More thoroughly fix issues with pickling Panda objects in Python 3

This also adds DatagramBuffer, a class for writing datagrams to memory and reading them from there again.

dtool/src/interrogate/interfaceMakerPythonNative.cxx

@@ -4808,18 +4808,9 @@ write_function_instance(ostream &out, FunctionRemap *remap,
 
         if (args_type == AT_single_arg) {
           out << "#if PY_MAJOR_VERSION >= 3\n";
-          // As a special hack to fix pickling in Python 3, if the method name
-          // starts with py_decode_, we take a bytes object instead of a str.
-          if (remap->_cppfunc->get_local_name().substr(0, 10) == "py_decode_") {
-            indent(out, indent_level) << "if (PyBytes_AsStringAndSize(arg, (char **)&"
-              << param_name << "_str, &" << param_name << "_len) == -1) {\n";
-            indent(out, indent_level + 2) << param_name << "_str = NULL;\n";
-            indent(out, indent_level) << "}\n";
-          } else {
-            indent(out, indent_level)
-              << param_name << "_str = PyUnicode_AsUTF8AndSize(arg, &"
-              << param_name << "_len);\n";
-          }
+          indent(out, indent_level)
+            << param_name << "_str = PyUnicode_AsUTF8AndSize(arg, &"
+            << param_name << "_len);\n";
           out << "#else\n"; // NB. PyString_AsStringAndSize also accepts a PyUnicode.
           indent(out, indent_level) << "if (PyString_AsStringAndSize(arg, (char **)&"
             << param_name << "_str, &" << param_name << "_len) == -1) {\n";

dtool/src/interrogatedb/py_panda.I

@@ -222,7 +222,7 @@ ALWAYS_INLINE PyObject *Dtool_WrapValue(PyObject *value) {
   return value;
 }
 
-ALWAYS_INLINE PyObject *Dtool_WrapValue(const std::vector<unsigned char> &value) {
+ALWAYS_INLINE PyObject *Dtool_WrapValue(const vector_uchar &value) {
 #if PY_MAJOR_VERSION >= 3
   return PyBytes_FromStringAndSize((char *)value.data(), (Py_ssize_t)value.size());
 #else

dtool/src/interrogatedb/py_panda.h

@@ -29,6 +29,7 @@
 #endif
 
 #include "pnotify.h"
+#include "vector_uchar.h"
 
 #if defined(HAVE_PYTHON) && !defined(CPPPARSER)
 
@@ -549,7 +550,7 @@ ALWAYS_INLINE PyObject *Dtool_WrapValue(char value);
 ALWAYS_INLINE PyObject *Dtool_WrapValue(wchar_t value);
 ALWAYS_INLINE PyObject *Dtool_WrapValue(nullptr_t);
 ALWAYS_INLINE PyObject *Dtool_WrapValue(PyObject *value);
-ALWAYS_INLINE PyObject *Dtool_WrapValue(const std::vector<unsigned char> &value);
+ALWAYS_INLINE PyObject *Dtool_WrapValue(const vector_uchar &value);
 
 #if PY_MAJOR_VERSION >= 0x02060000
 ALWAYS_INLINE PyObject *Dtool_WrapValue(Py_buffer *value);

panda/src/gobj/textureCollection_ext.cxx

@@ -78,9 +78,7 @@ __reduce__(PyObject *self) const {
 
   // Since a TextureCollection is itself an iterator, we can simply pass it as
   // the fourth tuple component.
-  PyObject *result = Py_BuildValue("(O()OO)", this_class, Py_None, self);
-  Py_DECREF(this_class);
-  return result;
+  return Py_BuildValue("(N()OO)", this_class, Py_None, self);
 }
 
 #endif  // HAVE_PYTHON

panda/src/pgraph/nodePath.I

@@ -2103,11 +2103,11 @@ get_name() const {
  * This method is used by __reduce__ to handle streaming of NodePaths to a
  * pickle file.
  */
-INLINE string NodePath::
+INLINE vector_uchar NodePath::
 encode_to_bam_stream() const {
-  string data;
+  vector_uchar data;
   if (!encode_to_bam_stream(data)) {
-    return string();
+    data.clear();
   }
   return data;
 }

panda/src/pgraph/nodePath.cxx

@@ -70,6 +70,7 @@
 #include "modelNode.h"
 #include "bam.h"
 #include "bamWriter.h"
+#include "datagramBuffer.h"
 
 // stack seems to overflow on Intel C++ at 7000.  If we need more than 7000,
 // need to increase stack size.
@@ -5576,28 +5577,24 @@ write_bam_stream(ostream &out) const {
  * calls this function.
  */
 bool NodePath::
-encode_to_bam_stream(string &data, BamWriter *writer) const {
+encode_to_bam_stream(vector_uchar &data, BamWriter *writer) const {
   data.clear();
   ostringstream stream;
 
-  DatagramOutputFile dout;
-  if (!dout.open(stream)) {
-    return false;
-  }
-
+  DatagramBuffer buffer;
   BamWriter local_writer;
   bool used_local_writer = false;
   if (writer == NULL) {
     // Create our own writer.
 
-    if (!dout.write_header(_bam_header)) {
+    if (!buffer.write_header(_bam_header)) {
       return false;
     }
     writer = &local_writer;
     used_local_writer = true;
   }
 
-  writer->set_target(&dout);
+  writer->set_target(&buffer);
 
   int num_nodes = get_num_nodes();
   if (used_local_writer && num_nodes > 1) {
@@ -5615,7 +5612,7 @@ encode_to_bam_stream(string &data, BamWriter *writer) const {
   dg.add_uint8(_error_type);
   dg.add_int32(num_nodes);
 
-  if (!dout.put_datagram(dg)) {
+  if (!buffer.put_datagram(dg)) {
     writer->set_target(NULL);
     return false;
   }
@@ -5631,7 +5628,7 @@ encode_to_bam_stream(string &data, BamWriter *writer) const {
   }
   writer->set_target(NULL);
 
-  data = stream.str();
+  buffer.swap_data(data);
   return true;
 }
 
@@ -5640,22 +5637,17 @@ encode_to_bam_stream(string &data, BamWriter *writer) const {
  * extracts and returns the NodePath on that string.  Returns NULL on error.
  */
 NodePath NodePath::
-decode_from_bam_stream(const string &data, BamReader *reader) {
+decode_from_bam_stream(vector_uchar data, BamReader *reader) {
   NodePath result;
 
-  istringstream stream(data);
-
-  DatagramInputFile din;
-  if (!din.open(stream)) {
-    return NodePath::fail();
-  }
+  DatagramBuffer buffer(move(data));
 
   BamReader local_reader;
   if (reader == NULL) {
     // Create a local reader.
 
     string head;
-    if (!din.read_header(head, _bam_header.size())) {
+    if (!buffer.read_header(head, _bam_header.size())) {
       return NodePath::fail();
     }
 
@@ -5666,11 +5658,11 @@ decode_from_bam_stream(const string &data, BamReader *reader) {
     reader = &local_reader;
   }
 
-  reader->set_source(&din);
+  reader->set_source(&buffer);
 
   // One initial datagram to encode the error type, and the number of nodes.
   Datagram dg;
-  if (!din.get_datagram(dg)) {
+  if (!buffer.get_datagram(dg)) {
     return NodePath::fail();
   }
 

panda/src/pgraph/nodePath.h

@@ -940,9 +940,9 @@ PUBLISHED:
   BLOCKING bool write_bam_file(const Filename &filename) const;
   BLOCKING bool write_bam_stream(ostream &out) const;
 
-  INLINE string encode_to_bam_stream() const;
-  bool encode_to_bam_stream(string &data, BamWriter *writer = NULL) const;
-  static NodePath decode_from_bam_stream(const string &data, BamReader *reader = NULL);
+  INLINE vector_uchar encode_to_bam_stream() const;
+  bool encode_to_bam_stream(vector_uchar &data, BamWriter *writer = nullptr) const;
+  static NodePath decode_from_bam_stream(vector_uchar data, BamReader *reader = nullptr);
 
 private:
   static NodePathComponent *

panda/src/pgraph/nodePath_ext.cxx

@@ -120,7 +120,7 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
 
   // We have a non-empty NodePath.
 
-  string bam_stream;
+  vector_uchar bam_stream;
   if (!_this->encode_to_bam_stream(bam_stream, writer)) {
     ostringstream stream;
     stream << "Could not bamify " << _this;
@@ -150,7 +150,6 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
   } else {
     // The traditional pickle support: call the non-persistent version of this
     // function.
-
     func = Extension<TypedWritable>::find_global_decode(this_class, "py_decode_NodePath_from_bam_stream");
     if (func == NULL) {
       PyErr_SetString(PyExc_TypeError, "Couldn't find py_decode_NodePath_from_bam_stream()");
@@ -159,14 +158,15 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
     }
   }
 
-#if PY_MAJOR_VERSION >= 3
-  PyObject *result = Py_BuildValue("(O(y#))", func, bam_stream.data(), (Py_ssize_t) bam_stream.size());
-#else
-  PyObject *result = Py_BuildValue("(O(s#))", func, bam_stream.data(), (Py_ssize_t) bam_stream.size());
-#endif
-  Py_DECREF(func);
-  Py_DECREF(this_class);
-  return result;
+  // PyTuple_SET_ITEM conveniently borrows the reference it is passed.
+  PyObject *args = PyTuple_New(2);
+  PyTuple_SET_ITEM(args, 0, this_class);
+  PyTuple_SET_ITEM(args, 1, Dtool_WrapValue(bam_stream));
+
+  PyObject *tuple = PyTuple_New(2);
+  PyTuple_SET_ITEM(tuple, 0, func);
+  PyTuple_SET_ITEM(tuple, 1, args);
+  return tuple;
 }
 
 /**
@@ -190,15 +190,15 @@ find_net_python_tag(PyObject *key) const {
  * This wrapper is defined as a global function to suit pickle's needs.
  */
 NodePath
-py_decode_NodePath_from_bam_stream(const string &data) {
-  return py_decode_NodePath_from_bam_stream_persist(NULL, data);
+py_decode_NodePath_from_bam_stream(vector_uchar data) {
+  return py_decode_NodePath_from_bam_stream_persist(nullptr, move(data));
 }
 
 /**
  * This wrapper is defined as a global function to suit pickle's needs.
  */
 NodePath
-py_decode_NodePath_from_bam_stream_persist(PyObject *unpickler, const string &data) {
+py_decode_NodePath_from_bam_stream_persist(PyObject *unpickler, vector_uchar data) {
   BamReader *reader = NULL;
   if (unpickler != NULL) {
     PyObject *py_reader = PyObject_GetAttrString(unpickler, "bamReader");
@@ -211,7 +211,7 @@ py_decode_NodePath_from_bam_stream_persist(PyObject *unpickler, const string &da
     }
   }
 
-  return NodePath::decode_from_bam_stream(data, reader);
+  return NodePath::decode_from_bam_stream(move(data), reader);
 }
 
 /**

panda/src/pgraph/nodePath_ext.h

@@ -56,8 +56,8 @@ public:
 };
 
 BEGIN_PUBLISH
-NodePath py_decode_NodePath_from_bam_stream(const string &data);
-NodePath py_decode_NodePath_from_bam_stream_persist(PyObject *unpickler, const string &data);
+NodePath py_decode_NodePath_from_bam_stream(vector_uchar data);
+NodePath py_decode_NodePath_from_bam_stream_persist(PyObject *unpickler, vector_uchar data);
 END_PUBLISH
 
 #include "nodePath_ext.I"

panda/src/pgraph/pandaNode.cxx

@@ -2124,8 +2124,8 @@ is_ambient_light() const {
 }
 
 /**
- * Reads the string created by a previous call to encode_to_bam_stream(), and
- * extracts and returns the single object on that string.  Returns NULL on
+ * Reads the bytes created by a previous call to encode_to_bam_stream(), and
+ * extracts and returns the single object on those bytes.  Returns NULL on
  * error.
  *
  * This method is intended to replace decode_raw_from_bam_stream() when you
@@ -2134,15 +2134,15 @@ is_ambient_light() const {
  * responsible for maintaining the reference count on the return value.
  */
 PT(PandaNode) PandaNode::
-decode_from_bam_stream(const string &data, BamReader *reader) {
+decode_from_bam_stream(vector_uchar data, BamReader *reader) {
   TypedWritable *object;
   ReferenceCount *ref_ptr;
 
-  if (!TypedWritable::decode_raw_from_bam_stream(object, ref_ptr, data, reader)) {
-    return NULL;
+  if (TypedWritable::decode_raw_from_bam_stream(object, ref_ptr, move(data), reader)) {
+    return DCAST(PandaNode, object);
+  } else {
+    return nullptr;
   }
-
-  return DCAST(PandaNode, object);
 }
 
 /**

panda/src/pgraph/pandaNode.h

@@ -321,7 +321,7 @@ PUBLISHED:
   INLINE int get_fancy_bits(Thread *current_thread = Thread::get_current_thread()) const;
 
 PUBLISHED:
-  static PT(PandaNode) decode_from_bam_stream(const string &data, BamReader *reader = NULL);
+  static PT(PandaNode) decode_from_bam_stream(vector_uchar data, BamReader *reader = nullptr);
 
 protected:
   class BoundsData;

panda/src/putil/datagramBuffer.I

@@ -0,0 +1,68 @@
+/**
+ * PANDA 3D SOFTWARE
+ * Copyright (c) Carnegie Mellon University.  All rights reserved.
+ *
+ * All use of this software is subject to the terms of the revised BSD
+ * license.  You should have received a copy of this license along
+ * with this source code in a file named "LICENSE."
+ *
+ * @file datagramBuffer.I
+ * @author rdb
+ * @date 2017-11-07
+ */
+
+/**
+ * Initializes an empty datagram buffer.
+ */
+INLINE DatagramBuffer::
+DatagramBuffer() :
+  _read_offset(0),
+  _wrote_first_datagram(false),
+  _read_first_datagram(false) {
+}
+
+/**
+ * Initializes the buffer with the given data.
+ */
+INLINE DatagramBuffer::
+DatagramBuffer(vector_uchar data) :
+  _data(move(data)),
+  _read_offset(0),
+  _wrote_first_datagram(false),
+  _read_first_datagram(false) {
+}
+
+/**
+ * Clears the internal buffer.
+ */
+INLINE void DatagramBuffer::
+clear() {
+  _data.clear();
+  _read_offset = 0;
+  _wrote_first_datagram = false;
+  _read_first_datagram = false;
+}
+
+/**
+ * Returns the internal buffer.
+ */
+INLINE const vector_uchar &DatagramBuffer::
+get_data() const {
+  return _data;
+}
+
+/**
+ * Replaces the data in the internal buffer.
+ */
+INLINE void DatagramBuffer::
+set_data(vector_uchar data) {
+  _data = move(data);
+}
+
+/**
+ * Swaps the data in the internal buffer with that of the other buffer.
+ */
+INLINE void DatagramBuffer::
+swap_data(vector_uchar &other) {
+  _data.swap(other);
+}

panda/src/putil/datagramBuffer.cxx

@@ -0,0 +1,152 @@
+/**
+ * PANDA 3D SOFTWARE
+ * Copyright (c) Carnegie Mellon University.  All rights reserved.
+ *
+ * All use of this software is subject to the terms of the revised BSD
+ * license.  You should have received a copy of this license along
+ * with this source code in a file named "LICENSE."
+ *
+ * @file datagramBuffer.cxx
+ * @author rdb
+ * @date 2017-11-07
+ */
+
+#include "datagramBuffer.h"
+
+/**
+ * Writes a sequence of bytes to the beginning of the datagram file.  This may
+ * be called any number of times after the file has been opened and before the
+ * first datagram is written.  It may not be called once the first datagram is
+ * written.
+ */
+bool DatagramBuffer::
+write_header(const string &header) {
+  nassertr(!_wrote_first_datagram, false);
+
+  _data.insert(_data.end(), header.begin(), header.end());
+  return true;
+}
+
+/**
+ * Writes the given datagram to the file.  Returns true on success, false if
+ * there is an error.
+ */
+bool DatagramBuffer::
+put_datagram(const Datagram &data) {
+  _wrote_first_datagram = true;
+
+  // First, write the size of the upcoming datagram.
+  size_t num_bytes = data.get_length();
+  size_t offset = _data.size();
+
+  if (num_bytes == (uint32_t)-1 || num_bytes != (uint32_t)num_bytes) {
+    // Write a large value as a 64-bit size.
+    _data.resize(offset + num_bytes + 4 + sizeof(uint64_t));
+    _data[offset++] = 0xff;
+    _data[offset++] = 0xff;
+    _data[offset++] = 0xff;
+    _data[offset++] = 0xff;
+
+    LittleEndian s(&num_bytes, sizeof(uint64_t));
+    memcpy(&_data[offset], s.get_data(), sizeof(uint64_t));
+    offset += sizeof(uint64_t);
+  } else {
+    // Write a value that fits in 32 bits.
+    _data.resize(offset + num_bytes + sizeof(uint32_t));
+
+    LittleEndian s(&num_bytes, sizeof(uint32_t));
+    memcpy(&_data[offset], s.get_data(), sizeof(uint32_t));
+    offset += sizeof(uint32_t);
+  }
+
+  // Now, write the datagram itself.
+  memcpy(&_data[offset], data.get_data(), data.get_length());
+  return true;
+}
+
+/**
+ * This does absolutely nothing.
+ */
+void DatagramBuffer::
+flush() {
+}
+
+/**
+ * Reads a sequence of bytes from the beginning of the datagram file.  This
+ * may be called any number of times after the file has been opened and before
+ * the first datagram is read.  It may not be called once the first datagram
+ * has been read.
+ */
+bool DatagramBuffer::
+read_header(string &header, size_t num_bytes) {
+  nassertr(!_read_first_datagram, false);
+  if (_read_offset + num_bytes > _data.size()) {
+    return false;
+  }
+
+  header = string((char *)&_data[_read_offset], num_bytes);
+  _read_offset += num_bytes;
+  return true;
+}
+
+/**
+ * Reads the next datagram from the file.  Returns true on success, false if
+ * there is an error or end of file.
+ */
+bool DatagramBuffer::
+get_datagram(Datagram &data) {
+  _read_first_datagram = true;
+  if (_read_offset + sizeof(uint32_t) > _data.size()) {
+    // Reached the end of the buffer.
+    return false;
+  }
+
+  // First, get the size of the upcoming datagram.
+  uint32_t num_bytes_32;
+  LittleEndian s(&_data[_read_offset], 0, sizeof(uint32_t));
+  s.store_value(&num_bytes_32, sizeof(uint32_t));
+  _read_offset += 4;
+
+  if (num_bytes_32 == 0) {
+    // A special case for a zero-length datagram: no need to try to read any
+    // data.
+    data.clear();
+    return true;
+  }
+
+  size_t num_bytes = (size_t)num_bytes_32;
+  if (num_bytes_32 == (uint32_t)-1) {
+    // Another special case for a value larger than 32 bits.
+    uint64_t num_bytes_64;
+    LittleEndian s(&_data[_read_offset], 0, sizeof(uint64_t));
+    s.store_value(&num_bytes_64, sizeof(uint64_t));
+    _read_offset += 8;
+
+    num_bytes = (size_t)num_bytes_64;
+    nassertr((uint64_t)num_bytes == num_bytes_64, false);
+  }
+
+  // Make sure we have this much data to read.
+  nassertr_always(_read_offset + num_bytes <= _data.size(), false);
+
+  data = Datagram(&_data[_read_offset], num_bytes);
+  _read_offset += num_bytes;
+  return true;
+}
+
+/**
+ * Returns true if the buffer has reached the end-of-buffer.  This test may
+ * only be made after a call to read_header() or get_datagram() has failed.
+ */
+bool DatagramBuffer::
+is_eof() {
+  return (_read_offset + sizeof(uint32_t)) > _data.size();
+}
+
+/**
+ * Returns true if the buffer has reached an error condition.
+ */
+bool DatagramBuffer::
+is_error() {
+  return false;
+}

panda/src/putil/datagramBuffer.h

@@ -0,0 +1,63 @@
+/**
+ * PANDA 3D SOFTWARE
+ * Copyright (c) Carnegie Mellon University.  All rights reserved.
+ *
+ * All use of this software is subject to the terms of the revised BSD
+ * license.  You should have received a copy of this license along
+ * with this source code in a file named "LICENSE."
+ *
+ * @file datagramBuffer.h
+ * @author rdb
+ * @date 2017-11-07
+ */
+
+#ifndef DATAGRAMBUFFER_H
+#define DATAGRAMBUFFER_H
+
+#include "pandabase.h"
+#include "datagramSink.h"
+#include "vector_uchar.h"
+
+/**
+ * This class can be used to write a series of datagrams into a memory buffer.
+ * It acts as both a datagram sink and generator; you can fill it up with
+ * datagrams and then read as many datagrams from it.
+ *
+ * This uses the same format as DatagramInputFile and DatagramOutputFile,
+ * meaning that Datagram sizes are always stored little-endian.
+ */
+class EXPCL_PANDA_PUTIL DatagramBuffer : public DatagramSink, public DatagramGenerator {
+PUBLISHED:
+  INLINE DatagramBuffer();
+  INLINE explicit DatagramBuffer(vector_uchar data);
+
+  INLINE void clear();
+
+public:
+  bool write_header(const string &header);
+  virtual bool put_datagram(const Datagram &data) override;
+  virtual void flush() override;
+
+  bool read_header(string &header, size_t num_bytes);
+  virtual bool get_datagram(Datagram &data) override;
+  virtual bool is_eof() override;
+
+  virtual bool is_error() override;
+
+  INLINE const vector_uchar &get_data() const;
+  INLINE void set_data(vector_uchar data);
+  INLINE void swap_data(vector_uchar &other);
+
+PUBLISHED:
+  MAKE_PROPERTY(data, get_data, set_data);
+
+private:
+  vector_uchar _data;
+  size_t _read_offset;
+  bool _wrote_first_datagram;
+  bool _read_first_datagram;
+};
+
+#include "datagramBuffer.I"
+
+#endif

panda/src/putil/p3putil_composite1.cxx

@@ -22,6 +22,7 @@
 #include "copyOnWriteObject.cxx"
 #include "copyOnWritePointer.cxx"
 #include "cPointerCallbackObject.cxx"
+#include "datagramBuffer.cxx"
 #include "datagramInputFile.cxx"
 #include "datagramOutputFile.cxx"
 #include "doubleBitMask.cxx"

panda/src/putil/typedWritable.I

@@ -53,22 +53,21 @@ get_bam_modified() const {
   return _bam_modified;
 }
 
-
 /**
  * Converts the TypedWritable object into a single stream of data using a
- * BamWriter, and returns that data as a string string.  Returns empty string
- * on failure.
+ * BamWriter, and returns that data as a bytes object.  Returns an empty bytes
+ * object on failure.
  *
  * This is a convenience method particularly useful for cases when you are
  * only serializing a single object.  If you have many objects to process, it
  * is more efficient to use the same BamWriter to serialize all of them
  * together.
  */
-INLINE string TypedWritable::
+INLINE vector_uchar TypedWritable::
 encode_to_bam_stream() const {
-  string data;
+  vector_uchar data;
   if (!encode_to_bam_stream(data)) {
-    return string();
+    data.clear();
   }
   return data;
 }

panda/src/putil/typedWritable.cxx

@@ -14,8 +14,7 @@
 #include "typedWritable.h"
 #include "bamWriter.h"
 #include "bamReader.h"
-#include "datagramOutputFile.h"
-#include "datagramInputFile.h"
+#include "datagramBuffer.h"
 #include "lightMutexHolder.h"
 #include "bam.h"
 
@@ -134,52 +133,43 @@ as_reference_count() {
  * together.
  */
 bool TypedWritable::
-encode_to_bam_stream(string &data, BamWriter *writer) const {
+encode_to_bam_stream(vector_uchar &data, BamWriter *writer) const {
   data.clear();
-  ostringstream stream;
 
-  // We use nested scoping to ensure the destructors get called in the right
-  // order.
-  {
-    DatagramOutputFile dout;
-    if (!dout.open(stream)) {
+  DatagramBuffer buffer;
+  if (writer == nullptr) {
+    // Create our own writer.
+
+    if (!buffer.write_header(_bam_header)) {
       return false;
     }
 
-    if (writer == NULL) {
-      // Create our own writer.
-
-      if (!dout.write_header(_bam_header)) {
-        return false;
-      }
-
-      BamWriter writer(&dout);
-      if (!writer.init()) {
-        return false;
-      }
-
-      if (!writer.write_object(this)) {
-        return false;
-      }
-    } else {
-      // Use the existing writer.
-      writer->set_target(&dout);
-      bool result = writer->write_object(this);
-      writer->set_target(NULL);
-      if (!result) {
-        return false;
-      }
+    BamWriter writer(&buffer);
+    if (!writer.init()) {
+      return false;
+    }
+
+    if (!writer.write_object(this)) {
+      return false;
+    }
+  } else {
+    // Use the existing writer.
+    writer->set_target(&buffer);
+    bool result = writer->write_object(this);
+    writer->set_target(nullptr);
+    if (!result) {
+      return false;
     }
   }
 
-  data = stream.str();
+  buffer.swap_data(data);
   return true;
 }
 
 /**
- * Reads the string created by a previous call to encode_to_bam_stream(), and
- * extracts the single object on that string.  Returns true on success, false
- * on on error.
+ * Reads the bytes created by a previous call to encode_to_bam_stream(), and
+ * extracts the single object on those bytes.  Returns true on success, false
+ * on error.
  *
  * This variant sets the TypedWritable and ReferenceCount pointers separately;
  * both are pointers to the same object.  The reference count is not
@@ -198,18 +188,14 @@ encode_to_bam_stream(string &data, BamWriter *writer) const {
  */
 bool TypedWritable::
 decode_raw_from_bam_stream(TypedWritable *&ptr, ReferenceCount *&ref_ptr,
-                           const string &data, BamReader *reader) {
-  istringstream stream(data);
+                           vector_uchar data, BamReader *reader) {
 
-  DatagramInputFile din;
-  if (!din.open(stream)) {
-    return false;
-  }
+  DatagramBuffer buffer(move(data));
 
   if (reader == NULL) {
     // Create a local reader.
     string head;
-    if (!din.read_header(head, _bam_header.size())) {
+    if (!buffer.read_header(head, _bam_header.size())) {
       return false;
     }
 
@@ -217,7 +203,7 @@ decode_raw_from_bam_stream(TypedWritable *&ptr, ReferenceCount *&ref_ptr,
       return false;
     }
 
-    BamReader reader(&din);
+    BamReader reader(&buffer);
     if (!reader.init()) {
       return false;
     }
@@ -241,7 +227,7 @@ decode_raw_from_bam_stream(TypedWritable *&ptr, ReferenceCount *&ref_ptr,
 
   } else {
     // Use the existing reader.
-    reader->set_source(&din);
+    reader->set_source(&buffer);
     if (!reader->read_object(ptr, ref_ptr)) {
       reader->set_source(NULL);
       return false;

panda/src/putil/typedWritable.h

@@ -19,6 +19,7 @@
 #include "pvector.h"
 #include "lightMutex.h"
 #include "updateSeq.h"
+#include "vector_uchar.h"
 
 class BamReader;
 class BamWriter;
@@ -62,11 +63,11 @@ PUBLISHED:
   EXTENSION(PyObject *__reduce__(PyObject *self) const);
   EXTENSION(PyObject *__reduce_persist__(PyObject *self, PyObject *pickler) const);
 
-  INLINE string encode_to_bam_stream() const;
-  bool encode_to_bam_stream(string &data, BamWriter *writer = NULL) const;
+  INLINE vector_uchar encode_to_bam_stream() const;
+  bool encode_to_bam_stream(vector_uchar &data, BamWriter *writer = NULL) const;
   static bool decode_raw_from_bam_stream(TypedWritable *&ptr,
                                          ReferenceCount *&ref_ptr,
-                                         const string &data,
+                                         vector_uchar data,
                                          BamReader *reader = NULL);
 
 private:

panda/src/putil/typedWritableReferenceCount.cxx

@@ -26,8 +26,8 @@ as_reference_count() {
 }
 
 /**
- * Reads the string created by a previous call to encode_to_bam_stream(), and
- * extracts and returns the single object on that string.  Returns NULL on
+ * Reads the bytes created by a previous call to encode_to_bam_stream(), and
+ * extracts and returns the single object on those bytes.  Returns NULL on
  * error.
  *
  * This method is intended to replace decode_raw_from_bam_stream() when you
@@ -37,13 +37,13 @@ as_reference_count() {
  * reference count on the return value.
  */
 PT(TypedWritableReferenceCount) TypedWritableReferenceCount::
-decode_from_bam_stream(const string &data, BamReader *reader) {
+decode_from_bam_stream(vector_uchar data, BamReader *reader) {
   TypedWritable *object;
   ReferenceCount *ref_ptr;
 
-  if (!TypedWritable::decode_raw_from_bam_stream(object, ref_ptr, data, reader)) {
-    return NULL;
+  if (TypedWritable::decode_raw_from_bam_stream(object, ref_ptr, move(data), reader)) {
+    return DCAST(TypedWritableReferenceCount, object);
+  } else {
+    return nullptr;
   }
-
-  return DCAST(TypedWritableReferenceCount, object);
 }

panda/src/putil/typedWritableReferenceCount.h

@@ -37,7 +37,7 @@ public:
   virtual ReferenceCount *as_reference_count();
 
 PUBLISHED:
-  static PT(TypedWritableReferenceCount) decode_from_bam_stream(const string &data, BamReader *reader = NULL);
+  static PT(TypedWritableReferenceCount) decode_from_bam_stream(vector_uchar data, BamReader *reader = nullptr);
 
 public:
   virtual TypeHandle get_type() const {

panda/src/putil/typedWritable_ext.cxx

@@ -71,7 +71,7 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
   }
 
   // First, streamify the object, if possible.
-  string bam_stream;
+  vector_uchar bam_stream;
   if (!_this->encode_to_bam_stream(bam_stream, writer)) {
     ostringstream stream;
     stream << "Could not bamify object of type " << _this->get_type() << "\n";
@@ -101,7 +101,6 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
   } else {
     // The traditional pickle support: call the non-persistent version of this
     // function.
-
     func = find_global_decode(this_class, "py_decode_TypedWritable_from_bam_stream");
     if (func == NULL) {
       PyErr_SetString(PyExc_TypeError, "Couldn't find py_decode_TypedWritable_from_bam_stream()");
@@ -110,14 +109,15 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
     }
   }
 
-#if PY_MAJOR_VERSION >= 3
-  PyObject *result = Py_BuildValue("(O(Oy#))", func, this_class, bam_stream.data(), (Py_ssize_t) bam_stream.size());
-#else
-  PyObject *result = Py_BuildValue("(O(Os#))", func, this_class, bam_stream.data(), (Py_ssize_t) bam_stream.size());
-#endif
-  Py_DECREF(func);
-  Py_DECREF(this_class);
-  return result;
+  // PyTuple_SET_ITEM conveniently borrows the reference it is passed.
+  PyObject *args = PyTuple_New(2);
+  PyTuple_SET_ITEM(args, 0, this_class);
+  PyTuple_SET_ITEM(args, 1, Dtool_WrapValue(bam_stream));
+
+  PyObject *tuple = PyTuple_New(2);
+  PyTuple_SET_ITEM(tuple, 0, func);
+  PyTuple_SET_ITEM(tuple, 1, args);
+  return tuple;
 }
 
 /**
@@ -131,7 +131,8 @@ __reduce_persist__(PyObject *self, PyObject *pickler) const {
  */
 PyObject *Extension<TypedWritable>::
 find_global_decode(PyObject *this_class, const char *func_name) {
-  PyObject *module_name = PyObject_GetAttrString(this_class, "__module__");
+  // Get the module in which BamWriter is defined.
+  PyObject *module_name = PyObject_GetAttrString((PyObject *)&Dtool_BamWriter, "__module__");
   if (module_name != NULL) {
     // borrowed reference
     PyObject *sys_modules = PyImport_GetModuleDict();
@@ -146,8 +147,8 @@ find_global_decode(PyObject *this_class, const char *func_name) {
         }
       }
     }
+    Py_DECREF(module_name);
   }
-  Py_DECREF(module_name);
 
   PyObject *bases = PyObject_GetAttrString(this_class, "__bases__");
   if (bases != NULL) {
@@ -178,8 +179,8 @@ find_global_decode(PyObject *this_class, const char *func_name) {
  * properly handle self-referential BAM objects.
  */
 PyObject *
-py_decode_TypedWritable_from_bam_stream(PyObject *this_class, const string &data) {
-  return py_decode_TypedWritable_from_bam_stream_persist(NULL, this_class, data);
+py_decode_TypedWritable_from_bam_stream(PyObject *this_class, const vector_uchar &data) {
+  return py_decode_TypedWritable_from_bam_stream_persist(nullptr, this_class, data);
 }
 
 /**
@@ -192,7 +193,7 @@ py_decode_TypedWritable_from_bam_stream(PyObject *this_class, const string &data
  * direct/src/stdpy.
  */
 PyObject *
-py_decode_TypedWritable_from_bam_stream_persist(PyObject *pickler, PyObject *this_class, const string &data) {
+py_decode_TypedWritable_from_bam_stream_persist(PyObject *pickler, PyObject *this_class, const vector_uchar &data) {
 
   PyObject *py_reader = NULL;
   if (pickler != NULL) {
@@ -210,28 +211,30 @@ py_decode_TypedWritable_from_bam_stream_persist(PyObject *pickler, PyObject *thi
   // decode_from_bam_stream appropriate to this class.
 
   PyObject *func = PyObject_GetAttrString(this_class, "decode_from_bam_stream");
-  if (func == NULL) {
-    return NULL;
+  if (func == nullptr) {
+    Py_XDECREF(py_reader);
+    return nullptr;
+  }
+
+  PyObject *bytes = Dtool_WrapValue(data);
+  if (bytes == nullptr) {
+    Py_DECREF(func);
+    Py_XDECREF(py_reader);
+    return nullptr;
   }
 
   PyObject *result;
-  if (py_reader != NULL){
-#if PY_MAJOR_VERSION >= 3
-    result = PyObject_CallFunction(func, (char *)"(y#O)", data.data(), (Py_ssize_t) data.size(), py_reader);
-#else
-    result = PyObject_CallFunction(func, (char *)"(s#O)", data.data(), (Py_ssize_t) data.size(), py_reader);
-#endif
+  if (py_reader != nullptr) {
+    result = PyObject_CallFunctionObjArgs(func, bytes, py_reader, nullptr);
     Py_DECREF(py_reader);
   } else {
-#if PY_MAJOR_VERSION >= 3
-    result = PyObject_CallFunction(func, (char *)"(y#)", data.data(), (Py_ssize_t) data.size());
-#else
-    result = PyObject_CallFunction(func, (char *)"(s#)", data.data(), (Py_ssize_t) data.size());
-#endif
+    result = PyObject_CallFunctionObjArgs(func, bytes, nullptr);
   }
+  Py_DECREF(bytes);
+  Py_DECREF(func);
 
-  if (result == NULL) {
-    return NULL;
+  if (result == nullptr) {
+    return nullptr;
   }
 
   if (result == Py_None) {

panda/src/putil/typedWritable_ext.h

@@ -33,12 +33,11 @@ public:
   PyObject *__reduce_persist__(PyObject *self, PyObject *pickler) const;
 
   static PyObject *find_global_decode(PyObject *this_class, const char *func_name);
-
 };
 
 BEGIN_PUBLISH
-PyObject *py_decode_TypedWritable_from_bam_stream(PyObject *this_class, const string &data);
-PyObject *py_decode_TypedWritable_from_bam_stream_persist(PyObject *unpickler, PyObject *this_class, const string &data);
+PyObject *py_decode_TypedWritable_from_bam_stream(PyObject *this_class, const vector_uchar &data);
+PyObject *py_decode_TypedWritable_from_bam_stream_persist(PyObject *unpickler, PyObject *this_class, const vector_uchar &data);
 END_PUBLISH
 
 #endif  // HAVE_PYTHON