Export of internal Abseil changes

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6e9f93888bbe6718997ed90bbd049f1f3572b066 by Abseil Team <absl-team@google.com>:

Fix status to be safe for self move assignment.

PiperOrigin-RevId: 346815392

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35cae74a977f258e81dfbe925fb5a34cb6632036 by Gennadiy Rozental <rogeeff@google.com>:

Eliminate unnecessary access to the global vars.

PiperOrigin-RevId: 346777168

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e7e786c243069060f5d6c1c945decb4b0b83f95b by Andy Getzendanner <durandal@google.com>:

Internal change.

PiperOrigin-RevId: 346685656

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4ccd41c48f1a83cfa20b3ea534f743dd7d788376 by Abseil Team <absl-team@google.com>:

Move CordRep Ref() and Unref() logic into cord_internal.h

This change moves Ref() and Unref() logic out of cord.cc into cord_internal. The main purpose is to make upcoming ring buffer changes easier to isolate from existing cord.cc code. Notice that this removes the nullptr check from Unref() and now requires it to be non null (which held true most times). We may need to rethink if the 'unref unlikely one' is the common case: are cordreps most likely shared? This may be something between 'root' and non root nodes, i.e., is it more likely for leaf / flat nodes in large cords to be shared than top level cordreps being shared? Vice versa? Benchmarks say that we mostly shouldn't care, the caveat being that atomic ops seem more expensive on upcoming archs (arcadia) so we should error on the side of an extra IsOne() branch saving us single owned atomic ops.

PiperOrigin-RevId: 346676121

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f0babab103b9e60d61ba09482d468985e43eceb3 by Samuel Benzaquen <sbenza@google.com>:

Fix iterator based constructor and `.insert` members to only require
EmplaceConstructible as the standard specifies.

PiperOrigin-RevId: 346616707

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8f48eedda02277f9c96a88ed7726e34b557cce20 by Evan Brown <ezb@google.com>:

Fix a bug in binary_search_impl when there's a transparent, three-way comparator that has different equivalence classes for different lookup types.

Add a new can_have_multiple_equivalent_keys method to share the common logic for these cases.

PiperOrigin-RevId: 346605948

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649183cb3cc9383431de9c81fb1c0f885d4001ae by Abseil Team <absl-team@google.com>:

Add benchmark for accessing a Duration flag.

PiperOrigin-RevId: 346594843

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fefdb046520871af63ce2229e2f7cccfc0483dea by Abseil Team <absl-team@google.com>:

Restructure CordReader for upcoming ring buffer changes.

PiperOrigin-RevId: 346410642

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8b2f50e7da0ebab06ead5f94e366e984ca23cb6a by Abseil Team <absl-team@google.com>:

Wire in an internal-only flag to toggle upcoming ring buffer changes on/off for experimentation.

PiperOrigin-RevId: 346199111
GitOrigin-RevId: 6e9f93888bbe6718997ed90bbd049f1f3572b066
Change-Id: I8f34866b25a79209cb5448bbb28dd3044111d2e9

2 files changed, 17 insertions, 0 deletions

diff --git a/absl/time/BUILD.bazel b/absl/time/BUILD.bazel
index 991241a0..3e25ca26 100644
--- a/absl/time/BUILD.bazel
+++ b/absl/time/BUILD.bazel
@@ -119,6 +119,7 @@ cc_test(
         ":time",
         "//absl/base",
         "//absl/base:core_headers",
+        "//absl/flags:flag",
         "//absl/hash",
         "@com_github_google_benchmark//:benchmark_main",
     ],
diff --git a/absl/time/duration_benchmark.cc b/absl/time/duration_benchmark.cc
index 83a836c8..56820f37 100644
--- a/absl/time/duration_benchmark.cc
+++ b/absl/time/duration_benchmark.cc
@@ -18,9 +18,14 @@
 #include <string>
 
 #include "absl/base/attributes.h"
+#include "absl/flags/flag.h"
 #include "absl/time/time.h"
 #include "benchmark/benchmark.h"
 
+ABSL_FLAG(absl::Duration, absl_duration_flag_for_benchmark,
+          absl::Milliseconds(1),
+          "Flag to use for benchmarking duration flag access speed.");
+
 namespace {
 
 //
@@ -425,4 +430,15 @@ void BM_Duration_ParseDuration(benchmark::State& state) {
 }
 BENCHMARK(BM_Duration_ParseDuration)->DenseRange(0, kNumDurations - 1);
 
+//
+// Flag access
+//
+void BM_Duration_GetFlag(benchmark::State& state) {
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(
+        absl::GetFlag(FLAGS_absl_duration_flag_for_benchmark));
+  }
+}
+BENCHMARK(BM_Duration_GetFlag);
+
 }  // namespace