.timeout_add(1000, self.init_printing)
 
     def init_printing(self):
+        if not HAS_PRINTING:
+            return
         try:
-            from xpra.platform.printing import on_printers_modified
-            printlog("on_printers_modified=%s", on_printers_modified)
-            on_printers_modified(self.send_printers)
+            from xpra.platform.printing import init_printing
+            printlog("init_printing=%s", init_printing)
+            init_printing(self.send_printers)
             self.do_send_printers()
         except Exception:
             log.warn("failed to send printers", exc_info=True)
 
+    def cleanup_printing(self):
+        if not HAS_PRINTING:
+            return
+        try:
+            from xpra.platform.printing import cleanup_printing
+            printlog("cleanup_printing=%s", cleanup_printing)
+            cleanup_printing()
+        except Exception:
+            log.warn("failed to cleanup printing subsystem", exc_info=True)
+
     def send_printers(self, *args):
         #dbus can fire dozens of times for a single printer change
         #so we wait a bit and fire via a timer to try to batch things together:

src/xpra/platform/printing.py

@@ -21,22 +21,25 @@ def print_files(printer, filenames, title, options):
 def printing_finished(printpid):
     return True
 
-def on_printers_modified(callback):
+def init_printing(printers_modified_callback=None):
     pass
 
+def cleanup_printing():
+    pass
 
 #default implementation uses pycups:
 from xpra.platform import platform_import
 try:
-    from xpra.platform.pycups_printing import get_printers, print_files, printing_finished, on_printers_modified
-    assert get_printers and print_files and printing_finished and on_printers_modified
+    from xpra.platform.pycups_printing import get_printers, print_files, printing_finished, init_printing, cleanup_printing
+    assert get_printers and print_files and printing_finished and init_printing, cleanup_printing
 except Exception as e:
     #ignore the error on win32:
     if not sys.platform.startswith("win"):
         err("cannot use pycups for printing: %s", e)
 
 platform_import(globals(), "printing", False,
-                "on_printers_modified",
+                "init_printing",
+                "cleanup_printing",
                 "get_printers",
                 "print_files",
                 "printing_finished")

src/xpra/platform/pycups_printing.py

@@ -30,6 +30,14 @@
     PRINTER_PREFIX = "Xpra:"
 PRINTER_PREFIX = os.environ.get("XPRA_PRINTER_PREFIX", PRINTER_PREFIX)
 
+DEFAULT_CUPS_DBUS = str(int(not sys.platform.startswith("darwin")))
+CUPS_DBUS = os.environ.get("XPRA_CUPS_DBUS", DEFAULT_CUPS_DBUS)=="1"
+POLLING_DELAY = int(os.environ.get("XPRA_CUPS_POLLING_DELAY", "60"))
+log("pycups settings: DEFAULT_CUPS_DBUS=%s, CUPS_DBUS=%s, POLLING_DELAY=%s", DEFAULT_CUPS_DBUS, CUPS_DBUS, POLLING_DELAY)
+log("pycups settings: PRINTER_PREFIX=%s, ADD_LOCAL_PRINTERS=%s", PRINTER_PREFIX, ADD_LOCAL_PRINTERS)
+log("pycups settings: PPD_FILE=%s, ALLOW=%s", PPD_FILE, ALLOW)
+log("pycups settings: FORWARDER_TMPDIR=%s", FORWARDER_TMPDIR)
+
 
 #allows us to inject the lpadmin command
 def set_lpadmin_command(lpadmin):
@@ -82,7 +90,7 @@ def remove_printer(name):
     exec_lpadmin(["-x", PRINTER_PREFIX+sanitize_name(name)])
 
 
-dbus_init = False
+dbus_init = None
 printers_modified_callback = None
 DBUS_PATH="/com/redhat/PrinterSpooler"
 DBUS_IFACE="com.redhat.PrinterSpooler"
@@ -92,28 +100,58 @@ def handle_dbus_signal(*args):
     printers_modified_callback()
 
 def init_dbus_listener():
+    if not CUPS_DBUS:
+        return False
     global dbus_init
     log("init_dbus_listener() dbus_init=%s", dbus_init)
-    if dbus_init:
-        return
-    dbus_init = True
-    try:
-        from xpra.x11.dbus_common import  init_system_bus
-        system_bus = init_system_bus()
-        log("system bus: %s", system_bus)
-        sig_match = system_bus.add_signal_receiver(handle_dbus_signal, path=DBUS_PATH, dbus_interface=DBUS_IFACE)
-        log("system_bus.add_signal_receiver(..)=%s", sig_match)
-    except Exception:
-        if sys.platform.startswith("darwin"):
-            log("no dbus on osx")
-        else:
-            log.error("failed to initialize dbus cups event listener", exc_info=True)
-
-def on_printers_modified(callback):
+    if dbus_init is None:
+        try:
+            from xpra.x11.dbus_common import init_system_bus
+            system_bus = init_system_bus()
+            log("system bus: %s", system_bus)
+            sig_match = system_bus.add_signal_receiver(handle_dbus_signal, path=DBUS_PATH, dbus_interface=DBUS_IFACE)
+            log("system_bus.add_signal_receiver(..)=%s", sig_match)
+            dbus_init = True
+        except Exception:
+            if sys.platform.startswith("darwin"):
+                log("no dbus on osx")
+            else:
+                log.error("failed to initialize dbus cups event listener", exc_info=True)
+            dbus_init = False
+    return dbus_init
+
+def check_printers():
+    global printers_modified_callback
+    #we don't actually check anything here and just
+    #fire the callback every time, relying in client_base
+    #to notice that nothing has changed and avoid sending the same printers to the server
+    log("check_printers() printers_modified_callback=%s", printers_modified_callback)
+    printers_modified_callback()
+    schedule_polling_timer()
+
+_polling_timer = None
+def schedule_polling_timer():
+    #fallback to polling:
+    import threading
+    global _polling_timer
+    _polling_timer = threading.Timer(POLLING_DELAY, check_printers)
+    _polling_timer.start()
+
+def init_printing(callback):
     global printers_modified_callback
-    log("on_printers_modified(%s) printers_modified_callback=%s", callback, printers_modified_callback)
+    log("init_printing(%s) printers_modified_callback=%s", callback, printers_modified_callback)
     printers_modified_callback = callback
-    init_dbus_listener()
+    if not init_dbus_listener():
+        log("init_printing(%s) will use polling", callback)
+        schedule_polling_timer()
+
+def cleanup_printing():
+    global _polling_timer
+    try:
+        _polling_timer.cancel()
+        _polling_timer = None
+    except:
+        pass
 
 
 def get_printers():

src/xpra/platform/win32/printing.py

@@ -34,9 +34,9 @@
 PROCESSES = {}
 
 printers_modified_callback = None
-def on_printers_modified(callback):
+def init_printing(callback):
     global printers_modified_callback
-    log("on_printers_modified(%s) printers_modified_callback=%s", callback, printers_modified_callback)
+    log("init_printing(%s) printers_modified_callback=%s", callback, printers_modified_callback)
     printers_modified_callback = callback
     try:
         init_winspool_listener()