Schedule a batch of asynchronous symlink deletions after optional preconditions.

Description

Make sure you read the docs for handle::unlink() for important caveats. Note that on operating systems with an unstable handle::path(true) you need to be cautious of deleting files by handle as any hard link to that file may be deleted instead of the one you intended. To work around this, portable code should delete by directory handle as the precondition and known leafname. Related types: path_req

Synopsis

future dispatcher::rmsymlink(const std::vector< path_req > & reqs)

Parameters

Returns

A batch of op handles.

Header

#include <boost/afio/v2/afio.hpp>

Race Guarantees

Complexity

Amortised O(N) to dispatch. Amortised O(N/threadpool) to complete if symlink deletion is constant time.

Exception Model

Propagates exceptions of any input preconditions with an errored state at the point of dispatch, and throws a std::invalid_argument if any inputs have values which could not possibly be correct. Once a batch of input ops has been verified at the point of entry as not errored, you are guaranteed that the batch is atomically scheduled as a whole, unless a failure to allocate memory occurs.

Example

using namespace BOOST_AFIO_V2_NAMESPACE;
using BOOST_AFIO_V2_NAMESPACE::rmdir;
std::shared_ptr<boost::afio::dispatcher> dispatcher =
boost::afio::make_dispatcher().get();
current_dispatcher_guard h(dispatcher);

// Free function
try
{
  // Schedule creating a directory called testdir
  auto mkdir(async_dir("testdir", boost::afio::file_flags::create));
  // Schedule creating a file called testfile in testdir only when testdir has been
  // created
  auto mkfile(async_file(mkdir, "testfile", boost::afio::file_flags::create));
  // Schedule creating a symbolic link called linktodir to the item referred to by
  // the precondition
  // i.e. testdir. Note that on Windows you can only symbolic link directories.
  auto mklink(
  async_symlink(mkdir, "linktodir", mkdir, boost::afio::file_flags::create));

  // Schedule deleting the symbolic link only after when it has been created
  auto rmlink(async_rmsymlink(mklink));
  // Schedule deleting the file only after when it has been created
  auto rmfile(async_close(async_rmfile(mkfile)));
  // Schedule waiting until both the preceding operations have finished
  auto barrier(dispatcher->barrier({rmlink, rmfile}));
  // Schedule deleting the directory only after the barrier completes
  auto rmdir(async_rmdir(depends(barrier.front(), mkdir)));
  // Check ops for errors
  boost::afio::when_all_p(mkdir, mkfile, mklink, rmlink, rmfile, rmdir).wait();
}
catch(...)
{
  std::cerr << boost::current_exception_diagnostic_information(true) << std::endl;
  throw;
}

// Batch
try
{
  // Schedule creating a directory called testdir
  auto mkdir(
  dispatcher->dir(std::vector<boost::afio::path_req>(
                  1, boost::afio::path_req(
                     "testdir", boost::afio::file_flags::create))).front());
  // Schedule creating a file called testfile in testdir only when testdir has been
  // created
  auto mkfile(dispatcher->file(std::vector<boost::afio::path_req>(
                               1, boost::afio::path_req::relative(
                                  mkdir, "testfile",
                                  boost::afio::file_flags::create))).front());
  // Schedule creating a symbolic link called linktodir to the item referred to by
  // the precondition
  // i.e. testdir. Note that on Windows you can only symbolic link directories.
  // Note that creating
  // symlinks must *always* be as an absolute path, as that is how they are stored.
  auto mklink(dispatcher->symlink(std::vector<boost::afio::path_req>(
                                  1, boost::afio::path_req::absolute(
                                     mkdir, "testdir/linktodir",
                                     boost::afio::file_flags::create))).front());

  // Schedule deleting the symbolic link only after when it has been created
  auto rmlink(dispatcher->close(std::vector<future<>>(
                                1, dispatcher->rmsymlink(mklink))).front());
  // Schedule deleting the file only after when it has been created
  auto rmfile(
  dispatcher->close(std::vector<future<>>(1, dispatcher->rmfile(mkfile))).front());
  // Schedule waiting until both the preceding operations have finished
  auto barrier(dispatcher->barrier({rmlink, rmfile}));
  // Schedule deleting the directory only after the barrier completes
  auto rmdir(
  dispatcher->rmdir(std::vector<path_req>(
                    1, dispatcher->depends(barrier.front(), mkdir))).front());
  // Check ops for errors
  boost::afio::when_all_p(mkdir, mkfile, mklink, rmlink, rmfile, rmdir).wait();
}
catch(...)
{
  std::cerr << boost::current_exception_diagnostic_information(true) << std::endl;
  throw;
}