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types.h
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types.h
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/*
* Copyright (C) 2018 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.
*/
#pragma once
#include <string.h>
#include <algorithm>
#include <memory>
#include <utility>
#include <vector>
#include <android-base/logging.h>
#include "fdevent/fdevent.h"
#include "sysdeps/uio.h"
// Essentially std::vector<char>, except without zero initialization or reallocation.
struct Block {
using iterator = char*;
Block() = default;
explicit Block(size_t size) { allocate(size); }
template <typename Iterator>
Block(Iterator begin, Iterator end) : Block(end - begin) {
std::copy(begin, end, data_.get());
}
Block(const Block& copy) = delete;
Block(Block&& move) noexcept
: data_(std::exchange(move.data_, nullptr)),
capacity_(std::exchange(move.capacity_, 0)),
size_(std::exchange(move.size_, 0)) {}
Block& operator=(const Block& copy) = delete;
Block& operator=(Block&& move) noexcept {
clear();
data_ = std::exchange(move.data_, nullptr);
capacity_ = std::exchange(move.capacity_, 0);
size_ = std::exchange(move.size_, 0);
return *this;
}
~Block() = default;
void resize(size_t new_size) {
if (!data_) {
allocate(new_size);
} else {
CHECK_GE(capacity_, new_size);
size_ = new_size;
}
}
template <typename InputIt>
void assign(InputIt begin, InputIt end) {
clear();
allocate(end - begin);
std::copy(begin, end, data_.get());
}
void clear() {
data_.reset();
capacity_ = 0;
size_ = 0;
}
size_t capacity() const { return capacity_; }
size_t size() const { return size_; }
bool empty() const { return size() == 0; }
char* data() { return data_.get(); }
const char* data() const { return data_.get(); }
char* begin() { return data_.get(); }
const char* begin() const { return data_.get(); }
char* end() { return data() + size_; }
const char* end() const { return data() + size_; }
char& operator[](size_t idx) { return data()[idx]; }
const char& operator[](size_t idx) const { return data()[idx]; }
bool operator==(const Block& rhs) const {
return size() == rhs.size() && memcmp(data(), rhs.data(), size()) == 0;
}
private:
void allocate(size_t size) {
CHECK(data_ == nullptr);
CHECK_EQ(0ULL, capacity_);
CHECK_EQ(0ULL, size_);
if (size != 0) {
// This isn't std::make_unique because that's equivalent to `new char[size]()`, which
// value-initializes the array instead of leaving it uninitialized. As an optimization,
// call new without parentheses to avoid this costly initialization.
data_.reset(new char[size]);
capacity_ = size;
size_ = size;
}
}
std::unique_ptr<char[]> data_;
size_t capacity_ = 0;
size_t size_ = 0;
};
struct amessage {
uint32_t command; /* command identifier constant */
uint32_t arg0; /* first argument */
uint32_t arg1; /* second argument */
uint32_t data_length; /* length of payload (0 is allowed) */
uint32_t data_check; /* checksum of data payload */
uint32_t magic; /* command ^ 0xffffffff */
};
struct apacket {
using payload_type = Block;
amessage msg;
payload_type payload;
};
struct IOVector {
using value_type = char;
using block_type = Block;
using size_type = size_t;
IOVector() = default;
explicit IOVector(block_type&& block) { append(std::move(block)); }
IOVector(const IOVector& copy) = delete;
IOVector(IOVector&& move) noexcept : IOVector() { *this = std::move(move); }
IOVector& operator=(const IOVector& copy) = delete;
IOVector& operator=(IOVector&& move) noexcept;
const value_type* front_data() const {
if (chain_.empty()) {
return nullptr;
}
return chain_[start_index_].data() + begin_offset_;
}
size_type front_size() const {
if (chain_.empty()) {
return 0;
}
return chain_[start_index_].size() - begin_offset_;
}
size_type size() const { return chain_length_ - begin_offset_; }
bool empty() const { return size() == 0; }
// Return the last block so the caller can still reuse its allocated capacity
// or it can be simply ignored.
block_type clear();
void drop_front(size_type len);
// Split the first |len| bytes out of this chain into its own.
IOVector take_front(size_type len);
// Add a nonempty block to the chain.
void append(block_type&& block) {
if (block.size() == 0) {
return;
}
CHECK_NE(0ULL, block.size());
chain_length_ += block.size();
chain_.emplace_back(std::move(block));
}
void trim_front();
private:
void trim_chain_front();
// Drop the front block from the chain, and update chain_length_ appropriately.
void pop_front_block();
// Iterate over the blocks with a callback with an operator()(const char*, size_t).
template <typename Fn>
void iterate_blocks(Fn&& callback) const {
if (size() == 0) {
return;
}
for (size_t i = start_index_; i < chain_.size(); ++i) {
const auto& block = chain_[i];
const char* begin = block.data();
size_t length = block.size();
if (i == start_index_) {
CHECK_GE(block.size(), begin_offset_);
begin += begin_offset_;
length -= begin_offset_;
}
callback(begin, length);
}
}
public:
// Copy all of the blocks into a single block.
template <typename CollectionType = block_type>
CollectionType coalesce() const& {
CollectionType result;
if (size() == 0) {
return result;
}
result.resize(size());
size_t offset = 0;
iterate_blocks([&offset, &result](const char* data, size_t len) {
memcpy(&result[offset], data, len);
offset += len;
});
return result;
}
block_type coalesce() &&;
template <typename FunctionType>
auto coalesced(FunctionType&& f) const {
if (chain_.size() == start_index_ + 1) {
// If we only have one block, we can use it directly.
return f(chain_[start_index_].data() + begin_offset_, size());
} else {
// Otherwise, copy to a single block.
auto data = coalesce();
return f(data.data(), data.size());
}
}
// Get a list of iovecs that can be used to write out all of the blocks.
std::vector<adb_iovec> iovecs() const;
private:
// Total length of all of the blocks in the chain.
size_t chain_length_ = 0;
size_t begin_offset_ = 0;
size_t start_index_ = 0;
std::vector<block_type> chain_;
};
// An implementation of weak pointers tied to the fdevent run loop.
//
// This allows for code to submit a request for an object, and upon receiving
// a response, know whether the object is still alive, or has been destroyed
// because of other reasons. We keep a list of living weak_ptrs in each object,
// and clear the weak_ptrs when the object is destroyed. This is safe, because
// we require that both the destructor of the referent and the get method on
// the weak_ptr are executed on the main thread.
template <typename T>
struct enable_weak_from_this;
template <typename T>
struct weak_ptr {
weak_ptr() = default;
explicit weak_ptr(T* ptr) { reset(ptr); }
weak_ptr(const weak_ptr& copy) { reset(copy.get()); }
weak_ptr(weak_ptr&& move) {
reset(move.get());
move.reset();
}
~weak_ptr() { reset(); }
weak_ptr& operator=(const weak_ptr& copy) {
if (© == this) {
return *this;
}
reset(copy.get());
return *this;
}
weak_ptr& operator=(weak_ptr&& move) {
if (&move == this) {
return *this;
}
reset(move.get());
move.reset();
return *this;
}
T* get() const {
check_main_thread();
return ptr_;
}
void reset(T* ptr = nullptr) {
check_main_thread();
if (ptr == ptr_) {
return;
}
if (ptr_) {
ptr_->weak_ptrs_.erase(
std::remove(ptr_->weak_ptrs_.begin(), ptr_->weak_ptrs_.end(), this));
}
ptr_ = ptr;
if (ptr_) {
ptr_->weak_ptrs_.push_back(this);
}
}
private:
friend struct enable_weak_from_this<T>;
T* ptr_ = nullptr;
};
template <typename T>
struct enable_weak_from_this {
~enable_weak_from_this() {
if (!weak_ptrs_.empty()) {
check_main_thread();
for (auto& weak : weak_ptrs_) {
weak->ptr_ = nullptr;
}
weak_ptrs_.clear();
}
}
weak_ptr<T> weak() { return weak_ptr<T>(static_cast<T*>(this)); }
void schedule_deletion() {
fdevent_run_on_main_thread([this]() { delete static_cast<T*>(this); });
}
private:
friend struct weak_ptr<T>;
std::vector<weak_ptr<T>*> weak_ptrs_;
};