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-rw-r--r--absl/random/internal/BUILD.bazel1
-rw-r--r--absl/strings/internal/cordz_info.h5
-rw-r--r--absl/strings/internal/resize_uninitialized.h23
-rw-r--r--absl/strings/internal/resize_uninitialized_test.cc23
-rw-r--r--absl/strings/str_cat.cc8
-rw-r--r--absl/time/internal/cctz/src/time_zone_format_test.cc4
6 files changed, 57 insertions, 7 deletions
diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel
index 612b1505..90efe85a 100644
--- a/absl/random/internal/BUILD.bazel
+++ b/absl/random/internal/BUILD.bazel
@@ -717,7 +717,6 @@ cc_test(
cc_test(
name = "iostream_state_saver_test",
- size = "small",
srcs = ["iostream_state_saver_test.cc"],
linkopts = ABSL_DEFAULT_LINKOPTS,
deps = [
diff --git a/absl/strings/internal/cordz_info.h b/absl/strings/internal/cordz_info.h
index 13aaee17..026d5b99 100644
--- a/absl/strings/internal/cordz_info.h
+++ b/absl/strings/internal/cordz_info.h
@@ -158,6 +158,11 @@ class ABSL_LOCKABLE CordzInfo : public CordzHandle {
return rep_;
}
+ // Sets the current value of `rep_` for testing purposes only.
+ void SetCordRepForTesting(CordRep* rep) ABSL_NO_THREAD_SAFETY_ANALYSIS {
+ rep_ = rep;
+ }
+
// Returns the stack trace for where the cord was first sampled. Cords are
// potentially sampled when they promote from an inlined cord to a tree or
// ring representation, which is not necessarily the location where the cord
diff --git a/absl/strings/internal/resize_uninitialized.h b/absl/strings/internal/resize_uninitialized.h
index e42628e3..749c66e7 100644
--- a/absl/strings/internal/resize_uninitialized.h
+++ b/absl/strings/internal/resize_uninitialized.h
@@ -17,6 +17,7 @@
#ifndef ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
#define ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
+#include <algorithm>
#include <string>
#include <type_traits>
#include <utility>
@@ -66,6 +67,28 @@ inline void STLStringResizeUninitialized(string_type* s, size_t new_size) {
ResizeUninitializedTraits<string_type>::Resize(s, new_size);
}
+// Used to ensure exponential growth so that the amortized complexity of
+// increasing the string size by a small amount is O(1), in contrast to
+// O(str->size()) in the case of precise growth.
+template <typename string_type>
+void STLStringReserveAmortized(string_type* s, size_t new_size) {
+ const size_t cap = s->capacity();
+ if (new_size > cap) {
+ // Make sure to always grow by at least a factor of 2x.
+ s->reserve((std::max)(new_size, 2 * cap));
+ }
+}
+
+// Like STLStringResizeUninitialized(str, new_size), except guaranteed to use
+// exponential growth so that the amortized complexity of increasing the string
+// size by a small amount is O(1), in contrast to O(str->size()) in the case of
+// precise growth.
+template <typename string_type>
+void STLStringResizeUninitializedAmortized(string_type* s, size_t new_size) {
+ STLStringReserveAmortized(s, new_size);
+ STLStringResizeUninitialized(s, new_size);
+}
+
} // namespace strings_internal
ABSL_NAMESPACE_END
} // namespace absl
diff --git a/absl/strings/internal/resize_uninitialized_test.cc b/absl/strings/internal/resize_uninitialized_test.cc
index 0f8b3c2a..01ee476b 100644
--- a/absl/strings/internal/resize_uninitialized_test.cc
+++ b/absl/strings/internal/resize_uninitialized_test.cc
@@ -24,11 +24,13 @@ int resize_call_count = 0;
// resize() method has been called.
struct resizable_string {
size_t size() const { return 0; }
+ size_t capacity() const { return 0; }
char& operator[](size_t) {
static char c = '\0';
return c;
}
void resize(size_t) { resize_call_count += 1; }
+ void reserve(size_t) {}
};
int resize_default_init_call_count = 0;
@@ -37,12 +39,14 @@ int resize_default_init_call_count = 0;
// resize() and __resize_default_init() methods have been called.
struct resize_default_init_string {
size_t size() const { return 0; }
+ size_t capacity() const { return 0; }
char& operator[](size_t) {
static char c = '\0';
return c;
}
void resize(size_t) { resize_call_count += 1; }
void __resize_default_init(size_t) { resize_default_init_call_count += 1; }
+ void reserve(size_t) {}
};
TEST(ResizeUninit, WithAndWithout) {
@@ -60,6 +64,9 @@ TEST(ResizeUninit, WithAndWithout) {
absl::strings_internal::STLStringResizeUninitialized(&rs, 237);
EXPECT_EQ(resize_call_count, 1);
EXPECT_EQ(resize_default_init_call_count, 0);
+ absl::strings_internal::STLStringResizeUninitializedAmortized(&rs, 1000);
+ EXPECT_EQ(resize_call_count, 2);
+ EXPECT_EQ(resize_default_init_call_count, 0);
}
resize_call_count = 0;
@@ -76,7 +83,23 @@ TEST(ResizeUninit, WithAndWithout) {
absl::strings_internal::STLStringResizeUninitialized(&rus, 237);
EXPECT_EQ(resize_call_count, 0);
EXPECT_EQ(resize_default_init_call_count, 1);
+ absl::strings_internal::STLStringResizeUninitializedAmortized(&rus, 1000);
+ EXPECT_EQ(resize_call_count, 0);
+ EXPECT_EQ(resize_default_init_call_count, 2);
+ }
+}
+
+TEST(ResizeUninit, Amortized) {
+ std::string str;
+ size_t prev_cap = str.capacity();
+ int cap_increase_count = 0;
+ for (int i = 0; i < 1000; ++i) {
+ absl::strings_internal::STLStringResizeUninitializedAmortized(&str, i);
+ size_t new_cap = str.capacity();
+ if (new_cap > prev_cap) ++cap_increase_count;
+ prev_cap = new_cap;
}
+ EXPECT_LT(cap_increase_count, 50);
}
} // namespace
diff --git a/absl/strings/str_cat.cc b/absl/strings/str_cat.cc
index dd5d25b0..f4a77493 100644
--- a/absl/strings/str_cat.cc
+++ b/absl/strings/str_cat.cc
@@ -174,7 +174,7 @@ void AppendPieces(std::string* dest,
ASSERT_NO_OVERLAP(*dest, piece);
total_size += piece.size();
}
- strings_internal::STLStringResizeUninitialized(dest, total_size);
+ strings_internal::STLStringResizeUninitializedAmortized(dest, total_size);
char* const begin = &(*dest)[0];
char* out = begin + old_size;
@@ -199,7 +199,7 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b) {
ASSERT_NO_OVERLAP(*dest, a);
ASSERT_NO_OVERLAP(*dest, b);
std::string::size_type old_size = dest->size();
- strings_internal::STLStringResizeUninitialized(
+ strings_internal::STLStringResizeUninitializedAmortized(
dest, old_size + a.size() + b.size());
char* const begin = &(*dest)[0];
char* out = begin + old_size;
@@ -214,7 +214,7 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b,
ASSERT_NO_OVERLAP(*dest, b);
ASSERT_NO_OVERLAP(*dest, c);
std::string::size_type old_size = dest->size();
- strings_internal::STLStringResizeUninitialized(
+ strings_internal::STLStringResizeUninitializedAmortized(
dest, old_size + a.size() + b.size() + c.size());
char* const begin = &(*dest)[0];
char* out = begin + old_size;
@@ -231,7 +231,7 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b,
ASSERT_NO_OVERLAP(*dest, c);
ASSERT_NO_OVERLAP(*dest, d);
std::string::size_type old_size = dest->size();
- strings_internal::STLStringResizeUninitialized(
+ strings_internal::STLStringResizeUninitializedAmortized(
dest, old_size + a.size() + b.size() + c.size() + d.size());
char* const begin = &(*dest)[0];
char* out = begin + old_size;
diff --git a/absl/time/internal/cctz/src/time_zone_format_test.cc b/absl/time/internal/cctz/src/time_zone_format_test.cc
index a11f93e2..294f2e22 100644
--- a/absl/time/internal/cctz/src/time_zone_format_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_format_test.cc
@@ -1135,7 +1135,7 @@ TEST(Parse, ExtendedSeconds) {
// All %E<prec>S cases are treated the same as %E*S on input.
auto precisions = {"*", "0", "1", "2", "3", "4", "5", "6", "7",
"8", "9", "10", "11", "12", "13", "14", "15"};
- for (const std::string& prec : precisions) {
+ for (const std::string prec : precisions) {
const std::string fmt = "%E" + prec + "S";
SCOPED_TRACE(fmt);
time_point<chrono::nanoseconds> tp = unix_epoch;
@@ -1217,7 +1217,7 @@ TEST(Parse, ExtendedSubeconds) {
// All %E<prec>f cases are treated the same as %E*f on input.
auto precisions = {"*", "0", "1", "2", "3", "4", "5", "6", "7",
"8", "9", "10", "11", "12", "13", "14", "15"};
- for (const std::string& prec : precisions) {
+ for (const std::string prec : precisions) {
const std::string fmt = "%E" + prec + "f";
SCOPED_TRACE(fmt);
time_point<chrono::nanoseconds> tp = unix_epoch - chrono::seconds(1);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-15 03:31:31 +0000