Separate usb device handle from usb device. (deprecate)

chrome/browser/usb/usb_service.cc

Index: chrome/browser/usb/usb_service.cc
diff --git a/chrome/browser/usb/usb_service.cc b/chrome/browser/usb/usb_service.cc
index 038786debf85048856500ce8f184578faade605f..e4c20b4dc39075aae0567c6a75f7572971fa0505 100644
--- a/chrome/browser/usb/usb_service.cc
+++ b/chrome/browser/usb/usb_service.cc
@@ -4,13 +4,17 @@
 
 #include "chrome/browser/usb/usb_service.h"
 
+#include <cstring>
+#include <set>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
-#include "chrome/browser/usb/usb_device.h"
+#include "base/synchronization/lock.h"
+#include "chrome/browser/usb/usb_device_handle.h"
+#include "content/public/browser/browser_thread.h"
 #include "third_party/libusb/src/libusb/libusb.h"
 
 #if defined(OS_CHROMEOS)
@@ -20,61 +24,197 @@
 #endif  // defined(OS_CHROMEOS)
 
 using std::vector;
+using std::set;
+using content::BrowserThread;
+using base::PlatformThreadHandle;
+using base::RefCountedThreadSafe;
 
-// The UsbEventHandler works around a design flaw in the libusb interface. There
-// is currently no way to signal to libusb that any caller into one of the event
+// The UsbEventHandler dispatches USB events on separate thread. There is
+// currently no way to signal to libusb that any caller into one of the event
 // handler calls should return without handling any events.
+//
+// This class manages the polling thread and assures the thread exits safely.
+// This class is only visible to UsbContext. UsbContext manages its life cycle.
 class UsbEventHandler : public base::PlatformThread::Delegate {
- public:
-  explicit UsbEventHandler(PlatformUsbContext context)
-      : running_(true), context_(context) {
-    base::PlatformThread::CreateNonJoinable(0, this);
-  }
+ private:
+  friend class UsbContext;
+  friend struct base::DefaultDeleter<UsbEventHandler>;
 
-  virtual ~UsbEventHandler() {}
+  explicit UsbEventHandler(PlatformUsbContext context);
+  virtual ~UsbEventHandler();
 
   virtual void ThreadMain() OVERRIDE {
-    base::PlatformThread::SetName("UsbEventHandler");
-
-    DLOG(INFO) << "UsbEventHandler started.";
-    while (running_) {
+    base::PlatformThread::SetName("UsbEventDispatcher");
+    VLOG(1) << "UsbEventDispatcher started.";
+    while (true) {
+      {
+        base::AutoLock running_guard(running_lock_);
+        if (!running_) break;
+      }
       libusb_handle_events(context_);
     }
-    DLOG(INFO) << "UsbEventHandler shutting down.";
-    libusb_exit(context_);
-
-    delete this;
+    VLOG(1) << "UsbEventDispatcher shutting down.";
   }
 
   void Stop() {
-    running_ = false;
+    {
+      base::AutoLock running_guard(running_lock_);
+      running_ = false;
+    }
+    // Send an event to interrupt the the polling.
+    libusb_send_event(context_);
+    // Wait for the thread to exit.
+    base::PlatformThread::Join(thread_handle);
   }
 
+  volatile bool running_;
+  base::Lock running_lock_;
+  const PlatformUsbContext context_;
+  PlatformThreadHandle thread_handle;
+  DISALLOW_COPY_AND_ASSIGN(UsbEventHandler);
+};
+
+UsbEventHandler::UsbEventHandler(PlatformUsbContext context)
+    : running_(true), context_(context), thread_handle(0) {
+  base::PlatformThread::Create(0, this, &thread_handle);
+}
+
+UsbEventHandler::~UsbEventHandler() {}
+
+// Ref-counted wrapper for PlatformUsbContext.
+// It also manages the life-cycle of UsbEventHandler
+class UsbContext : public RefCountedThreadSafe<UsbContext> {
+ public:
+  UsbContext();
+  PlatformUsbContext context() const { return context_; }
+
  private:
-  bool running_;
-  PlatformUsbContext context_;
+  friend class RefCountedThreadSafe<UsbContext>;
 
-  DISALLOW_EVIL_CONSTRUCTORS(UsbEventHandler);
+  virtual ~UsbContext();
+  PlatformUsbContext context_;
+  scoped_ptr<UsbEventHandler> event_handler_;
 };
 
-UsbService::UsbService() {
+UsbContext::UsbContext()
+    : context_(NULL) {
   libusb_init(&context_);
-  event_handler_ = new UsbEventHandler(context_);
+  event_handler_.reset(new UsbEventHandler(context_));
 }
 
-UsbService::~UsbService() {}
-
-void UsbService::Cleanup() {
+UsbContext::~UsbContext() {
   event_handler_->Stop();
-  event_handler_ = NULL;
+  event_handler_.reset(NULL);
+  // The following statement will inform the event handler to stop waiting.
+  libusb_exit(context_);
+}
+
+// UsbDevice class uniquely represents a USB devices recognized by libusb and
+// maintains all its opened handles. It is assigned with an unique id by
+// UsbService. Once the device is disconnected it will invalidate all the
+// UsbDeviceHandle objects attached to it. The class is only visible to
+// UsbService and other classes need to access the device using its unique id.
+class UsbDevice : public base::NonThreadSafe {
+ public:
+  explicit UsbDevice(UsbContext* context, PlatformUsbDevice device,
+                     const int unique_id, const uint16 vendor_id,
+                     const uint16 product_id);
+  virtual ~UsbDevice();
+  PlatformUsbDevice device() const { return device_; }
+  int unique_id() const { return unique_id_; }
+  int vendor_id() const { return vendor_id_; }
+  int product_id() const { return product_id_; }
+
+  scoped_refptr<UsbDeviceHandle> OpenDevice(UsbService* service);
+  void CloseDeviceHandle(UsbDeviceHandle* device);
+
+ private:
+  // Retain the context so it will not be release before the destruction
+  // of the UsbDevice object.
+  scoped_refptr<UsbContext> context_;
+  vector<scoped_refptr<UsbDeviceHandle> > handles_;
+  const PlatformUsbDevice device_;
+  const uint16 unique_id_;
+  const uint16 vendor_id_;
+  const int product_id_;
+  DISALLOW_COPY_AND_ASSIGN(UsbDevice);
+};
+
+UsbDevice::UsbDevice(UsbContext* context, PlatformUsbDevice device,
+                     const int unique_id, const uint16 vendor_id,
+                     const uint16 product_id)
+    : context_(context),
+      device_(device),
+      unique_id_(unique_id),
+      vendor_id_(vendor_id),
+      product_id_(product_id) {
+  DCHECK(CalledOnValidThread());
+  libusb_ref_device(device_);
+}
+
+UsbDevice::~UsbDevice() {
+  DCHECK(CalledOnValidThread());
+  libusb_unref_device(device_);
+
+  // Device is lost.
+  // Invalidates all the opened handle.
+  for (vector<scoped_refptr<UsbDeviceHandle> >::iterator it = handles_.begin();
+       it != handles_.end(); ++it) {
+    it->get()->InternalClose();
+  }
+  STLClearObject(&handles_);
+}
+
+scoped_refptr<UsbDeviceHandle> UsbDevice::OpenDevice(UsbService* service) {
+  DCHECK(CalledOnValidThread());
+  PlatformUsbDeviceHandle handle;
+  if (0 == libusb_open(device_, &handle)) {
+    scoped_refptr<UsbDeviceHandle> wrapper =
+        make_scoped_refptr(new UsbDeviceHandle(service, unique_id_, vendor_id_,
+                                               product_id_, handle));
+    handles_.push_back(wrapper);
+    return wrapper;
+  }
+  return scoped_refptr<UsbDeviceHandle>();
+}
+
+void UsbDevice::CloseDeviceHandle(UsbDeviceHandle* device) {
+  DCHECK(CalledOnValidThread());
+  device->InternalClose();
+  for (vector<scoped_refptr<UsbDeviceHandle> >::iterator it = handles_.begin();
+       it != handles_.end(); ++it) {
+    if (it->get() == device) {
+      handles_.erase(it);
+      return;
+    }
+  }
+}
+
+UsbService::UsbService()
+    : context_(new UsbContext()),
+      next_unique_id_(1),
+      device_enumeration_scheduled_(false) {
+  // This class will be consequently called on FILE thread.
+  DetachFromThread();
 }
 
-void UsbService::FindDevices(const uint16 vendor_id,
-                             const uint16 product_id,
-                             int interface_id,
-                             vector<scoped_refptr<UsbDevice> >* devices,
+UsbService::~UsbService() {
+  // The destructor will be called on UI thread.
+  DetachFromThread();
+}
+
+void UsbService::Shutdown() {
+  context_ = NULL;
+  for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
+    BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, it->second);
+  }
+  devices_.clear();
+}
+
+void UsbService::FindDevices(const uint16 vendor_id, const uint16 product_id,
+                             const int interface_id, vector<int>* devices,
                              const base::Callback<void()>& callback) {
-  DCHECK(event_handler_) << "FindDevices called after event handler stopped.";
+  DCHECK(CalledOnValidThread());
 #if defined(OS_CHROMEOS)
   // ChromeOS builds on non-ChromeOS machines (dev) should not attempt to
   // use permission broker.
@@ -105,10 +245,10 @@ void UsbService::FindDevices(const uint16 vendor_id,
 }
 
 void UsbService::FindDevicesImpl(const uint16 vendor_id,
-                                 const uint16 product_id,
-                                 vector<scoped_refptr<UsbDevice> >* devices,
+                                 const uint16 product_id, vector<int>* devices,
                                  const base::Callback<void()>& callback,
                                  bool success) {
+  DCHECK(CalledOnValidThread());
   base::ScopedClosureRunner run_callback(callback);
 
   devices->clear();
@@ -116,91 +256,92 @@ void UsbService::FindDevicesImpl(const uint16 vendor_id,
   // If the permission broker was unable to obtain permission for the specified
   // devices then there is no point in attempting to enumerate the devices. On
   // platforms without a permission broker, we assume permission is granted.
-  if (!success)
-    return;
+  if (!success) return;
 
-  DeviceVector enumerated_devices;
-  EnumerateDevices(&enumerated_devices);
-  if (enumerated_devices.empty())
-    return;
+  EnumerateDevices();
 
-  for (unsigned int i = 0; i < enumerated_devices.size(); ++i) {
-    PlatformUsbDevice device = enumerated_devices[i].device();
-    if (DeviceMatches(device, vendor_id, product_id)) {
-      UsbDevice* const wrapper = LookupOrCreateDevice(device);
-      if (wrapper)
-        devices->push_back(wrapper);
-    }
+  for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
+    if (DeviceMatches(it->second, vendor_id, product_id))
+      devices->push_back(it->second->unique_id());
   }
 }
 
-void UsbService::CloseDevice(scoped_refptr<UsbDevice> device) {
-  DCHECK(event_handler_) << "CloseDevice called after event handler stopped.";
-
-  PlatformUsbDevice platform_device = libusb_get_device(device->handle());
-  if (!ContainsKey(devices_, platform_device)) {
-    LOG(WARNING) << "CloseDevice called for device we're not tracking!";
-    return;
+scoped_refptr<UsbDeviceHandle> UsbService::OpenDevice(int device) {
+  DCHECK(CalledOnValidThread());
+  EnumerateDevices();
+  for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
+    if (it->second->unique_id() == device)
+      return it->second->OpenDevice(this);
   }
-
-  devices_.erase(platform_device);
-  libusb_close(device->handle());
-}
-
-UsbService::RefCountedPlatformUsbDevice::RefCountedPlatformUsbDevice(
-    PlatformUsbDevice device) : device_(device) {
-  libusb_ref_device(device_);
+  return NULL;
 }
 
-UsbService::RefCountedPlatformUsbDevice::RefCountedPlatformUsbDevice(
-    const RefCountedPlatformUsbDevice& other) : device_(other.device_) {
-  libusb_ref_device(device_);
-}
+void UsbService::CloseDeviceHandle(scoped_refptr<UsbDeviceHandle> device) {
+  DCHECK(CalledOnValidThread());
+  int id = device->device();
 
-UsbService::RefCountedPlatformUsbDevice::~RefCountedPlatformUsbDevice() {
-  libusb_unref_device(device_);
+  for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
+    if (it->second->unique_id() == id) {
+      it->second->CloseDeviceHandle(device);
+      break;
+    }
+  }
 }
 
-PlatformUsbDevice UsbService::RefCountedPlatformUsbDevice::device() {
-  return device_;
+void UsbService::ScheduleEnumerateDevice() {
+  DCHECK(CalledOnValidThread());
+  if (device_enumeration_scheduled_)
+    return;
+  device_enumeration_scheduled_ = true;
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&UsbService::EnumerateDevices, base::Unretained(this)));
 }
 
-void UsbService::EnumerateDevices(DeviceVector* output) {
-  STLClearObject(output);
-
+void UsbService::EnumerateDevices() {
+  DCHECK(CalledOnValidThread());
+  device_enumeration_scheduled_ = false;
   libusb_device** devices = NULL;
-  const ssize_t device_count = libusb_get_device_list(context_, &devices);
+  const ssize_t device_count =
+      libusb_get_device_list(context_->context(), &devices);
   if (device_count < 0)
     return;
 
-  for (int i = 0; i < device_count; ++i) {
-    libusb_device* device = devices[i];
-    libusb_ref_device(device);
-    output->push_back(RefCountedPlatformUsbDevice(device));
+  set<int> connected_devices;
+  vector<PlatformUsbDevice> disconnected_devices;
+
+  // Populates new devices.
+  for (ssize_t i = 0; i < device_count; ++i) {
+    if (!ContainsKey(devices_, devices[i])) {
+      libusb_device_descriptor descriptor;
+      if (0 != libusb_get_device_descriptor(devices[i], &descriptor))
+        continue;
+      devices_[devices[i]] = new UsbDevice(context_.get(), devices[i],
+                                           next_unique_id_, descriptor.idVendor,
+                                           descriptor.idProduct);
+      ++next_unique_id_;
+    }
+    connected_devices.insert(devices_[devices[i]]->unique_id());
+  }
+
+  // Find disconnected devices.
+  for (DeviceMap::iterator it = devices_.begin(); it != devices_.end(); ++it) {
+    if (!ContainsKey(connected_devices, it->second->unique_id())) {
+      disconnected_devices.push_back(it->first);
+    }
   }
 
+  // Remove disconnected devices from devices_.
+  for (size_t i = 0; i < disconnected_devices.size(); ++i) {
+    // This should delete those devices and invalidate their handles.
+    // It might take long.
+    delete devices_[disconnected_devices[i]];
+    devices_.erase(disconnected_devices[i]);
+  }
   libusb_free_device_list(devices, true);
 }
 
-bool UsbService::DeviceMatches(PlatformUsbDevice device,
-                               const uint16 vendor_id,
+bool UsbService::DeviceMatches(const UsbDevice* device, const uint16 vendor_id,
                                const uint16 product_id) {
-  libusb_device_descriptor descriptor;
-  if (libusb_get_device_descriptor(device, &descriptor))
-    return false;
-  return descriptor.idVendor == vendor_id && descriptor.idProduct == product_id;
-}
-
-UsbDevice* UsbService::LookupOrCreateDevice(PlatformUsbDevice device) {
-  if (!ContainsKey(devices_, device)) {
-    libusb_device_handle* handle = NULL;
-    if (libusb_open(device, &handle)) {
-      LOG(WARNING) << "Could not open device.";
-      return NULL;
-    }
-
-    UsbDevice* wrapper = new UsbDevice(this, handle);
-    devices_[device] = wrapper;
-  }
-  return devices_[device].get();
+  return device->vendor_id() == vendor_id && device->product_id() == product_id;
 }