5830c699f2
When we recycle log files, we need to mix the log number into the CRC for each record. Note that for logs that don't get recycled (like the manifest), we always pass a log_number of 0 and false. Signed-off-by: Sage Weil <sage@redhat.com>
113 lines
3.3 KiB
C++
113 lines
3.3 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "db/log_writer.h"
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#include <stdint.h>
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#include "rocksdb/env.h"
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#include "util/coding.h"
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#include "util/crc32c.h"
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#include "util/file_reader_writer.h"
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namespace rocksdb {
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namespace log {
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Writer::Writer(unique_ptr<WritableFileWriter>&& dest,
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uint64_t log_number, bool recycle_log_files)
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: dest_(std::move(dest)),
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block_offset_(0),
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log_number_(log_number),
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recycle_log_files_(recycle_log_files) {
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for (int i = 0; i <= kMaxRecordType; i++) {
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char t = static_cast<char>(i);
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type_crc_[i] = crc32c::Value(&t, 1);
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}
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}
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Writer::~Writer() {
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}
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Status Writer::AddRecord(const Slice& slice) {
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const char* ptr = slice.data();
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size_t left = slice.size();
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// Fragment the record if necessary and emit it. Note that if slice
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// is empty, we still want to iterate once to emit a single
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// zero-length record
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Status s;
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bool begin = true;
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do {
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const int leftover = kBlockSize - block_offset_;
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assert(leftover >= 0);
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if (leftover < kHeaderSize) {
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// Switch to a new block
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if (leftover > 0) {
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// Fill the trailer (literal below relies on kHeaderSize being 7)
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assert(kHeaderSize == 7);
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dest_->Append(Slice("\x00\x00\x00\x00\x00\x00", leftover));
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}
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block_offset_ = 0;
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}
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// Invariant: we never leave < kHeaderSize bytes in a block.
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assert(static_cast<int>(kBlockSize) - block_offset_ >= kHeaderSize);
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const size_t avail = kBlockSize - block_offset_ - kHeaderSize;
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const size_t fragment_length = (left < avail) ? left : avail;
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RecordType type;
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const bool end = (left == fragment_length);
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if (begin && end) {
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type = kFullType;
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} else if (begin) {
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type = kFirstType;
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} else if (end) {
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type = kLastType;
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} else {
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type = kMiddleType;
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}
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s = EmitPhysicalRecord(type, ptr, fragment_length);
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ptr += fragment_length;
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left -= fragment_length;
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begin = false;
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} while (s.ok() && left > 0);
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return s;
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}
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Status Writer::EmitPhysicalRecord(RecordType t, const char* ptr, size_t n) {
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assert(n <= 0xffff); // Must fit in two bytes
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assert(block_offset_ + kHeaderSize + n <= kBlockSize);
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// Format the header
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char buf[kHeaderSize];
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buf[4] = static_cast<char>(n & 0xff);
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buf[5] = static_cast<char>(n >> 8);
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buf[6] = static_cast<char>(t);
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// Compute the crc of the record type and the payload.
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uint32_t crc = crc32c::Extend(type_crc_[t], ptr, n);
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crc = crc32c::Mask(crc); // Adjust for storage
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EncodeFixed32(buf, crc);
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// Write the header and the payload
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Status s = dest_->Append(Slice(buf, kHeaderSize));
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if (s.ok()) {
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s = dest_->Append(Slice(ptr, n));
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if (s.ok()) {
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s = dest_->Flush();
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}
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}
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block_offset_ += kHeaderSize + n;
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return s;
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}
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} // namespace log
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} // namespace rocksdb
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