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-rw-r--r--absl/hash/internal/spy_hash_state.h24
-rw-r--r--absl/strings/BUILD.bazel1
-rw-r--r--absl/strings/CMakeLists.txt1
-rw-r--r--absl/strings/cord_test.cc21
4 files changed, 35 insertions, 12 deletions
diff --git a/absl/hash/internal/spy_hash_state.h b/absl/hash/internal/spy_hash_state.h
index 09728266..357c301c 100644
--- a/absl/hash/internal/spy_hash_state.h
+++ b/absl/hash/internal/spy_hash_state.h
@@ -149,20 +149,20 @@ class SpyHashStateImpl : public HashStateBase<SpyHashStateImpl<T>> {
const unsigned char* begin,
size_t size) {
const size_t large_chunk_stride = PiecewiseChunkSize();
- if (size > large_chunk_stride) {
- // Combining a large contiguous buffer must have the same effect as
- // doing it piecewise by the stride length, followed by the (possibly
- // empty) remainder.
- while (size >= large_chunk_stride) {
- hash_state = SpyHashStateImpl::combine_contiguous(
- std::move(hash_state), begin, large_chunk_stride);
- begin += large_chunk_stride;
- size -= large_chunk_stride;
- }
+ // Combining a large contiguous buffer must have the same effect as
+ // doing it piecewise by the stride length, followed by the (possibly
+ // empty) remainder.
+ while (size > large_chunk_stride) {
+ hash_state = SpyHashStateImpl::combine_contiguous(
+ std::move(hash_state), begin, large_chunk_stride);
+ begin += large_chunk_stride;
+ size -= large_chunk_stride;
}
- hash_state.hash_representation_.emplace_back(
- reinterpret_cast<const char*>(begin), size);
+ if (size > 0) {
+ hash_state.hash_representation_.emplace_back(
+ reinterpret_cast<const char*>(begin), size);
+ }
return hash_state;
}
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index 8e8371b3..ed2ab04f 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -918,6 +918,7 @@ cc_test(
"//absl/container:fixed_array",
"//absl/functional:function_ref",
"//absl/hash",
+ "//absl/hash:hash_testing",
"//absl/log",
"//absl/log:check",
"//absl/random",
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index 1b245362..ce9c5e46 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -1072,6 +1072,7 @@ absl_cc_test(
absl::fixed_array
absl::function_ref
absl::hash
+ absl::hash_testing
absl::log
absl::optional
absl::random_random
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index f1a5f39c..69b1a69e 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -42,6 +42,7 @@
#include "absl/container/fixed_array.h"
#include "absl/functional/function_ref.h"
#include "absl/hash/hash.h"
+#include "absl/hash/hash_testing.h"
#include "absl/log/check.h"
#include "absl/log/log.h"
#include "absl/random/random.h"
@@ -2013,6 +2014,26 @@ TEST(CordTest, CordMemoryUsageBTree) {
rep2_size);
}
+TEST(CordTest, TestHashFragmentation) {
+ // Make sure we hit these boundary cases precisely.
+ EXPECT_EQ(1024, absl::hash_internal::PiecewiseChunkSize());
+ EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly({
+ absl::Cord(),
+ absl::MakeFragmentedCord({std::string(600, 'a'), std::string(600, 'a')}),
+ absl::MakeFragmentedCord({std::string(1200, 'a')}),
+ absl::MakeFragmentedCord({std::string(900, 'b'), std::string(900, 'b')}),
+ absl::MakeFragmentedCord({std::string(1800, 'b')}),
+ absl::MakeFragmentedCord(
+ {std::string(2000, 'c'), std::string(2000, 'c')}),
+ absl::MakeFragmentedCord({std::string(4000, 'c')}),
+ absl::MakeFragmentedCord({std::string(1024, 'd')}),
+ absl::MakeFragmentedCord({std::string(1023, 'd'), "d"}),
+ absl::MakeFragmentedCord({std::string(1025, 'e')}),
+ absl::MakeFragmentedCord({std::string(1024, 'e'), "e"}),
+ absl::MakeFragmentedCord({std::string(1023, 'e'), "e", "e"}),
+ }));
+}
+
// Regtest for a change that had to be rolled back because it expanded out
// of the InlineRep too soon, which was observable through MemoryUsage().
TEST_P(CordTest, CordMemoryUsageInlineRep) {