Fix issue 474: a race between the f*_unlocked() STDIO calls in
env_posix.cc and concurrent application calls to fflush(NULL). The fix is to avoid using stdio in env_posix.cc but add our own buffering where we need it. Added a test to reproduce the bug. Added a test for Env reads/writes. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=170738066
This commit is contained in:
sanjay
Victor Costan
parent
bcd9a8ea4a
commit
7e12c00ecf
@ -25,6 +25,13 @@ static std::string RandomString(Random* rnd, int len) {
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return r;
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}
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static std::string RandomKey(Random* rnd) {
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int len = (rnd->OneIn(3)
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? 1 // Short sometimes to encourage collisions
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: (rnd->OneIn(100) ? rnd->Skewed(10) : rnd->Uniform(10)));
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return test::RandomKey(rnd, len);
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}
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namespace {
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class AtomicCounter {
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private:
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@ -1394,6 +1401,15 @@ TEST(DBTest, L0_CompactionBug_Issue44_b) {
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ASSERT_EQ("(->)(c->cv)", Contents());
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}
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TEST(DBTest, Fflush_Issue474) {
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static const int kNum = 100000;
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Random rnd(test::RandomSeed());
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for (int i = 0; i < kNum; i++) {
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fflush(NULL);
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ASSERT_OK(Put(RandomKey(&rnd), RandomString(&rnd, 100)));
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}
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}
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TEST(DBTest, ComparatorCheck) {
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class NewComparator : public Comparator {
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public:
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@ -1959,13 +1975,6 @@ class ModelDB: public DB {
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KVMap map_;
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};
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static std::string RandomKey(Random* rnd) {
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int len = (rnd->OneIn(3)
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? 1 // Short sometimes to encourage collisions
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: (rnd->OneIn(100) ? rnd->Skewed(10) : rnd->Uniform(10)));
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return test::RandomKey(rnd, len);
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}
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static bool CompareIterators(int step,
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DB* model,
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DB* db,
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@ -34,6 +34,8 @@ namespace {
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static int open_read_only_file_limit = -1;
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static int mmap_limit = -1;
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static const size_t kBufSize = 65536;
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static Status PosixError(const std::string& context, int err_number) {
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if (err_number == ENOENT) {
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return Status::NotFound(context, strerror(err_number));
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@ -96,30 +98,32 @@ class Limiter {
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class PosixSequentialFile: public SequentialFile {
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private:
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std::string filename_;
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FILE* file_;
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int fd_;
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public:
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PosixSequentialFile(const std::string& fname, FILE* f)
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: filename_(fname), file_(f) { }
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virtual ~PosixSequentialFile() { fclose(file_); }
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PosixSequentialFile(const std::string& fname, int fd)
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: filename_(fname), fd_(fd) {}
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virtual ~PosixSequentialFile() { close(fd_); }
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virtual Status Read(size_t n, Slice* result, char* scratch) {
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Status s;
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size_t r = fread_unlocked(scratch, 1, n, file_);
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*result = Slice(scratch, r);
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if (r < n) {
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if (feof(file_)) {
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// We leave status as ok if we hit the end of the file
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} else {
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// A partial read with an error: return a non-ok status
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while (true) {
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ssize_t r = read(fd_, scratch, n);
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if (r < 0) {
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if (errno == EINTR) {
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continue; // Retry
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}
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s = PosixError(filename_, errno);
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break;
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}
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*result = Slice(scratch, r);
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break;
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}
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return s;
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}
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virtual Status Skip(uint64_t n) {
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if (fseek(file_, n, SEEK_CUR)) {
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if (lseek(fd_, n, SEEK_CUR) == static_cast<off_t>(-1)) {
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return PosixError(filename_, errno);
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}
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return Status::OK();
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@ -213,42 +217,64 @@ class PosixMmapReadableFile: public RandomAccessFile {
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class PosixWritableFile : public WritableFile {
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private:
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// buf_[0, pos_-1] contains data to be written to fd_.
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std::string filename_;
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FILE* file_;
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int fd_;
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char buf_[kBufSize];
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size_t pos_;
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public:
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PosixWritableFile(const std::string& fname, FILE* f)
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: filename_(fname), file_(f) { }
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PosixWritableFile(const std::string& fname, int fd)
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: filename_(fname), fd_(fd), pos_(0) { }
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~PosixWritableFile() {
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if (file_ != NULL) {
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if (fd_ >= 0) {
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// Ignoring any potential errors
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fclose(file_);
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FlushBuffered();
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}
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}
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virtual Status Append(const Slice& data) {
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size_t r = fwrite_unlocked(data.data(), 1, data.size(), file_);
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if (r != data.size()) {
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return PosixError(filename_, errno);
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size_t n = data.size();
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const char* p = data.data();
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// Fit as much as possible into buffer.
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size_t copy = std::min(n, kBufSize - pos_);
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memcpy(buf_ + pos_, p, copy);
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p += copy;
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n -= copy;
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pos_ += copy;
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if (n == 0) {
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return Status::OK();
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}
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return Status::OK();
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// Can't fit in buffer, so need to do at least one write.
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Status s = FlushBuffered();
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if (!s.ok()) {
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return s;
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}
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// Small writes go to buffer, large writes are written directly.
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if (n < kBufSize) {
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memcpy(buf_, p, n);
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pos_ = n;
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return Status::OK();
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}
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return WriteRaw(p, n);
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}
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virtual Status Close() {
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Status result;
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if (fclose(file_) != 0) {
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Status result = FlushBuffered();
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const int r = close(fd_);
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if (r < 0 && result.ok()) {
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result = PosixError(filename_, errno);
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}
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file_ = NULL;
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fd_ = -1;
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return result;
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}
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virtual Status Flush() {
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if (fflush_unlocked(file_) != 0) {
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return PosixError(filename_, errno);
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}
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return Status::OK();
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return FlushBuffered();
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}
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Status SyncDirIfManifest() {
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@ -284,12 +310,36 @@ class PosixWritableFile : public WritableFile {
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if (!s.ok()) {
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return s;
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}
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if (fflush_unlocked(file_) != 0 ||
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fdatasync(fileno(file_)) != 0) {
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s = Status::IOError(filename_, strerror(errno));
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s = FlushBuffered();
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if (s.ok()) {
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if (fdatasync(fd_) != 0) {
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s = PosixError(filename_, errno);
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}
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}
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return s;
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}
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private:
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Status FlushBuffered() {
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Status s = WriteRaw(buf_, pos_);
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pos_ = 0;
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return s;
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}
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Status WriteRaw(const char* p, size_t n) {
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while (n > 0) {
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ssize_t r = write(fd_, p, n);
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if (r < 0) {
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if (errno == EINTR) {
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continue; // Retry
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}
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return PosixError(filename_, errno);
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}
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p += r;
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n -= r;
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}
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return Status::OK();
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}
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};
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static int LockOrUnlock(int fd, bool lock) {
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@ -338,12 +388,12 @@ class PosixEnv : public Env {
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virtual Status NewSequentialFile(const std::string& fname,
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SequentialFile** result) {
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FILE* f = fopen(fname.c_str(), "r");
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if (f == NULL) {
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int fd = open(fname.c_str(), O_RDONLY);
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if (fd < 0) {
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*result = NULL;
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return PosixError(fname, errno);
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} else {
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*result = new PosixSequentialFile(fname, f);
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*result = new PosixSequentialFile(fname, fd);
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return Status::OK();
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}
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}
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@ -379,12 +429,12 @@ class PosixEnv : public Env {
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virtual Status NewWritableFile(const std::string& fname,
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WritableFile** result) {
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Status s;
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FILE* f = fopen(fname.c_str(), "w");
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if (f == NULL) {
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int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
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if (fd < 0) {
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*result = NULL;
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s = PosixError(fname, errno);
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} else {
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*result = new PosixWritableFile(fname, f);
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*result = new PosixWritableFile(fname, fd);
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}
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return s;
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}
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@ -392,12 +442,12 @@ class PosixEnv : public Env {
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virtual Status NewAppendableFile(const std::string& fname,
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WritableFile** result) {
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Status s;
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FILE* f = fopen(fname.c_str(), "a");
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if (f == NULL) {
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int fd = open(fname.c_str(), O_APPEND | O_RDWR | O_CREAT, 0644);
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if (fd < 0) {
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*result = NULL;
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s = PosixError(fname, errno);
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} else {
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*result = new PosixWritableFile(fname, f);
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*result = new PosixWritableFile(fname, fd);
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}
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return s;
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}
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@ -6,6 +6,7 @@
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#include "port/port.h"
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#include "util/testharness.h"
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#include "util/testutil.h"
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namespace leveldb {
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@ -27,6 +28,55 @@ static void SetBool(void* ptr) {
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reinterpret_cast<port::AtomicPointer*>(ptr)->NoBarrier_Store(ptr);
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}
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TEST(EnvTest, ReadWrite) {
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Random rnd(test::RandomSeed());
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// Get file to use for testing.
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std::string test_dir;
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ASSERT_OK(env_->GetTestDirectory(&test_dir));
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std::string test_file_name = test_dir + "/open_on_read.txt";
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WritableFile* wfile_tmp;
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ASSERT_OK(env_->NewWritableFile(test_file_name, &wfile_tmp));
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std::unique_ptr<WritableFile> wfile(wfile_tmp);
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// Fill a file with data generated via a sequence of randomly sized writes.
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static const size_t kDataSize = 10 * 1048576;
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std::string data;
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while (data.size() < kDataSize) {
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int len = rnd.Skewed(18); // Up to 2^18 - 1, but typically much smaller
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std::string r;
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test::RandomString(&rnd, len, &r);
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ASSERT_OK(wfile->Append(r));
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data += r;
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if (rnd.OneIn(10)) {
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ASSERT_OK(wfile->Flush());
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}
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}
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ASSERT_OK(wfile->Sync());
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ASSERT_OK(wfile->Close());
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wfile.reset();
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// Read all data using a sequence of randomly sized reads.
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SequentialFile* rfile_tmp;
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ASSERT_OK(env_->NewSequentialFile(test_file_name, &rfile_tmp));
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std::unique_ptr<SequentialFile> rfile(rfile_tmp);
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std::string read_result;
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std::string scratch;
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while (read_result.size() < data.size()) {
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int len = std::min<int>(rnd.Skewed(18), data.size() - read_result.size());
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scratch.resize(std::max(len, 1)); // at least 1 so &scratch[0] is legal
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Slice read;
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ASSERT_OK(rfile->Read(len, &read, &scratch[0]));
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if (len > 0) {
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ASSERT_GT(read.size(), 0);
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}
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ASSERT_LE(read.size(), len);
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read_result.append(read.data(), read.size());
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}
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ASSERT_EQ(read_result, data);
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}
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TEST(EnvTest, RunImmediately) {
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port::AtomicPointer called (NULL);
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env_->Schedule(&SetBool, &called);
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