Add locking. Not really tested, apart from the absence of double locking.thread-safe

6 files changed, 121 insertions, 61 deletions

diff --git a/cffi/api.py b/cffi/api.py
index d11fcf5..0a57eb2 100644
--- a/cffi/api.py
+++ b/cffi/api.py
@@ -1,4 +1,5 @@
 import types
+from .lock import allocate_lock
 
 try:
     callable
@@ -61,6 +62,7 @@ class FFI(object):
             # rely on it!  It's probably not going to work well.)
 
         self._backend = backend
+        self._lock = allocate_lock()
         self._parser = cparser.Parser()
         self._cached_btypes = {}
         self._parsed_types = types.ModuleType('parsed_types').__dict__
@@ -74,7 +76,8 @@ class FFI(object):
             if name.startswith('RTLD_'):
                 setattr(self, name, getattr(backend, name))
         #
-        self.BVoidP = self._get_cached_btype(model.voidp_type)
+        with self._lock:
+            self.BVoidP = self._get_cached_btype(model.voidp_type)
         if isinstance(backend, types.ModuleType):
             # _cffi_backend: attach these constants to the class
             if not hasattr(FFI, 'NULL'):
@@ -95,11 +98,12 @@ class FFI(object):
             if not isinstance(csource, basestring):
                 raise TypeError("cdef() argument must be a string")
             csource = csource.encode('ascii')
-        self._parser.parse(csource, override=override)
-        self._cdefsources.append(csource)
-        if override:
-            for cache in self._function_caches:
-                cache.clear()
+        with self._lock:
+            self._parser.parse(csource, override=override)
+            self._cdefsources.append(csource)
+            if override:
+                for cache in self._function_caches:
+                    cache.clear()
 
     def dlopen(self, name, flags=0):
         """Load and return a dynamic library identified by 'name'.
@@ -109,28 +113,41 @@ class FFI(object):
         library we only look for the actual (untyped) symbols.
         """
         assert isinstance(name, basestring) or name is None
-        lib, function_cache = _make_ffi_library(self, name, flags)
-        self._function_caches.append(function_cache)
-        self._libraries.append(lib)
+        with self._lock:
+            lib, function_cache = _make_ffi_library(self, name, flags)
+            self._function_caches.append(function_cache)
+            self._libraries.append(lib)
         return lib
 
+    def _typeof_locked(self, cdecl):
+        # call me with the lock!
+        key = cdecl
+        if key in self._parsed_types:
+            return self._parsed_types[key]
+        #
+        if not isinstance(cdecl, str):    # unicode, on Python 2
+            cdecl = cdecl.encode('ascii')
+        #
+        type = self._parser.parse_type(cdecl)
+        if hasattr(type, 'as_function_pointer'):
+            really_a_function_type = True
+            type = type.as_function_pointer()
+        else:
+            really_a_function_type = False
+        btype = self._get_cached_btype(type)
+        result = btype, really_a_function_type
+        self._parsed_types[key] = result
+        return result
+
     def _typeof(self, cdecl, consider_function_as_funcptr=False):
         # string -> ctype object
         try:
-            btype, really_a_function_type = self._parsed_types[cdecl]
+            result = self._parsed_types[cdecl]
         except KeyError:
-            key = cdecl
-            if not isinstance(cdecl, str):    # unicode, on Python 2
-                cdecl = cdecl.encode('ascii')
-            type = self._parser.parse_type(cdecl)
-            if hasattr(type, 'as_function_pointer'):
-                really_a_function_type = True
-                type = type.as_function_pointer()
-            else:
-                really_a_function_type = False
-            btype = self._get_cached_btype(type)
-            self._parsed_types[key] = btype, really_a_function_type
+            with self._lock:
+                result = self._typeof_locked(cdecl)
         #
+        btype, really_a_function_type = result
         if really_a_function_type and not consider_function_as_funcptr:
             raise CDefError("the type %r is a function type, not a "
                             "pointer-to-function type" % (cdecl,))
@@ -151,7 +168,8 @@ class FFI(object):
                 return res
         if (isinstance(cdecl, types.FunctionType)
                 and hasattr(cdecl, '_cffi_base_type')):
-            return self._get_cached_btype(cdecl._cffi_base_type)
+            with self._lock:
+                return self._get_cached_btype(cdecl._cffi_base_type)
         raise TypeError(type(cdecl))
 
     def sizeof(self, cdecl):
@@ -288,14 +306,17 @@ class FFI(object):
         data.  Later, when this new cdata object is garbage-collected,
         'destructor(old_cdata_object)' will be called.
         """
-        try:
-            gc_weakrefs = self.gc_weakrefs
-        except AttributeError:
-            from .gc_weakref import GcWeakrefs
-            gc_weakrefs = self.gc_weakrefs = GcWeakrefs(self)
-        return gc_weakrefs.build(cdata, destructor)
+        with self._lock:
+            try:
+                gc_weakrefs = self.gc_weakrefs
+            except AttributeError:
+                from .gc_weakref import GcWeakrefs
+                gc_weakrefs = self.gc_weakrefs = GcWeakrefs(self)
+            return gc_weakrefs.build(cdata, destructor)
 
     def _get_cached_btype(self, type):
+        assert self._lock.acquire(False) is False
+        # call me with the lock!
         try:
             BType = self._cached_btypes[type]
         except KeyError:
@@ -330,7 +351,8 @@ class FFI(object):
 
     def _pointer_to(self, ctype):
         from . import model
-        return model.pointer_cache(self, ctype)
+        with self._lock:
+            return model.pointer_cache(self, ctype)
 
     def addressof(self, cdata, field=None):
         """Return the address of a <cdata 'struct-or-union'>.
@@ -350,10 +372,12 @@ class FFI(object):
         variables, which must anyway be accessed directly from the
         lib object returned by the original FFI instance.
         """
-        self._parser.include(ffi_to_include._parser)
-        self._cdefsources.append('[')
-        self._cdefsources.extend(ffi_to_include._cdefsources)
-        self._cdefsources.append(']')
+        with ffi_to_include._lock:
+            with self._lock:
+                self._parser.include(ffi_to_include._parser)
+                self._cdefsources.append('[')
+                self._cdefsources.extend(ffi_to_include._cdefsources)
+                self._cdefsources.append(']')
 
     def new_handle(self, x):
         return self._backend.newp_handle(self.BVoidP, x)
@@ -380,7 +404,7 @@ def _make_ffi_library(ffi, libname, flags):
         backendlib = backend.load_library(path, flags)
     copied_enums = []
     #
-    def make_accessor(name):
+    def make_accessor_locked(name):
         key = 'function ' + name
         if key in ffi._parser._declarations:
             tp = ffi._parser._declarations[key]
@@ -412,11 +436,17 @@ def _make_ffi_library(ffi, libname, flags):
                     if enumname not in library.__dict__:
                         library.__dict__[enumname] = enumval
             copied_enums.append(True)
+            if name in library.__dict__:
+                return
         #
-        if name in library.__dict__:   # copied from an enum value just above,
-            return                     # or multithread's race condition
         raise AttributeError(name)
     #
+    def make_accessor(name):
+        with ffi._lock:
+            if name in library.__dict__ or name in FFILibrary.__dict__:
+                return    # added by another thread while waiting for the lock
+            make_accessor_locked(name)
+    #
     class FFILibrary(object):
         def __getattr__(self, name):
             make_accessor(name)
@@ -452,4 +482,5 @@ def _builtin_function_type(func):
     except (KeyError, AttributeError, TypeError):
         return None
     else:
-        return ffi._get_cached_btype(tp)
+        with ffi._lock:
+            return ffi._get_cached_btype(tp)
diff --git a/cffi/gc_weakref.py b/cffi/gc_weakref.py
index 31621fd..a2c0967 100644
--- a/cffi/gc_weakref.py
+++ b/cffi/gc_weakref.py
@@ -14,6 +14,6 @@ class GcWeakrefs(object):
 
     def build(self, cdata, destructor):
         # make a new cdata of the same type as the original one
-        new_cdata = self.ffi.cast(self.ffi.typeof(cdata), cdata)
+        new_cdata = self.ffi.cast(self.ffi._backend.typeof(cdata), cdata)
         self.data[ref(new_cdata, self.remove)] = destructor, cdata
         return new_cdata
diff --git a/cffi/lock.py b/cffi/lock.py
index e93cc8b..db91b71 100644
--- a/cffi/lock.py
+++ b/cffi/lock.py
@@ -10,3 +10,21 @@ else:
         from _thread import allocate_lock
     except ImportError:
         from _dummy_thread import allocate_lock
+
+
+##import sys
+##l1 = allocate_lock
+
+##class allocate_lock(object):
+##    def __init__(self):
+##        self._real = l1()
+##    def __enter__(self):
+##        for i in range(4, 0, -1):
+##            print sys._getframe(i).f_code
+##        print
+##        return self._real.__enter__()
+##    def __exit__(self, *args):
+##        return self._real.__exit__(*args)
+##    def acquire(self, f):
+##        assert f is False
+##        return self._real.acquire(f)
diff --git a/cffi/vengine_gen.py b/cffi/vengine_gen.py
index d012ef8..2d01db8 100644
--- a/cffi/vengine_gen.py
+++ b/cffi/vengine_gen.py
@@ -276,7 +276,7 @@ class VGenericEngine(object):
             return     # nothing to do with opaque structs
         layoutfuncname = '_cffi_layout_%s_%s' % (prefix, name)
         #
-        BFunc = self.ffi.typeof("ssize_t(*)(ssize_t)")
+        BFunc = self.ffi._typeof_locked("ssize_t(*)(ssize_t)")[0]
         function = module.load_function(BFunc, layoutfuncname)
         layout = []
         num = 0
@@ -386,15 +386,16 @@ class VGenericEngine(object):
     def _load_constant(self, is_int, tp, name, module):
         funcname = '_cffi_const_%s' % name
         if is_int:
-            BFunc = self.ffi.typeof("int(*)(long long*)")
+            BType = self.ffi._typeof_locked("long long*")[0]
+            BFunc = self.ffi._typeof_locked("int(*)(long long*)")[0]
             function = module.load_function(BFunc, funcname)
-            p = self.ffi.new("long long*")
+            p = self.ffi.new(BType)
             negative = function(p)
             value = int(p[0])
             if value < 0 and not negative:
                 value += (1 << (8*self.ffi.sizeof("long long")))
         else:
-            BFunc = self.ffi.typeof(tp.get_c_name('(*)(void)', name))
+            BFunc = self.ffi._typeof_locked(tp.get_c_name('(*)(void)', name))[0]
             function = module.load_function(BFunc, funcname)
             value = function()
         return value
@@ -438,10 +439,11 @@ class VGenericEngine(object):
             tp.enumvalues = tuple(enumvalues)
             tp.partial_resolved = True
         else:
-            BFunc = self.ffi.typeof("int(*)(char*)")
+            BType = self.ffi._typeof_locked("char[]")[0]
+            BFunc = self.ffi._typeof_locked("int(*)(char*)")[0]
             funcname = '_cffi_e_%s_%s' % (prefix, name)
             function = module.load_function(BFunc, funcname)
-            p = self.ffi.new("char[]", 256)
+            p = self.ffi.new(BType, 256)
             if function(p) < 0:
                 error = self.ffi.string(p)
                 if sys.version_info >= (3,):
@@ -493,7 +495,7 @@ class VGenericEngine(object):
                                               # sense that "a=..." is forbidden
             if tp.length == '...':
                 funcname = '_cffi_sizeof_%s' % (name,)
-                BFunc = self.ffi.typeof('size_t(*)(void)')
+                BFunc = self.ffi._typeof_locked('size_t(*)(void)')[0]
                 function = module.load_function(BFunc, funcname)
                 size = function()
                 BItemType = self.ffi._get_cached_btype(tp.item)
@@ -516,7 +518,7 @@ class VGenericEngine(object):
         # remove ptr=<cdata 'int *'> from the library instance, and replace
         # it by a property on the class, which reads/writes into ptr[0].
         funcname = '_cffi_var_%s' % name
-        BFunc = self.ffi.typeof(tp.get_c_name('*(*)(void)', name))
+        BFunc = self.ffi._typeof_locked(tp.get_c_name('*(*)(void)', name))[0]
         function = module.load_function(BFunc, funcname)
         ptr = function()
         def getter(library):
diff --git a/cffi/verifier.py b/cffi/verifier.py
index 0b941d4..9603a7e 100644
--- a/cffi/verifier.py
+++ b/cffi/verifier.py
@@ -42,18 +42,21 @@ class Verifier(object):
     def write_source(self, file=None):
         """Write the C source code.  It is produced in 'self.sourcefilename',
         which can be tweaked beforehand."""
-        if self._has_source and file is None:
-            raise ffiplatform.VerificationError("source code already written")
-        self._write_source(file)
+        with self.ffi._lock:
+            if self._has_source and file is None:
+                raise ffiplatform.VerificationError(
+                    "source code already written")
+            self._write_source(file)
 
     def compile_module(self):
         """Write the C source code (if not done already) and compile it.
         This produces a dynamic link library in 'self.modulefilename'."""
-        if self._has_module:
-            raise ffiplatform.VerificationError("module already compiled")
-        if not self._has_source:
-            self._write_source()
-        self._compile_module()
+        with self.ffi._lock:
+            if self._has_module:
+                raise ffiplatform.VerificationError("module already compiled")
+            if not self._has_source:
+                self._write_source()
+            self._compile_module()
 
     def load_library(self):
         """Get a C module from this Verifier instance.
@@ -62,11 +65,14 @@ class Verifier(object):
         operations to the C module.  If necessary, the C code is written
         and compiled first.
         """
-        if not self._has_module:
-            self._locate_module()
+        with self.ffi._lock:
             if not self._has_module:
-                self.compile_module()
-        return self._load_library()
+                self._locate_module()
+                if not self._has_module:
+                    if not self._has_source:
+                        self._write_source()
+                    self._compile_module()
+            return self._load_library()
 
     def get_module_name(self):
         basename = os.path.basename(self.modulefilename)
@@ -81,7 +87,9 @@ class Verifier(object):
 
     def get_extension(self):
         if not self._has_source:
-            self._write_source()
+            with self.ffi._lock:
+                if not self._has_source:
+                    self._write_source()
         sourcename = ffiplatform.maybe_relative_path(self.sourcefilename)
         modname = self.get_module_name()
         return ffiplatform.get_extension(sourcename, modname, **self.kwds)
diff --git a/testing/test_parsing.py b/testing/test_parsing.py
index d5bf273..73c2277 100644
--- a/testing/test_parsing.py
+++ b/testing/test_parsing.py
@@ -130,8 +130,9 @@ def test_typedef_array_convert_array_to_pointer():
     ffi.cdef("""
         typedef int (*fn_t)(int[5]);
         """)
-    type = ffi._parser.parse_type("fn_t")
-    BType = ffi._get_cached_btype(type)
+    with ffi._lock:
+        type = ffi._parser.parse_type("fn_t")
+        BType = ffi._get_cached_btype(type)
     assert str(BType) == '<func (<pointer to <int>>), <int>, False>'
 
 def test_remove_comments():