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Code Issues Releases Wiki Activity

ircd::fs::aio: Minor tweak call pattern for wait(request).

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This commit is contained in:
Jason Volk 2019-04-22 09:29:09 -07:00
parent acd774c3ee
commit c04708aca4
2 changed files with 38 additions and 26 deletions
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60
ircd/fs_aio.cc
View file

@ -404,7 +404,7 @@ ircd::fs::aio::request::operator()()
system->submit(*this);
// Wait for completion
system->wait(*this);
while(!system->wait(*this));
assert(completed());
assert(retval <= ssize_t(submitted_bytes));
@ -618,34 +618,44 @@ ircd::fs::aio::system::wait()
return true;
}
void
/// Block the current context while waiting for results.
///
/// This function returns true when the request completes and it's safe to
/// continue. This function intercepts all exceptions and cancels the request
/// if it's appropriate before rethrowing; after which it is safe to continue.
///
/// If this function returns false it is not safe to continue; it *must* be
/// called again until it no longer returns false.
bool
ircd::fs::aio::system::wait(request &request)
try
{
assert(ctx::current == request.waiter);
while(!request.completed()) try
{
while(!request.completed())
ctx::wait();
}
catch(...)
return true;
}
catch(...)
{
// When the ctx is interrupted we're obliged to cancel the request
// if it has not reached a completed state.
if(request.completed())
throw;
// The handler callstack is invoked synchronously on this stack for
// requests which are still in our userspace queue.
if(request.queued())
{
// When the ctx is interrupted we're obliged to cancel the request
// if it has not reached a completed state.
if(request.completed())
throw;
// The handler callstack is invoked synchronously on this stack for
// requests which are still in our userspace queue.
if(request.queued())
{
request.cancel();
throw;
}
// The handler callstack is invoked asynchronously for requests
// submitted to the kernel; we *must* wait for that by blocking
// ctx interrupts and terminations and continue to wait.
continue;
request.cancel();
throw;
}
// The handler callstack is invoked asynchronously for requests
// submitted to the kernel; we *must* wait for that by blocking
// ctx interrupts and terminations and continue to wait. The caller
// must loop into this call again until it returns true or throws.
return false;
}
bool
@ -727,7 +737,7 @@ catch(const std::system_error &e)
return false;
}
void
bool
ircd::fs::aio::system::submit(request &request)
{
assert(request.opts);
@ -771,6 +781,8 @@ ircd::fs::aio::system::submit(request &request)
auto handler(std::bind(&system::chase, this));
ircd::defer(descriptor, std::move(handler));
}
return true;
}
/// The chaser is posted to the IRCd event loop after the first request.

4
ircd/fs_aio.h
View file

@ -75,9 +75,9 @@ struct ircd::fs::aio::system
size_t submit() noexcept;
void chase() noexcept;
void submit(request &);
bool submit(request &);
bool cancel(request &);
void wait(request &);
bool wait(request &);
// Control panel
bool wait();