Added tools for findings references between objects

pyhprof/references.py

@@ -0,0 +1,157 @@
+"""Utilities for finding the connections between different objects.
+Primarily for computing the deep (i.e. retained) size of objects, which includes the
+size of objects they reference.
+"""
+
+import struct
+from collections import deque
+
+from .constants import ARRAY_OVERHEAD, TYPE_SIZES
+from .parsers import HProfParser, HeapDumpParser
+from .heap_blocks import ClassDump, InstanceDump, ObjectArrayDump, PrimitiveArrayDump
+
+
+
+# TODO: Make this code worth with either id sizes of 4 or 8
+ID_SIZE = 8
+
+
+class BaseReference(object):
+    def __init__(self, base_size, children={}):
+        self.base_size = base_size
+        self.children = children
+
+    def resolve_children(self, references):
+        for k, c in self.children.iteritems():
+            self.children[k] = references.get(c)
+
+    def bfs_children(self):
+        seen = {self}
+        queue = deque([self])
+        while queue:
+            n = queue.popleft()
+            yield n
+            for child in n.children.itervalues():
+                if child is not None and child not in seen:
+                    seen.add(n)
+                    queue.append(child)
+
+    def count_deep_children(self):
+        return sum(1 for _ in self.bfs_children())
+
+    def compute_deep_size(self):
+        return sum(n.base_size for n in self.bfs_children())
+
+
+class JavaClass(object):
+    def __init__(self, name, parent_class_id, instance_fields):
+        self.name = name
+        self.parent_class_id = parent_class_id
+        self.instance_fields = instance_fields
+
+    def __str__(self):
+        return 'Class<%s>' % self.name
+
+
+class InstanceReference(BaseReference):
+    def __init__(self, cls, base_size, fields):
+        super(InstanceReference, self).__init__(base_size, fields)
+        self.cls = cls
+
+    @classmethod
+    def build_from_instance_dump(cls, strings, instance_cls, instance):
+        offset = 0
+        fields = {}
+        for name_id, tp in instance_cls.instance_fields:
+            if tp == 'OBJECT':
+                id = struct.unpack('>Q', instance.bytes[offset:offset + ID_SIZE])[0]
+                name = strings[name_id]
+                fields[name] = id
+                offset += ID_SIZE
+            else:
+                offset += TYPE_SIZES[tp]
+        return cls(instance_cls, len(instance.bytes), fields)
+
+    def __str__(self):
+        return 'Instance<%s>' % self.cls.name
+
+
+class ObjectArrayReference(BaseReference):
+    def __init__(self, elements):
+        super(ObjectArrayReference, self).__init__(
+            ARRAY_OVERHEAD + len(elements) * ID_SIZE,
+            {i: el for i, el in enumerate(elements)}
+        )
+
+    def __str__(self):
+        return 'Object Array Length %d' % len(self.children)
+
+
+class PrimitiveArrayReference(BaseReference):
+    def __init__(self, element_type, element_size, number_of_elements):
+        super(PrimitiveArrayReference, self).__init__(
+            ARRAY_OVERHEAD + element_size * number_of_elements
+        )
+        self.element_type = element_type
+        self.element_size = element_size
+        self.number_of_elements = number_of_elements
+
+    def __str__(self):
+        return '%s Array Length %d' % (self.element_type, self.number_of_elements)
+
+
+class ReferenceBuilder(object):
+    def __init__(self, f):
+        self.f = f
+        self.strings = {}
+        self.class_name_ids = {}
+        self.classes = {}
+        self.references = {}
+
+    def build(self):
+        heap_dump = self.read_hprof()
+        self.read_references(heap_dump)
+        for c in self.classes.values():
+            c.parent_class = self.references.get(c.parent_class_id)
+        for r in self.references.values():
+            r.resolve_children(self.references)
+        return self.references.values()
+
+    def read_hprof(self):
+        p = HProfParser(self.f)
+        while True:
+            try:
+                b = p.read_next_block()
+            except EOFError:
+                break
+            if not b:
+                break
+            if b.tag_name == 'HEAP_DUMP':
+                return b
+            elif b.tag_name == 'STRING':
+                self.strings[b.id] = b.contents
+            elif b.tag_name == 'LOAD_CLASS':
+                self.class_name_ids[b.class_id] = b.class_name_id
+        assert 0
+
+    def read_references(self, heap_dump):
+        self.f.seek(heap_dump.start)
+        p = HeapDumpParser(self.f, ID_SIZE)
+
+        for i, el in enumerate(p):
+            if not i % 200000:
+                print i
+            if isinstance(el, ClassDump):
+                self.classes[el.id] = JavaClass(self.strings[self.class_name_ids[el.id]],
+                                                el.super_class_id,
+                                                el.instance_fields)
+            elif isinstance(el, InstanceDump):
+                self.references[el.id] = InstanceReference.build_from_instance_dump(
+                    self.strings,
+                    self.classes[el.class_object_id],
+                    el
+                )
+            elif isinstance(el, ObjectArrayDump):
+                self.references[el.id] = ObjectArrayReference(el.elements)
+            elif isinstance(el, PrimitiveArrayDump):
+                self.references[el.id] = PrimitiveArrayReference(el.element_type, p.type_size(el.element_type), el.size)