alignment is on in ReadaheadRandomAccessFile::Read()
Summary: Closes https://github.com/facebook/rocksdb/pull/1857 Differential Revision: D4534518 Pulled By: wat-ze-hex fbshipit-source-id: b456946
This commit is contained in:
Yulia Kartseva
Facebook Github Bot
parent
381fd32247
commit
ebc8a79980
@ -431,13 +431,15 @@ class ReadaheadRandomAccessFile : public RandomAccessFile {
|
||||
ReadaheadRandomAccessFile(std::unique_ptr<RandomAccessFile>&& file,
|
||||
size_t readahead_size)
|
||||
: file_(std::move(file)),
|
||||
readahead_size_(readahead_size),
|
||||
alignment_(file_->GetRequiredBufferAlignment()),
|
||||
readahead_size_(Roundup(readahead_size, alignment_)),
|
||||
forward_calls_(file_->ShouldForwardRawRequest()),
|
||||
buffer_(),
|
||||
buffer_offset_(0),
|
||||
buffer_len_(0) {
|
||||
if (!forward_calls_) {
|
||||
buffer_.reset(new char[readahead_size_]);
|
||||
buffer_.Alignment(alignment_);
|
||||
buffer_.AllocateNewBuffer(readahead_size_ + alignment_);
|
||||
} else if (readahead_size_ > 0) {
|
||||
file_->EnableReadAhead();
|
||||
}
|
||||
@ -463,31 +465,45 @@ class ReadaheadRandomAccessFile : public RandomAccessFile {
|
||||
|
||||
std::unique_lock<std::mutex> lk(lock_);
|
||||
|
||||
size_t copied = 0;
|
||||
// if offset between [buffer_offset_, buffer_offset_ + buffer_len>
|
||||
if (offset >= buffer_offset_ && offset < buffer_len_ + buffer_offset_) {
|
||||
uint64_t offset_in_buffer = offset - buffer_offset_;
|
||||
copied = std::min(buffer_len_ - static_cast<size_t>(offset_in_buffer), n);
|
||||
memcpy(scratch, buffer_.get() + offset_in_buffer, copied);
|
||||
if (copied == n) {
|
||||
// fully cached
|
||||
*result = Slice(scratch, n);
|
||||
return Status::OK();
|
||||
}
|
||||
size_t cached_len = 0;
|
||||
// Check if there is a cache hit, means that [offset, offset + n) is either
|
||||
// complitely or partially in the buffer
|
||||
// If it's completely cached, including end of file case when offset + n is
|
||||
// greater than EOF, return
|
||||
if (TryReadFromCache_(offset, n, &cached_len, scratch) &&
|
||||
(cached_len == n ||
|
||||
// End of file
|
||||
buffer_len_ < readahead_size_ + alignment_)) {
|
||||
*result = Slice(scratch, cached_len);
|
||||
return Status::OK();
|
||||
}
|
||||
size_t advanced_offset = offset + cached_len;
|
||||
// In the case of cache hit advanced_offset is already aligned, means that
|
||||
// chunk_offset equals to advanced_offset
|
||||
size_t chunk_offset = TruncateToPageBoundary(alignment_, advanced_offset);
|
||||
Slice readahead_result;
|
||||
Status s = file_->Read(offset + copied, readahead_size_, &readahead_result,
|
||||
buffer_.get());
|
||||
Status s = file_->Read(chunk_offset, readahead_size_ + alignment_,
|
||||
&readahead_result, buffer_.BufferStart());
|
||||
if (!s.ok()) {
|
||||
return s;
|
||||
}
|
||||
// In the case of cache miss, i.e. when cached_len equals 0, an offset can
|
||||
// exceed the file end position, so the following check is required
|
||||
if (advanced_offset < chunk_offset + readahead_result.size()) {
|
||||
// In the case of cache miss, the first chunk_padding bytes in buffer_ are
|
||||
// stored for alignment only and must be skipped
|
||||
size_t chunk_padding = advanced_offset - chunk_offset;
|
||||
auto remaining_len =
|
||||
std::min(readahead_result.size() - chunk_padding, n - cached_len);
|
||||
memcpy(scratch + cached_len, readahead_result.data() + chunk_padding,
|
||||
remaining_len);
|
||||
*result = Slice(scratch, cached_len + remaining_len);
|
||||
} else {
|
||||
*result = Slice(scratch, cached_len);
|
||||
}
|
||||
|
||||
auto left_to_copy = std::min(readahead_result.size(), n - copied);
|
||||
memcpy(scratch + copied, readahead_result.data(), left_to_copy);
|
||||
*result = Slice(scratch, copied + left_to_copy);
|
||||
|
||||
if (readahead_result.data() == buffer_.get()) {
|
||||
buffer_offset_ = offset + copied;
|
||||
if (readahead_result.data() == buffer_.BufferStart()) {
|
||||
buffer_offset_ = chunk_offset;
|
||||
buffer_len_ = readahead_result.size();
|
||||
} else {
|
||||
buffer_len_ = 0;
|
||||
@ -507,12 +523,26 @@ class ReadaheadRandomAccessFile : public RandomAccessFile {
|
||||
}
|
||||
|
||||
private:
|
||||
bool TryReadFromCache_(uint64_t offset, size_t n, size_t* cached_len,
|
||||
char* scratch) const {
|
||||
if (offset < buffer_offset_ || offset >= buffer_offset_ + buffer_len_) {
|
||||
*cached_len = 0;
|
||||
return false;
|
||||
}
|
||||
uint64_t offset_in_buffer = offset - buffer_offset_;
|
||||
*cached_len =
|
||||
std::min(buffer_len_ - static_cast<size_t>(offset_in_buffer), n);
|
||||
memcpy(scratch, buffer_.BufferStart() + offset_in_buffer, *cached_len);
|
||||
return true;
|
||||
}
|
||||
|
||||
std::unique_ptr<RandomAccessFile> file_;
|
||||
const size_t alignment_;
|
||||
size_t readahead_size_;
|
||||
const bool forward_calls_;
|
||||
|
||||
mutable std::mutex lock_;
|
||||
mutable std::unique_ptr<char[]> buffer_;
|
||||
mutable AlignedBuffer buffer_;
|
||||
mutable uint64_t buffer_offset_;
|
||||
mutable size_t buffer_len_;
|
||||
};
|
||||
|
||||
@ -3,10 +3,12 @@
|
||||
// LICENSE file in the root directory of this source tree. An additional grant
|
||||
// of patent rights can be found in the PATENTS file in the same directory.
|
||||
//
|
||||
#include <vector>
|
||||
#include "util/file_reader_writer.h"
|
||||
#include <algorithm>
|
||||
#include <vector>
|
||||
#include "util/random.h"
|
||||
#include "util/testharness.h"
|
||||
#include "util/testutil.h"
|
||||
|
||||
namespace rocksdb {
|
||||
|
||||
@ -127,6 +129,108 @@ TEST_F(WritableFileWriterTest, AppendStatusReturn) {
|
||||
}
|
||||
#endif
|
||||
|
||||
class ReadaheadRandomAccessFileTest
|
||||
: public testing::Test,
|
||||
public testing::WithParamInterface<size_t> {
|
||||
public:
|
||||
static std::vector<size_t> GetReadaheadSizeList() {
|
||||
return {1lu << 12, 1lu << 16};
|
||||
}
|
||||
virtual void SetUp() override {
|
||||
readahead_size_ = GetParam();
|
||||
scratch_.reset(new char[2 * readahead_size_]);
|
||||
ResetSourceStr();
|
||||
}
|
||||
ReadaheadRandomAccessFileTest() : control_contents_() {}
|
||||
std::string Read(uint64_t offset, size_t n) {
|
||||
Slice result;
|
||||
test_read_holder_->Read(offset, n, &result, scratch_.get());
|
||||
return std::string(result.data(), result.size());
|
||||
}
|
||||
void ResetSourceStr(const std::string& str = "") {
|
||||
auto write_holder = std::unique_ptr<WritableFileWriter>(
|
||||
test::GetWritableFileWriter(new test::StringSink(&control_contents_)));
|
||||
write_holder->Append(Slice(str));
|
||||
write_holder->Flush();
|
||||
auto read_holder = std::unique_ptr<RandomAccessFile>(
|
||||
new test::StringSource(control_contents_));
|
||||
test_read_holder_ =
|
||||
NewReadaheadRandomAccessFile(std::move(read_holder), readahead_size_);
|
||||
}
|
||||
size_t GetReadaheadSize() const { return readahead_size_; }
|
||||
|
||||
private:
|
||||
size_t readahead_size_;
|
||||
Slice control_contents_;
|
||||
std::unique_ptr<RandomAccessFile> test_read_holder_;
|
||||
std::unique_ptr<char[]> scratch_;
|
||||
};
|
||||
|
||||
TEST_P(ReadaheadRandomAccessFileTest, EmptySourceStrTest) {
|
||||
ASSERT_EQ("", Read(0, 1));
|
||||
ASSERT_EQ("", Read(0, 0));
|
||||
ASSERT_EQ("", Read(13, 13));
|
||||
}
|
||||
|
||||
TEST_P(ReadaheadRandomAccessFileTest, SourceStrLenLessThanReadaheadSizeTest) {
|
||||
std::string str = "abcdefghijklmnopqrs";
|
||||
ResetSourceStr(str);
|
||||
ASSERT_EQ(str.substr(3, 4), Read(3, 4));
|
||||
ASSERT_EQ(str.substr(0, 3), Read(0, 3));
|
||||
ASSERT_EQ(str, Read(0, str.size()));
|
||||
ASSERT_EQ(str.substr(7, std::min(static_cast<int>(str.size()) - 7, 30)),
|
||||
Read(7, 30));
|
||||
ASSERT_EQ("", Read(100, 100));
|
||||
}
|
||||
|
||||
TEST_P(ReadaheadRandomAccessFileTest,
|
||||
SourceStrLenCanBeGreaterThanReadaheadSizeTest) {
|
||||
Random rng(42);
|
||||
for (int k = 0; k < 100; ++k) {
|
||||
size_t strLen = k * GetReadaheadSize() +
|
||||
rng.Uniform(static_cast<int>(GetReadaheadSize()));
|
||||
std::string str =
|
||||
test::RandomHumanReadableString(&rng, static_cast<int>(strLen));
|
||||
ResetSourceStr(str);
|
||||
for (int test = 1; test <= 100; ++test) {
|
||||
size_t offset = rng.Uniform(static_cast<int>(strLen));
|
||||
size_t n = rng.Uniform(static_cast<int>(GetReadaheadSize()));
|
||||
ASSERT_EQ(str.substr(offset, std::min(n, str.size() - offset)),
|
||||
Read(offset, n));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
TEST_P(ReadaheadRandomAccessFileTest, NExceedReadaheadTest) {
|
||||
Random rng(7);
|
||||
size_t strLen = 4 * GetReadaheadSize() +
|
||||
rng.Uniform(static_cast<int>(GetReadaheadSize()));
|
||||
std::string str =
|
||||
test::RandomHumanReadableString(&rng, static_cast<int>(strLen));
|
||||
ResetSourceStr(str);
|
||||
for (int test = 1; test <= 100; ++test) {
|
||||
size_t offset = rng.Uniform(static_cast<int>(strLen));
|
||||
size_t n =
|
||||
GetReadaheadSize() + rng.Uniform(static_cast<int>(GetReadaheadSize()));
|
||||
ASSERT_EQ(str.substr(offset, std::min(n, str.size() - offset)),
|
||||
Read(offset, n));
|
||||
}
|
||||
}
|
||||
|
||||
INSTANTIATE_TEST_CASE_P(
|
||||
EmptySourceStrTest, ReadaheadRandomAccessFileTest,
|
||||
::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
|
||||
INSTANTIATE_TEST_CASE_P(
|
||||
SourceStrLenLessThanReadaheadSizeTest, ReadaheadRandomAccessFileTest,
|
||||
::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
|
||||
INSTANTIATE_TEST_CASE_P(
|
||||
SourceStrLenCanBeGreaterThanReadaheadSizeTest,
|
||||
ReadaheadRandomAccessFileTest,
|
||||
::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
|
||||
INSTANTIATE_TEST_CASE_P(
|
||||
NExceedReadaheadTest, ReadaheadRandomAccessFileTest,
|
||||
::testing::ValuesIn(ReadaheadRandomAccessFileTest::GetReadaheadSizeList()));
|
||||
|
||||
} // namespace rocksdb
|
||||
|
||||
int main(int argc, char** argv) {
|
||||
|
||||
Loading…
Reference in New Issue
Block a user