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authorGravatar Abseil Team <absl-team@google.com>2019-02-25 11:52:11 -0800
committerGravatar Jon Cohen <cohenjon@google.com>2019-02-25 15:03:46 -0500
commit308ce31528a7edfa39f5f6d36142278a0ae1bf45 (patch)
tree403fb7710f1ffecbc2851fa51009c651e49c3e25 /absl
parent93d155bc4414f6c121bb1f19dba9fdb27c8943bc (diff)
Export of internal Abseil changes.
-- e4e4a3460b64ba0571be217b04ec286bfac6b6bf by Tom Manshreck <shreck@google.com>: Internal change PiperOrigin-RevId: 235573160 -- 200323f1243e20c201d20bdab4c15a20346a27e5 by CJ Johnson <johnsoncj@google.com>: Removed unneded template parameter from InlinedVector internal functions PiperOrigin-RevId: 234910222 -- 2f1bba53c9ca40d0718c4c1edfcfea40edd5049e by CJ Johnson <johnsoncj@google.com>: Add comment highlighting the fact that the InlinedVector(&&, alloc) move constructor overload will still commit pointer theft in one case PiperOrigin-RevId: 234899890 GitOrigin-RevId: e4e4a3460b64ba0571be217b04ec286bfac6b6bf Change-Id: I0aabbabb96e9a057a55ed6b42591ea43b4609efe
Diffstat (limited to 'absl')
-rw-r--r--absl/container/inlined_vector.h62
-rw-r--r--absl/container/internal/hashtablez_sampler.h18
2 files changed, 52 insertions, 28 deletions
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index 5c9e6d97..e8daf6af 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -156,11 +156,11 @@ class InlinedVector {
std::copy(first, last, std::back_inserter(*this));
}
- // Creates a copy of `other` using `other`'s allocator.
+ // Creates a copy of an `other` inlined vector using `other`'s allocator.
InlinedVector(const InlinedVector& other)
: InlinedVector(other, other.allocator()) {}
- // Creates a copy of `other` but with a specified allocator.
+ // Creates a copy of an `other` inlined vector using a specified allocator.
InlinedVector(const InlinedVector& other, const allocator_type& alloc)
: allocator_and_tag_(alloc) {
reserve(other.size());
@@ -173,14 +173,19 @@ class InlinedVector {
}
}
- // Creates an inlined vector by moving in the contents of `other`.
+ // Creates an inlined vector by moving in the contents of an `other` inlined
+ // vector without performing any allocations. If `other` contains allocated
+ // memory, the newly-created instance will take ownership of that memory
+ // (leaving `other` itself empty). However, if `other` does not contain any
+ // allocated memory, the new inlined vector will will perform element-wise
+ // move construction of `other`s elements.
//
- // NOTE: This move constructor does not allocate and only moves the underlying
- // objects, so its `noexcept` specification depends on whether moving the
- // underlying objects can throw or not. We assume:
- // a) move constructors should only throw due to allocation failure and
- // b) if `value_type`'s move constructor allocates, it uses the same
- // allocation function as the `InlinedVector`'s allocator, so the move
+ // NOTE: since no allocation is performed for the inlined vector in either
+ // case, the `noexcept(...)` specification depends on whether moving the
+ // underlying objects can throw. We assume:
+ // a) Move constructors should only throw due to allocation failure.
+ // b) If `value_type`'s move constructor allocates, it uses the same
+ // allocation function as the `InlinedVector`'s allocator. Thus, the move
// constructor is non-throwing if the allocator is non-throwing or
// `value_type`'s move constructor is specified as `noexcept`.
InlinedVector(InlinedVector&& other) noexcept(
@@ -202,14 +207,19 @@ class InlinedVector {
}
}
- // Creates an inlined vector by moving in the contents of `other`.
+ // Creates an inlined vector by moving in the contents of an `other` inlined
+ // vector, performing allocations with the specified `alloc` allocator. If
+ // `other`'s allocator is not equal to `alloc` and `other` contains allocated
+ // memory, this move constructor will create a new allocation.
//
- // NOTE: This move constructor allocates and subsequently moves the underlying
- // objects, so its `noexcept` specification depends on whether the allocation
- // can throw and whether moving the underlying objects can throw. Based on the
- // same assumptions as above, the `noexcept` specification is dominated by
- // whether the allocation can throw regardless of whether `value_type`'s move
- // constructor is specified as `noexcept`.
+ // NOTE: since allocation is performed in this case, this constructor can
+ // only be `noexcept` if the specified allocator is also `noexcept`. If this
+ // is the case, or if `other` contains allocated memory, this constructor
+ // performs element-wise move construction of its contents.
+ //
+ // Only in the case where `other`'s allocator is equal to `alloc` and `other`
+ // contains allocated memory will the newly created inlined vector take
+ // ownership of `other`'s allocated memory.
InlinedVector(InlinedVector&& other, const allocator_type& alloc) noexcept(
absl::allocator_is_nothrow<allocator_type>::value)
: allocator_and_tag_(alloc) {
@@ -1110,9 +1120,9 @@ class InlinedVector {
}
}
- template <typename ForwardIterator>
- void AssignForwardRange(ForwardIterator first, ForwardIterator last) {
- static_assert(IsAtLeastForwardIterator<ForwardIterator>::value, "");
+ template <typename ForwardIt>
+ void AssignForwardRange(ForwardIt first, ForwardIt last) {
+ static_assert(IsAtLeastForwardIterator<ForwardIt>::value, "");
auto length = std::distance(first, last);
@@ -1134,9 +1144,9 @@ class InlinedVector {
}
}
- template <typename ForwardIterator>
- void AppendForwardRange(ForwardIterator first, ForwardIterator last) {
- static_assert(IsAtLeastForwardIterator<ForwardIterator>::value, "");
+ template <typename ForwardIt>
+ void AppendForwardRange(ForwardIt first, ForwardIt last) {
+ static_assert(IsAtLeastForwardIterator<ForwardIt>::value, "");
auto length = std::distance(first, last);
reserve(size() + length);
@@ -1162,10 +1172,10 @@ class InlinedVector {
return it_pair.first;
}
- template <typename ForwardIterator>
- iterator InsertWithForwardRange(const_iterator position,
- ForwardIterator first, ForwardIterator last) {
- static_assert(IsAtLeastForwardIterator<ForwardIterator>::value, "");
+ template <typename ForwardIt>
+ iterator InsertWithForwardRange(const_iterator position, ForwardIt first,
+ ForwardIt last) {
+ static_assert(IsAtLeastForwardIterator<ForwardIt>::value, "");
assert(position >= begin() && position <= end());
if (ABSL_PREDICT_FALSE(first == last))
diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h
index e2d8f364..547954f7 100644
--- a/absl/container/internal/hashtablez_sampler.h
+++ b/absl/container/internal/hashtablez_sampler.h
@@ -12,8 +12,12 @@
// See the License for the specific language governing permissions and
// limitations under the License.
//
-// This is a low level library to sample hashtables and collect runtime
-// statistics about them.
+// -----------------------------------------------------------------------------
+// File: hashtablez_sampler.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines the API for a low level library to sample hashtables
+// and collect runtime statistics about them.
//
// `HashtablezSampler` controls the lifecycle of `HashtablezInfo` objects which
// store information about a single sample.
@@ -22,6 +26,16 @@
// `Sample()` and `Unsample()` make use of a single global sampler with
// properties controlled by the flags hashtablez_enabled,
// hashtablez_sample_rate, and hashtablez_max_samples.
+//
+// WARNING
+//
+// Using this sampling API may cause sampled Swiss tables to use the global
+// allocator (operator `new`) in addition to any custom allocator. If you
+// are using a table in an unusual circumstance where allocation or calling a
+// linux syscall is unacceptable, this could interfere.
+//
+//
+// This utility is internal-only. Use at your own risk.
#ifndef ABSL_CONTAINER_INTERNAL_HASHTABLEZ_SAMPLER_H_
#define ABSL_CONTAINER_INTERNAL_HASHTABLEZ_SAMPLER_H_