Export of internal Abseil changes

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f825cf3feb6db06522b2b4ee785de7dfa325780d by Martijn Vels <mvels@google.com>:

Move Cordz test helpers to cordz_test_helpers library

PiperOrigin-RevId: 370059941

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5080249da6a4f5cc2b546aed48503fd028670379 by Martijn Vels <mvels@google.com>:

Add new Cordz instrumentation on AppendTree.

PiperOrigin-RevId: 369968167

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21092b889fad34ec605894e311b436d5f417456f by Benjamin Barenblat <bbaren@google.com>:

Round floats using round(x), not static_cast<int>(x + 0.5)

Adding 0.5 to an IEEE float may cause one bit of precision loss, which
is enough to change the result in certain cases. For example,

    static_cast<int>(std::round(0.49999999999999994)) == 0
    static_cast<int>(0.49999999999999994 + 0.5) == 1

PiperOrigin-RevId: 369926519
GitOrigin-RevId: f825cf3feb6db06522b2b4ee785de7dfa325780d
Change-Id: Ib78ce1faec79f06578933db5dc6fc05de043ead1

1 files changed, 129 insertions, 0 deletions

diff --git a/absl/strings/cordz_test_helpers.h b/absl/strings/cordz_test_helpers.h
new file mode 100644
index 00000000..453c2f9d
--- /dev/null
+++ b/absl/strings/cordz_test_helpers.h
@@ -0,0 +1,129 @@
+// Copyright 2021 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_CORDZ_TEST_HELPERS_H_
+#define ABSL_STRINGS_CORDZ_TEST_HELPERS_H_
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/strings/cord.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cordz_info.h"
+#include "absl/strings/internal/cordz_sample_token.h"
+#include "absl/strings/internal/cordz_statistics.h"
+#include "absl/strings/internal/cordz_update_tracker.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// Returns the CordzInfo for the cord, or nullptr if the cord is not sampled.
+inline const cord_internal::CordzInfo* GetCordzInfoForTesting(
+    const Cord& cord) {
+  return cord.contents_.cordz_info();
+}
+
+// Returns true if the provided cordz_info is in the list of sampled cords.
+inline bool CordzInfoIsListed(const cord_internal::CordzInfo* cordz_info,
+                              cord_internal::CordzSampleToken token = {}) {
+  for (const cord_internal::CordzInfo& info : token) {
+    if (cordz_info == &info) return true;
+  }
+  return false;
+}
+
+// Matcher on Cord that verifies all of:
+// - the cord is sampled
+// - the CordzInfo of the cord is listed / discoverable.
+// - the reported CordzStatistics match the cord's actual properties
+// - the cord has an (initial) UpdateTracker count of 1 for `method`
+MATCHER_P(HasValidCordzInfoOf, method, "CordzInfo matches cord") {
+  const cord_internal::CordzInfo* cord_info = GetCordzInfoForTesting(arg);
+  if (cord_info == nullptr) {
+    *result_listener << "cord is not sampled";
+    return false;
+  }
+  if (!CordzInfoIsListed(cord_info)) {
+    *result_listener << "cord is sampled, but not listed";
+    return false;
+  }
+  cord_internal::CordzStatistics stat = cord_info->GetCordzStatistics();
+  if (stat.size != arg.size()) {
+    *result_listener << "cordz size " << stat.size
+                     << " does not match cord size " << arg.size();
+    return false;
+  }
+  if (stat.update_tracker.Value(method) != 1) {
+    *result_listener << "Expected method count 1 for " << method << ", found "
+                     << stat.update_tracker.Value(method);
+    return false;
+  }
+  return true;
+}
+
+// Cordz will only update with a new rate once the previously scheduled event
+// has fired. When we disable Cordz, a long delay takes place where we won't
+// consider profiling new Cords. CordzSampleIntervalHelper will burn through
+// that interval and allow for testing that assumes that the average sampling
+// interval is a particular value.
+class CordzSamplingIntervalHelper {
+ public:
+  explicit CordzSamplingIntervalHelper(int32_t interval)
+      : orig_mean_interval_(absl::cord_internal::get_cordz_mean_interval()) {
+    absl::cord_internal::set_cordz_mean_interval(interval);
+    absl::cord_internal::cordz_set_next_sample_for_testing(interval);
+  }
+
+  ~CordzSamplingIntervalHelper() {
+    absl::cord_internal::set_cordz_mean_interval(orig_mean_interval_);
+    absl::cord_internal::cordz_set_next_sample_for_testing(orig_mean_interval_);
+  }
+
+ private:
+  int32_t orig_mean_interval_;
+};
+
+// Wrapper struct managing a small CordRep `rep`
+struct TestCordRep {
+  cord_internal::CordRepFlat* rep;
+
+  TestCordRep() {
+    rep = cord_internal::CordRepFlat::New(100);
+    rep->length = 100;
+    memset(rep->Data(), 1, 100);
+  }
+  ~TestCordRep() { cord_internal::CordRep::Unref(rep); }
+};
+
+// Wrapper struct managing a small CordRep `rep`, and
+// an InlineData `data` initialized with that CordRep.
+struct TestCordData {
+  TestCordRep rep;
+  cord_internal::InlineData data{rep.rep};
+};
+
+// Creates a Cord that is not sampled
+template <typename... Args>
+Cord UnsampledCord(Args... args) {
+  CordzSamplingIntervalHelper never(9999);
+  Cord cord(std::forward<Args>(args)...);
+  ABSL_ASSERT(GetCordzInfoForTesting(cord) == nullptr);
+  return cord;
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_CORDZ_TEST_HELPERS_H_