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writer.cc
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writer.cc
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#include <array>
#include <cstring>
#include <fstream>
#include <limits>
#include <sstream>
#include <iostream>
#include "./portable_endian.h"
#include "./internal.h"
#include "./recordio.h"
namespace grail {
namespace recordio {
Writer::~Writer() {}
WriterIndexer::~WriterIndexer() {}
namespace {
class FileCloser {
public:
bool Close() {
out.close();
return out.good();
}
std::ofstream out;
};
// class BaseWriter implements a raw writer w/o any transformation.
class BaseWriter {
public:
explicit BaseWriter(std::ostream* out, internal::Magic magic,
std::unique_ptr<FileCloser> cleanup,
std::unique_ptr<WriterIndexer> indexer)
: out_(out),
initial_pos_(out->tellp()),
magic_(magic),
cleanup_(std::move(cleanup)),
indexer_(std::move(indexer)) {}
// Write accepts two spans and writes them both, contiguously, into a single
// record. It accepts two just to avoid an extra data copy in the packed
// writer.
bool Write(ByteSpan one, ByteSpan two) {
uint64_t block_start = static_cast<uint64_t>(out_->tellp() - initial_pos_);
if (!WriteHeader(one.size() + two.size())) return false;
out_->write(reinterpret_cast<const char*>(one.data()), one.size());
if (!out_->good()) {
SetError(std::string("Failed to write data part 1: ") +
std::strerror(errno));
return false;
}
if (two.size() > 0) {
out_->write(reinterpret_cast<const char*>(two.data()), two.size());
if (!out_->good()) {
SetError(std::string("Failed to write data part 2: ") +
std::strerror(errno));
return false;
}
}
if (indexer_ != nullptr) {
std::string error = indexer_->IndexBlock(block_start);
if (!error.empty()) {
SetError(std::string("Indexer error: ") + error);
return false;
}
}
return true;
}
bool Close() {
if (cleanup_ != nullptr && !cleanup_->Close()) {
SetError(std::string("Failed to close output file: ") +
std::strerror(errno));
return false;
}
return true;
}
Error GetError() { return err_; }
void SetError(const std::string& err) {
if (err_.empty()) {
err_ = err;
}
}
private:
bool WriteLEUint64(uint64_t v) {
uint64_t le = htole64(v);
out_->write(reinterpret_cast<const char*>(&le), sizeof le);
return out_->good();
}
bool WriteLEUint32(uint32_t v) {
uint32_t le = htole64(v);
out_->write(reinterpret_cast<const char*>(&le), sizeof le);
return out_->good();
}
// Write the header for this block to out_, where size is the number of bytes
// of data that will be written in the block.
bool WriteHeader(uint64_t size) {
out_->write(reinterpret_cast<const char*>(magic_.data()), magic_.size());
if (!out_->good()) {
SetError("Failed to write header magic");
return false;
}
WriteLEUint64(size);
if (!out_->good()) {
SetError("Failed to write header size");
return false;
}
uint64_t size_le = htole64(size);
uint32_t size_crc32 =
internal::Crc32(reinterpret_cast<uint8_t*>(&size_le), sizeof size_le);
WriteLEUint32(size_crc32);
if (!out_->good()) {
SetError("Failed to write header size checksum");
return false;
}
return true;
}
std::ostream* const out_;
const std::streampos initial_pos_;
const internal::Magic magic_;
const std::unique_ptr<FileCloser> cleanup_;
std::string err_;
const std::unique_ptr<WriterIndexer> indexer_;
};
// Implementation of an unpacked writer.
class UnpackedWriterImpl : public Writer {
public:
explicit UnpackedWriterImpl(std::ostream* out,
std::unique_ptr<Transformer> transformer,
std::unique_ptr<WriterIndexer> indexer,
std::unique_ptr<FileCloser> cleanup)
: r_(out, internal::MagicUnpacked, std::move(cleanup),
std::move(indexer)),
transformer_(std::move(transformer)) {}
bool Write(ByteSpan in) {
if (transformer_ != nullptr) {
IoVec iov(&in, 1);
IoVec out;
Error err = transformer_->Transform(iov, &out);
if (!err.empty()) {
r_.SetError(err);
return false;
}
if (out.size() != 1) {
std::cerr << "TODO: Transformer returned multiple iovec\n";
abort();
}
in = out[0];
}
return r_.Write(in, ByteSpan{nullptr, 0});
}
bool Close() { return r_.Close(); }
Error GetError() { return r_.GetError(); }
private:
BaseWriter r_; // Underlying unpacked writer.
const std::unique_ptr<Transformer> transformer_;
};
class PackedHeaderBuilder {
public:
PackedHeaderBuilder() : items_count_(0) {}
bool AddItemSize(uint32_t size) {
if (items_count_ == std::numeric_limits<uint32_t>::max()) {
return false;
}
items_count_++;
AppendUVarint(&sizes_, size);
return true;
}
int64_t items_count() { return items_count_; }
void AppendHeader(std::vector<uint8_t>* buf) {
// We need to compute the CRC32 of items count and all of the item sizes.
// To avoid allocating a temporary buffer, we copy them into the output
// buffer first, compute the checksum, then write it into place.
auto checksum_offset = buf->size();
buf->insert(buf->end(), sizeof(uint32_t), static_cast<uint8_t>(0));
auto varints_offset = buf->size();
AppendUVarint(buf, items_count_);
buf->insert(buf->end(), sizes_.cbegin(), sizes_.cend());
uint32_t checksum = internal::Crc32(buf->data() + varints_offset,
buf->size() - varints_offset);
WriteLEUint32At(buf, checksum_offset, checksum);
}
void Clear() {
items_count_ = 0;
sizes_.clear();
}
private:
void AppendUVarint(std::vector<uint8_t>* buf, uint64_t v) {
while (v >= 0x80) {
buf->push_back(static_cast<uint8_t>(v) | 0x80);
v >>= 7;
}
buf->push_back(static_cast<uint8_t>(v));
}
void WriteLEUint32At(std::vector<uint8_t>* buf, size_t offset, uint32_t v) {
uint32_t le = htole64(v);
std::copy(reinterpret_cast<const uint8_t*>(&le),
reinterpret_cast<const uint8_t*>(&le) + sizeof le,
buf->begin() + offset);
}
int64_t items_count_;
std::vector<uint8_t> sizes_;
};
class PackedWriterImpl : public Writer {
public:
explicit PackedWriterImpl(std::ostream* out,
std::unique_ptr<Transformer> transformer,
std::unique_ptr<WriterIndexer> indexer,
std::unique_ptr<FileCloser> cleanup,
const uint32_t max_packed_items,
const uint32_t max_packed_bytes)
: r_(out, internal::MagicPacked, std::move(cleanup), std::move(indexer)),
transformer_(std::move(transformer)),
max_packed_items_(max_packed_items),
max_packed_bytes_(max_packed_bytes) {}
bool Write(ByteSpan item) {
if (static_cast<int>(item.size()) > max_packed_bytes_) {
r_.SetError("Item size exceeds block size");
return false;
}
if ((header_builder_.items_count() + 1) > max_packed_items_ ||
static_cast<int>(buffered_items_.size() + item.size()) >
max_packed_bytes_) {
if (!Flush()) {
return false;
}
}
if (!header_builder_.AddItemSize(item.size())) {
r_.SetError("Could not add new item");
return false;
}
buffered_items_.insert(buffered_items_.end(), item.begin(), item.end());
return true;
}
bool Close() {
if (!Flush()) {
return false;
}
return r_.Close();
}
Error GetError() { return r_.GetError(); }
private:
bool Flush() {
std::vector<uint8_t> header;
header_builder_.AppendHeader(&header);
ByteSpan transformed = {buffered_items_.data(), buffered_items_.size()};
if (transformer_ != nullptr) {
IoVec iov(&transformed, 1);
IoVec out;
internal::Error err = transformer_->Transform(iov, &out);
if (!err.empty()) {
r_.SetError(err);
return false;
}
if (out.size() != 1) {
std::cerr << "TODO: Transformer returned multiple iovec\n";
abort();
}
transformed = out[0];
}
if (!r_.Write(ByteSpan{header.data(), header.size()}, transformed)) {
return false;
}
header_builder_.Clear();
buffered_items_.clear();
return true;
}
BaseWriter r_; // Underlying unpacked writer.
const std::unique_ptr<Transformer> transformer_;
const int64_t max_packed_items_;
const int64_t max_packed_bytes_;
PackedHeaderBuilder header_builder_;
std::vector<uint8_t> buffered_items_;
};
} // namespace
WriterOpts DefaultWriterOpts(const std::string& path) {
WriterOpts r;
if (internal::HasSuffix(path, ".grail-rio")) {
return r;
}
if (internal::HasSuffix(path, ".grail-rpk")) {
r.packed = true;
return r;
}
if (internal::HasSuffix(path, ".grail-rpk-gz")) {
r.packed = true;
r.transformer = FlateTransformer();
return r;
}
// Punt. The writer will cause an error.
return r;
}
std::unique_ptr<Writer> NewWriter(std::ostream* out, WriterOpts opts) {
if (opts.packed) {
return std::unique_ptr<Writer>(new PackedWriterImpl(
out, std::move(opts.transformer), std::move(opts.indexer), nullptr,
opts.max_packed_items, opts.max_packed_bytes));
} else {
return std::unique_ptr<Writer>(new UnpackedWriterImpl(
out, std::move(opts.transformer), std::move(opts.indexer), nullptr));
}
}
std::unique_ptr<Writer> NewWriter(const std::string& path) {
auto opts = DefaultWriterOpts(path);
std::unique_ptr<FileCloser> c(new FileCloser);
c->out.open(path.c_str());
if (opts.packed) {
return std::unique_ptr<Writer>(new PackedWriterImpl(
&c->out, std::move(opts.transformer), std::move(opts.indexer),
std::move(c), opts.max_packed_items, opts.max_packed_bytes));
} else {
return std::unique_ptr<Writer>(
new UnpackedWriterImpl(&c->out, std::move(opts.transformer),
std::move(opts.indexer), std::move(c)));
}
}
} // namespace recordio
} // namespace grail