smalloc: initial implementation

smalloc is a simple utility for quickly allocating external memory onto
js objects. This will be used to centralize how memory is managed in
node, and will become the backer for Buffers. So in the future crypto's
SlabBuffer, stream's SlabAllocator will be removed.

Note on the js API: because no arguments are optional the order of
arguments have been placed to match their cc counterparts as closely as
possible.

node.gyp

@@ -105,6 +105,7 @@
         'src/node_zlib.cc',
         'src/pipe_wrap.cc',
         'src/signal_wrap.cc',
+        'src/smalloc.cc',
         'src/string_bytes.cc',
         'src/stream_wrap.cc',
         'src/slab_allocator.cc',
@@ -134,6 +135,7 @@
         'src/node_wrap.h',
         'src/pipe_wrap.h',
         'src/queue.h',
+        'src/smalloc.h',
         'src/tty_wrap.h',
         'src/tcp_wrap.h',
         'src/udp_wrap.h',

src/node_extensions.h

@@ -29,6 +29,7 @@ NODE_EXT_LIST_ITEM(node_evals)
 NODE_EXT_LIST_ITEM(node_fs)
 NODE_EXT_LIST_ITEM(node_http_parser)
 NODE_EXT_LIST_ITEM(node_os)
+NODE_EXT_LIST_ITEM(node_smalloc)
 NODE_EXT_LIST_ITEM(node_zlib)
 
 // libuv rewrite

src/smalloc.cc

@@ -0,0 +1,305 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
+#include "node.h"
+#include "smalloc.h"
+
+#include "v8.h"
+#include "v8-profiler.h"
+
+#include <string.h>
+#include <assert.h>
+
+#define ALLOC_ID (0xA10C)
+
+namespace node {
+
+namespace smalloc {
+
+using v8::Arguments;
+using v8::FunctionTemplate;
+using v8::Handle;
+using v8::HandleScope;
+using v8::HeapProfiler;
+using v8::Isolate;
+using v8::Local;
+using v8::Object;
+using v8::Persistent;
+using v8::RetainedObjectInfo;
+using v8::String;
+using v8::Uint32;
+using v8::Value;
+using v8::kExternalUnsignedByteArray;
+
+
+struct CallbackInfo {
+  void* hint;
+  FreeCallback cb;
+};
+
+typedef v8::WeakReferenceCallbacks<Object, char>::Revivable Callback;
+typedef v8::WeakReferenceCallbacks<Object, void>::Revivable CallbackFree;
+
+Callback target_cb;
+CallbackFree target_free_cb;
+
+void TargetCallback(Isolate* isolate, Persistent<Object>* target, char* arg);
+void TargetFreeCallback(Isolate* isolate,
+                        Persistent<Object>* target,
+                        void* arg);
+
+
+// for internal use: copyOnto(source, source_start, dest, dest_start, length)
+Handle<Value> CopyOnto(const Arguments& args) {
+  HandleScope scope(node_isolate);
+
+  Local<Object> source = args[0]->ToObject();
+  Local<Object> dest = args[2]->ToObject();
+  size_t source_start = args[1]->Uint32Value();
+  size_t dest_start = args[3]->Uint32Value();
+  size_t length = args[4]->Uint32Value();
+  size_t source_length = source->GetIndexedPropertiesExternalArrayDataLength();
+  size_t dest_length = dest->GetIndexedPropertiesExternalArrayDataLength();
+  char* source_data = static_cast<char*>(
+                              source->GetIndexedPropertiesExternalArrayData());
+  char* dest_data = static_cast<char*>(
+                                dest->GetIndexedPropertiesExternalArrayData());
+
+  assert(source_data != NULL);
+  assert(dest_data != NULL);
+  // necessary to check in case (source|dest)_start _and_ length overflow
+  assert(length <= source_length);
+  assert(length <= dest_length);
+  assert(source_start <= source_length);
+  assert(dest_start <= dest_length);
+  // now we can guarantee these will catch oob access and *_start overflow
+  assert(source_start + length <= source_length);
+  assert(dest_start + length <= dest_length);
+
+  memmove(dest_data + dest_start, source_data + source_start, length);
+
+  return Undefined(node_isolate);
+}
+
+
+// for internal use: dest._data = sliceOnto(source, dest, start, end);
+Handle<Value> SliceOnto(const Arguments& args) {
+  HandleScope scope(node_isolate);
+
+  Local<Object> source = args[0]->ToObject();
+  Local<Object> dest = args[1]->ToObject();
+  char* source_data = static_cast<char*>(source->
+                                  GetIndexedPropertiesExternalArrayData());
+  size_t source_len = source->GetIndexedPropertiesExternalArrayDataLength();
+  size_t start = args[2]->Uint32Value();
+  size_t end = args[3]->Uint32Value();
+
+  assert(!dest->HasIndexedPropertiesInExternalArrayData());
+  assert(source_data != NULL);
+  assert(end <= source_len);
+  assert(start <= end);
+
+  dest->SetIndexedPropertiesToExternalArrayData(source_data + start,
+                                                kExternalUnsignedByteArray,
+                                                end - start);
+
+  return scope.Close(source);
+}
+
+
+// for internal use: alloc(obj, n);
+Handle<Value> Alloc(const Arguments& args) {
+  HandleScope scope(node_isolate);
+
+  Local<Object> obj = args[0]->ToObject();
+  size_t length = args[1]->Uint32Value();
+
+  Alloc(obj, length);
+
+  return scope.Close(obj);
+}
+
+
+void Alloc(Handle<Object> obj, size_t length) {
+  assert(length <= kMaxLength);
+
+  char* data = new char[length];
+  Alloc(obj, data, length);
+}
+
+
+void Alloc(Handle<Object> obj, char* data, size_t length) {
+  assert(data != NULL);
+
+  Persistent<Object> p_obj(node_isolate, obj);
+
+  node_isolate->AdjustAmountOfExternalAllocatedMemory(length);
+  p_obj.MakeWeak(node_isolate, data, target_cb);
+  p_obj.MarkIndependent(node_isolate);
+  p_obj.SetWrapperClassId(node_isolate, ALLOC_ID);
+  p_obj->SetIndexedPropertiesToExternalArrayData(data,
+                                                 kExternalUnsignedByteArray,
+                                                 length);
+}
+
+
+void TargetCallback(Isolate* isolate, Persistent<Object>* target, char* data) {
+  int len = (*target)->GetIndexedPropertiesExternalArrayDataLength();
+  if (data != NULL && len > 0) {
+    isolate->AdjustAmountOfExternalAllocatedMemory(-len);
+    delete[] data;
+  }
+  (*target).Dispose();
+  (*target).Clear();
+}
+
+
+void Alloc(Handle<Object> obj, size_t length, FreeCallback fn, void* hint) {
+  assert(length <= kMaxLength);
+
+  char* data = new char[length];
+  Alloc(obj, data, length, fn, hint);
+}
+
+
+void Alloc(Handle<Object> obj,
+           char* data,
+           size_t length,
+           FreeCallback fn,
+           void* hint) {
+  assert(data != NULL);
+
+  CallbackInfo* cb_info = new CallbackInfo;
+  cb_info->cb = fn;
+  cb_info->hint = hint;
+  Persistent<Object> p_obj(node_isolate, obj);
+
+  node_isolate->AdjustAmountOfExternalAllocatedMemory(length +
+                                                      sizeof(*cb_info));
+  p_obj.MakeWeak(node_isolate, static_cast<void*>(cb_info), target_free_cb);
+  p_obj.MarkIndependent(node_isolate);
+  p_obj.SetWrapperClassId(node_isolate, ALLOC_ID);
+  p_obj->SetIndexedPropertiesToExternalArrayData(data,
+                                                 kExternalUnsignedByteArray,
+                                                 length);
+}
+
+
+// TODO(trevnorris): running AllocDispose will cause data == NULL, which is
+// then passed to cb_info->cb, which the user will need to check for.
+void TargetFreeCallback(Isolate* isolate,
+                        Persistent<Object>* target,
+                        void* arg) {
+  Local<Object> obj = **target;
+  int len = obj->GetIndexedPropertiesExternalArrayDataLength();
+  char* data = static_cast<char*>(obj->GetIndexedPropertiesExternalArrayData());
+  CallbackInfo* cb_info = static_cast<CallbackInfo*>(arg);
+  isolate->AdjustAmountOfExternalAllocatedMemory(-(len + sizeof(*cb_info)));
+  (*target).Dispose();
+  (*target).Clear();
+  cb_info->cb(data, cb_info->hint);
+  delete cb_info;
+}
+
+
+class RetainedAllocInfo: public RetainedObjectInfo {
+public:
+  RetainedAllocInfo(Handle<Value> wrapper);
+  virtual void Dispose();
+  virtual bool IsEquivalent(RetainedObjectInfo* other);
+  virtual intptr_t GetHash();
+  virtual const char* GetLabel();
+  virtual intptr_t GetSizeInBytes();
+
+private:
+  static const char label_[];
+  char* data_;
+  int length_;
+};
+
+
+const char RetainedAllocInfo::label_[] = "smalloc";
+
+
+RetainedAllocInfo::RetainedAllocInfo(Handle<Value> wrapper) {
+  Local<Object> obj = wrapper->ToObject();
+  length_ = obj->GetIndexedPropertiesExternalArrayDataLength();
+  data_ = static_cast<char*>(obj->GetIndexedPropertiesExternalArrayData());
+}
+
+
+void RetainedAllocInfo::Dispose() {
+  delete this;
+}
+
+
+bool RetainedAllocInfo::IsEquivalent(RetainedObjectInfo* other) {
+  return label_ == other->GetLabel() &&
+         data_ == static_cast<RetainedAllocInfo*>(other)->data_;
+}
+
+
+intptr_t RetainedAllocInfo::GetHash() {
+  return reinterpret_cast<intptr_t>(data_);
+}
+
+
+const char* RetainedAllocInfo::GetLabel() {
+  return label_;
+}
+
+
+intptr_t RetainedAllocInfo::GetSizeInBytes() {
+  return length_;
+}
+
+
+RetainedObjectInfo* WrapperInfo(uint16_t class_id, Handle<Value> wrapper) {
+  return new RetainedAllocInfo(wrapper);
+}
+
+
+void Initialize(Handle<Object> exports) {
+  exports->Set(String::New("copyOnto"),
+               FunctionTemplate::New(CopyOnto)->GetFunction());
+  exports->Set(String::New("sliceOnto"),
+               FunctionTemplate::New(SliceOnto)->GetFunction());
+
+  exports->Set(String::New("alloc"),
+               FunctionTemplate::New(Alloc)->GetFunction());
+
+  exports->Set(String::New("kMaxLength"),
+               Uint32::New(kMaxLength, node_isolate));
+
+  target_cb = TargetCallback;
+  target_free_cb = TargetFreeCallback;
+
+  HeapProfiler* heap_profiler = node_isolate->GetHeapProfiler();
+  heap_profiler->SetWrapperClassInfoProvider(ALLOC_ID, WrapperInfo);
+}
+
+
+}  // namespace smalloc
+
+}  // namespace node
+
+NODE_MODULE(node_smalloc, node::smalloc::Initialize)

src/smalloc.h

@@ -0,0 +1,63 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef NODE_SMALLOC_H_
+#define NODE_SMALLOC_H_
+
+#include "v8.h"
+
+namespace node {
+
+/**
+ * Simple memory allocator.
+ *
+ * Utilities for external memory allocation management. Is an abstraction for
+ * v8's external array data handling to simplify and centralize how this is
+ * managed.
+ */
+namespace smalloc {
+
+// mirrors deps/v8/src/objects.h
+static const unsigned int kMaxLength = 0x3fffffff;
+
+typedef void (*FreeCallback)(char* data, void* hint);
+
+/**
+ * Allocate external memory and set to passed object. If data is passed then
+ * will use that instead of allocating new.
+ */
+void Alloc(v8::Handle<v8::Object> obj, size_t length);
+void Alloc(v8::Handle<v8::Object> obj, char* data, size_t length);
+void Alloc(v8::Handle<v8::Object> obj,
+           size_t length,
+           FreeCallback fn,
+           void* hint);
+void Alloc(v8::Handle<v8::Object> obj,
+           char* data,
+           size_t length,
+           FreeCallback fn,
+           void* hint);
+
+}  // namespace smalloc
+
+}  // namespace node
+
+#endif  // NODE_SMALLOC_H_