15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Copyright (c) 2012 The Chromium Authors. All rights reserved. 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// found in the LICENSE file. 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "ppapi/proxy/gamepad_resource.h" 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <string.h> 85f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 95f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)#include "base/bind.h" 105f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)#include "base/threading/platform_thread.h" 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "ppapi/proxy/dispatch_reply_message.h" 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "ppapi/proxy/ppapi_messages.h" 135f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)#include "ppapi/shared_impl/ppb_gamepad_shared.h" 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 155f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)namespace ppapi { 165f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)namespace proxy { 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 182a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)namespace { 195f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 205f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)// This is the read logic from content/common/gamepad_seqlock.h 215f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)base::subtle::Atomic32 ReadBegin(const base::subtle::Atomic32* sequence) { 225f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) base::subtle::Atomic32 version; 235f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) for (;;) { 245f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) version = base::subtle::NoBarrier_Load(sequence); 255f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 265f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) // If the counter is even, then the associated data might be in a 275f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) // consistent state, so we can try to read. 285f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) if ((version & 1) == 0) 295f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) break; 305f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 315f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) // Otherwise, the writer is in the middle of an update. Retry the read. 325f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) base::PlatformThread::YieldCurrentThread(); 335f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) } 345f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) return version; 355f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} 365f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 375f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)bool ReadRetry(const base::subtle::Atomic32* sequence, 385f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) base::subtle::Atomic32 version) { 395f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) // If the sequence number was updated then a read should be re-attempted. 405f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) // -- Load fence, read membarrier 415f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) return base::subtle::Release_Load(sequence) != version; 425f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} 435f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 445f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} // namespace 455f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 465f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)GamepadResource::GamepadResource(Connection connection, PP_Instance instance) 475f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) : PluginResource(connection, instance), 485f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) buffer_(NULL) { 495f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) memset(&last_read_, 0, sizeof(last_read_)); 505f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 515f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) SendCreate(BROWSER, PpapiHostMsg_Gamepad_Create()); 525f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) Call<PpapiPluginMsg_Gamepad_SendMemory>( 535f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) BROWSER, 545f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) PpapiHostMsg_Gamepad_RequestMemory(), 555f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) base::Bind(&GamepadResource::OnPluginMsgSendMemory, this)); 565f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} 575f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 585f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)GamepadResource::~GamepadResource() { 595f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles)} 605f1c94371a64b3196d4be9466099bb892df9b88eTorne (Richard Coles) 612a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles)thunk::PPB_Gamepad_API* GamepadResource::AsPPB_Gamepad_API() { 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return this; 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 64 65void GamepadResource::Sample(PP_Instance /* instance */, 66 PP_GamepadsSampleData* data) { 67 if (!buffer_) { 68 // Browser hasn't sent back our shared memory, give the plugin gamepad 69 // data corresponding to "not connected". 70 memset(data, 0, sizeof(PP_GamepadsSampleData)); 71 return; 72 } 73 74 // ========== 75 // DANGER 76 // ========== 77 // 78 // This logic is duplicated in the renderer as well. If you change it, that 79 // also needs to be in sync. See gamepad_shared_memory_reader.cc. 80 81 // Only try to read this many times before failing to avoid waiting here 82 // very long in case of contention with the writer. 83 const int kMaximumContentionCount = 10; 84 int contention_count = -1; 85 base::subtle::Atomic32 version; 86 WebKitGamepads read_into; 87 do { 88 version = ReadBegin(&buffer_->sequence); 89 memcpy(&read_into, &buffer_->buffer, sizeof(read_into)); 90 ++contention_count; 91 if (contention_count == kMaximumContentionCount) 92 break; 93 } while (ReadRetry(&buffer_->sequence, version)); 94 95 // In the event of a read failure, just leave the last read data as-is (the 96 // hardware thread is taking unusally long). 97 if (contention_count < kMaximumContentionCount) 98 ConvertWebKitGamepadData(read_into, &last_read_); 99 100 memcpy(data, &last_read_, sizeof(PP_GamepadsSampleData)); 101} 102 103void GamepadResource::OnPluginMsgSendMemory( 104 const ResourceMessageReplyParams& params) { 105 // On failure, the handle will be null and the CHECK below will be tripped. 106 base::SharedMemoryHandle handle = base::SharedMemory::NULLHandle(); 107 params.TakeSharedMemoryHandleAtIndex(0, &handle); 108 109 shared_memory_.reset(new base::SharedMemory(handle, true)); 110 CHECK(shared_memory_->Map(sizeof(ContentGamepadHardwareBuffer))); 111 buffer_ = static_cast<const ContentGamepadHardwareBuffer*>( 112 shared_memory_->memory()); 113} 114 115} // namespace proxy 116} // namespace ppapi 117