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ircd::ctx: Reorder the interruption point conditional branches.

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This commit is contained in:
Jason Volk 2018-12-22 13:19:02 -08:00
parent b5f4aeb67d
commit 0ed9382db0
1 changed files with 18 additions and 20 deletions
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38
ircd/ctx.cc
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@ -247,33 +247,39 @@ ircd::ctx::ctx::interruption_point()
context::TERMINATED | context::INTERRUPTED
};
// Fast test-and-bail for the very likely case there is no interrupt.
if(likely((this->flags & flags) == 0))
return;
// The NOINTERRUPT flag works by pretending there is no interrupt flag
// set and also does not clear the flag. This allows the interrupt
// to remain pending until the uninterruptible section is complete.
if(this->flags & context::NOINTERRUPT)
return;
// Termination shouldn't be used for normal operation so please eat this
// branch misprediction.
if(unlikely(termination_point(std::nothrow)))
throw terminated{};
if(unlikely(interruption_point(std::nothrow)))
if(interruption_point(std::nothrow))
throw interrupted
{
"ctx(%p) '%s'", (const void *)this, name
"ctx:%lu '%s'", id, name
};
}
/// Returns true if this context has been flagged for termination.
/// Does not clear the flag.
/// Returns true if this context has been flagged for termination. Does not
/// clear the flag. Sets the NOINTERRUPT flag so the context cannot be further
// interrupted which simplifies the termination process.
bool
ircd::ctx::ctx::termination_point(std::nothrow_t)
{
if(unlikely(flags & context::TERMINATED))
if(flags & context::TERMINATED)
{
// see: interruption_point().
if(flags & context::NOINTERRUPT)
return false;
assert(~flags & context::NOINTERRUPT);
flags |= context::NOINTERRUPT;
mark(prof::event::CUR_TERMINATE);
assert(flags & ~context::NOINTERRUPT);
return true;
}
else return false;
@ -284,19 +290,11 @@ ircd::ctx::ctx::termination_point(std::nothrow_t)
bool
ircd::ctx::ctx::interruption_point(std::nothrow_t)
{
// Interruption shouldn't be used for normal operation,
// so please eat this branch misprediction.
if(unlikely(flags & context::INTERRUPTED))
if(flags & context::INTERRUPTED)
{
// The NOINTERRUPT flag works by pretending there is no INTERRUPTED
// flag set and also does not clear the flag. This allows the interrupt
// to remaing pending until the uninterruptible section is complete.
if(flags & context::NOINTERRUPT)
return false;
assert(~flags & context::NOINTERRUPT);
flags &= ~context::INTERRUPTED;
mark(prof::event::CUR_INTERRUPT);
assert(~flags & context::NOINTERRUPT);
return true;
}
else return false;