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fix(storage): fix tellg() values #12844

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merged 2 commits into from
Oct 8, 2023
Merged

fix(storage): fix tellg() values #12844

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d9878dd
fix(storage): fix tellg() values
coryan Oct 7, 2023
c258c6d
Address review comments
coryan Oct 8, 2023
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3 changes: 1 addition & 2 deletions google/cloud/storage/client.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -70,8 +70,7 @@ ObjectReadStream Client::ReadObjectImpl(
}
auto stream =
ObjectReadStream(std::make_unique<internal::ObjectReadStreambuf>(
request, *std::move(source),
request.GetOption<ReadFromOffset>().value_or(0)));
request, *std::move(source)));
(void)stream.peek();
#if !GOOGLE_CLOUD_CPP_HAVE_EXCEPTIONS
// Without exceptions the streambuf cannot report errors, so we have to
Expand Down
23 changes: 20 additions & 3 deletions google/cloud/storage/internal/object_read_streambuf.cc
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Expand Up @@ -22,12 +22,22 @@ namespace cloud {
namespace storage {
GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_BEGIN
namespace internal {
namespace {

std::streamoff InitialOffset(ReadObjectRangeRequest const& request) {
if (request.HasOption<ReadLast>()) {
return -request.GetOption<ReadLast>().value();
}
return request.StartingByte();
}

} // namespace

ObjectReadStreambuf::ObjectReadStreambuf(
ReadObjectRangeRequest const& request,
std::unique_ptr<ObjectReadSource> source, std::streamoff pos_in_stream)
std::unique_ptr<ObjectReadSource> source)
: source_(std::move(source)),
source_pos_(pos_in_stream),
source_pos_(static_cast<std::streamoff>(InitialOffset(request))),
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Why do we need to static cast to std::streamoff when it looks like InitialOffset() already returns a std::streamoff?

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D'oh! That is what happens when you refactor to a function and forget to clean up the call site.

hash_function_(CreateHashFunction(request)),
hash_validator_(CreateHashValidator(request)) {}

Expand All @@ -51,6 +61,7 @@ ObjectReadStreambuf::pos_type ObjectReadStreambuf::seekoff(
// recreated in the general case, which doesn't fit the current code
// organization. We can, however, at least implement the bare minimum of this
// function allowing `tellg()` to work.
if (source_pos_ < 0) return -1;
if (which == std::ios_base::in && dir == std::ios_base::cur && off == 0) {
return source_pos_ - in_avail();
}
Expand Down Expand Up @@ -198,7 +209,6 @@ std::streamsize ObjectReadStreambuf::xsgetn(char* s, std::streamsize count) {
hash_function_->Update(absl::string_view{s + offset, read->bytes_received});
hash_validator_->ProcessHashValues(read->hashes);
offset += static_cast<std::streamsize>(read->bytes_received);
source_pos_ += static_cast<std::streamoff>(read->bytes_received);
for (auto const& kv : read->response.headers) {
headers_.emplace(kv.first, kv.second);
}
Expand All @@ -207,6 +217,13 @@ std::streamsize ObjectReadStreambuf::xsgetn(char* s, std::streamsize count) {
if (!storage_class_) storage_class_ = std::move(read->storage_class);
if (!size_) size_ = std::move(read->size);
if (!transformation_) transformation_ = std::move(read->transformation);

if (source_pos_ >= 0) {
source_pos_ += static_cast<std::streamoff>(read->bytes_received);
} else if (size_) {
source_pos_ = *size_ + source_pos_ +
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Use source_pos_ += ... too?

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Done.

static_cast<std::streamoff>(read->bytes_received);
}
return run_validator_if_closed(Status());
}

Expand Down
3 changes: 1 addition & 2 deletions google/cloud/storage/internal/object_read_streambuf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,7 @@ namespace internal {
class ObjectReadStreambuf : public std::basic_streambuf<char> {
public:
ObjectReadStreambuf(ReadObjectRangeRequest const& request,
std::unique_ptr<ObjectReadSource> source,
std::streamoff pos_in_stream);
std::unique_ptr<ObjectReadSource> source);

/// Create a streambuf in a permanent error status.
ObjectReadStreambuf(ReadObjectRangeRequest const& request, Status status);
Expand Down
83 changes: 81 additions & 2 deletions google/cloud/storage/internal/object_read_streambuf_test.cc
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Expand Up @@ -32,6 +32,85 @@ TEST(ObjectReadStreambufTest, FailedTellg) {
EXPECT_EQ(-1, stream.tellg());
}

TEST(ObjectReadStreambufTest, TellgReadFromOffset) {
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
EXPECT_CALL(*read_source, Read)
.WillOnce(Return(ReadSourceResult{15, {}}))
.WillOnce(Return(ReadSourceResult{10, {}}));
ObjectReadStreambuf buf(
ReadObjectRangeRequest{}.set_option(ReadFromOffset(1024)),
std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(stream.tellg(), 1024);
std::vector<char> v(1024);
stream.read(v.data(), 15);
EXPECT_EQ(stream.tellg(), 1024 + 15);
stream.read(v.data(), 10);
EXPECT_EQ(stream.tellg(), 1024 + 15 + 10);
}

TEST(ObjectReadStreambufTest, TellgReadRange) {
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
EXPECT_CALL(*read_source, Read)
.WillOnce(Return(ReadSourceResult{15, {}}))
.WillOnce(Return(ReadSourceResult{10, {}}));
ObjectReadStreambuf buf(
ReadObjectRangeRequest{}.set_option(ReadRange(2048, 4096)),
std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(stream.tellg(), 2048);
std::vector<char> v(1024);
stream.read(v.data(), 15);
EXPECT_EQ(stream.tellg(), 2048 + 15);
stream.read(v.data(), 10);
EXPECT_EQ(stream.tellg(), 2048 + 15 + 10);
}

TEST(ObjectReadStreambufTest, TellgReadLastUnknownSize) {
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
EXPECT_CALL(*read_source, Read)
.WillOnce(Return(ReadSourceResult{15, {}}))
.WillOnce(Return(ReadSourceResult{10, {}}));
ObjectReadStreambuf buf(ReadObjectRangeRequest{}.set_option(ReadLast(512)),
std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(stream.tellg(), -1);
std::vector<char> v(1024);
stream.read(v.data(), 15);
EXPECT_EQ(stream.tellg(), -1);
stream.read(v.data(), 10);
EXPECT_EQ(stream.tellg(), -1);
}

TEST(ObjectReadStreambufTest, TellgReadLastSize) {
auto make_response = [](std::size_t count) {
auto response = ReadSourceResult{count, {}};
response.size = 2048;
return response;
};
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
EXPECT_CALL(*read_source, Read)
.WillOnce(Return(make_response(15)))
.WillOnce(Return(make_response(10)));
ObjectReadStreambuf buf(ReadObjectRangeRequest{}.set_option(ReadLast(512)),
std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(stream.tellg(), -1);
std::vector<char> v(1024);
stream.read(v.data(), 15);
EXPECT_EQ(stream.tellg(), 2048 - 512 + 15);
stream.read(v.data(), 10);
EXPECT_EQ(stream.tellg(), 2048 - 512 + 15 + 10);
}

TEST(ObjectReadStreambufTest, Success) {
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
Expand All @@ -40,7 +119,7 @@ TEST(ObjectReadStreambufTest, Success) {
.WillOnce(Return(ReadSourceResult{15, {}}))
.WillOnce(Return(ReadSourceResult{15, {}}))
.WillOnce(Return(ReadSourceResult{128 * 1024, {}}));
ObjectReadStreambuf buf(ReadObjectRangeRequest{}, std::move(read_source), 0);
ObjectReadStreambuf buf(ReadObjectRangeRequest{}, std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(0, stream.tellg());
Expand Down Expand Up @@ -68,7 +147,7 @@ TEST(ObjectReadStreambufTest, WrongSeek) {
auto read_source = std::make_unique<testing::MockObjectReadSource>();
EXPECT_CALL(*read_source, IsOpen()).WillRepeatedly(Return(true));
EXPECT_CALL(*read_source, Read).WillOnce(Return(ReadSourceResult{10, {}}));
ObjectReadStreambuf buf(ReadObjectRangeRequest{}, std::move(read_source), 0);
ObjectReadStreambuf buf(ReadObjectRangeRequest{}, std::move(read_source));

std::istream stream(&buf);
EXPECT_EQ(0, stream.tellg());
Expand Down
29 changes: 29 additions & 0 deletions google/cloud/storage/tests/object_media_integration_test.cc
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Expand Up @@ -355,6 +355,35 @@ TEST_F(ObjectMediaIntegrationTest, ReadLastChunkReadLast) {
EXPECT_EQ(large_text.substr(kObjectSize - 129 * kKiB), actual);
}

/// @test Read the last chunk of an object by setting ReadLast option.
TEST_F(ObjectMediaIntegrationTest, ReadLastTellg) {
StatusOr<Client> client = MakeIntegrationTestClient();
ASSERT_STATUS_OK(client);

auto object_name = MakeRandomObjectName();

// This produces an object larger than 3MiB, but with a size that is not a
// multiple of 128KiB.
auto constexpr kKiB = 1024L;
auto constexpr kObjectSize = 256 * kKiB;
auto const expected = MakeRandomData(kObjectSize);
auto insert = client->InsertObject(bucket_name_, object_name, expected,
IfGenerationMatch(0));
ASSERT_STATUS_OK(insert);
ScheduleForDelete(*insert);

// Create an iostream to read the last 129KiB of the object, but simulate an
// application that does not know how large that last chunk is.
auto is = client->ReadObject(bucket_name_, object_name, ReadLast(129 * kKiB));
EXPECT_EQ(is.tellg(), kObjectSize - 129 * kKiB);
std::vector<char> buffer(1024 * kKiB);
is.read(buffer.data(), 1000);
EXPECT_EQ(is.gcount(), 1000);
EXPECT_EQ(is.tellg(), kObjectSize - 129 * kKiB + 1000);
auto const actual = std::string(buffer.data(), 1000);
EXPECT_EQ(actual, expected.substr(kObjectSize - 129 * kKiB, 1000));
}

/// @test Read an object by chunks of equal size.
TEST_F(ObjectMediaIntegrationTest, ReadByChunk) {
StatusOr<Client> client = MakeIntegrationTestClient();
Expand Down