add leveldb

lib/leveldb/db/log_test.cc

@@ -0,0 +1,563 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "db/log_reader.h"
+#include "db/log_writer.h"
+#include "leveldb/env.h"
+#include "util/coding.h"
+#include "util/crc32c.h"
+#include "util/random.h"
+
+namespace leveldb {
+namespace log {
+
+// Construct a string of the specified length made out of the supplied
+// partial string.
+static std::string BigString(const std::string& partial_string, size_t n) {
+  std::string result;
+  while (result.size() < n) {
+    result.append(partial_string);
+  }
+  result.resize(n);
+  return result;
+}
+
+// Construct a string from a number
+static std::string NumberString(int n) {
+  char buf[50];
+  std::snprintf(buf, sizeof(buf), "%d.", n);
+  return std::string(buf);
+}
+
+// Return a skewed potentially long string
+static std::string RandomSkewedString(int i, Random* rnd) {
+  return BigString(NumberString(i), rnd->Skewed(17));
+}
+
+class LogTest : public testing::Test {
+ public:
+  LogTest()
+      : reading_(false),
+        writer_(new Writer(&dest_)),
+        reader_(new Reader(&source_, &report_, true /*checksum*/,
+                           0 /*initial_offset*/)) {}
+
+  ~LogTest() {
+    delete writer_;
+    delete reader_;
+  }
+
+  void ReopenForAppend() {
+    delete writer_;
+    writer_ = new Writer(&dest_, dest_.contents_.size());
+  }
+
+  void Write(const std::string& msg) {
+    ASSERT_TRUE(!reading_) << "Write() after starting to read";
+    writer_->AddRecord(Slice(msg));
+  }
+
+  size_t WrittenBytes() const { return dest_.contents_.size(); }
+
+  std::string Read() {
+    if (!reading_) {
+      reading_ = true;
+      source_.contents_ = Slice(dest_.contents_);
+    }
+    std::string scratch;
+    Slice record;
+    if (reader_->ReadRecord(&record, &scratch)) {
+      return record.ToString();
+    } else {
+      return "EOF";
+    }
+  }
+
+  void IncrementByte(int offset, int delta) {
+    dest_.contents_[offset] += delta;
+  }
+
+  void SetByte(int offset, char new_byte) {
+    dest_.contents_[offset] = new_byte;
+  }
+
+  void ShrinkSize(int bytes) {
+    dest_.contents_.resize(dest_.contents_.size() - bytes);
+  }
+
+  void FixChecksum(int header_offset, int len) {
+    // Compute crc of type/len/data
+    uint32_t crc = crc32c::Value(&dest_.contents_[header_offset + 6], 1 + len);
+    crc = crc32c::Mask(crc);
+    EncodeFixed32(&dest_.contents_[header_offset], crc);
+  }
+
+  void ForceError() { source_.force_error_ = true; }
+
+  size_t DroppedBytes() const { return report_.dropped_bytes_; }
+
+  std::string ReportMessage() const { return report_.message_; }
+
+  // Returns OK iff recorded error message contains "msg"
+  std::string MatchError(const std::string& msg) const {
+    if (report_.message_.find(msg) == std::string::npos) {
+      return report_.message_;
+    } else {
+      return "OK";
+    }
+  }
+
+  void WriteInitialOffsetLog() {
+    for (int i = 0; i < num_initial_offset_records_; i++) {
+      std::string record(initial_offset_record_sizes_[i],
+                         static_cast<char>('a' + i));
+      Write(record);
+    }
+  }
+
+  void StartReadingAt(uint64_t initial_offset) {
+    delete reader_;
+    reader_ = new Reader(&source_, &report_, true /*checksum*/, initial_offset);
+  }
+
+  void CheckOffsetPastEndReturnsNoRecords(uint64_t offset_past_end) {
+    WriteInitialOffsetLog();
+    reading_ = true;
+    source_.contents_ = Slice(dest_.contents_);
+    Reader* offset_reader = new Reader(&source_, &report_, true /*checksum*/,
+                                       WrittenBytes() + offset_past_end);
+    Slice record;
+    std::string scratch;
+    ASSERT_TRUE(!offset_reader->ReadRecord(&record, &scratch));
+    delete offset_reader;
+  }
+
+  void CheckInitialOffsetRecord(uint64_t initial_offset,
+                                int expected_record_offset) {
+    WriteInitialOffsetLog();
+    reading_ = true;
+    source_.contents_ = Slice(dest_.contents_);
+    Reader* offset_reader =
+        new Reader(&source_, &report_, true /*checksum*/, initial_offset);
+
+    // Read all records from expected_record_offset through the last one.
+    ASSERT_LT(expected_record_offset, num_initial_offset_records_);
+    for (; expected_record_offset < num_initial_offset_records_;
+         ++expected_record_offset) {
+      Slice record;
+      std::string scratch;
+      ASSERT_TRUE(offset_reader->ReadRecord(&record, &scratch));
+      ASSERT_EQ(initial_offset_record_sizes_[expected_record_offset],
+                record.size());
+      ASSERT_EQ(initial_offset_last_record_offsets_[expected_record_offset],
+                offset_reader->LastRecordOffset());
+      ASSERT_EQ((char)('a' + expected_record_offset), record.data()[0]);
+    }
+    delete offset_reader;
+  }
+
+ private:
+  class StringDest : public WritableFile {
+   public:
+    Status Close() override { return Status::OK(); }
+    Status Flush() override { return Status::OK(); }
+    Status Sync() override { return Status::OK(); }
+    Status Append(const Slice& slice) override {
+      contents_.append(slice.data(), slice.size());
+      return Status::OK();
+    }
+
+    std::string contents_;
+  };
+
+  class StringSource : public SequentialFile {
+   public:
+    StringSource() : force_error_(false), returned_partial_(false) {}
+
+    Status Read(size_t n, Slice* result, char* scratch) override {
+      EXPECT_TRUE(!returned_partial_) << "must not Read() after eof/error";
+
+      if (force_error_) {
+        force_error_ = false;
+        returned_partial_ = true;
+        return Status::Corruption("read error");
+      }
+
+      if (contents_.size() < n) {
+        n = contents_.size();
+        returned_partial_ = true;
+      }
+      *result = Slice(contents_.data(), n);
+      contents_.remove_prefix(n);
+      return Status::OK();
+    }
+
+    Status Skip(uint64_t n) override {
+      if (n > contents_.size()) {
+        contents_.clear();
+        return Status::NotFound("in-memory file skipped past end");
+      }
+
+      contents_.remove_prefix(n);
+
+      return Status::OK();
+    }
+
+    Slice contents_;
+    bool force_error_;
+    bool returned_partial_;
+  };
+
+  class ReportCollector : public Reader::Reporter {
+   public:
+    ReportCollector() : dropped_bytes_(0) {}
+    void Corruption(size_t bytes, const Status& status) override {
+      dropped_bytes_ += bytes;
+      message_.append(status.ToString());
+    }
+
+    size_t dropped_bytes_;
+    std::string message_;
+  };
+
+  // Record metadata for testing initial offset functionality
+  static size_t initial_offset_record_sizes_[];
+  static uint64_t initial_offset_last_record_offsets_[];
+  static int num_initial_offset_records_;
+
+  StringDest dest_;
+  StringSource source_;
+  ReportCollector report_;
+  bool reading_;
+  Writer* writer_;
+  Reader* reader_;
+};
+
+size_t LogTest::initial_offset_record_sizes_[] = {
+    10000,  // Two sizable records in first block
+    10000,
+    2 * log::kBlockSize - 1000,  // Span three blocks
+    1,
+    13716,                          // Consume all but two bytes of block 3.
+    log::kBlockSize - kHeaderSize,  // Consume the entirety of block 4.
+};
+
+uint64_t LogTest::initial_offset_last_record_offsets_[] = {
+    0,
+    kHeaderSize + 10000,
+    2 * (kHeaderSize + 10000),
+    2 * (kHeaderSize + 10000) + (2 * log::kBlockSize - 1000) + 3 * kHeaderSize,
+    2 * (kHeaderSize + 10000) + (2 * log::kBlockSize - 1000) + 3 * kHeaderSize +
+        kHeaderSize + 1,
+    3 * log::kBlockSize,
+};
+
+// LogTest::initial_offset_last_record_offsets_ must be defined before this.
+int LogTest::num_initial_offset_records_ =
+    sizeof(LogTest::initial_offset_last_record_offsets_) / sizeof(uint64_t);
+
+TEST_F(LogTest, Empty) { ASSERT_EQ("EOF", Read()); }
+
+TEST_F(LogTest, ReadWrite) {
+  Write("foo");
+  Write("bar");
+  Write("");
+  Write("xxxx");
+  ASSERT_EQ("foo", Read());
+  ASSERT_EQ("bar", Read());
+  ASSERT_EQ("", Read());
+  ASSERT_EQ("xxxx", Read());
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ("EOF", Read());  // Make sure reads at eof work
+}
+
+TEST_F(LogTest, ManyBlocks) {
+  for (int i = 0; i < 100000; i++) {
+    Write(NumberString(i));
+  }
+  for (int i = 0; i < 100000; i++) {
+    ASSERT_EQ(NumberString(i), Read());
+  }
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, Fragmentation) {
+  Write("small");
+  Write(BigString("medium", 50000));
+  Write(BigString("large", 100000));
+  ASSERT_EQ("small", Read());
+  ASSERT_EQ(BigString("medium", 50000), Read());
+  ASSERT_EQ(BigString("large", 100000), Read());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, MarginalTrailer) {
+  // Make a trailer that is exactly the same length as an empty record.
+  const int n = kBlockSize - 2 * kHeaderSize;
+  Write(BigString("foo", n));
+  ASSERT_EQ(kBlockSize - kHeaderSize, WrittenBytes());
+  Write("");
+  Write("bar");
+  ASSERT_EQ(BigString("foo", n), Read());
+  ASSERT_EQ("", Read());
+  ASSERT_EQ("bar", Read());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, MarginalTrailer2) {
+  // Make a trailer that is exactly the same length as an empty record.
+  const int n = kBlockSize - 2 * kHeaderSize;
+  Write(BigString("foo", n));
+  ASSERT_EQ(kBlockSize - kHeaderSize, WrittenBytes());
+  Write("bar");
+  ASSERT_EQ(BigString("foo", n), Read());
+  ASSERT_EQ("bar", Read());
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(0, DroppedBytes());
+  ASSERT_EQ("", ReportMessage());
+}
+
+TEST_F(LogTest, ShortTrailer) {
+  const int n = kBlockSize - 2 * kHeaderSize + 4;
+  Write(BigString("foo", n));
+  ASSERT_EQ(kBlockSize - kHeaderSize + 4, WrittenBytes());
+  Write("");
+  Write("bar");
+  ASSERT_EQ(BigString("foo", n), Read());
+  ASSERT_EQ("", Read());
+  ASSERT_EQ("bar", Read());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, AlignedEof) {
+  const int n = kBlockSize - 2 * kHeaderSize + 4;
+  Write(BigString("foo", n));
+  ASSERT_EQ(kBlockSize - kHeaderSize + 4, WrittenBytes());
+  ASSERT_EQ(BigString("foo", n), Read());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, OpenForAppend) {
+  Write("hello");
+  ReopenForAppend();
+  Write("world");
+  ASSERT_EQ("hello", Read());
+  ASSERT_EQ("world", Read());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, RandomRead) {
+  const int N = 500;
+  Random write_rnd(301);
+  for (int i = 0; i < N; i++) {
+    Write(RandomSkewedString(i, &write_rnd));
+  }
+  Random read_rnd(301);
+  for (int i = 0; i < N; i++) {
+    ASSERT_EQ(RandomSkewedString(i, &read_rnd), Read());
+  }
+  ASSERT_EQ("EOF", Read());
+}
+
+// Tests of all the error paths in log_reader.cc follow:
+
+TEST_F(LogTest, ReadError) {
+  Write("foo");
+  ForceError();
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(kBlockSize, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("read error"));
+}
+
+TEST_F(LogTest, BadRecordType) {
+  Write("foo");
+  // Type is stored in header[6]
+  IncrementByte(6, 100);
+  FixChecksum(0, 3);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(3, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("unknown record type"));
+}
+
+TEST_F(LogTest, TruncatedTrailingRecordIsIgnored) {
+  Write("foo");
+  ShrinkSize(4);  // Drop all payload as well as a header byte
+  ASSERT_EQ("EOF", Read());
+  // Truncated last record is ignored, not treated as an error.
+  ASSERT_EQ(0, DroppedBytes());
+  ASSERT_EQ("", ReportMessage());
+}
+
+TEST_F(LogTest, BadLength) {
+  const int kPayloadSize = kBlockSize - kHeaderSize;
+  Write(BigString("bar", kPayloadSize));
+  Write("foo");
+  // Least significant size byte is stored in header[4].
+  IncrementByte(4, 1);
+  ASSERT_EQ("foo", Read());
+  ASSERT_EQ(kBlockSize, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("bad record length"));
+}
+
+TEST_F(LogTest, BadLengthAtEndIsIgnored) {
+  Write("foo");
+  ShrinkSize(1);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(0, DroppedBytes());
+  ASSERT_EQ("", ReportMessage());
+}
+
+TEST_F(LogTest, ChecksumMismatch) {
+  Write("foo");
+  IncrementByte(0, 10);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(10, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("checksum mismatch"));
+}
+
+TEST_F(LogTest, UnexpectedMiddleType) {
+  Write("foo");
+  SetByte(6, kMiddleType);
+  FixChecksum(0, 3);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(3, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("missing start"));
+}
+
+TEST_F(LogTest, UnexpectedLastType) {
+  Write("foo");
+  SetByte(6, kLastType);
+  FixChecksum(0, 3);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(3, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("missing start"));
+}
+
+TEST_F(LogTest, UnexpectedFullType) {
+  Write("foo");
+  Write("bar");
+  SetByte(6, kFirstType);
+  FixChecksum(0, 3);
+  ASSERT_EQ("bar", Read());
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(3, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("partial record without end"));
+}
+
+TEST_F(LogTest, UnexpectedFirstType) {
+  Write("foo");
+  Write(BigString("bar", 100000));
+  SetByte(6, kFirstType);
+  FixChecksum(0, 3);
+  ASSERT_EQ(BigString("bar", 100000), Read());
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ(3, DroppedBytes());
+  ASSERT_EQ("OK", MatchError("partial record without end"));
+}
+
+TEST_F(LogTest, MissingLastIsIgnored) {
+  Write(BigString("bar", kBlockSize));
+  // Remove the LAST block, including header.
+  ShrinkSize(14);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ("", ReportMessage());
+  ASSERT_EQ(0, DroppedBytes());
+}
+
+TEST_F(LogTest, PartialLastIsIgnored) {
+  Write(BigString("bar", kBlockSize));
+  // Cause a bad record length in the LAST block.
+  ShrinkSize(1);
+  ASSERT_EQ("EOF", Read());
+  ASSERT_EQ("", ReportMessage());
+  ASSERT_EQ(0, DroppedBytes());
+}
+
+TEST_F(LogTest, SkipIntoMultiRecord) {
+  // Consider a fragmented record:
+  //    first(R1), middle(R1), last(R1), first(R2)
+  // If initial_offset points to a record after first(R1) but before first(R2)
+  // incomplete fragment errors are not actual errors, and must be suppressed
+  // until a new first or full record is encountered.
+  Write(BigString("foo", 3 * kBlockSize));
+  Write("correct");
+  StartReadingAt(kBlockSize);
+
+  ASSERT_EQ("correct", Read());
+  ASSERT_EQ("", ReportMessage());
+  ASSERT_EQ(0, DroppedBytes());
+  ASSERT_EQ("EOF", Read());
+}
+
+TEST_F(LogTest, ErrorJoinsRecords) {
+  // Consider two fragmented records:
+  //    first(R1) last(R1) first(R2) last(R2)
+  // where the middle two fragments disappear.  We do not want
+  // first(R1),last(R2) to get joined and returned as a valid record.
+
+  // Write records that span two blocks
+  Write(BigString("foo", kBlockSize));
+  Write(BigString("bar", kBlockSize));
+  Write("correct");
+
+  // Wipe the middle block
+  for (int offset = kBlockSize; offset < 2 * kBlockSize; offset++) {
+    SetByte(offset, 'x');
+  }
+
+  ASSERT_EQ("correct", Read());
+  ASSERT_EQ("EOF", Read());
+  const size_t dropped = DroppedBytes();
+  ASSERT_LE(dropped, 2 * kBlockSize + 100);
+  ASSERT_GE(dropped, 2 * kBlockSize);
+}
+
+TEST_F(LogTest, ReadStart) { CheckInitialOffsetRecord(0, 0); }
+
+TEST_F(LogTest, ReadSecondOneOff) { CheckInitialOffsetRecord(1, 1); }
+
+TEST_F(LogTest, ReadSecondTenThousand) { CheckInitialOffsetRecord(10000, 1); }
+
+TEST_F(LogTest, ReadSecondStart) { CheckInitialOffsetRecord(10007, 1); }
+
+TEST_F(LogTest, ReadThirdOneOff) { CheckInitialOffsetRecord(10008, 2); }
+
+TEST_F(LogTest, ReadThirdStart) { CheckInitialOffsetRecord(20014, 2); }
+
+TEST_F(LogTest, ReadFourthOneOff) { CheckInitialOffsetRecord(20015, 3); }
+
+TEST_F(LogTest, ReadFourthFirstBlockTrailer) {
+  CheckInitialOffsetRecord(log::kBlockSize - 4, 3);
+}
+
+TEST_F(LogTest, ReadFourthMiddleBlock) {
+  CheckInitialOffsetRecord(log::kBlockSize + 1, 3);
+}
+
+TEST_F(LogTest, ReadFourthLastBlock) {
+  CheckInitialOffsetRecord(2 * log::kBlockSize + 1, 3);
+}
+
+TEST_F(LogTest, ReadFourthStart) {
+  CheckInitialOffsetRecord(
+      2 * (kHeaderSize + 1000) + (2 * log::kBlockSize - 1000) + 3 * kHeaderSize,
+      3);
+}
+
+TEST_F(LogTest, ReadInitialOffsetIntoBlockPadding) {
+  CheckInitialOffsetRecord(3 * log::kBlockSize - 3, 5);
+}
+
+TEST_F(LogTest, ReadEnd) { CheckOffsetPastEndReturnsNoRecords(0); }
+
+TEST_F(LogTest, ReadPastEnd) { CheckOffsetPastEndReturnsNoRecords(5); }
+
+}  // namespace log
+}  // namespace leveldb
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}