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authorGravatar Abseil Team <absl-team@google.com>2021-02-10 08:52:54 -0800
committerGravatar Derek Mauro <dmauro@google.com>2021-02-10 17:01:18 -0500
commit1d1ad2292bb5c7be26074e516b4cc70d9cc469f9 (patch)
tree698d051a6c78c3b64e71b245d62a7ca80ee5b66a /absl
parent2aa00ab2f22cf4e0e85e622c3254d483b2ddfb30 (diff)
Export of internal Abseil changes
-- f9476c95cf7625d7b0fc4661f253b0aac4341044 by Abseil Team <absl-team@google.com>: Add a test to verify that the new checksum field in Hashtablez is calculated PiperOrigin-RevId: 356744293 -- ff8a3612463000e8c3d451e50367a3c65cb6cf21 by Abseil Team <absl-team@google.com>: Remove the implied support comment for port.h, attributes.h, and integral_types.h's C compatibility from the header documentations. Abseil-cpp is a C++ library; this brings port.h, attributes.h, and integral_types.h, into our stance for the rest of Abseil (aka, no assurance of C compatibility) There is no guarantee that future changes to port.h, attributes.h, and integral_types.h, and their dependencies, will remain compatible with C, even for macros and definitions that currently are. PiperOrigin-RevId: 356727505 -- be62292016381deee628dbb3f36cb6009bcc0282 by Abseil Team <absl-team@google.com>: internal change PiperOrigin-RevId: 356608125 -- 13b35f17171df3d6853ea7088797b3be611505fc by Evan Brown <ezb@google.com>: Clarify the comments for CapacityToGrowth/GrowthToLowerboundCapacity methods to specify the intent that capacity should equal growth when `capacity+1 < kWidth`. Also add testing for this behavior. PiperOrigin-RevId: 356579041 GitOrigin-RevId: f9476c95cf7625d7b0fc4661f253b0aac4341044 Change-Id: Iadd094d109b4869998f2427319ef66d1cf1e8eff
Diffstat (limited to 'absl')
-rw-r--r--absl/base/attributes.h2
-rw-r--r--absl/base/port.h1
-rw-r--r--absl/container/internal/raw_hash_set.h14
-rw-r--r--absl/container/internal/raw_hash_set_test.cc34
-rw-r--r--absl/status/status_test.cc1
5 files changed, 40 insertions, 12 deletions
diff --git a/absl/base/attributes.h b/absl/base/attributes.h
index f14f7bb0..faa5b27e 100644
--- a/absl/base/attributes.h
+++ b/absl/base/attributes.h
@@ -18,8 +18,6 @@
// These macros are used within Abseil and allow the compiler to optimize, where
// applicable, certain function calls.
//
-// This file is used for both C and C++!
-//
// Most macros here are exposing GCC or Clang features, and are stubbed out for
// other compilers.
//
diff --git a/absl/base/port.h b/absl/base/port.h
index 6c28068d..5bc4d6cd 100644
--- a/absl/base/port.h
+++ b/absl/base/port.h
@@ -14,7 +14,6 @@
//
// This files is a forwarding header for other headers containing various
// portability macros and functions.
-// This file is used for both C and C++!
#ifndef ABSL_BASE_PORT_H_
#define ABSL_BASE_PORT_H_
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 74b2ef4c..80fc2cba 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -468,8 +468,16 @@ inline size_t NormalizeCapacity(size_t n) {
return n ? ~size_t{} >> countl_zero(n) : 1;
}
-// We use 7/8th as maximum load factor.
-// For 16-wide groups, that gives an average of two empty slots per group.
+// General notes on capacity/growth methods below:
+// - We use 7/8th as maximum load factor. For 16-wide groups, that gives an
+// average of two empty slots per group.
+// - For (capacity+1) >= Group::kWidth, growth is 7/8*capacity.
+// - For (capacity+1) < Group::kWidth, growth == capacity. In this case, we
+// never need to probe (the whole table fits in one group) so we don't need a
+// load factor less than 1.
+
+// Given `capacity` of the table, returns the size (i.e. number of full slots)
+// at which we should grow the capacity.
inline size_t CapacityToGrowth(size_t capacity) {
assert(IsValidCapacity(capacity));
// `capacity*7/8`
@@ -480,7 +488,7 @@ inline size_t CapacityToGrowth(size_t capacity) {
return capacity - capacity / 8;
}
// From desired "growth" to a lowerbound of the necessary capacity.
-// Might not be a valid one and required NormalizeCapacity().
+// Might not be a valid one and requires NormalizeCapacity().
inline size_t GrowthToLowerboundCapacity(size_t growth) {
// `growth*8/7`
if (Group::kWidth == 8 && growth == 7) {
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index 0fba46ff..81c4b47c 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -14,6 +14,7 @@
#include "absl/container/internal/raw_hash_set.h"
+#include <atomic>
#include <cmath>
#include <cstdint>
#include <deque>
@@ -22,6 +23,8 @@
#include <numeric>
#include <random>
#include <string>
+#include <unordered_map>
+#include <unordered_set>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
@@ -48,11 +51,10 @@ struct RawHashSetTestOnlyAccess {
namespace {
-using ::testing::DoubleNear;
using ::testing::ElementsAre;
+using ::testing::Eq;
using ::testing::Ge;
using ::testing::Lt;
-using ::testing::Optional;
using ::testing::Pair;
using ::testing::UnorderedElementsAre;
@@ -75,8 +77,14 @@ TEST(Util, GrowthAndCapacity) {
for (size_t growth = 0; growth < 10000; ++growth) {
SCOPED_TRACE(growth);
size_t capacity = NormalizeCapacity(GrowthToLowerboundCapacity(growth));
- // The capacity is large enough for `growth`
+ // The capacity is large enough for `growth`.
EXPECT_THAT(CapacityToGrowth(capacity), Ge(growth));
+ // For (capacity+1) < kWidth, growth should equal capacity.
+ if (capacity + 1 < Group::kWidth) {
+ EXPECT_THAT(CapacityToGrowth(capacity), Eq(capacity));
+ } else {
+ EXPECT_THAT(CapacityToGrowth(capacity), Lt(capacity));
+ }
if (growth != 0 && capacity > 1) {
// There is no smaller capacity that works.
EXPECT_THAT(CapacityToGrowth(capacity / 2), Lt(growth));
@@ -1875,18 +1883,34 @@ TEST(RawHashSamplerTest, Sample) {
auto& sampler = HashtablezSampler::Global();
size_t start_size = 0;
- start_size += sampler.Iterate([&](const HashtablezInfo&) { ++start_size; });
+ std::unordered_set<const HashtablezInfo*> preexisting_info;
+ start_size += sampler.Iterate([&](const HashtablezInfo& info) {
+ preexisting_info.insert(&info);
+ ++start_size;
+ });
std::vector<IntTable> tables;
for (int i = 0; i < 1000000; ++i) {
tables.emplace_back();
tables.back().insert(1);
+ tables.back().insert(i % 5);
}
size_t end_size = 0;
- end_size += sampler.Iterate([&](const HashtablezInfo&) { ++end_size; });
+ std::unordered_map<size_t, int> observed_checksums;
+ end_size += sampler.Iterate([&](const HashtablezInfo& info) {
+ if (preexisting_info.count(&info) == 0) {
+ observed_checksums[info.hashes_bitwise_xor.load(
+ std::memory_order_relaxed)]++;
+ }
+ ++end_size;
+ });
EXPECT_NEAR((end_size - start_size) / static_cast<double>(tables.size()),
0.01, 0.005);
+ EXPECT_EQ(observed_checksums.size(), 5);
+ for (const auto& [_, count] : observed_checksums) {
+ EXPECT_NEAR((100 * count) / static_cast<double>(tables.size()), 0.2, 0.05);
+ }
}
#endif // ABSL_INTERNAL_HASHTABLEZ_SAMPLE
diff --git a/absl/status/status_test.cc b/absl/status/status_test.cc
index 25333fa2..24eaed61 100644
--- a/absl/status/status_test.cc
+++ b/absl/status/status_test.cc
@@ -460,5 +460,4 @@ TEST(Status, Swap) {
test_swap(no_payload, with_payload);
test_swap(with_payload, no_payload);
}
-
} // namespace