media/libaaudio/src/utility/HandleTracker.cpp - third_party/android/platform/frameworks/av - Git at Google

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  */

 #define LOG_TAG "AAudio"
 //#define LOG_NDEBUG 0
 #include <utils/Log.h>

 #include <assert.h>
 #include <new>
 #include <stdint.h>
 #include <utils/Mutex.h>

 #include <aaudio/AAudio.h>
 #include "HandleTracker.h"

 using android::Mutex;

 // Handle format is: tgggiiii
 // where each letter is 4 bits, t=type, g=generation, i=index

 #define TYPE_SIZE           4
 #define GENERATION_SIZE    12
 #define INDEX_SIZE         16

 #define GENERATION_INVALID  0
 #define GENERATION_SHIFT    INDEX_SIZE

 #define TYPE_MASK           ((1 << TYPE_SIZE) - 1)
 #define GENERATION_MASK     ((1 << GENERATION_SIZE) - 1)
 #define INDEX_MASK          ((1 << INDEX_SIZE) - 1)

 #define SLOT_UNAVAILABLE    (-1)

 // Error if handle is negative so type is limited to bottom half.
 #define HANDLE_INVALID_TYPE TYPE_MASK

 static_assert(HANDLE_TRACKER_MAX_TYPES == (1 << (TYPE_SIZE - 1)),
     "Mismatch between header and cpp.");
 static_assert(HANDLE_TRACKER_MAX_HANDLES == (1 << (INDEX_SIZE)),
     "Mismatch between header and cpp.");

 HandleTracker::HandleTracker(uint32_t maxHandles)
         : mMaxHandleCount(maxHandles)
         , mHandleHeaders(nullptr)
 {
     assert(maxHandles <= HANDLE_TRACKER_MAX_HANDLES);
     // Allocate arrays to hold addresses and validation info.
     mHandleAddresses = (handle_tracker_address_t *)
             new(std::nothrow) handle_tracker_address_t[maxHandles];
     if (mHandleAddresses != nullptr) {
         mHandleHeaders = new(std::nothrow) handle_tracker_header_t[maxHandles];

         if (mHandleHeaders != nullptr) {
             handle_tracker_header_t initialHeader = buildHeader(0, 1);
             // Initialize linked list of free nodes. nullptr terminated.
             for (uint32_t i = 0; i < (maxHandles - 1); i++) {
                 mHandleAddresses[i] = &mHandleAddresses[i + 1]; // point to next node
                 mHandleHeaders[i] = initialHeader;
             }
             mNextFreeAddress = &mHandleAddresses[0];
             mHandleAddresses[maxHandles - 1] = nullptr;
             mHandleHeaders[maxHandles - 1] = 0;
         } else {
             delete[] mHandleAddresses; // so the class appears uninitialized
             mHandleAddresses = nullptr;
         }
     }
 }

 HandleTracker::~HandleTracker()
 {
     Mutex::Autolock _l(mLock);
     delete[] mHandleAddresses;
     delete[] mHandleHeaders;
     mHandleAddresses = nullptr;
 }

 bool HandleTracker::isInitialized() const {
     return mHandleAddresses != nullptr;
 }

 handle_tracker_slot_t HandleTracker::allocateSlot_l() {
     void **allocated = mNextFreeAddress;
     if (allocated == nullptr) {
         return SLOT_UNAVAILABLE;
     }
     // Remove this slot from the head of the linked list.
     mNextFreeAddress = (void **) *allocated;
     return (allocated - mHandleAddresses);
 }

 handle_tracker_generation_t HandleTracker::nextGeneration_l(handle_tracker_slot_t index) {
     handle_tracker_generation_t generation = (mHandleHeaders[index] + 1) & GENERATION_MASK;
     // Avoid generation zero so that 0x0 is not a valid handle.
     if (generation == GENERATION_INVALID) {
         generation++;
     }
     return generation;
 }

 aaudio_handle_t HandleTracker::put(handle_tracker_type_t type, void *address)
 {
     if (type < 0 || type >= HANDLE_TRACKER_MAX_TYPES) {
         return static_cast<aaudio_handle_t>(AAUDIO_ERROR_OUT_OF_RANGE);
     }
     if (!isInitialized()) {
         return static_cast<aaudio_handle_t>(AAUDIO_ERROR_NO_MEMORY);
     }

     Mutex::Autolock _l(mLock);

     // Find an empty slot.
     handle_tracker_slot_t index = allocateSlot_l();
     if (index == SLOT_UNAVAILABLE) {
         ALOGE("HandleTracker::put() no room for more handles");
         return static_cast<aaudio_handle_t>(AAUDIO_ERROR_NO_FREE_HANDLES);
     }

     // Cycle the generation counter so stale handles can be detected.
     handle_tracker_generation_t generation = nextGeneration_l(index); // reads header table
     handle_tracker_header_t inputHeader = buildHeader(type, generation);

     // These two writes may need to be observed by other threads or cores during get().
     mHandleHeaders[index] = inputHeader;
     mHandleAddresses[index] = address;
     // TODO use store release to enforce memory order with get()

     // Generate a handle.
     aaudio_handle_t handle = buildHandle(inputHeader, index);

     ALOGV("HandleTracker::put(%p) returns 0x%08x", address, handle);
     return handle;
 }

 handle_tracker_slot_t HandleTracker::handleToIndex(handle_tracker_type_t type,
                                                    aaudio_handle_t handle) const
 {
     // Validate the handle.
     handle_tracker_slot_t index = extractIndex(handle);
     if (index >= mMaxHandleCount) {
         ALOGE("HandleTracker::handleToIndex() invalid handle = 0x%08X", handle);
         return static_cast<aaudio_handle_t>(AAUDIO_ERROR_INVALID_HANDLE);
     }
     handle_tracker_generation_t handleGeneration = extractGeneration(handle);
     handle_tracker_header_t inputHeader = buildHeader(type, handleGeneration);
     // We do not need to synchronize this access to mHandleHeaders because it is constant for
     // the lifetime of the handle.
     if (inputHeader != mHandleHeaders[index]) {
         ALOGE("HandleTracker::handleToIndex() inputHeader = 0x%08x != mHandleHeaders[%d] = 0x%08x",
              inputHeader, index, mHandleHeaders[index]);
         return static_cast<aaudio_handle_t>(AAUDIO_ERROR_INVALID_HANDLE);
     }
     return index;
 }

 handle_tracker_address_t HandleTracker::get(handle_tracker_type_t type, aaudio_handle_t handle) const
 {
     if (!isInitialized()) {
         return nullptr;
     }
     handle_tracker_slot_t index = handleToIndex(type, handle);
     if (index >= 0) {
         // We do not need to synchronize this access to mHandleHeaders because this slot
         // is allocated and, therefore, not part of the linked list of free slots.
         return mHandleAddresses[index];
     } else {
         return nullptr;
     }
 }

 handle_tracker_address_t HandleTracker::remove(handle_tracker_type_t type, aaudio_handle_t handle) {
     if (!isInitialized()) {
         return nullptr;
     }

     Mutex::Autolock _l(mLock);

     handle_tracker_slot_t index = handleToIndex(type,handle);
     if (index >= 0) {
         handle_tracker_address_t address = mHandleAddresses[index];

         // Invalidate the header type but preserve the generation count.
         handle_tracker_generation_t generation = mHandleHeaders[index] & GENERATION_MASK;
         handle_tracker_header_t inputHeader = buildHeader(
                 (handle_tracker_type_t) HANDLE_INVALID_TYPE, generation);
         mHandleHeaders[index] = inputHeader;

         // Add this slot to the head of the linked list.
         mHandleAddresses[index] = mNextFreeAddress;
         mNextFreeAddress = (handle_tracker_address_t *) &mHandleAddresses[index];
         return address;
     } else {
         return nullptr;
     }
 }

 aaudio_handle_t HandleTracker::buildHandle(handle_tracker_header_t typeGeneration,
                                          handle_tracker_slot_t index) {
     return (aaudio_handle_t)((typeGeneration << GENERATION_SHIFT) | (index & INDEX_MASK));
 }

 handle_tracker_header_t HandleTracker::buildHeader(handle_tracker_type_t type,
                                     handle_tracker_generation_t generation)
 {
     return (handle_tracker_header_t) (((type & TYPE_MASK) << GENERATION_SIZE)
         | (generation & GENERATION_MASK));
 }

 handle_tracker_slot_t HandleTracker::extractIndex(aaudio_handle_t handle)
 {
     return handle & INDEX_MASK;
 }

 handle_tracker_generation_t HandleTracker::extractGeneration(aaudio_handle_t handle)
 {
     return (handle >> GENERATION_SHIFT) & GENERATION_MASK;
 }
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	*/

	#define LOG_TAG "AAudio"
	//#define LOG_NDEBUG 0
	#include <utils/Log.h>

	#include <assert.h>
	#include <new>
	#include <stdint.h>
	#include <utils/Mutex.h>

	#include <aaudio/AAudio.h>
	#include "HandleTracker.h"

	using android::Mutex;

	// Handle format is: tgggiiii
	// where each letter is 4 bits, t=type, g=generation, i=index

	#define TYPE_SIZE 4
	#define GENERATION_SIZE 12
	#define INDEX_SIZE 16

	#define GENERATION_INVALID 0
	#define GENERATION_SHIFT INDEX_SIZE

	#define TYPE_MASK ((1 << TYPE_SIZE) - 1)
	#define GENERATION_MASK ((1 << GENERATION_SIZE) - 1)
	#define INDEX_MASK ((1 << INDEX_SIZE) - 1)

	#define SLOT_UNAVAILABLE (-1)

	// Error if handle is negative so type is limited to bottom half.
	#define HANDLE_INVALID_TYPE TYPE_MASK

	static_assert(HANDLE_TRACKER_MAX_TYPES == (1 << (TYPE_SIZE - 1)),
	"Mismatch between header and cpp.");
	static_assert(HANDLE_TRACKER_MAX_HANDLES == (1 << (INDEX_SIZE)),
	"Mismatch between header and cpp.");

	HandleTracker::HandleTracker(uint32_t maxHandles)
	: mMaxHandleCount(maxHandles)
	, mHandleHeaders(nullptr)
	{
	assert(maxHandles <= HANDLE_TRACKER_MAX_HANDLES);
	// Allocate arrays to hold addresses and validation info.
	mHandleAddresses = (handle_tracker_address_t *)
	new(std::nothrow) handle_tracker_address_t[maxHandles];
	if (mHandleAddresses != nullptr) {
	mHandleHeaders = new(std::nothrow) handle_tracker_header_t[maxHandles];

	if (mHandleHeaders != nullptr) {
	handle_tracker_header_t initialHeader = buildHeader(0, 1);
	// Initialize linked list of free nodes. nullptr terminated.
	for (uint32_t i = 0; i < (maxHandles - 1); i++) {
	mHandleAddresses[i] = &mHandleAddresses[i + 1]; // point to next node
	mHandleHeaders[i] = initialHeader;
	}
	mNextFreeAddress = &mHandleAddresses[0];
	mHandleAddresses[maxHandles - 1] = nullptr;
	mHandleHeaders[maxHandles - 1] = 0;
	} else {
	delete[] mHandleAddresses; // so the class appears uninitialized
	mHandleAddresses = nullptr;
	}
	}
	}

	HandleTracker::~HandleTracker()
	{
	Mutex::Autolock _l(mLock);
	delete[] mHandleAddresses;
	delete[] mHandleHeaders;
	mHandleAddresses = nullptr;
	}

	bool HandleTracker::isInitialized() const {
	return mHandleAddresses != nullptr;
	}

	handle_tracker_slot_t HandleTracker::allocateSlot_l() {
	void **allocated = mNextFreeAddress;
	if (allocated == nullptr) {
	return SLOT_UNAVAILABLE;
	}
	// Remove this slot from the head of the linked list.
	mNextFreeAddress = (void *) allocated;
	return (allocated - mHandleAddresses);
	}

	handle_tracker_generation_t HandleTracker::nextGeneration_l(handle_tracker_slot_t index) {
	handle_tracker_generation_t generation = (mHandleHeaders[index] + 1) & GENERATION_MASK;
	// Avoid generation zero so that 0x0 is not a valid handle.
	if (generation == GENERATION_INVALID) {
	generation++;
	}
	return generation;
	}

	aaudio_handle_t HandleTracker::put(handle_tracker_type_t type, void *address)
	{
	if (type < 0 \|\| type >= HANDLE_TRACKER_MAX_TYPES) {
	return static_cast<aaudio_handle_t>(AAUDIO_ERROR_OUT_OF_RANGE);
	}
	if (!isInitialized()) {
	return static_cast<aaudio_handle_t>(AAUDIO_ERROR_NO_MEMORY);
	}

	Mutex::Autolock _l(mLock);

	// Find an empty slot.
	handle_tracker_slot_t index = allocateSlot_l();
	if (index == SLOT_UNAVAILABLE) {
	ALOGE("HandleTracker::put() no room for more handles");
	return static_cast<aaudio_handle_t>(AAUDIO_ERROR_NO_FREE_HANDLES);
	}

	// Cycle the generation counter so stale handles can be detected.
	handle_tracker_generation_t generation = nextGeneration_l(index); // reads header table
	handle_tracker_header_t inputHeader = buildHeader(type, generation);

	// These two writes may need to be observed by other threads or cores during get().
	mHandleHeaders[index] = inputHeader;
	mHandleAddresses[index] = address;
	// TODO use store release to enforce memory order with get()

	// Generate a handle.
	aaudio_handle_t handle = buildHandle(inputHeader, index);

	ALOGV("HandleTracker::put(%p) returns 0x%08x", address, handle);
	return handle;
	}

	handle_tracker_slot_t HandleTracker::handleToIndex(handle_tracker_type_t type,
	aaudio_handle_t handle) const
	{
	// Validate the handle.
	handle_tracker_slot_t index = extractIndex(handle);
	if (index >= mMaxHandleCount) {
	ALOGE("HandleTracker::handleToIndex() invalid handle = 0x%08X", handle);
	return static_cast<aaudio_handle_t>(AAUDIO_ERROR_INVALID_HANDLE);
	}
	handle_tracker_generation_t handleGeneration = extractGeneration(handle);
	handle_tracker_header_t inputHeader = buildHeader(type, handleGeneration);
	// We do not need to synchronize this access to mHandleHeaders because it is constant for
	// the lifetime of the handle.
	if (inputHeader != mHandleHeaders[index]) {
	ALOGE("HandleTracker::handleToIndex() inputHeader = 0x%08x != mHandleHeaders[%d] = 0x%08x",
	inputHeader, index, mHandleHeaders[index]);
	return static_cast<aaudio_handle_t>(AAUDIO_ERROR_INVALID_HANDLE);
	}
	return index;
	}

	handle_tracker_address_t HandleTracker::get(handle_tracker_type_t type, aaudio_handle_t handle) const
	{
	if (!isInitialized()) {
	return nullptr;
	}
	handle_tracker_slot_t index = handleToIndex(type, handle);
	if (index >= 0) {
	// We do not need to synchronize this access to mHandleHeaders because this slot
	// is allocated and, therefore, not part of the linked list of free slots.
	return mHandleAddresses[index];
	} else {
	return nullptr;
	}
	}

	handle_tracker_address_t HandleTracker::remove(handle_tracker_type_t type, aaudio_handle_t handle) {
	if (!isInitialized()) {
	return nullptr;
	}

	Mutex::Autolock _l(mLock);

	handle_tracker_slot_t index = handleToIndex(type,handle);
	if (index >= 0) {
	handle_tracker_address_t address = mHandleAddresses[index];

	// Invalidate the header type but preserve the generation count.
	handle_tracker_generation_t generation = mHandleHeaders[index] & GENERATION_MASK;
	handle_tracker_header_t inputHeader = buildHeader(
	(handle_tracker_type_t) HANDLE_INVALID_TYPE, generation);
	mHandleHeaders[index] = inputHeader;

	// Add this slot to the head of the linked list.
	mHandleAddresses[index] = mNextFreeAddress;
	mNextFreeAddress = (handle_tracker_address_t *) &mHandleAddresses[index];
	return address;
	} else {
	return nullptr;
	}
	}

	aaudio_handle_t HandleTracker::buildHandle(handle_tracker_header_t typeGeneration,
	handle_tracker_slot_t index) {
	return (aaudio_handle_t)((typeGeneration << GENERATION_SHIFT) \| (index & INDEX_MASK));
	}

	handle_tracker_header_t HandleTracker::buildHeader(handle_tracker_type_t type,
	handle_tracker_generation_t generation)
	{
	return (handle_tracker_header_t) (((type & TYPE_MASK) << GENERATION_SIZE)
	\| (generation & GENERATION_MASK));
	}

	handle_tracker_slot_t HandleTracker::extractIndex(aaudio_handle_t handle)
	{
	return handle & INDEX_MASK;
	}

	handle_tracker_generation_t HandleTracker::extractGeneration(aaudio_handle_t handle)
	{
	return (handle >> GENERATION_SHIFT) & GENERATION_MASK;
	}