folly::test::CaptureFD Class Reference

#include <TestUtil.h>

Classes
struct	NoOpChunkCob

Public Types
using	ChunkCob = std::function< void(folly::StringPiece)>

Public Member Functions
	CaptureFD (int fd, ChunkCob chunk_cob=NoOpChunkCob())
	~CaptureFD ()
void	release ()
std::string	read () const
std::string	readIncremental ()

Private Attributes
ChunkCob	chunkCob_
TemporaryFile	file_
int	fd_
int	oldFDCopy_
off_t	readOffset_

Detailed Description

Temporarily capture a file descriptor by redirecting it into a file. You can consume its entire output thus far via read(), incrementally via readIncremental(), or via callback using chunk_cob. Great for testing logging (see also glog*Pattern()).

Definition at line 222 of file TestUtil.h.

Member Typedef Documentation

using folly::test::CaptureFD::ChunkCob = std::function<void(folly::StringPiece)>

Definition at line 229 of file TestUtil.h.

Constructor & Destructor Documentation

folly::test::CaptureFD::CaptureFD ( int  fd, ChunkCob  chunk_cob = NoOpChunkCob()  )

explicit

chunk_cob is is guaranteed to consume all the captured output. It is invoked on each readIncremental(), and also on FD release to capture as-yet unread lines. Chunks can be empty.

Definition at line 185 of file TestUtil.cpp.

References folly::netops::close(), fd_, file_, oldFDCopy_, and folly::test::TemporaryFile::path().

    : chunkCob_(std::move(chunk_cob)), fd_(fd), readOffset_(0) {
  oldFDCopy_ = dup(fd_);
  PCHECK(oldFDCopy_ != -1) << "Could not copy FD " << fd_;

  int file_fd = open(file_.path().string().c_str(), O_WRONLY | O_CREAT, 0600);
  PCHECK(dup2(file_fd, fd_) != -1)
      << "Could not replace FD " << fd_ << " with " << file_fd;
  PCHECK(close(file_fd) != -1) << "Could not close " << file_fd;
}

folly::test::CaptureFD::~CaptureFD

(

)

Definition at line 206 of file TestUtil.cpp.

References release().

                      {
  release();
}

Member Function Documentation

std::string folly::test::CaptureFD::read

(

)

const

Reads the whole file into a string, but does not remove the redirect.

Definition at line 210 of file TestUtil.cpp.

References file_, folly::test::TemporaryFile::path(), folly::readFile(), and string.

                                {
  std::string contents;
  std::string filename = file_.path().string();
  PCHECK(folly::readFile(filename.c_str(), contents));
  return contents;
}

std::string folly::test::CaptureFD::readIncremental

(

)

Read any bytes that were appended to the file since the last readIncremental. Great for testing line-by-line output.

Definition at line 217 of file TestUtil.cpp.

References chunkCob_, f, folly::File::fd(), file_, folly::openNoInt(), folly::test::TemporaryFile::path(), folly::preadFull(), readOffset_, folly::size(), and string.

Referenced by release(), and TEST().

                                     {
  std::string filename = file_.path().string();
  // Yes, I know that I could just keep the file open instead. So sue me.
  folly::File f(openNoInt(filename.c_str(), O_RDONLY), true);
  auto size = size_t(lseek(f.fd(), 0, SEEK_END) - readOffset_);
  std::unique_ptr<char[]> buf(new char[size]);
  auto bytes_read = folly::preadFull(f.fd(), buf.get(), size, readOffset_);
  PCHECK(ssize_t(size) == bytes_read);
  readOffset_ += off_t(size);
  chunkCob_(StringPiece(buf.get(), buf.get() + size));
  return std::string(buf.get(), size);
}

void folly::test::CaptureFD::release

(

)

Restore the captured FD to its original state. It can be useful to do this before the destructor so that you can read() the captured data and log about it to the formerly captured stderr or stdout.

Definition at line 196 of file TestUtil.cpp.

References folly::netops::close(), fd_, oldFDCopy_, and readIncremental().

Referenced by ~CaptureFD().

                        {
  if (oldFDCopy_ != fd_) {
    readIncremental(); // Feed chunkCob_
    PCHECK(dup2(oldFDCopy_, fd_) != -1)
        << "Could not restore old FD " << oldFDCopy_ << " into " << fd_;
    PCHECK(close(oldFDCopy_) != -1) << "Could not close " << oldFDCopy_;
    oldFDCopy_ = fd_; // Make this call idempotent
  }
}

Member Data Documentation

ChunkCob folly::test::CaptureFD::chunkCob_

private

Definition at line 258 of file TestUtil.h.

Referenced by readIncremental().

int folly::test::CaptureFD::fd_

private

Definition at line 261 of file TestUtil.h.

Referenced by CaptureFD(), and release().

TemporaryFile folly::test::CaptureFD::file_

private

Definition at line 259 of file TestUtil.h.

Referenced by CaptureFD(), read(), and readIncremental().

int folly::test::CaptureFD::oldFDCopy_

private

Definition at line 262 of file TestUtil.h.

Referenced by CaptureFD(), and release().

off_t folly::test::CaptureFD::readOffset_

private

Definition at line 264 of file TestUtil.h.

Referenced by readIncremental().

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The documentation for this class was generated from the following files:

• proxygen/folly/folly/experimental/TestUtil.h
• proxygen/folly/folly/experimental/TestUtil.cpp