Experimental USB API implementation.

chrome/browser/usb/usb_service.cc

+// Copyright (c) 2012 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 "chrome/browser/usb/usb_service.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/stl_util.h"
+#include "chrome/browser/usb/usb_device.h"
+#include "third_party/libusb/libusb/libusb.h"
+
+UsbService::UsbService() : running_(true), thread_("UsbThread") {
+  libusb_init(&context_);
+  thread_.Start();
+  PostHandleEventTask();
+}
+
+UsbService::~UsbService() {}
+
+// TODO(gdk): There is currently no clean way to indicate to the event handler
+// thread that it must break out of the handling loop before the event timeout,
+// therefore we currently are at the whim of the event handler timeout before
+// the message handling thread can be joined.
+void UsbService::Cleanup() {
+  running_ = false;
+
+  if (!devices_.empty()) {
+    libusb_close(devices_.begin()->second->handle());
+  } else {
+    LOG(WARNING) << "UsbService cannot force the USB event-handler thread to "
+                 << "exit because there are no open devices with which to "
+                 << "manipulate it. It maybe take up to 60 (!) seconds for the "
+                 << "thread to join from this point.";
+  }
+
+  thread_.message_loop()->PostTask(FROM_HERE, base::Bind(&UsbService::Shutdown,
+      base::Unretained(this)));
+}
+
+UsbDevice *UsbService::FindDevice(const uint16 vendor_id,
+                                  const uint16 product_id) {
+  const std::pair<uint16, uint16> key = std::make_pair(vendor_id, product_id);
+  if (ContainsKey(devices_, key)) {
+    return devices_[key];
+  }
+
+  libusb_device_handle *const handle = libusb_open_device_with_vid_pid(
+      context_, vendor_id, product_id);
+  if (!handle) {
+    return NULL;
+  }
+
+  UsbDevice *const device = new UsbDevice(this, handle);
+  devices_[key] = device;
+
+  return device;
+}
+
+void UsbService::CloseDevice(scoped_refptr<UsbDevice> device) {
+  DCHECK(running_) << "Cannot close device after service has stopped running.";
+
+  for (DeviceMap::iterator i = devices_.begin(); i != devices_.end(); ++i) {
+    if (i->second.get() == device.get()) {
+      devices_.erase(i);
+      libusb_close(device->handle());
+      return;
+    }
+  }
+}
+
+void UsbService::PostHandleEventTask() {
+  thread_.message_loop()->PostTask(FROM_HERE, base::Bind(
+      &UsbService::HandleEvent, base::Unretained(this)));
+}
+
+void UsbService::HandleEvent() {
+  libusb_handle_events_completed(context_, NULL);
+  if (running_) {
+    PostHandleEventTask();
+  }
+}
+
+void UsbService::Shutdown() {
+  libusb_exit(context_);
+}