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98 rivejä
2.4 KiB
98 rivejä
2.4 KiB
#include "vlog_reader.h"
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#include "leveldb/env.h"
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#include "util/coding.h"
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namespace leveldb {
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namespace log {
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VlogReader::VlogReader(SequentialFile *file, Reporter* reporter)
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: file_(file),
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file_random_(nullptr),
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reporter_(reporter),
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backing_store_(new char[kBlockSize]),
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buffer_(),
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eof_(false),
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last_record_offset_(0) {}
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VlogReader::VlogReader(RandomAccessFile *file, Reporter* reporter)
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: file_(nullptr),
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file_random_(file),
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reporter_(reporter),
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backing_store_(new char[kBlockSize]),
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buffer_(),
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eof_(false),
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last_record_offset_(0) {}
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VlogReader::~VlogReader() { delete[] backing_store_; }
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bool VlogReader::ReadValue(uint64_t offset, size_t length, Slice *key_value, char *scratch) {
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if (file_random_ == nullptr) {
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return false;
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}
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/* 随机读取一个 RandomAccessFile，使用对应的读接口 Read 函数 */
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Status status = file_random_->Read(offset, length, key_value, scratch);
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if (!status.ok()) {
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return false;
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}
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return true;
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}
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bool VlogReader::ReadRecord(Slice *record, std::string *scratch) {
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if (ReadPhysicalRecord(scratch)) {
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*record = *scratch;
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return true;
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}
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return false;
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}
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uint64_t VlogReader::LastRecordOffset() const {
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return last_record_offset_;
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}
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void VlogReader::ReportCorruption(uint64_t bytes, const Status &reason) {
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if (reporter_ != nullptr) {
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reporter_->Corruption(static_cast<size_t>(bytes), reason);
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}
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}
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bool VlogReader::ReadPhysicalRecord(std::string *result) {
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result->clear();
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buffer_.clear();
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char* tmp_head = new char[vHeaderSize];
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/* 顺序读取一个 SequentialFile，使用对应的读接口 Read 函数 */
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Status status = file_->Read(vHeaderSize, &buffer_, tmp_head);
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if (!status.ok()) {
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buffer_.clear();
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ReportCorruption(kBlockSize, status);
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eof_ = true;
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return false;
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} else if (buffer_.size() < vHeaderSize) {
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eof_ = true;
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}
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if (!eof_) {
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result->assign(buffer_.data(),buffer_.size());
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uint32_t length = DecodeFixed32(buffer_.data());
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buffer_.clear();
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char* tmp = new char[length];
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status = file_->Read(length, &buffer_, tmp);
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if (status.ok() && buffer_.size() == length) {
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*result += buffer_.ToString();
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} else {
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eof_ = true;
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}
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delete [] tmp;
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}
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delete [] tmp_head;
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if (eof_) {
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result->clear();
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return false;
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}
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return true;
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}
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} // namespace log
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} // namespace leveldb
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