node/src/stream_wrap.cc

#include <node.h>
#include <node_buffer.h>
#include <stream_wrap.h>
#include <req_wrap.h>


namespace node {


#define SLAB_SIZE (1024 * 1024)
#define MIN(a, b) ((a) < (b) ? (a) : (b))


using v8::Object;
using v8::Handle;
using v8::Local;
using v8::Persistent;
using v8::Value;
using v8::HandleScope;
using v8::FunctionTemplate;
using v8::String;
using v8::Function;
using v8::TryCatch;
using v8::Context;
using v8::Arguments;
using v8::Integer;


#define UNWRAP \
  assert(!args.Holder().IsEmpty()); \
  assert(args.Holder()->InternalFieldCount() > 0); \
  StreamWrap* wrap =  \
      static_cast<StreamWrap*>(args.Holder()->GetPointerFromInternalField(0)); \
  if (!wrap) { \
    SetErrno(UV_EBADF); \
    return scope.Close(Integer::New(-1)); \
  }


typedef class ReqWrap<uv_shutdown_t> ShutdownWrap;
typedef class ReqWrap<uv_write_t> WriteWrap;


static size_t slab_used;
static uv_stream_t* handle_that_last_alloced;
Persistent<String> slab_sym;
Persistent<String> buffer_sym;
Persistent<String> write_queue_size_sym;
bool initialized;


void StreamWrap::Initialize(Handle<Object> target) {
  if (initialized) {
    return;
  } else {
    initialized = true;
  }

  HandleScope scope;

  slab_sym = Persistent<String>::New(String::NewSymbol("slab"));
  buffer_sym = Persistent<String>::New(String::NewSymbol("buffer"));
  write_queue_size_sym =
    Persistent<String>::New(String::NewSymbol("writeQueueSize"));
}


StreamWrap::StreamWrap(Handle<Object> object, uv_stream_t* stream) {
  HandleScope scope;

  stream_ = stream;
  stream->data = this;

  assert(object_.IsEmpty());
  assert(object->InternalFieldCount() > 0);
  object_ = v8::Persistent<v8::Object>::New(object);
  object_->SetPointerInInternalField(0, this);

  UpdateWriteQueueSize();
}


StreamWrap::~StreamWrap() {
  assert(object_.IsEmpty());
}


// Free the C++ object on the close callback.
void StreamWrap::OnClose(uv_handle_t* handle) {
  StreamWrap* wrap = static_cast<StreamWrap*>(handle->data);

  // The wrap object should still be there.
  assert(wrap->object_.IsEmpty() == false);

  wrap->object_->SetPointerInInternalField(0, NULL);
  wrap->object_.Dispose();
  wrap->object_.Clear();
  delete wrap;
}


void StreamWrap::UpdateWriteQueueSize() {
  object_->Set(write_queue_size_sym, Integer::New(stream_->write_queue_size));
}


Handle<Value> StreamWrap::ReadStart(const Arguments& args) {
  HandleScope scope;

  UNWRAP

  int r = uv_read_start(wrap->stream_, OnAlloc, OnRead);

  // Error starting the tcp.
  if (r) SetErrno(uv_last_error().code);

  return scope.Close(Integer::New(r));
}


Handle<Value> StreamWrap::ReadStop(const Arguments& args) {
  HandleScope scope;

  UNWRAP

  int r = uv_read_stop(wrap->stream_);

  // Error starting the tcp.
  if (r) SetErrno(uv_last_error().code);

  return scope.Close(Integer::New(r));
}


inline char* StreamWrap::NewSlab(Handle<Object> global,
                                        Handle<Object> wrap_obj) {
  Buffer* b = Buffer::New(SLAB_SIZE);
  global->SetHiddenValue(slab_sym, b->handle_);
  assert(Buffer::Length(b) == SLAB_SIZE);
  slab_used = 0;
  wrap_obj->SetHiddenValue(slab_sym, b->handle_);
  return Buffer::Data(b);
}


uv_buf_t StreamWrap::OnAlloc(uv_stream_t* handle, size_t suggested_size) {
  HandleScope scope;

  StreamWrap* wrap = static_cast<StreamWrap*>(handle->data);
  assert(wrap->stream_ == handle);

  char* slab = NULL;

  Handle<Object> global = Context::GetCurrent()->Global();
  Local<Value> slab_v = global->GetHiddenValue(slab_sym);

  if (slab_v.IsEmpty()) {
    // No slab currently. Create a new one.
    slab = NewSlab(global, wrap->object_);
  } else {
    // Use existing slab.
    Local<Object> slab_obj = slab_v->ToObject();
    slab = Buffer::Data(slab_obj);
    assert(Buffer::Length(slab_obj) == SLAB_SIZE);
    assert(SLAB_SIZE >= slab_used);

    // If less than 64kb is remaining on the slab allocate a new one.
    if (SLAB_SIZE - slab_used < 64 * 1024) {
      slab = NewSlab(global, wrap->object_);
    } else {
      wrap->object_->SetHiddenValue(slab_sym, slab_obj);
    }
  }

  uv_buf_t buf;
  buf.base = slab + slab_used;
  buf.len = MIN(SLAB_SIZE - slab_used, suggested_size);

  wrap->slab_offset_ = slab_used;
  slab_used += buf.len;

  handle_that_last_alloced = handle;

  return buf;
}

void StreamWrap::OnRead(uv_stream_t* handle, ssize_t nread, uv_buf_t buf) {
  HandleScope scope;

  StreamWrap* wrap = static_cast<StreamWrap*>(handle->data);

  // We should not be getting this callback if someone as already called
  // uv_close() on the handle.
  assert(wrap->object_.IsEmpty() == false);

  // Remove the reference to the slab to avoid memory leaks;
  Local<Value> slab_v = wrap->object_->GetHiddenValue(slab_sym);
  wrap->object_->SetHiddenValue(slab_sym, v8::Null());

  if (nread < 0)  {
    // EOF or Error
    if (handle_that_last_alloced == handle) {
      slab_used -= buf.len;
    }

    SetErrno(uv_last_error().code);
    MakeCallback(wrap->object_, "onread", 0, NULL);
    return;
  }

  assert(nread <= buf.len);

  if (handle_that_last_alloced == handle) {
    slab_used -= (buf.len - nread);
  }

  if (nread > 0) {
    Local<Value> argv[3] = {
      slab_v,
      Integer::New(wrap->slab_offset_),
      Integer::New(nread)
    };
    MakeCallback(wrap->object_, "onread", 3, argv);
  }
}

// TODO: share me?
Handle<Value> StreamWrap::Close(const Arguments& args) {
  HandleScope scope;

  UNWRAP

  assert(!wrap->object_.IsEmpty());
  int r = uv_close((uv_handle_t*) wrap->stream_, OnClose);

  if (r) {
    SetErrno(uv_last_error().code);

    wrap->object_->SetPointerInInternalField(0, NULL);
    wrap->object_.Dispose();
    wrap->object_.Clear();
  }
  return scope.Close(Integer::New(r));
}


Handle<Value> StreamWrap::Write(const Arguments& args) {
  HandleScope scope;

  UNWRAP

  // The first argument is a buffer.
  assert(Buffer::HasInstance(args[0]));
  Local<Object> buffer_obj = args[0]->ToObject();

  size_t offset = 0;
  size_t length = Buffer::Length(buffer_obj);

  if (args.Length() > 1) {
    offset = args[1]->IntegerValue();
  }

  if (args.Length() > 2) {
    length = args[2]->IntegerValue();
  }

  WriteWrap* req_wrap = new WriteWrap();

  req_wrap->object_->SetHiddenValue(buffer_sym, buffer_obj);

  uv_buf_t buf;
  buf.base = Buffer::Data(buffer_obj) + offset;
  buf.len = length;

  int r = uv_write(&req_wrap->req_, wrap->stream_, &buf, 1, StreamWrap::AfterWrite);

  req_wrap->Dispatched();

  wrap->UpdateWriteQueueSize();

  if (r) {
    SetErrno(uv_last_error().code);
    delete req_wrap;
    return scope.Close(v8::Null());
  } else {
    return scope.Close(req_wrap->object_);
  }
}


void StreamWrap::AfterWrite(uv_write_t* req, int status) {
  WriteWrap* req_wrap = (WriteWrap*) req->data;
  StreamWrap* wrap = (StreamWrap*) req->handle->data;

  HandleScope scope;

  // The wrap and request objects should still be there.
  assert(req_wrap->object_.IsEmpty() == false);
  assert(wrap->object_.IsEmpty() == false);

  if (status) {
    SetErrno(uv_last_error().code);
  }

  wrap->UpdateWriteQueueSize();

  Local<Value> argv[4] = {
    Integer::New(status),
    Local<Value>::New(wrap->object_),
    Local<Value>::New(req_wrap->object_),
    req_wrap->object_->GetHiddenValue(buffer_sym),
  };

  MakeCallback(req_wrap->object_, "oncomplete", 4, argv);

  delete req_wrap;
}


Handle<Value> StreamWrap::Shutdown(const Arguments& args) {
  HandleScope scope;

  UNWRAP

  ShutdownWrap* req_wrap = new ShutdownWrap();

  int r = uv_shutdown(&req_wrap->req_, wrap->stream_, AfterShutdown);

  req_wrap->Dispatched();

  if (r) {
    SetErrno(uv_last_error().code);
    delete req_wrap;
    return scope.Close(v8::Null());
  } else {
    return scope.Close(req_wrap->object_);
  }
}


void StreamWrap::AfterShutdown(uv_shutdown_t* req, int status) {
  ReqWrap<uv_shutdown_t>* req_wrap = (ReqWrap<uv_shutdown_t>*) req->data;
  StreamWrap* wrap = (StreamWrap*) req->handle->data;

  // The wrap and request objects should still be there.
  assert(req_wrap->object_.IsEmpty() == false);
  assert(wrap->object_.IsEmpty() == false);

  HandleScope scope;

  if (status) {
    SetErrno(uv_last_error().code);
  }

  Local<Value> argv[3] = {
    Integer::New(status),
    Local<Value>::New(wrap->object_),
    Local<Value>::New(req_wrap->object_)
  };

  MakeCallback(req_wrap->object_, "oncomplete", 3, argv);

  delete req_wrap;
}


}