Save and restore state of the game

Ability to 'save' (when the user closes the Activity) and 'restore' (when the
user launch it from the Journal or the Home without holding Alt) the state of
the game.

For this ability I had to upgrade 'olpcgames' to 1.6 because
'olpcgames.FILE_READ_REQUEST' and 'olpcgames.FILE_WRITE_REQUEST' events are
added in that version and those events are needed for this.

The data is saved (as JSON, with json module) in the 'event.metadata["state"]' and the timestamp state is saved in 'event.filename'.

This commit solves ticket #2393:
 * http://bugs.sugarlabs.org/ticket/2393

Signed-off-by: Manuel Kaufmann <humitos@gmail.com>
Signed-off-by: Rafael Ortiz <rafael@activitycentral.com>

1 files changed, 241 insertions, 51 deletions

diff --git a/olpcgames/eventwrap.py b/olpcgames/eventwrap.py
index 92fbabb..402109c 100644
--- a/olpcgames/eventwrap.py
+++ b/olpcgames/eventwrap.py
@@ -4,32 +4,131 @@ Provides methods which will be substituted into Pygame in order to
 provide the synthetic events that we will feed into the Pygame queue.
 These methods are registered by the "install" method.
 
-Extension:
+This event queue does not support getting events only of a certain type. 
+You need to get all pending events at a time, or filter them yourself. You 
+can, however, block and unblock events of certain types, so that may be 
+useful to you. 
 
-    last_event_time() -- returns period since the last event was produced
-        in seconds.  This can be used to create "pausing" effects for games.
+Set_grab doesn't do anything (you are not allowed to grab events). Sorry.
+
+Extensions:
+
+    wait( timeout=None ) -- allows you to wait for only a specified period 
+        before you return to the application.  Can be used to e.g. wait for a 
+        short period, then release some resources, then wait a bit more, then
+        release a few more resources, then a bit more...
 """
 import pygame
 import gtk
 import Queue
-import thread
+import thread, threading
 import logging
+from olpcgames import util
 
 log = logging.getLogger( 'olpcgames.eventwrap' )
 
-# This module reuses Pygame's Event, but
-# reimplements the event queue.
 from pygame.event import Event, event_name, pump as pygame_pump, get as pygame_get
 
 class Event(object):
     """Mock pygame events"""
-    def __init__(self, type, **named):
+    def __init__(self, type, dict=None,**named):
+        """Initialise the new event variables from dictionary and named become attributes"""
         self.type = type
+        if dict:
+            self.__dict__.update( dict )
         self.__dict__.update( named )
+    def _get_dict( self ):
+        return self.__dict__
+    dict = property( _get_dict )
+    def __repr__( self ):
+        result = []
+        for key,value in self.__dict__.items():
+            if not key.startswith( '_' ):
+                result.append( '%s = %r'%( key, value ))
+        return '%s( %s, %s )'%(
+            self.__class__.__name__,
+            self.type,
+            ",".join( result ),
+        )
+    def block( self ):
+        """Block until this event is finished processing
+        
+        Event process is only finalized on the *next* call to retrieve an event
+        after the processing operation in which the event is processed.  In some 
+        extremely rare cases we might actually see that happen, were the 
+        file-saving event (for example) causes the Pygame event loop to exit.
+        In that case, the GTK event loop *could* hang.
+        """
+        log.info( '''Blocking GTK thread on event: %s''', self )
+        self.__lock = threading.Event()
+        self.__lock.wait()
+    def retire( self ):
+        """Block the GTK event loop until this event is processed"""
+        try:
+            self.__lock.set()
+            log.info( '''Released GTK thread on event: %s''', self )
+        except AttributeError, err:
+            pass 
+
+class CallbackResult( object ):
+    def __init__( self, callable, args, named, callContext=None ):
+        """Perform callback in Pygame loop with args and named
+        
+        callContext is used to provide more information when there is 
+        a failure in the callback (for debugging purposes)
+        """
+        self.callable = callable
+        self.args = args 
+        self.named = named 
+        if callContext is None:
+            callContext = util.get_traceback( None )
+        self.callContext = callContext
+    def __call__( self ):
+        """Perform the actual callback in the Pygame event loop"""
+        try:
+            self.callable( *self.args, **self.named )
+        except Exception, err:
+            log.error(
+                """Failure in callback %s( *%s, **%s ): %s\n%s""",
+                getattr(self.callable, '__name__',self.callable), 
+                self.args, self.named,
+                util.get_traceback( err ),
+                self.callContext
+            )
+
 
-#print "Initializing own event.py"
+_EVENTS_TO_RETIRE = []
+
+def _releaseEvents( ):
+    """Release/retire previously-processed events"""
+    if _EVENTS_TO_RETIRE:
+        for event in _EVENTS_TO_RETIRE:
+            try:
+                event.retire()
+            except AttributeError, err:
+                pass
+
+def _processCallbacks( events ):
+    """Process any callbacks in events and remove from the stream"""
+    result = []
+    for event in events:
+        if isinstance( event, CallbackResult ):
+            event()
+        else:
+            result.append( event )
+    if events and not result:
+        result.append( 
+            Event( type=pygame.NOEVENT )
+        )
+    return result
+
+def _recordEvents( events ):
+    """Record the set of events to retire on the next iteration"""
+    global _EVENTS_TO_RETIRE
+    events = _processCallbacks( events )
+    _EVENTS_TO_RETIRE = events 
+    return events
 
-# Install myself on top of pygame.event
 def install():
     """Installs this module (eventwrap) as an in-place replacement for the pygame.event module.
    
@@ -41,31 +140,122 @@ def install():
     registers the handler itself, so you will always wind up with it registered when 
     you use olpcgames (the gtkEvent.Translator.hook_pygame method calls it).
     """
-    import eventwrap,pygame
+    log.info( 'Installing OLPCGames event wrapper' )
+    from olpcgames import eventwrap
+    import pygame
     pygame.event = eventwrap
     import sys
     sys.modules["pygame.event"] = eventwrap
-    
 
 # Event queue:
-g_events = Queue.Queue()
+class _FilterQueue( Queue.Queue ):
+    """Simple Queue sub-class with a put_left method"""
+    def get_type( self, filterFunction, block=True, timeout=None ):
+        """Get events of a given type
+        
+        Note: can raise Empty *even* when blocking if someone else 
+        pops the event off the queue before we get around to it.
+        """
+        self.not_empty.acquire()
+        try:
+            if not block:
+                if self._empty_type( filterFunction ):
+                    raise Queue.Empty
+            elif timeout is None:
+                while self._empty_type( filterFunction ):
+                    self.not_empty.wait()
+            else:
+                if timeout < 0:
+                    raise ValueError("'timeout' must be a positive number")
+                endtime = _time() + timeout
+                while self._empty_type( filterFunction ):
+                    remaining = endtime - _time()
+                    if remaining <= 0.0:
+                        raise Queue.Empty
+                    self.not_empty.wait(remaining)
+            item = self._get_type( filterFunction )
+            self.not_full.notify()
+            return item
+        finally:
+            self.not_empty.release()
+    def _empty_type( self, filterFunction ):
+        """Are we empty with respect to filterFunction?"""
+        for element in self.queue:
+            if filterFunction( element ):
+                return False 
+        return True
+    def _get_type( self, filterFunction ):
+        """Get the first instance which matches filterFunction"""
+        for element in self.queue:
+            if filterFunction( element ):
+                self.queue.remove( element )
+                return element 
+        # someone popped the event off the queue before we got to it!
+        raise Queue.Empty
+    def peek_type( self, filterFunction= lambda x: True ):
+        """Peek to see if we have filterFunction-matching element
+        
+        Note: obviously this is *not* thread safe, it's just informative...
+        """
+        try:
+            for element in self.queue:
+                if filterFunction( element ):
+                    return element
+            return None
+        except RuntimeError, err:
+            return None # none yet, at least
+    
+g_events = _FilterQueue()
 
 # Set of blocked events as set by set
 g_blocked = set()
-g_blockedlock = thread.allocate_lock()
+g_blockedlock = thread.allocate_lock() # should use threading instead
 g_blockAll = False
 
+def _typeChecker( types ):
+    """Create check whether an event is in types"""
+    try:
+        if 1 in types:
+            pass
+        def check( element ):
+            return element.type in types
+        return check
+    except TypeError, err:
+        def check( element ):
+            return element.type == types
+        return check
+
 def pump():
-    """Handle any window manager and other external events that aren't passed to the user. Call this periodically (once a frame) if you don't call get(), poll() or wait()."""
+    """Handle any window manager and other external events that aren't passed to the user
+    
+    Call this periodically (once a frame) if you don't call get(), poll() or wait()
+    """
     pygame_pump()
+    _releaseEvents()
 
-def get():
-    """Get a list of all pending events. (Unlike pygame, there's no option to filter by event type; you should use set_blocked() if you don't want to see certain events.)"""
+def get( types=None):
+    """Get a list of all pending events
+    
+    types -- either an integer event-type or a sequence of integer event types 
+        which restrict the set of event-types returned from the queue.  Keep in mind 
+        that if you do not remove events you may wind up with an eternally growing
+        queue or a full queue.  Normally you will want to remove all events in your 
+        top-level event-loop and propagate them yourself.
+    
+        Note: if you use types you lose all event ordering guarantees, events
+        may show up after events which were originally produced before them due to 
+        the re-ordering of the queue on filtering!
+    """
     pump()
     eventlist = []
     try:
-        while True:
-            eventlist.append(g_events.get(block=False))
+        if types:
+            check = _typeChecker( types )
+            while True:
+                eventlist.append(g_events.get_type( check, block=False))
+        else:
+            while True:
+                eventlist.append(g_events.get(block=False))
     except Queue.Empty:
         pass
     
@@ -73,32 +263,14 @@ def get():
     if pygameEvents:
         log.info( 'Raw Pygame events: %s', pygameEvents)
         eventlist.extend( pygameEvents )
-    if eventlist:
-        _set_last_event_time()
-    return eventlist
-
-_LAST_EVENT_TIME = 0
-    
-def _set_last_event_time( time=None ):
-    """Set this as the last event time"""
-    global _LAST_EVENT_TIME
-    if time is None:
-        time = pygame.time.get_ticks()
-    _LAST_EVENT_TIME = time 
-    return time 
-    
-def last_event_time( ):
-    """Return the last event type for pausing operations in seconds"""
-    global _LAST_EVENT_TIME
-    return (pygame.time.get_ticks() - _LAST_EVENT_TIME)/1000.
+    return _recordEvents( eventlist )
 
 def poll():
     """Get the next pending event if exists. Otherwise, return pygame.NOEVENT."""
     pump()
     try:
         result = g_events.get(block=False)
-        _set_last_event_time()
-        return result
+        return _recordEvents( [result] )[0]
     except Queue.Empty:
         return Event(pygame.NOEVENT)
 
@@ -107,30 +279,49 @@ def wait( timeout = None):
     """Get the next pending event, wait up to timeout if none
     
     timeout -- if present, only wait up to timeout seconds, if we 
-        do not find an event before then, return None
+        do not find an event before then, return None.  timeout 
+        is an OLPCGames-specific extension.
     """
     pump()
     try:
+        result = None 
         result = g_events.get(block=True, timeout=timeout)
-        _set_last_event_time()
-        return result
+        try:
+            return _recordEvents( [result] )[0]
+        except IndexError, err:
+            return Event( type=pygame.NOEVENT )
     except Queue.Empty, err:
         return None
 
 def peek(types=None):
-    """True if there is any pending event. (Unlike pygame, there's no option to
-    filter by event type)"""
+    """True if there is any pending event
+    
+    types -- optional set of event-types used to check whether 
+        an event is of interest.  If specified must be either a sequence 
+        of integers/longs or an integer/long.
+    """
+    if types:
+        check = _typeChecker( types )
+        return g_events.peek_type( check ) is not None
     return not g_events.empty()
     
 def clear():
-    """Dunno why you would do this, but throws every event out of the queue"""
+    """Clears the entire pending queue of events 
+    
+    Rarely used
+    """
     try:
+        discarded = []
         while True:
-            g_events.get(block=False)
+            discarded.append( g_events.get(block=False) )
+        discarded = _recordEvents( discarded )
+        _releaseEvents()
+        return discarded
     except Queue.Empty:
         pass
 
 def set_blocked(item):
+    """Block item/items from being added to the event queue"""
     g_blockedlock.acquire()
     try:
         # FIXME: we do not currently know how to block all event types when
@@ -140,6 +331,7 @@ def set_blocked(item):
         g_blockedlock.release()
     
 def set_allowed(item):
+    """Allow item/items to be added to the event queue"""
     g_blockedlock.acquire()
     try:
         if item is None:
@@ -160,18 +352,16 @@ def get_blocked(*args, **kwargs):
         g_blockedlock.release()
 
 def set_grab(grabbing):
-    # We don't do this.
-    pass
+    """This method will not be implemented"""
 
 def get_grab():
-    # We don't do this.
-    return False
+    """This method will not be implemented"""
 
 def post(event):
-    #print "posting on own"
+    """Post a new event to the Queue of events"""
     g_blockedlock.acquire()
     try:
-        if event.type not in g_blocked:
+        if getattr(event,'type',None) not in g_blocked:
             g_events.put(event, block=False)
     finally:
         g_blockedlock.release()