Add CherryPy to third_party.

third_party/cherrypy/lib/gctools.py

+import gc
+import inspect
+import os
+import sys
+import time
+ 
+try:
+    import objgraph
+except ImportError:
+    objgraph = None
+
+import cherrypy
+from cherrypy import _cprequest, _cpwsgi
+from cherrypy.process.plugins import SimplePlugin
+
+
+class ReferrerTree(object):
+    """An object which gathers all referrers of an object to a given depth."""
+
+    peek_length = 40
+
+    def __init__(self, ignore=None, maxdepth=2, maxparents=10):
+        self.ignore = ignore or []
+        self.ignore.append(inspect.currentframe().f_back)
+        self.maxdepth = maxdepth
+        self.maxparents = maxparents
+
+    def ascend(self, obj, depth=1):
+        """Return a nested list containing referrers of the given object."""
+        depth += 1
+        parents = []
+
+        # Gather all referrers in one step to minimize
+        # cascading references due to repr() logic.
+        refs = gc.get_referrers(obj)
+        self.ignore.append(refs)
+        if len(refs) > self.maxparents:
+            return [("[%s referrers]" % len(refs), [])]
+
+        try:
+            ascendcode = self.ascend.__code__
+        except AttributeError:
+            ascendcode = self.ascend.im_func.func_code
+        for parent in refs:
+            if inspect.isframe(parent) and parent.f_code is ascendcode:
+                continue
+            if parent in self.ignore:
+                continue
+            if depth <= self.maxdepth:
+                parents.append((parent, self.ascend(parent, depth)))
+            else:
+                parents.append((parent, []))
+
+        return parents
+
+    def peek(self, s):
+        """Return s, restricted to a sane length."""
+        if len(s) > (self.peek_length + 3):
+            half = self.peek_length // 2
+            return s[:half] + '...' + s[-half:]
+        else:
+            return s
+
+    def _format(self, obj, descend=True):
+        """Return a string representation of a single object."""
+        if inspect.isframe(obj):
+            filename, lineno, func, context, index = inspect.getframeinfo(obj)
+            return "<frame of function '%s'>" % func
+
+        if not descend:
+            return self.peek(repr(obj))
+
+        if isinstance(obj, dict):
+            return "{" + ", ".join(["%s: %s" % (self._format(k, descend=False),
+                                                self._format(v, descend=False))
+                                    for k, v in obj.items()]) + "}"
+        elif isinstance(obj, list):
+            return "[" + ", ".join([self._format(item, descend=False)
+                                    for item in obj]) + "]"
+        elif isinstance(obj, tuple):
+            return "(" + ", ".join([self._format(item, descend=False)
+                                    for item in obj]) + ")"
+
+        r = self.peek(repr(obj))
+        if isinstance(obj, (str, int, float)):
+            return r
+        return "%s: %s" % (type(obj), r)
+
+    def format(self, tree):
+        """Return a list of string reprs from a nested list of referrers."""
+        output = []
+        def ascend(branch, depth=1):
+            for parent, grandparents in branch:
+                output.append(("    " * depth) + self._format(parent))
+                if grandparents:
+                    ascend(grandparents, depth + 1)
+        ascend(tree)
+        return output
+
+
+def get_instances(cls):
+    return [x for x in gc.get_objects() if isinstance(x, cls)]
+
+
+class RequestCounter(SimplePlugin):
+    
+    def start(self):
+        self.count = 0
+    
+    def before_request(self):
+        self.count += 1
+    
+    def after_request(self):
+        self.count -=1
+request_counter = RequestCounter(cherrypy.engine)
+request_counter.subscribe()
+
+
+def get_context(obj):
+    if isinstance(obj, _cprequest.Request):
+        return "path=%s;stage=%s" % (obj.path_info, obj.stage)
+    elif isinstance(obj, _cprequest.Response):
+        return "status=%s" % obj.status
+    elif isinstance(obj, _cpwsgi.AppResponse):
+        return "PATH_INFO=%s" % obj.environ.get('PATH_INFO', '')
+    elif hasattr(obj, "tb_lineno"):
+        return "tb_lineno=%s" % obj.tb_lineno
+    return ""
+
+
+class GCRoot(object):
+    """A CherryPy page handler for testing reference leaks."""
+
+    classes = [(_cprequest.Request, 2, 2,
+                "Should be 1 in this request thread and 1 in the main thread."),
+               (_cprequest.Response, 2, 2,
+                "Should be 1 in this request thread and 1 in the main thread."),
+               (_cpwsgi.AppResponse, 1, 1,
+                "Should be 1 in this request thread only."),
+               ]
+
+    def index(self):
+        return "Hello, world!"
+    index.exposed = True
+
+    def stats(self):
+        output = ["Statistics:"]
+        
+        for trial in range(10):
+            if request_counter.count > 0:
+                break
+            time.sleep(0.5)
+        else:
+            output.append("\nNot all requests closed properly.")
+        
+        # gc_collect isn't perfectly synchronous, because it may
+        # break reference cycles that then take time to fully
+        # finalize. Call it thrice and hope for the best.
+        gc.collect()
+        gc.collect()
+        unreachable = gc.collect()
+        if unreachable:
+            if objgraph is not None:
+                final = objgraph.by_type('Nondestructible')
+                if final:
+                    objgraph.show_backrefs(final, filename='finalizers.png')
+
+            trash = {}
+            for x in gc.garbage:
+                trash[type(x)] = trash.get(type(x), 0) + 1
+            if trash:
+                output.insert(0, "\n%s unreachable objects:" % unreachable)
+                trash = [(v, k) for k, v in trash.items()]
+                trash.sort()
+                for pair in trash:
+                    output.append("    " + repr(pair))
+
+        # Check declared classes to verify uncollected instances.
+        # These don't have to be part of a cycle; they can be
+        # any objects that have unanticipated referrers that keep
+        # them from being collected.
+        allobjs = {}
+        for cls, minobj, maxobj, msg in self.classes:
+            allobjs[cls] = get_instances(cls)
+
+        for cls, minobj, maxobj, msg in self.classes:
+            objs = allobjs[cls]
+            lenobj = len(objs)
+            if lenobj < minobj or lenobj > maxobj:
+                if minobj == maxobj:
+                    output.append(
+                        "\nExpected %s %r references, got %s." %
+                        (minobj, cls, lenobj))
+                else:
+                    output.append(
+                        "\nExpected %s to %s %r references, got %s." %
+                        (minobj, maxobj, cls, lenobj))
+
+                for obj in objs:
+                    if objgraph is not None:
+                        ig = [id(objs), id(inspect.currentframe())]
+                        fname = "graph_%s_%s.png" % (cls.__name__, id(obj))
+                        objgraph.show_backrefs(
+                            obj, extra_ignore=ig, max_depth=4, too_many=20,
+                            filename=fname, extra_info=get_context)
+                    output.append("\nReferrers for %s (refcount=%s):" %
+                                  (repr(obj), sys.getrefcount(obj)))
+                    t = ReferrerTree(ignore=[objs], maxdepth=3)
+                    tree = t.ascend(obj)
+                    output.extend(t.format(tree))
+        
+        return "\n".join(output)
+    stats.exposed = True
+