From 2e0f52d25a6e165f406a922c2ab657b43e315eae Mon Sep 17 00:00:00 2001
From: Maged Michael <magedmichael@fb.com>
Date: Sat, 25 Mar 2017 03:28:15 -0700
Subject: [PATCH] (folly) Add lock holder interface to flat combining. Change
an assert to a static_assert.
Summary:
Two changes:
- Add a lock holder interface to enable users to move exclusive access and implicitly release the held lock.
- Change an assert to a static_assert to check at compile time if a provided function fits in the Function structure without dynamic allocation.
Reviewed By: djwatson
Differential Revision: D4770229
fbshipit-source-id: 89408164c08d7660231a6ca4e37637dd688356cd
---
.../flat_combining/FlatCombining.h | 22 +++++++++++++------
.../test/FlatCombiningTestHelpers.h | 16 +++++++++++++-
2 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/folly/experimental/flat_combining/FlatCombining.h b/folly/experimental/flat_combining/FlatCombining.h
index 9c033503..445d29a3 100644
--- a/folly/experimental/flat_combining/FlatCombining.h
+++ b/folly/experimental/flat_combining/FlatCombining.h
@@ -197,15 +197,16 @@ class FlatCombining {
template <typename Func>
void setFn(Func&& fn) {
+ static_assert(
+ std::is_nothrow_constructible<
+ folly::Function<void()>,
+ _t<std::decay<Func>>>::value,
+ "Try using a smaller function object that can fit in folly::Function "
+ "without allocation, or use the custom interface of requestFC() to "
+ "manage the requested function's arguments and results explicitly "
+ "in a custom request structure without allocation.");
fn_ = std::forward<Func>(fn);
assert(fn_);
- // If the following assertion is triggered, the user should
- // either change the provided function, i.e., fn, to fit in
- // folly::Function without allocation or use the custom
- // interface to request combining for fn and manage its
- // arguments (and results, if any) explicitly in a custom
- // request structure.
- assert(!fn_.hasAllocatedMemory());
}
void clearFn() {
@@ -276,6 +277,13 @@ class FlatCombining {
m_.lock();
}
+ // Give the caller exclusive access through a lock holder.
+ // No need for explicit release.
+ template <typename LockHolder>
+ void acquireExclusive(LockHolder& l) {
+ l = LockHolder(m_);
+ }
+
// Try to give the caller exclusive access. Returns true iff successful.
bool tryExclusive() {
return m_.try_lock();
diff --git a/folly/experimental/flat_combining/test/FlatCombiningTestHelpers.h b/folly/experimental/flat_combining/test/FlatCombiningTestHelpers.h
index f9b4980d..07742e12 100644
--- a/folly/experimental/flat_combining/test/FlatCombiningTestHelpers.h
+++ b/folly/experimental/flat_combining/test/FlatCombiningTestHelpers.h
@@ -104,7 +104,21 @@ uint64_t fc_test(
}
if (excl) {
- // test of unstructured exclusive access
+ // test of exclusive access through a lock holder
+ {
+ std::unique_lock<Mutex> l;
+ ex.acquireExclusive(l);
+ CHECK(!mutex);
+ mutex = true;
+ VLOG(2) << tid << " " << ex.getVal() << " ...........";
+ using namespace std::chrono_literals;
+ /* sleep override */ // for coverage
+ std::this_thread::sleep_for(10ms);
+ VLOG(2) << tid << " " << ex.getVal() << " ===========";
+ CHECK(mutex);
+ mutex = false;
+ }
+ // test of explicit acquisition and release of exclusive access
ex.acquireExclusive();
{
CHECK(!mutex);
--
2.34.1