diff --git a/lib/py/src/protocol/TBase.py b/lib/py/src/protocol/TBase.py
index 87caf0d..55da19e 100644
--- a/lib/py/src/protocol/TBase.py
+++ b/lib/py/src/protocol/TBase.py
@@ -17,14 +17,8 @@
 # under the License.
 #
 
-from thrift.protocol import TBinaryProtocol
 from thrift.transport import TTransport
 
-try:
-    from thrift.protocol import fastbinary
-except:
-    fastbinary = None
-
 
 class TBase(object):
     __slots__ = ()
@@ -47,27 +41,19 @@
         return not (self == other)
 
     def read(self, iprot):
-        if (iprot.__class__ == TBinaryProtocol.TBinaryProtocolAccelerated and
+        if (iprot._fast_decode is not None and
                 isinstance(iprot.trans, TTransport.CReadableTransport) and
-                self.thrift_spec is not None and
-                fastbinary is not None):
-            fastbinary.decode_binary(self,
-                                     iprot.trans,
-                                     (self.__class__, self.thrift_spec),
-                                     iprot.string_length_limit,
-                                     iprot.container_length_limit)
-            return
-        iprot.readStruct(self, self.thrift_spec)
+                self.thrift_spec is not None):
+            iprot._fast_decode(self, iprot, (self.__class__, self.thrift_spec))
+        else:
+            iprot.readStruct(self, self.thrift_spec)
 
     def write(self, oprot):
-        if (oprot.__class__ == TBinaryProtocol.TBinaryProtocolAccelerated and
-                self.thrift_spec is not None and
-                fastbinary is not None):
+        if (oprot._fast_encode is not None and self.thrift_spec is not None):
             oprot.trans.write(
-                fastbinary.encode_binary(
-                    self, (self.__class__, self.thrift_spec)))
-            return
-        oprot.writeStruct(self, self.thrift_spec)
+                oprot._fast_encode(self, (self.__class__, self.thrift_spec)))
+        else:
+            oprot.writeStruct(self, self.thrift_spec)
 
 
 class TExceptionBase(TBase, Exception):
@@ -86,14 +72,11 @@
 
     @classmethod
     def read(cls, iprot):
-        if (iprot.__class__ == TBinaryProtocol.TBinaryProtocolAccelerated and
+        if (iprot._fast_decode is not None and
                 isinstance(iprot.trans, TTransport.CReadableTransport) and
-                cls.thrift_spec is not None and
-                fastbinary is not None):
+                cls.thrift_spec is not None):
             self = cls()
-            return fastbinary.decode_binary(None,
-                                            iprot.trans,
-                                            (self.__class__, self.thrift_spec),
-                                            iprot.string_length_limit,
-                                            iprot.container_length_limit)
-        return iprot.readStruct(cls, cls.thrift_spec, True)
+            return iprot._fast_decode(None, iprot,
+                                      (self.__class__, self.thrift_spec))
+        else:
+            return iprot.readStruct(cls, cls.thrift_spec, True)
diff --git a/lib/py/src/protocol/TBinaryProtocol.py b/lib/py/src/protocol/TBinaryProtocol.py
index 7fce12f..f6be772 100644
--- a/lib/py/src/protocol/TBinaryProtocol.py
+++ b/lib/py/src/protocol/TBinaryProtocol.py
@@ -258,6 +258,7 @@
     We inherit from TBinaryProtocol so that the normal TBinaryProtocol
     encoding can happen if the fastbinary module doesn't work for some
     reason.  (TODO(dreiss): Make this happen sanely in more cases.)
+    To disable this behavior, pass fallback=False constructor argument.
 
     In order to take advantage of the C module, just use
     TBinaryProtocolAccelerated instead of TBinaryProtocol.
@@ -270,16 +271,31 @@
     """
     pass
 
+    def __init__(self, *args, **kwargs):
+        fallback = kwargs.pop('fallback', True)
+        super(TBinaryProtocolAccelerated, self).__init__(*args, **kwargs)
+        try:
+            from thrift.protocol import fastbinary
+        except ImportError:
+            if not fallback:
+                raise
+        else:
+            self._fast_decode = fastbinary.decode_binary
+            self._fast_encode = fastbinary.encode_binary
+
 
 class TBinaryProtocolAcceleratedFactory(object):
     def __init__(self,
                  string_length_limit=None,
-                 container_length_limit=None):
+                 container_length_limit=None,
+                 fallback=True):
         self.string_length_limit = string_length_limit
         self.container_length_limit = container_length_limit
+        self._fallback = fallback
 
     def getProtocol(self, trans):
         return TBinaryProtocolAccelerated(
             trans,
             string_length_limit=self.string_length_limit,
-            container_length_limit=self.container_length_limit)
+            container_length_limit=self.container_length_limit,
+            fallback=self._fallback)
diff --git a/lib/py/src/protocol/TCompactProtocol.py b/lib/py/src/protocol/TCompactProtocol.py
index 8d3db1a..16fd9be 100644
--- a/lib/py/src/protocol/TCompactProtocol.py
+++ b/lib/py/src/protocol/TCompactProtocol.py
@@ -424,3 +424,49 @@
         return TCompactProtocol(trans,
                                 self.string_length_limit,
                                 self.container_length_limit)
+
+
+class TCompactProtocolAccelerated(TCompactProtocol):
+    """C-Accelerated version of TCompactProtocol.
+
+    This class does not override any of TCompactProtocol's methods,
+    but the generated code recognizes it directly and will call into
+    our C module to do the encoding, bypassing this object entirely.
+    We inherit from TCompactProtocol so that the normal TCompactProtocol
+    encoding can happen if the fastbinary module doesn't work for some
+    reason.
+    To disable this behavior, pass fallback=False constructor argument.
+
+    In order to take advantage of the C module, just use
+    TCompactProtocolAccelerated instead of TCompactProtocol.
+    """
+    pass
+
+    def __init__(self, *args, **kwargs):
+        fallback = kwargs.pop('fallback', True)
+        super(TCompactProtocolAccelerated, self).__init__(*args, **kwargs)
+        try:
+            from thrift.protocol import fastbinary
+        except ImportError:
+            if not fallback:
+                raise
+        else:
+            self._fast_decode = fastbinary.decode_compact
+            self._fast_encode = fastbinary.encode_compact
+
+
+class TCompactProtocolAcceleratedFactory(object):
+    def __init__(self,
+                 string_length_limit=None,
+                 container_length_limit=None,
+                 fallback=True):
+        self.string_length_limit = string_length_limit
+        self.container_length_limit = container_length_limit
+        self._fallback = fallback
+
+    def getProtocol(self, trans):
+        return TCompactProtocolAccelerated(
+            trans,
+            string_length_limit=self.string_length_limit,
+            container_length_limit=self.container_length_limit,
+            fallback=self._fallback)
diff --git a/lib/py/src/protocol/TProtocol.py b/lib/py/src/protocol/TProtocol.py
index ed6938b..f29c58d 100644
--- a/lib/py/src/protocol/TProtocol.py
+++ b/lib/py/src/protocol/TProtocol.py
@@ -48,6 +48,8 @@
 
     def __init__(self, trans):
         self.trans = trans
+        self._fast_decode = None
+        self._fast_encode = None
 
     @staticmethod
     def _check_length(limit, length):
@@ -276,7 +278,7 @@
             yield read()
 
     def readFieldByTType(self, ttype, spec):
-        return self._read_by_ttype(ttype, spec, spec).next()
+        return next(self._read_by_ttype(ttype, spec, spec))
 
     def readContainerList(self, spec):
         ttype, tspec, is_immutable = spec
@@ -394,7 +396,7 @@
             yield write(v)
 
     def writeFieldByTType(self, ttype, val, spec):
-        self._write_by_ttype(ttype, [val], spec, spec).next()
+        next(self._write_by_ttype(ttype, [val], spec, spec))
 
 
 def checkIntegerLimits(i, bits):
diff --git a/lib/py/src/protocol/fastbinary.c b/lib/py/src/protocol/fastbinary.c
deleted file mode 100644
index da57c85..0000000
--- a/lib/py/src/protocol/fastbinary.c
+++ /dev/null
@@ -1,1289 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License. You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied. See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-#include <Python.h>
-#include "cStringIO.h"
-#include <stdint.h>
-#ifndef _WIN32
-# include <stdbool.h>
-# include <netinet/in.h>
-#else
-# include <WinSock2.h>
-# pragma comment (lib, "ws2_32.lib")
-# define BIG_ENDIAN (4321)
-# define LITTLE_ENDIAN (1234)
-# define BYTE_ORDER LITTLE_ENDIAN
-# if defined(_MSC_VER) && _MSC_VER < 1600
-   typedef int _Bool;
-#  define bool _Bool
-#  define false 0
-#  define true 1
-# endif
-# define inline __inline
-#endif
-
-/* Fix endianness issues on Solaris */
-#if defined (__SVR4) && defined (__sun)
- #if defined(__i386) && !defined(__i386__)
-  #define __i386__
- #endif
-
- #ifndef BIG_ENDIAN
-  #define BIG_ENDIAN (4321)
- #endif
- #ifndef LITTLE_ENDIAN
-  #define LITTLE_ENDIAN (1234)
- #endif
-
- /* I386 is LE, even on Solaris */
- #if !defined(BYTE_ORDER) && defined(__i386__)
-  #define BYTE_ORDER LITTLE_ENDIAN
- #endif
-#endif
-
-// TODO(dreiss): defval appears to be unused.  Look into removing it.
-// TODO(dreiss): Make parse_spec_args recursive, and cache the output
-//               permanently in the object.  (Malloc and orphan.)
-// TODO(dreiss): Why do we need cStringIO for reading, why not just char*?
-//               Can cStringIO let us work with a BufferedTransport?
-// TODO(dreiss): Don't ignore the rv from cwrite (maybe).
-
-/* ====== BEGIN UTILITIES ====== */
-
-#define INIT_OUTBUF_SIZE 128
-
-// Stolen out of TProtocol.h.
-// It would be a huge pain to have both get this from one place.
-typedef enum TType {
-  T_STOP       = 0,
-  T_VOID       = 1,
-  T_BOOL       = 2,
-  T_BYTE       = 3,
-  T_I08        = 3,
-  T_I16        = 6,
-  T_I32        = 8,
-  T_U64        = 9,
-  T_I64        = 10,
-  T_DOUBLE     = 4,
-  T_STRING     = 11,
-  T_UTF7       = 11,
-  T_STRUCT     = 12,
-  T_MAP        = 13,
-  T_SET        = 14,
-  T_LIST       = 15,
-  T_UTF8       = 16,
-  T_UTF16      = 17
-} TType;
-
-#ifndef __BYTE_ORDER
-# if defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
-#  define __BYTE_ORDER BYTE_ORDER
-#  define __LITTLE_ENDIAN LITTLE_ENDIAN
-#  define __BIG_ENDIAN BIG_ENDIAN
-# else
-#  error "Cannot determine endianness"
-# endif
-#endif
-
-// Same comment as the enum.  Sorry.
-#if __BYTE_ORDER == __BIG_ENDIAN
-# define ntohll(n) (n)
-# define htonll(n) (n)
-#elif __BYTE_ORDER == __LITTLE_ENDIAN
-# if defined(__GNUC__) && defined(__GLIBC__)
-#  include <byteswap.h>
-#  define ntohll(n) bswap_64(n)
-#  define htonll(n) bswap_64(n)
-# else /* GNUC & GLIBC */
-#  define ntohll(n) ( (((unsigned long long)ntohl(n)) << 32) + ntohl(n >> 32) )
-#  define htonll(n) ( (((unsigned long long)htonl(n)) << 32) + htonl(n >> 32) )
-# endif /* GNUC & GLIBC */
-#else /* __BYTE_ORDER */
-# error "Can't define htonll or ntohll!"
-#endif
-
-// Doing a benchmark shows that interning actually makes a difference, amazingly.
-#define INTERN_STRING(value) _intern_ ## value
-
-#define INT_CONV_ERROR_OCCURRED(v) ( ((v) == -1) && PyErr_Occurred() )
-#define CHECK_RANGE(v, min, max) ( ((v) <= (max)) && ((v) >= (min)) )
-
-/**
- * A cache of the spec_args for a set or list,
- * so we don't have to keep calling PyTuple_GET_ITEM.
- */
-typedef struct {
-  TType element_type;
-  PyObject* typeargs;
-  bool immutable;
-} SetListTypeArgs;
-
-/**
- * A cache of the spec_args for a map,
- * so we don't have to keep calling PyTuple_GET_ITEM.
- */
-typedef struct {
-  TType ktag;
-  TType vtag;
-  PyObject* ktypeargs;
-  PyObject* vtypeargs;
-  bool immutable;
-} MapTypeArgs;
-
-/**
- * A cache of the spec_args for a struct,
- * so we don't have to keep calling PyTuple_GET_ITEM.
- */
-typedef struct {
-  PyObject* klass;
-  PyObject* spec;
-  bool immutable;
-} StructTypeArgs;
-
-/**
- * A cache of the item spec from a struct specification,
- * so we don't have to keep calling PyTuple_GET_ITEM.
- */
-typedef struct {
-  int tag;
-  TType type;
-  PyObject* attrname;
-  PyObject* typeargs;
-  PyObject* defval;
-} StructItemSpec;
-
-/**
- * A cache of the two key attributes of a CReadableTransport,
- * so we don't have to keep calling PyObject_GetAttr.
- */
-typedef struct {
-  PyObject* stringiobuf;
-  PyObject* refill_callable;
-} DecodeBuffer;
-
-/** Pointer to interned string to speed up attribute lookup. */
-static PyObject* INTERN_STRING(cstringio_buf);
-/** Pointer to interned string to speed up attribute lookup. */
-static PyObject* INTERN_STRING(cstringio_refill);
-
-static inline bool
-check_ssize_t_32(Py_ssize_t len) {
-  // error from getting the int
-  if (INT_CONV_ERROR_OCCURRED(len)) {
-    return false;
-  }
-  if (!CHECK_RANGE(len, 0, INT32_MAX)) {
-    PyErr_SetString(PyExc_OverflowError, "size out of range: exceeded INT32_MAX");
-    return false;
-  }
-  return true;
-}
-
-static inline bool
-check_length_limit(Py_ssize_t len, long limit) {
-  if (!check_ssize_t_32(len)) {
-    return false;
-  }
-  if (len > limit) {
-    PyErr_Format(PyExc_OverflowError, "size exceeded specified limit: %d", limit);
-    return false;
-  }
-  return true;
-}
-
-static inline bool
-parse_pyint(PyObject* o, int32_t* ret, int32_t min, int32_t max) {
-  long val = PyInt_AsLong(o);
-
-  if (INT_CONV_ERROR_OCCURRED(val)) {
-    return false;
-  }
-  if (!CHECK_RANGE(val, min, max)) {
-    PyErr_SetString(PyExc_OverflowError, "int out of range");
-    return false;
-  }
-
-  *ret = (int32_t) val;
-  return true;
-}
-
-static bool
-is_utf8(PyObject* typeargs) {
-  return PyString_Check(typeargs) && !strncmp(PyString_AS_STRING(typeargs), "UTF8", 4);
-}
-
-/* --- FUNCTIONS TO PARSE STRUCT SPECIFICATOINS --- */
-
-static bool
-parse_set_list_args(SetListTypeArgs* dest, PyObject* typeargs) {
-  if (PyTuple_Size(typeargs) != 3) {
-    PyErr_SetString(PyExc_TypeError, "expecting tuple of size 3 for list/set type args");
-    return false;
-  }
-
-  dest->element_type = PyInt_AsLong(PyTuple_GET_ITEM(typeargs, 0));
-  if (INT_CONV_ERROR_OCCURRED(dest->element_type)) {
-    return false;
-  }
-
-  dest->typeargs = PyTuple_GET_ITEM(typeargs, 1);
-
-  dest->immutable = Py_True == PyTuple_GET_ITEM(typeargs, 2);
-
-  return true;
-}
-
-static bool
-parse_map_args(MapTypeArgs* dest, PyObject* typeargs) {
-  if (PyTuple_Size(typeargs) != 5) {
-    PyErr_SetString(PyExc_TypeError, "expecting 5 arguments for typeargs to map");
-    return false;
-  }
-
-  dest->ktag = PyInt_AsLong(PyTuple_GET_ITEM(typeargs, 0));
-  if (INT_CONV_ERROR_OCCURRED(dest->ktag)) {
-    return false;
-  }
-
-  dest->vtag = PyInt_AsLong(PyTuple_GET_ITEM(typeargs, 2));
-  if (INT_CONV_ERROR_OCCURRED(dest->vtag)) {
-    return false;
-  }
-
-  dest->ktypeargs = PyTuple_GET_ITEM(typeargs, 1);
-  dest->vtypeargs = PyTuple_GET_ITEM(typeargs, 3);
-  dest->immutable = Py_True == PyTuple_GET_ITEM(typeargs, 4);
-
-  return true;
-}
-
-static bool
-parse_struct_args(StructTypeArgs* dest, PyObject* typeargs) {
-  if (PyTuple_Size(typeargs) != 2) {
-    PyErr_SetString(PyExc_TypeError, "expecting tuple of size 2 for struct args");
-    return false;
-  }
-
-  dest->klass = PyTuple_GET_ITEM(typeargs, 0);
-  dest->spec = PyTuple_GET_ITEM(typeargs, 1);
-
-  return true;
-}
-
-static int
-parse_struct_item_spec(StructItemSpec* dest, PyObject* spec_tuple) {
-
-  // i'd like to use ParseArgs here, but it seems to be a bottleneck.
-  if (PyTuple_Size(spec_tuple) != 5) {
-    PyErr_Format(PyExc_TypeError, "expecting 5 arguments for spec tuple but got %d", (int)PyTuple_Size(spec_tuple));
-    return false;
-  }
-
-  dest->tag = PyInt_AsLong(PyTuple_GET_ITEM(spec_tuple, 0));
-  if (INT_CONV_ERROR_OCCURRED(dest->tag)) {
-    return false;
-  }
-
-  dest->type = PyInt_AsLong(PyTuple_GET_ITEM(spec_tuple, 1));
-  if (INT_CONV_ERROR_OCCURRED(dest->type)) {
-    return false;
-  }
-
-  dest->attrname = PyTuple_GET_ITEM(spec_tuple, 2);
-  dest->typeargs = PyTuple_GET_ITEM(spec_tuple, 3);
-  dest->defval = PyTuple_GET_ITEM(spec_tuple, 4);
-  return true;
-}
-
-/* ====== END UTILITIES ====== */
-
-
-/* ====== BEGIN WRITING FUNCTIONS ====== */
-
-/* --- LOW-LEVEL WRITING FUNCTIONS --- */
-
-static void writeByte(PyObject* outbuf, int8_t val) {
-  int8_t net = val;
-  PycStringIO->cwrite(outbuf, (char*)&net, sizeof(int8_t));
-}
-
-static void writeI16(PyObject* outbuf, int16_t val) {
-  int16_t net = (int16_t)htons(val);
-  PycStringIO->cwrite(outbuf, (char*)&net, sizeof(int16_t));
-}
-
-static void writeI32(PyObject* outbuf, int32_t val) {
-  int32_t net = (int32_t)htonl(val);
-  PycStringIO->cwrite(outbuf, (char*)&net, sizeof(int32_t));
-}
-
-static void writeI64(PyObject* outbuf, int64_t val) {
-  int64_t net = (int64_t)htonll(val);
-  PycStringIO->cwrite(outbuf, (char*)&net, sizeof(int64_t));
-}
-
-static void writeDouble(PyObject* outbuf, double dub) {
-  // Unfortunately, bitwise_cast doesn't work in C.  Bad C!
-  union {
-    double f;
-    int64_t t;
-  } transfer;
-  transfer.f = dub;
-  writeI64(outbuf, transfer.t);
-}
-
-
-/* --- MAIN RECURSIVE OUTPUT FUNCTION -- */
-
-static bool
-output_val(PyObject* output, PyObject* value, TType type, PyObject* typeargs) {
-  /*
-   * Refcounting Strategy:
-   *
-   * We assume that elements of the thrift_spec tuple are not going to be
-   * mutated, so we don't ref count those at all. Other than that, we try to
-   * keep a reference to all the user-created objects while we work with them.
-   * output_val assumes that a reference is already held. The *caller* is
-   * responsible for handling references
-   */
-
-  switch (type) {
-
-  case T_BOOL: {
-    int v = PyObject_IsTrue(value);
-    if (v == -1) {
-      return false;
-    }
-
-    writeByte(output, (int8_t) v);
-    break;
-  }
-  case T_I08: {
-    int32_t val;
-
-    if (!parse_pyint(value, &val, INT8_MIN, INT8_MAX)) {
-      return false;
-    }
-
-    writeByte(output, (int8_t) val);
-    break;
-  }
-  case T_I16: {
-    int32_t val;
-
-    if (!parse_pyint(value, &val, INT16_MIN, INT16_MAX)) {
-      return false;
-    }
-
-    writeI16(output, (int16_t) val);
-    break;
-  }
-  case T_I32: {
-    int32_t val;
-
-    if (!parse_pyint(value, &val, INT32_MIN, INT32_MAX)) {
-      return false;
-    }
-
-    writeI32(output, val);
-    break;
-  }
-  case T_I64: {
-    int64_t nval = PyLong_AsLongLong(value);
-
-    if (INT_CONV_ERROR_OCCURRED(nval)) {
-      return false;
-    }
-
-    if (!CHECK_RANGE(nval, INT64_MIN, INT64_MAX)) {
-      PyErr_SetString(PyExc_OverflowError, "int out of range");
-      return false;
-    }
-
-    writeI64(output, nval);
-    break;
-  }
-
-  case T_DOUBLE: {
-    double nval = PyFloat_AsDouble(value);
-    if (nval == -1.0 && PyErr_Occurred()) {
-      return false;
-    }
-
-    writeDouble(output, nval);
-    break;
-  }
-
-  case T_STRING: {
-    Py_ssize_t len = 0;
-    if (is_utf8(typeargs) && PyUnicode_Check(value))
-      value = PyUnicode_AsUTF8String(value);
-    len = PyString_Size(value);
-
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-
-    writeI32(output, (int32_t) len);
-    PycStringIO->cwrite(output, PyString_AsString(value), (int32_t) len);
-    break;
-  }
-
-  case T_LIST:
-  case T_SET: {
-    Py_ssize_t len;
-    SetListTypeArgs parsedargs;
-    PyObject *item;
-    PyObject *iterator;
-
-    if (!parse_set_list_args(&parsedargs, typeargs)) {
-      return false;
-    }
-
-    len = PyObject_Length(value);
-
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-
-    writeByte(output, parsedargs.element_type);
-    writeI32(output, (int32_t) len);
-
-    iterator =  PyObject_GetIter(value);
-    if (iterator == NULL) {
-      return false;
-    }
-
-    while ((item = PyIter_Next(iterator))) {
-      if (!output_val(output, item, parsedargs.element_type, parsedargs.typeargs)) {
-        Py_DECREF(item);
-        Py_DECREF(iterator);
-        return false;
-      }
-      Py_DECREF(item);
-    }
-
-    Py_DECREF(iterator);
-
-    if (PyErr_Occurred()) {
-      return false;
-    }
-
-    break;
-  }
-
-  case T_MAP: {
-    PyObject *k, *v;
-    Py_ssize_t pos = 0;
-    Py_ssize_t len;
-
-    MapTypeArgs parsedargs;
-
-    len = PyDict_Size(value);
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-
-    if (!parse_map_args(&parsedargs, typeargs)) {
-      return false;
-    }
-
-    writeByte(output, parsedargs.ktag);
-    writeByte(output, parsedargs.vtag);
-    writeI32(output, len);
-
-    // TODO(bmaurer): should support any mapping, not just dicts
-    while (PyDict_Next(value, &pos, &k, &v)) {
-      // TODO(dreiss): Think hard about whether these INCREFs actually
-      //               turn any unsafe scenarios into safe scenarios.
-      Py_INCREF(k);
-      Py_INCREF(v);
-
-      if (!output_val(output, k, parsedargs.ktag, parsedargs.ktypeargs)
-          || !output_val(output, v, parsedargs.vtag, parsedargs.vtypeargs)) {
-        Py_DECREF(k);
-        Py_DECREF(v);
-        return false;
-      }
-      Py_DECREF(k);
-      Py_DECREF(v);
-    }
-    break;
-  }
-
-  // TODO(dreiss): Consider breaking this out as a function
-  //               the way we did for decode_struct.
-  case T_STRUCT: {
-    StructTypeArgs parsedargs;
-    Py_ssize_t nspec;
-    Py_ssize_t i;
-
-    if (!parse_struct_args(&parsedargs, typeargs)) {
-      return false;
-    }
-
-    nspec = PyTuple_Size(parsedargs.spec);
-
-    if (nspec == -1) {
-      return false;
-    }
-
-    for (i = 0; i < nspec; i++) {
-      StructItemSpec parsedspec;
-      PyObject* spec_tuple;
-      PyObject* instval = NULL;
-
-      spec_tuple = PyTuple_GET_ITEM(parsedargs.spec, i);
-      if (spec_tuple == Py_None) {
-        continue;
-      }
-
-      if (!parse_struct_item_spec (&parsedspec, spec_tuple)) {
-        return false;
-      }
-
-      instval = PyObject_GetAttr(value, parsedspec.attrname);
-
-      if (!instval) {
-        return false;
-      }
-
-      if (instval == Py_None) {
-        Py_DECREF(instval);
-        continue;
-      }
-
-      writeByte(output, (int8_t) parsedspec.type);
-      writeI16(output, parsedspec.tag);
-
-      if (!output_val(output, instval, parsedspec.type, parsedspec.typeargs)) {
-        Py_DECREF(instval);
-        return false;
-      }
-
-      Py_DECREF(instval);
-    }
-
-    writeByte(output, (int8_t)T_STOP);
-    break;
-  }
-
-  case T_STOP:
-  case T_VOID:
-  case T_UTF16:
-  case T_UTF8:
-  case T_U64:
-  default:
-    PyErr_SetString(PyExc_TypeError, "Unexpected TType");
-    return false;
-
-  }
-
-  return true;
-}
-
-
-/* --- TOP-LEVEL WRAPPER FOR OUTPUT -- */
-
-static PyObject *
-encode_binary(PyObject *self, PyObject *args) {
-  PyObject* enc_obj;
-  PyObject* type_args;
-  PyObject* buf;
-  PyObject* ret = NULL;
-
-  if (!PyArg_ParseTuple(args, "OO", &enc_obj, &type_args)) {
-    return NULL;
-  }
-
-  buf = PycStringIO->NewOutput(INIT_OUTBUF_SIZE);
-  if (output_val(buf, enc_obj, T_STRUCT, type_args)) {
-    ret = PycStringIO->cgetvalue(buf);
-  }
-
-  Py_DECREF(buf);
-  return ret;
-}
-
-/* ====== END WRITING FUNCTIONS ====== */
-
-
-/* ====== BEGIN READING FUNCTIONS ====== */
-
-/* --- LOW-LEVEL READING FUNCTIONS --- */
-
-static void
-free_decodebuf(DecodeBuffer* d) {
-  Py_XDECREF(d->stringiobuf);
-  Py_XDECREF(d->refill_callable);
-}
-
-static bool
-decode_buffer_from_obj(DecodeBuffer* dest, PyObject* obj) {
-  dest->stringiobuf = PyObject_GetAttr(obj, INTERN_STRING(cstringio_buf));
-  if (!dest->stringiobuf) {
-    return false;
-  }
-
-  if (!PycStringIO_InputCheck(dest->stringiobuf)) {
-    free_decodebuf(dest);
-    PyErr_SetString(PyExc_TypeError, "expecting stringio input");
-    return false;
-  }
-
-  dest->refill_callable = PyObject_GetAttr(obj, INTERN_STRING(cstringio_refill));
-
-  if(!dest->refill_callable) {
-    free_decodebuf(dest);
-    return false;
-  }
-
-  if (!PyCallable_Check(dest->refill_callable)) {
-    free_decodebuf(dest);
-    PyErr_SetString(PyExc_TypeError, "expecting callable");
-    return false;
-  }
-
-  return true;
-}
-
-static bool readBytes(DecodeBuffer* input, char** output, int len) {
-  int read;
-
-  // TODO(dreiss): Don't fear the malloc.  Think about taking a copy of
-  //               the partial read instead of forcing the transport
-  //               to prepend it to its buffer.
-
-  read = PycStringIO->cread(input->stringiobuf, output, len);
-
-  if (read == len) {
-    return true;
-  } else if (read == -1) {
-    return false;
-  } else {
-    PyObject* newiobuf;
-
-    // using building functions as this is a rare codepath
-    newiobuf = PyObject_CallFunction(
-        input->refill_callable, "s#i", *output, read, len, NULL);
-    if (newiobuf == NULL) {
-      return false;
-    }
-
-    // must do this *AFTER* the call so that we don't deref the io buffer
-    Py_CLEAR(input->stringiobuf);
-    input->stringiobuf = newiobuf;
-
-    read = PycStringIO->cread(input->stringiobuf, output, len);
-
-    if (read == len) {
-      return true;
-    } else if (read == -1) {
-      return false;
-    } else {
-      // TODO(dreiss): This could be a valid code path for big binary blobs.
-      PyErr_SetString(PyExc_TypeError,
-          "refill claimed to have refilled the buffer, but didn't!!");
-      return false;
-    }
-  }
-}
-
-static int8_t readByte(DecodeBuffer* input) {
-  char* buf;
-  if (!readBytes(input, &buf, sizeof(int8_t))) {
-    return -1;
-  }
-
-  return *(int8_t*) buf;
-}
-
-static int16_t readI16(DecodeBuffer* input) {
-  char* buf;
-  if (!readBytes(input, &buf, sizeof(int16_t))) {
-    return -1;
-  }
-
-  return (int16_t) ntohs(*(int16_t*) buf);
-}
-
-static int32_t readI32(DecodeBuffer* input) {
-  char* buf;
-  if (!readBytes(input, &buf, sizeof(int32_t))) {
-    return -1;
-  }
-  return (int32_t) ntohl(*(int32_t*) buf);
-}
-
-
-static int64_t readI64(DecodeBuffer* input) {
-  char* buf;
-  if (!readBytes(input, &buf, sizeof(int64_t))) {
-    return -1;
-  }
-
-  return (int64_t) ntohll(*(int64_t*) buf);
-}
-
-static double readDouble(DecodeBuffer* input) {
-  union {
-    int64_t f;
-    double t;
-  } transfer;
-
-  transfer.f = readI64(input);
-  if (transfer.f == -1) {
-    return -1;
-  }
-  return transfer.t;
-}
-
-static bool
-checkTypeByte(DecodeBuffer* input, TType expected) {
-  TType got = readByte(input);
-  if (INT_CONV_ERROR_OCCURRED(got)) {
-    return false;
-  }
-
-  if (expected != got) {
-    PyErr_SetString(PyExc_TypeError, "got wrong ttype while reading field");
-    return false;
-  }
-  return true;
-}
-
-static bool
-skip(DecodeBuffer* input, TType type) {
-#define SKIPBYTES(n) \
-  do { \
-    if (!readBytes(input, &dummy_buf, (n))) { \
-      return false; \
-    } \
-  } while(0)
-
-  char* dummy_buf;
-
-  switch (type) {
-
-  case T_BOOL:
-  case T_I08: SKIPBYTES(1); break;
-  case T_I16: SKIPBYTES(2); break;
-  case T_I32: SKIPBYTES(4); break;
-  case T_I64:
-  case T_DOUBLE: SKIPBYTES(8); break;
-
-  case T_STRING: {
-    // TODO(dreiss): Find out if these check_ssize_t32s are really necessary.
-    int len = readI32(input);
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-    SKIPBYTES(len);
-    break;
-  }
-
-  case T_LIST:
-  case T_SET: {
-    TType etype;
-    int len, i;
-
-    etype = readByte(input);
-    if (etype == -1) {
-      return false;
-    }
-
-    len = readI32(input);
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-
-    for (i = 0; i < len; i++) {
-      if (!skip(input, etype)) {
-        return false;
-      }
-    }
-    break;
-  }
-
-  case T_MAP: {
-    TType ktype, vtype;
-    int len, i;
-
-    ktype = readByte(input);
-    if (ktype == -1) {
-      return false;
-    }
-
-    vtype = readByte(input);
-    if (vtype == -1) {
-      return false;
-    }
-
-    len = readI32(input);
-    if (!check_ssize_t_32(len)) {
-      return false;
-    }
-
-    for (i = 0; i < len; i++) {
-      if (!(skip(input, ktype) && skip(input, vtype))) {
-        return false;
-      }
-    }
-    break;
-  }
-
-  case T_STRUCT: {
-    while (true) {
-      TType type;
-
-      type = readByte(input);
-      if (type == -1) {
-        return false;
-      }
-
-      if (type == T_STOP)
-        break;
-
-      SKIPBYTES(2); // tag
-      if (!skip(input, type)) {
-        return false;
-      }
-    }
-    break;
-  }
-
-  case T_STOP:
-  case T_VOID:
-  case T_UTF16:
-  case T_UTF8:
-  case T_U64:
-  default:
-    PyErr_SetString(PyExc_TypeError, "Unexpected TType");
-    return false;
-
-  }
-
-  return true;
-
-#undef SKIPBYTES
-}
-
-
-/* --- HELPER FUNCTION FOR DECODE_VAL --- */
-
-static PyObject*
-decode_val(DecodeBuffer* input, TType type, PyObject* typeargs, long string_limit, long container_limit);
-
-static PyObject*
-decode_struct(DecodeBuffer* input, PyObject* output, PyObject* klass, PyObject* spec_seq, long string_limit, long container_limit) {
-  int spec_seq_len = PyTuple_Size(spec_seq);
-  bool immutable = output == Py_None;
-  PyObject* kwargs = NULL;
-  if (spec_seq_len == -1) {
-    return NULL;
-  }
-
-  if (immutable) {
-    kwargs = PyDict_New();
-    if (!kwargs) {
-      PyErr_SetString(PyExc_TypeError, "failed to prepare kwargument storage");
-      return NULL;
-    }
-  }
-
-  while (true) {
-    TType type;
-    int16_t tag;
-    PyObject* item_spec;
-    PyObject* fieldval = NULL;
-    StructItemSpec parsedspec;
-
-    type = readByte(input);
-    if (type == -1) {
-      goto error;
-    }
-    if (type == T_STOP) {
-      break;
-    }
-    tag = readI16(input);
-    if (INT_CONV_ERROR_OCCURRED(tag)) {
-      goto error;
-    }
-    if (tag >= 0 && tag < spec_seq_len) {
-      item_spec = PyTuple_GET_ITEM(spec_seq, tag);
-    } else {
-      item_spec = Py_None;
-    }
-
-    if (item_spec == Py_None) {
-      if (!skip(input, type)) {
-        goto error;
-      } else {
-        continue;
-      }
-    }
-
-    if (!parse_struct_item_spec(&parsedspec, item_spec)) {
-      goto error;
-    }
-    if (parsedspec.type != type) {
-      if (!skip(input, type)) {
-        PyErr_Format(PyExc_TypeError, "struct field had wrong type: expected %d but got %d", parsedspec.type, type);
-        goto error;
-      } else {
-        continue;
-      }
-    }
-
-    fieldval = decode_val(input, parsedspec.type, parsedspec.typeargs, string_limit, container_limit);
-    if (fieldval == NULL) {
-      goto error;
-    }
-
-    if ((immutable && PyDict_SetItem(kwargs, parsedspec.attrname, fieldval) == -1)
-        || (!immutable && PyObject_SetAttr(output, parsedspec.attrname, fieldval) == -1)) {
-      Py_DECREF(fieldval);
-      goto error;
-    }
-    Py_DECREF(fieldval);
-  }
-  if (immutable) {
-    PyObject* args = PyTuple_New(0);
-    PyObject* ret = NULL;
-    if (!args) {
-      PyErr_SetString(PyExc_TypeError, "failed to prepare argument storage");
-      goto error;
-    }
-    ret = PyObject_Call(klass, args, kwargs);
-    Py_DECREF(kwargs);
-    Py_DECREF(args);
-    return ret;
-  }
-  Py_INCREF(output);
-  return output;
-
-  error:
-  Py_XDECREF(kwargs);
-  return NULL;
-}
-
-
-/* --- MAIN RECURSIVE INPUT FUNCTION --- */
-
-// Returns a new reference.
-static PyObject*
-decode_val(DecodeBuffer* input, TType type, PyObject* typeargs, long string_limit, long container_limit) {
-  switch (type) {
-
-  case T_BOOL: {
-    int8_t v = readByte(input);
-    if (INT_CONV_ERROR_OCCURRED(v)) {
-      return NULL;
-    }
-
-    switch (v) {
-    case 0: Py_RETURN_FALSE;
-    case 1: Py_RETURN_TRUE;
-    // Don't laugh.  This is a potentially serious issue.
-    default: PyErr_SetString(PyExc_TypeError, "boolean out of range"); return NULL;
-    }
-    break;
-  }
-  case T_I08: {
-    int8_t v = readByte(input);
-    if (INT_CONV_ERROR_OCCURRED(v)) {
-      return NULL;
-    }
-
-    return PyInt_FromLong(v);
-  }
-  case T_I16: {
-    int16_t v = readI16(input);
-    if (INT_CONV_ERROR_OCCURRED(v)) {
-      return NULL;
-    }
-    return PyInt_FromLong(v);
-  }
-  case T_I32: {
-    int32_t v = readI32(input);
-    if (INT_CONV_ERROR_OCCURRED(v)) {
-      return NULL;
-    }
-    return PyInt_FromLong(v);
-  }
-
-  case T_I64: {
-    int64_t v = readI64(input);
-    if (INT_CONV_ERROR_OCCURRED(v)) {
-      return NULL;
-    }
-    // TODO(dreiss): Find out if we can take this fastpath always when
-    //               sizeof(long) == sizeof(long long).
-    if (CHECK_RANGE(v, LONG_MIN, LONG_MAX)) {
-      return PyInt_FromLong((long) v);
-    }
-
-    return PyLong_FromLongLong(v);
-  }
-
-  case T_DOUBLE: {
-    double v = readDouble(input);
-    if (v == -1.0 && PyErr_Occurred()) {
-      return false;
-    }
-    return PyFloat_FromDouble(v);
-  }
-
-  case T_STRING: {
-    Py_ssize_t len = readI32(input);
-    char* buf;
-    if (!readBytes(input, &buf, len)) {
-      return NULL;
-    }
-    if (!check_length_limit(len, string_limit)) {
-      return NULL;
-    }
-
-    if (is_utf8(typeargs))
-      return PyUnicode_DecodeUTF8(buf, len, 0);
-    else
-      return PyString_FromStringAndSize(buf, len);
-  }
-
-  case T_LIST:
-  case T_SET: {
-    SetListTypeArgs parsedargs;
-    int32_t len;
-    PyObject* ret = NULL;
-    int i;
-    bool use_tuple = false;
-
-    if (!parse_set_list_args(&parsedargs, typeargs)) {
-      return NULL;
-    }
-
-    if (!checkTypeByte(input, parsedargs.element_type)) {
-      return NULL;
-    }
-
-    len = readI32(input);
-    if (!check_length_limit(len, container_limit)) {
-      return NULL;
-    }
-
-    use_tuple = type == T_LIST && parsedargs.immutable;
-    ret = use_tuple ? PyTuple_New(len) : PyList_New(len);
-    if (!ret) {
-      return NULL;
-    }
-
-    for (i = 0; i < len; i++) {
-      PyObject* item = decode_val(input, parsedargs.element_type, parsedargs.typeargs, string_limit, container_limit);
-      if (!item) {
-        Py_DECREF(ret);
-        return NULL;
-      }
-      if (use_tuple) {
-        PyTuple_SET_ITEM(ret, i, item);
-      } else  {
-        PyList_SET_ITEM(ret, i, item);
-      }
-    }
-
-    // TODO(dreiss): Consider biting the bullet and making two separate cases
-    //               for list and set, avoiding this post facto conversion.
-    if (type == T_SET) {
-      PyObject* setret;
-      setret = parsedargs.immutable ? PyFrozenSet_New(ret) : PySet_New(ret);
-      Py_DECREF(ret);
-      return setret;
-    }
-    return ret;
-  }
-
-  case T_MAP: {
-    int32_t len;
-    int i;
-    MapTypeArgs parsedargs;
-    PyObject* ret = NULL;
-
-    if (!parse_map_args(&parsedargs, typeargs)) {
-      return NULL;
-    }
-
-    if (!checkTypeByte(input, parsedargs.ktag)) {
-      return NULL;
-    }
-    if (!checkTypeByte(input, parsedargs.vtag)) {
-      return NULL;
-    }
-
-    len = readI32(input);
-    if (!check_length_limit(len, container_limit)) {
-      return NULL;
-    }
-
-    ret = PyDict_New();
-    if (!ret) {
-      goto error;
-    }
-
-    for (i = 0; i < len; i++) {
-      PyObject* k = NULL;
-      PyObject* v = NULL;
-      k = decode_val(input, parsedargs.ktag, parsedargs.ktypeargs, string_limit, container_limit);
-      if (k == NULL) {
-        goto loop_error;
-      }
-      v = decode_val(input, parsedargs.vtag, parsedargs.vtypeargs, string_limit, container_limit);
-      if (v == NULL) {
-        goto loop_error;
-      }
-      if (PyDict_SetItem(ret, k, v) == -1) {
-        goto loop_error;
-      }
-
-      Py_DECREF(k);
-      Py_DECREF(v);
-      continue;
-
-      // Yuck!  Destructors, anyone?
-      loop_error:
-      Py_XDECREF(k);
-      Py_XDECREF(v);
-      goto error;
-    }
-
-    if (parsedargs.immutable) {
-      PyObject* thrift = PyImport_ImportModule("thrift.Thrift");
-      PyObject* cls = NULL;
-      PyObject* arg = NULL;
-      if (!thrift) {
-        goto error;
-      }
-      cls = PyObject_GetAttrString(thrift, "TFrozenDict");
-      if (!cls) {
-        goto error;
-      }
-      arg = PyTuple_New(1);
-      PyTuple_SET_ITEM(arg, 0, ret);
-      return PyObject_CallObject(cls, arg);
-    }
-
-    return ret;
-
-    error:
-    Py_XDECREF(ret);
-    return NULL;
-  }
-
-  case T_STRUCT: {
-    StructTypeArgs parsedargs;
-    if (!parse_struct_args(&parsedargs, typeargs)) {
-      return NULL;
-    }
-
-    return decode_struct(input, Py_None, parsedargs.klass, parsedargs.spec, string_limit, container_limit);
-  }
-
-  case T_STOP:
-  case T_VOID:
-  case T_UTF16:
-  case T_UTF8:
-  case T_U64:
-  default:
-    PyErr_SetString(PyExc_TypeError, "Unexpected TType");
-    return NULL;
-  }
-}
-
-static long as_long_or(PyObject* value, long default_value) {
-  long v = PyInt_AsLong(value);
-  if (INT_CONV_ERROR_OCCURRED(v)) {
-    PyErr_Clear();
-    return default_value;
-  }
-  return v;
-}
-
-
-/* --- TOP-LEVEL WRAPPER FOR INPUT -- */
-
-static PyObject*
-decode_binary(PyObject *self, PyObject *args) {
-  PyObject* output_obj = NULL;
-  PyObject* transport = NULL;
-  PyObject* typeargs = NULL;
-  StructTypeArgs parsedargs;
-  PyObject* string_limit_obj = NULL;
-  PyObject* container_limit_obj = NULL;
-  long string_limit = 0;
-  long container_limit = 0;
-  DecodeBuffer input = {0, 0};
-  PyObject* ret = NULL;
-
-  if (!PyArg_ParseTuple(args, "OOOOO", &output_obj, &transport, &typeargs, &string_limit_obj, &container_limit_obj)) {
-    return NULL;
-  }
-  string_limit = as_long_or(string_limit_obj, INT32_MAX);
-  container_limit = as_long_or(container_limit_obj, INT32_MAX);
-
-  if (!parse_struct_args(&parsedargs, typeargs)) {
-    return NULL;
-  }
-
-  if (!decode_buffer_from_obj(&input, transport)) {
-    return NULL;
-  }
-
-  ret = decode_struct(&input, output_obj, parsedargs.klass, parsedargs.spec, string_limit, container_limit);
-  free_decodebuf(&input);
-  return  ret;
-}
-
-/* ====== END READING FUNCTIONS ====== */
-
-
-/* -- PYTHON MODULE SETUP STUFF --- */
-
-static PyMethodDef ThriftFastBinaryMethods[] = {
-
-  {"encode_binary",  encode_binary, METH_VARARGS, ""},
-  {"decode_binary",  decode_binary, METH_VARARGS, ""},
-
-  {NULL, NULL, 0, NULL}        /* Sentinel */
-};
-
-PyMODINIT_FUNC
-initfastbinary(void) {
-#define INIT_INTERN_STRING(value) \
-  do { \
-    INTERN_STRING(value) = PyString_InternFromString(#value); \
-    if(!INTERN_STRING(value)) return; \
-  } while(0)
-
-  INIT_INTERN_STRING(cstringio_buf);
-  INIT_INTERN_STRING(cstringio_refill);
-#undef INIT_INTERN_STRING
-
-  PycString_IMPORT;
-  if (PycStringIO == NULL) return;
-
-  (void) Py_InitModule("thrift.protocol.fastbinary", ThriftFastBinaryMethods);
-}