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// 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 "device/usb/usb_context.h"
#include "base/atomicops.h"
#include "base/logging.h"
#include "base/threading/platform_thread.h"
#include "device/usb/usb_error.h"
#include "third_party/libusb/src/libusb/interrupt.h"
#include "third_party/libusb/src/libusb/libusb.h"
namespace device {
// 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
// handler calls should return without handling any events.
class UsbContext::UsbEventHandler : public base::PlatformThread::Delegate {
public:
explicit UsbEventHandler(libusb_context* context);
~UsbEventHandler() override;
// base::PlatformThread::Delegate
void ThreadMain() override;
void Stop();
private:
base::subtle::Atomic32 running_;
libusb_context* context_;
base::PlatformThreadHandle thread_handle_;
DISALLOW_COPY_AND_ASSIGN(UsbEventHandler);
};
UsbContext::UsbEventHandler::UsbEventHandler(libusb_context* context)
: context_(context), thread_handle_(0) {
base::subtle::Release_Store(&running_, 1);
bool success = base::PlatformThread::Create(0, this, &thread_handle_);
DCHECK(success) << "Failed to create USB IO handling thread.";
}
UsbContext::UsbEventHandler::~UsbEventHandler() {
libusb_exit(context_);
}
void UsbContext::UsbEventHandler::ThreadMain() {
base::PlatformThread::SetName("UsbEventHandler");
VLOG(1) << "UsbEventHandler started.";
while (base::subtle::Acquire_Load(&running_)) {
const int rv = libusb_handle_events(context_);
if (rv != LIBUSB_SUCCESS) {
VLOG(1) << "Failed to handle events: "
<< ConvertPlatformUsbErrorToString(rv);
}
}
VLOG(1) << "UsbEventHandler shutting down.";
delete this;
}
void UsbContext::UsbEventHandler::Stop() {
base::subtle::Release_Store(&running_, 0);
libusb_interrupt_handle_event(context_);
}
UsbContext::UsbContext(PlatformUsbContext context) : context_(context) {
// Ownership of the PlatformUsbContext is passed to the event handler thread.
event_handler_ = new UsbEventHandler(context_);
}
UsbContext::~UsbContext() {
DCHECK(thread_checker_.CalledOnValidThread());
event_handler_->Stop();
}
} // namespace device
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