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blob_file_iterator.cc
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/
blob_file_iterator.cc
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#include "blob_file_iterator.h"
#include "util.h"
#include "util/crc32c.h"
namespace rocksdb {
namespace titandb {
BlobFileIterator::BlobFileIterator(
std::unique_ptr<RandomAccessFileReader>&& file, uint64_t file_name,
uint64_t file_size, const TitanCFOptions& titan_cf_options)
: file_(std::move(file)),
file_number_(file_name),
file_size_(file_size),
titan_cf_options_(titan_cf_options) {}
BlobFileIterator::~BlobFileIterator() {}
bool BlobFileIterator::Init() {
Slice slice;
char header_buf[BlobFileHeader::kEncodedLength];
status_ = file_->Read(0, BlobFileHeader::kEncodedLength, &slice, header_buf);
if (!status_.ok()) {
return false;
}
BlobFileHeader blob_file_header;
status_ = blob_file_header.DecodeFrom(&slice);
if (!status_.ok()) {
return false;
}
char footer_buf[BlobFileFooter::kEncodedLength];
status_ = file_->Read(file_size_ - BlobFileFooter::kEncodedLength,
BlobFileFooter::kEncodedLength, &slice, footer_buf);
if (!status_.ok()) return false;
BlobFileFooter blob_file_footer;
status_ = blob_file_footer.DecodeFrom(&slice);
end_of_blob_record_ = file_size_ - BlobFileFooter::kEncodedLength -
blob_file_footer.meta_index_handle.size();
assert(end_of_blob_record_ > BlobFileHeader::kEncodedLength);
init_ = true;
return true;
}
void BlobFileIterator::SeekToFirst() {
if (!init_ && !Init()) return;
status_ = Status::OK();
iterate_offset_ = BlobFileHeader::kEncodedLength;
PrefetchAndGet();
}
bool BlobFileIterator::Valid() const { return valid_ && status().ok(); }
void BlobFileIterator::Next() {
assert(init_);
PrefetchAndGet();
}
Slice BlobFileIterator::key() const { return cur_blob_record_.key; }
Slice BlobFileIterator::value() const { return cur_blob_record_.value; }
void BlobFileIterator::IterateForPrev(uint64_t offset) {
if (!init_ && !Init()) return;
status_ = Status::OK();
if (offset >= end_of_blob_record_) {
iterate_offset_ = offset;
status_ = Status::InvalidArgument("Out of bound");
return;
}
uint64_t total_length = 0;
FixedSlice<kBlobHeaderSize> header_buffer;
iterate_offset_ = BlobFileHeader::kEncodedLength;
for (; iterate_offset_ < offset; iterate_offset_ += total_length) {
status_ = file_->Read(iterate_offset_, kBlobHeaderSize, &header_buffer,
header_buffer.get());
if (!status_.ok()) return;
status_ = decoder_.DecodeHeader(&header_buffer);
if (!status_.ok()) return;
total_length = kBlobHeaderSize + decoder_.GetRecordSize();
}
if (iterate_offset_ > offset) iterate_offset_ -= total_length;
valid_ = false;
}
void BlobFileIterator::GetBlobRecord() {
FixedSlice<kBlobHeaderSize> header_buffer;
status_ = file_->Read(iterate_offset_, kBlobHeaderSize, &header_buffer,
header_buffer.get());
if (!status_.ok()) return;
status_ = decoder_.DecodeHeader(&header_buffer);
if (!status_.ok()) return;
Slice record_slice;
auto record_size = decoder_.GetRecordSize();
buffer_.reserve(record_size);
status_ = file_->Read(iterate_offset_ + kBlobHeaderSize, record_size,
&record_slice, buffer_.data());
if (status_.ok()) {
status_ =
decoder_.DecodeRecord(&record_slice, &cur_blob_record_, &uncompressed_);
}
if (!status_.ok()) return;
cur_record_offset_ = iterate_offset_;
cur_record_size_ = kBlobHeaderSize + record_size;
iterate_offset_ += cur_record_size_;
valid_ = true;
}
void BlobFileIterator::PrefetchAndGet() {
if (iterate_offset_ >= end_of_blob_record_) {
valid_ = false;
return;
}
if (readahead_begin_offset_ > iterate_offset_ ||
readahead_end_offset_ < iterate_offset_) {
// alignment
readahead_begin_offset_ =
iterate_offset_ - (iterate_offset_ & (kDefaultPageSize - 1));
readahead_end_offset_ = readahead_begin_offset_;
readahead_size_ = kMinReadaheadSize;
}
auto min_blob_size =
iterate_offset_ + kBlobHeaderSize + titan_cf_options_.min_blob_size;
if (readahead_end_offset_ <= min_blob_size) {
while (readahead_end_offset_ + readahead_size_ <= min_blob_size &&
readahead_size_ < kMaxReadaheadSize)
readahead_size_ <<= 1;
file_->Prefetch(readahead_end_offset_, readahead_size_);
readahead_end_offset_ += readahead_size_;
readahead_size_ = std::min(kMaxReadaheadSize, readahead_size_ << 1);
}
GetBlobRecord();
if (readahead_end_offset_ < iterate_offset_) {
readahead_end_offset_ = iterate_offset_;
}
}
BlobFileMergeIterator::BlobFileMergeIterator(
std::vector<std::unique_ptr<BlobFileIterator>>&& blob_file_iterators)
: blob_file_iterators_(std::move(blob_file_iterators)) {}
bool BlobFileMergeIterator::Valid() const {
if (current_ == nullptr) return false;
if (!status().ok()) return false;
return current_->Valid() && current_->status().ok();
}
void BlobFileMergeIterator::SeekToFirst() {
for (auto& iter : blob_file_iterators_) {
iter->SeekToFirst();
if (iter->status().ok() && iter->Valid()) min_heap_.push(iter.get());
}
if (!min_heap_.empty()) {
current_ = min_heap_.top();
min_heap_.pop();
} else {
status_ = Status::Aborted("No iterator is valid");
}
}
void BlobFileMergeIterator::Next() {
assert(current_ != nullptr);
current_->Next();
if (current_->status().ok() && current_->Valid()) min_heap_.push(current_);
current_ = min_heap_.top();
min_heap_.pop();
}
Slice BlobFileMergeIterator::key() const {
assert(current_ != nullptr);
return current_->key();
}
Slice BlobFileMergeIterator::value() const {
assert(current_ != nullptr);
return current_->value();
}
} // namespace titandb
} // namespace rocksdb