Revision 346d1069c3031468cf5cb06299f018a873c9fb33 authored by Daniel Black on 26 June 2018, 05:42:35 UTC, committed by Facebook Github Bot on 26 June 2018, 05:58:19 UTC
Summary: Pinned the alignment of StatisticsData to the cacheline size rather than just extending its size (which could go over two cache lines)if unaligned in allocation. Avoid compile errors in the process as per individual commit messages. strengthen static_assert to CACHELINE rather than the highest common multiple. Closes https://github.com/facebook/rocksdb/pull/4036 Differential Revision: D8582844 Pulled By: yiwu-arbug fbshipit-source-id: 363c37029f28e6093e06c60b987bca9aa204bc71
1 parent 6d454d7
log_reader.h
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <memory>
#include <stdint.h>
#include "db/log_format.h"
#include "rocksdb/slice.h"
#include "rocksdb/status.h"
#include "rocksdb/options.h"
namespace rocksdb {
class SequentialFileReader;
class Logger;
using std::unique_ptr;
namespace log {
/**
* Reader is a general purpose log stream reader implementation. The actual job
* of reading from the device is implemented by the SequentialFile interface.
*
* Please see Writer for details on the file and record layout.
*/
class Reader {
public:
// Interface for reporting errors.
class Reporter {
public:
virtual ~Reporter();
// Some corruption was detected. "size" is the approximate number
// of bytes dropped due to the corruption.
virtual void Corruption(size_t bytes, const Status& status) = 0;
};
// Create a reader that will return log records from "*file".
// "*file" must remain live while this Reader is in use.
//
// If "reporter" is non-nullptr, it is notified whenever some data is
// dropped due to a detected corruption. "*reporter" must remain
// live while this Reader is in use.
//
// If "checksum" is true, verify checksums if available.
//
// The Reader will start reading at the first record located at physical
// position >= initial_offset within the file.
Reader(std::shared_ptr<Logger> info_log,
// @lint-ignore TXT2 T25377293 Grandfathered in
unique_ptr<SequentialFileReader>&& file,
Reporter* reporter, bool checksum, uint64_t initial_offset,
uint64_t log_num);
~Reader();
// Read the next record into *record. Returns true if read
// successfully, false if we hit end of the input. May use
// "*scratch" as temporary storage. The contents filled in *record
// will only be valid until the next mutating operation on this
// reader or the next mutation to *scratch.
bool ReadRecord(Slice* record, std::string* scratch,
WALRecoveryMode wal_recovery_mode =
WALRecoveryMode::kTolerateCorruptedTailRecords);
// Returns the physical offset of the last record returned by ReadRecord.
//
// Undefined before the first call to ReadRecord.
uint64_t LastRecordOffset();
// returns true if the reader has encountered an eof condition.
bool IsEOF() {
return eof_;
}
// when we know more data has been written to the file. we can use this
// function to force the reader to look again in the file.
// Also aligns the file position indicator to the start of the next block
// by reading the rest of the data from the EOF position to the end of the
// block that was partially read.
void UnmarkEOF();
SequentialFileReader* file() { return file_.get(); }
private:
std::shared_ptr<Logger> info_log_;
const unique_ptr<SequentialFileReader> file_;
Reporter* const reporter_;
bool const checksum_;
char* const backing_store_;
Slice buffer_;
bool eof_; // Last Read() indicated EOF by returning < kBlockSize
bool read_error_; // Error occurred while reading from file
// Offset of the file position indicator within the last block when an
// EOF was detected.
size_t eof_offset_;
// Offset of the last record returned by ReadRecord.
uint64_t last_record_offset_;
// Offset of the first location past the end of buffer_.
uint64_t end_of_buffer_offset_;
// Offset at which to start looking for the first record to return
uint64_t const initial_offset_;
// which log number this is
uint64_t const log_number_;
// Whether this is a recycled log file
bool recycled_;
// Extend record types with the following special values
enum {
kEof = kMaxRecordType + 1,
// Returned whenever we find an invalid physical record.
// Currently there are three situations in which this happens:
// * The record has an invalid CRC (ReadPhysicalRecord reports a drop)
// * The record is a 0-length record (No drop is reported)
// * The record is below constructor's initial_offset (No drop is reported)
kBadRecord = kMaxRecordType + 2,
// Returned when we fail to read a valid header.
kBadHeader = kMaxRecordType + 3,
// Returned when we read an old record from a previous user of the log.
kOldRecord = kMaxRecordType + 4,
// Returned when we get a bad record length
kBadRecordLen = kMaxRecordType + 5,
// Returned when we get a bad record checksum
kBadRecordChecksum = kMaxRecordType + 6,
};
// Skips all blocks that are completely before "initial_offset_".
//
// Returns true on success. Handles reporting.
bool SkipToInitialBlock();
// Return type, or one of the preceding special values
unsigned int ReadPhysicalRecord(Slice* result, size_t* drop_size);
// Read some more
bool ReadMore(size_t* drop_size, int *error);
// Reports dropped bytes to the reporter.
// buffer_ must be updated to remove the dropped bytes prior to invocation.
void ReportCorruption(size_t bytes, const char* reason);
void ReportDrop(size_t bytes, const Status& reason);
// No copying allowed
Reader(const Reader&);
void operator=(const Reader&);
};
} // namespace log
} // namespace rocksdb
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