Modularize Compact Language Detector 2 (CLD2) data sources

components/translate/content/renderer/data_file_renderer_cld_data_provider.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "data_file_renderer_cld_data_provider.h"
+
+#include "base/basictypes.h"
+#include "base/files/file.h"
+#include "base/files/memory_mapped_file.h"
+#include "base/lazy_instance.h"
+#include "components/translate/content/common/data_file_cld_data_provider_messages.h"
+#include "content/public/renderer/render_view_observer.h"
+#include "ipc/ipc_message.h"
+#include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_platform_file.h"
+#include "third_party/cld_2/src/public/compact_lang_det.h"
+
+namespace {
+
+// A struct that contains the pointer to the CLD mmap. Used so that we can
+// leverage LazyInstance:Leaky to properly scope the lifetime of the mmap.
+struct CLDMmapWrapper {
+  CLDMmapWrapper() { value = NULL; }
+  base::MemoryMappedFile* value;
+};
+base::LazyInstance<CLDMmapWrapper>::Leaky g_cld_mmap =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace translate {
+
+// Implementation of the static factory method from RendererCldDataProvider,
+// hooking up this specific implementation for all of Chromium.
+RendererCldDataProvider* CreateRendererCldDataProviderFor(
+    content::RenderViewObserver* render_view_observer) {
+  return new DataFileRendererCldDataProvider(render_view_observer);
+}
+
+DataFileRendererCldDataProvider::DataFileRendererCldDataProvider(
+    content::RenderViewObserver* render_view_observer)
+    : render_view_observer_(render_view_observer) {
+}
+
+DataFileRendererCldDataProvider::~DataFileRendererCldDataProvider() {
+}
+
+bool DataFileRendererCldDataProvider::OnMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(DataFileRendererCldDataProvider, message)
+  IPC_MESSAGE_HANDLER(ChromeViewMsg_CldDataFileAvailable, OnCldDataAvailable)
+  IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void DataFileRendererCldDataProvider::SendCldDataRequest() {
+  // Else, send the IPC message to the browser process requesting the data...
+  render_view_observer_->Send(new ChromeViewHostMsg_NeedCldDataFile(
+      render_view_observer_->routing_id()));
+}
+
+bool DataFileRendererCldDataProvider::IsCldDataAvailable() {
+  // This neatly removes the need for code that depends on the generalized
+  // RendererCldDataProvider to #ifdef on CLD2_DYNAMIC_MODE
+  return CLD2::isDataLoaded();  // ground truth, independent of our state.
+}
+
+void DataFileRendererCldDataProvider::SetCldAvailableCallback(
+    base::Callback<void(void)> callback) {
+  cld_available_callback_ = callback;
+}
+
+void DataFileRendererCldDataProvider::OnCldDataAvailable(
+    const IPC::PlatformFileForTransit ipc_file_handle,
+    const uint64 data_offset,
+    const uint64 data_length) {
+  LoadCldData(IPC::PlatformFileForTransitToFile(ipc_file_handle),
+              data_offset,
+              data_length);
+}
+
+void DataFileRendererCldDataProvider::LoadCldData(base::File file,
+                                                  const uint64 data_offset,
+                                                  const uint64 data_length) {
+  // Terminate immediately if data is already loaded.
+  if (IsCldDataAvailable())
+    return;
+
+  if (!file.IsValid()) {
+    LOG(ERROR) << "Can't find the CLD data file.";
+    return;
+  }
+
+  // mmap the file
+  g_cld_mmap.Get().value = new base::MemoryMappedFile();
+  bool initialized = g_cld_mmap.Get().value->Initialize(file.Pass());
+  if (!initialized) {
+    LOG(ERROR) << "mmap initialization failed";
+    delete g_cld_mmap.Get().value;
+    g_cld_mmap.Get().value = NULL;
+    return;
+  }
+
+  // Sanity checks
+  uint64 max_int32 = std::numeric_limits<int32>::max();
+  if (data_length + data_offset > g_cld_mmap.Get().value->length() ||
+      data_length > max_int32) {  // max signed 32 bit integer
+    LOG(ERROR) << "Illegal mmap config: data_offset=" << data_offset
+               << ", data_length=" << data_length
+               << ", mmap->length()=" << g_cld_mmap.Get().value->length();
+    delete g_cld_mmap.Get().value;
+    g_cld_mmap.Get().value = NULL;
+    return;
+  }
+
+  // Initialize the CLD subsystem... and it's all done!
+  const uint8* data_ptr = g_cld_mmap.Get().value->data() + data_offset;
+  CLD2::loadDataFromRawAddress(data_ptr, data_length);
+  DCHECK(CLD2::isDataLoaded()) << "Failed to load CLD data from mmap";
+  if (!cld_available_callback_.is_null()) {
+    cld_available_callback_.Run();
+  }
+}
+
+}  // namespace translate