作者: 韩晨旭 10225101440 李畅 10225102463
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// 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 "db/log_reader.h"
#include "db/log_writer.h"
#include "include/env.h"
#include "util/coding.h"
#include "util/crc32c.h"
#include "util/random.h"
#include "util/testharness.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];
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 {
private:
class StringDest : public WritableFile {
public:
std::string contents_;
virtual Status Close() { return Status::OK(); }
virtual Status Flush() { return Status::OK(); }
virtual Status Sync() { return Status::OK(); }
virtual Status Append(const Slice& slice) {
contents_.append(slice.data(), slice.size());
return Status::OK();
}
};
class StringSource : public SequentialFile {
public:
Slice contents_;
bool force_error_;
bool returned_partial_;
StringSource() : force_error_(false), returned_partial_(false) { }
virtual Status Read(size_t n, Slice* result, char* scratch) {
ASSERT_TRUE(!returned_partial_) << "must not Read() after eof/error";
ASSERT_EQ(kBlockSize, n);
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();
}
};
class ReportCollector : public Reader::Reporter {
public:
size_t dropped_bytes_;
std::string message_;
ReportCollector() : dropped_bytes_(0) { }
virtual void Corruption(size_t bytes, const Status& status) {
dropped_bytes_ += bytes;
message_.append(status.ToString());
}
};
StringDest dest_;
StringSource source_;
ReportCollector report_;
bool reading_;
Writer writer_;
Reader reader_;
public:
LogTest() : reading_(false),
writer_(&dest_),
reader_(&source_, &report_, true/*checksum*/) {
}
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_;
}
// 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";
}
}
};
TEST(LogTest, Empty) {
ASSERT_EQ("EOF", Read());
}
TEST(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(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(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(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(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(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(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(LogTest, ReadError) {
Write("foo");
ForceError();
ASSERT_EQ("EOF", Read());
ASSERT_EQ(kBlockSize, DroppedBytes());
ASSERT_EQ("OK", MatchError("read error"));
}
TEST(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(LogTest, TruncatedTrailingRecord) {
Write("foo");
ShrinkSize(4); // Drop all payload as well as a header byte
ASSERT_EQ("EOF", Read());
ASSERT_EQ(kHeaderSize - 1, DroppedBytes());
ASSERT_EQ("OK", MatchError("truncated record at end of file"));
}
TEST(LogTest, BadLength) {
Write("foo");
ShrinkSize(1);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(kHeaderSize + 2, DroppedBytes());
ASSERT_EQ("OK", MatchError("bad record length"));
}
TEST(LogTest, ChecksumMismatch) {
Write("foo");
IncrementByte(0, 10);
ASSERT_EQ("EOF", Read());
ASSERT_EQ(10, DroppedBytes());
ASSERT_EQ("OK", MatchError("checksum mismatch"));
}
TEST(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(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(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(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(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 int dropped = DroppedBytes();
ASSERT_LE(dropped, 2*kBlockSize + 100);
ASSERT_GE(dropped, 2*kBlockSize);
}
}
}
int main(int argc, char** argv) {
return leveldb::test::RunAllTests();
}