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#include "buffer.hh"
#include <algorithm>
#include <cassert>
#include <vector>
namespace {
class Round : public Buffer {
public:
explicit Round(size_t size)
: data_(std::make_unique<char[]>(size)), size_(size) {}
bool empty() const override {
return rptr_ == wptr_ && !full_;
}
bool full() const override {
return rptr_ == wptr_ && full_;
}
void clear() override {
rptr_ = wptr_ = 0;
full_ = false;
}
char const* rbuf(size_t want, size_t& avail) override {
if (rptr_ < wptr_) {
avail = wptr_ - rptr_;
} else if (rptr_ == wptr_ && !full_) {
avail = 0;
} else {
avail = size_ - rptr_;
if (want > avail) {
auto* target = data_.get();
for (; rptr_ < size_; ++rptr_) {
std::swap(*target, data_[rptr_]);
++target;
}
rptr_ = 0;
wptr_ += avail;
if (wptr_ == size_) {
assert(full_);
wptr_ = 0;
avail = size_ - rptr_;
} else {
avail = wptr_ - rptr_;
}
}
}
return data_.get() + rptr_;
}
void rcommit(size_t bytes) override {
if (bytes == 0)
return;
full_ = false;
assert(rptr_ < wptr_ ? rptr_ + bytes <= wptr_ : rptr_ + bytes <= size_);
rptr_ += bytes;
if (rptr_ == size_)
rptr_ = 0;
if (rptr_ == wptr_)
rptr_ = wptr_ = 0;
}
char* wbuf(size_t request, size_t& avail) override {
if (wptr_ < rptr_) {
avail = rptr_ - wptr_;
} else if (rptr_ == wptr_ && full_) {
avail = 0;
} else {
avail = size_ - wptr_;
if (avail < request && wptr_ != 0 && rptr_ != 0) {
std::copy(data_.get() + rptr_, data_.get() + wptr_, data_.get());
auto size = wptr_ - rptr_;
wptr_ = size;
rptr_ = 0;
avail = size_ - wptr_;
}
}
return data_.get() + wptr_;
}
void wcommit(size_t bytes) override {
if (bytes == 0)
return;
assert(wptr_ < rptr_ ? wptr_ + bytes <= rptr_ : wptr_ + bytes <= size_);
wptr_ += bytes;
if (wptr_ == size_)
wptr_ = 0;
if (wptr_ == rptr_)
full_ = true;
}
private:
std::unique_ptr<char[]> data_;
size_t const size_;
size_t rptr_{0};
size_t wptr_{0};
bool full_{false};
};
class Growing : public Buffer {
public:
Growing(size_t base_size, size_t max_size)
: base_size_(base_size), max_size_(max_size), data_(base_size) {
}
bool empty() const override {
return rptr_ == wptr_;
}
bool full() const override {
return rptr_ == 0 && wptr_ == max_size_;
}
void clear() override {
data_.resize(base_size_);
rptr_ = wptr_ = 0;
}
char const* rbuf(size_t, size_t& avail) override {
avail = wptr_ - rptr_;
return data_.data() + rptr_;
}
void rcommit(size_t bytes) override {
assert(rptr_ + bytes <= wptr_);
rptr_ += bytes;
if (rptr_ == wptr_)
rptr_ = wptr_ = 0;
}
char* wbuf(size_t request, size_t& avail) override {
avail = data_.size() - wptr_;
if (request > avail && rptr_ > 0) {
std::copy(data_.begin() + rptr_, data_.begin() + wptr_, data_.begin());
wptr_ -= rptr_;
rptr_ = 0;
avail = data_.size() - wptr_;
}
if (request > avail && data_.size() < max_size_) {
data_.resize(
std::min(max_size_,
data_.size() + std::max(request - avail,
(max_size_ - base_size_) / 8)));
avail = data_.size() - wptr_;
}
return data_.data() + wptr_;
}
void wcommit(size_t bytes) override {
assert(wptr_ + bytes <= data_.size());
wptr_ += bytes;
}
private:
size_t const base_size_;
size_t const max_size_;
std::vector<char> data_;
size_t rptr_{0};
size_t wptr_{0};
};
class Null : public Buffer {
public:
bool empty() const override {
return true;
}
char const* rbuf(size_t, size_t& avail) override {
avail = 0;
return buf_;
}
void rcommit(size_t bytes) override {
assert(bytes == 0);
}
bool full() const override {
return false;
}
void clear() override {}
char* wbuf(size_t, size_t& avail) override {
avail = sizeof(buf_);
return buf_;
}
void wcommit(size_t) override {
}
private:
char buf_[4096];
};
} // namespace
std::unique_ptr<Buffer> Buffer::fixed(size_t size) {
return std::make_unique<Round>(size);
}
std::unique_ptr<Buffer> Buffer::growing(size_t base_size, size_t max_size) {
return std::make_unique<Growing>(base_size, max_size);
}
std::unique_ptr<Buffer> Buffer::null() {
return std::make_unique<Null>();
}
size_t Buffer::write(void const* data, size_t len) {
assert(data);
if (len == 0)
return 0;
auto* d = reinterpret_cast<char const*>(data);
size_t wrote = 0;
while (true) {
size_t avail;
auto want = len - wrote;
auto* ptr = wbuf(want, avail);
if (avail == 0)
return wrote;
if (avail >= want) {
std::copy_n(d + wrote, want, ptr);
wcommit(want);
return len;
}
std::copy_n(d + wrote, avail, ptr);
wcommit(avail);
wrote += avail;
}
}
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