From 0e9921b75a0fdd639a504ec8443fc1fe801becd7 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 1 Sep 2020 09:39:43 -0700 Subject: Export of internal Abseil changes -- 23500704dd7c2642fad49f88c07ce41ebaab12e4 by Abseil Team : Change fetch_add() to store(1 + load()) As there is only one concurrent writer to the Info struct, we can avoid using the more expensive fetch_add() function. PiperOrigin-RevId: 329523785 -- 79e5018dba2e117ad89b76367165a604b3f24045 by Abseil Team : Record rehash count in hashtablez This will help identify which containers could benefit from a reserve call. PiperOrigin-RevId: 329510552 -- e327e54b805d67556f934fa7f7dc2d4e72fa066a by Abseil Team : Fix -Wsign-compare issues. These lines could theoretically have overflowed in cases of very large stack traces etc. Very unlikely, but this was causing warnings when built with -Wsign-compare, which we intend to enable with Chromium. In none of these three cases is it trivial to switch to a range-based for loop. PiperOrigin-RevId: 329415195 -- 08aca2fc75e8b3ad1201849987b64148fe48f283 by Xiaoyi Zhang : Release absl::StatusOr. PiperOrigin-RevId: 329353348 -- bf4d2a7f8b089e2adf14d32b0e39de0a981005c3 by Xiaoyi Zhang : Internal change PiperOrigin-RevId: 329337031 -- 42fa7d2fb993bbfc344954227cf1eeb801eca065 by Abseil Team : Internal change PiperOrigin-RevId: 329099807 GitOrigin-RevId: 23500704dd7c2642fad49f88c07ce41ebaab12e4 Change-Id: I6713e4ca3bb0ab2ced5e487827ae036ab8ac61f1 --- absl/container/internal/hashtablez_sampler.cc | 1 + absl/container/internal/hashtablez_sampler.h | 15 +++++++++++++-- absl/container/internal/hashtablez_sampler_test.cc | 3 +++ 3 files changed, 17 insertions(+), 2 deletions(-) (limited to 'absl/container') diff --git a/absl/container/internal/hashtablez_sampler.cc b/absl/container/internal/hashtablez_sampler.cc index 886524f1..e4484fbb 100644 --- a/absl/container/internal/hashtablez_sampler.cc +++ b/absl/container/internal/hashtablez_sampler.cc @@ -67,6 +67,7 @@ void HashtablezInfo::PrepareForSampling() { capacity.store(0, std::memory_order_relaxed); size.store(0, std::memory_order_relaxed); num_erases.store(0, std::memory_order_relaxed); + num_rehashes.store(0, std::memory_order_relaxed); max_probe_length.store(0, std::memory_order_relaxed); total_probe_length.store(0, std::memory_order_relaxed); hashes_bitwise_or.store(0, std::memory_order_relaxed); diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h index e140ee00..b2a30c9a 100644 --- a/absl/container/internal/hashtablez_sampler.h +++ b/absl/container/internal/hashtablez_sampler.h @@ -73,6 +73,7 @@ struct HashtablezInfo { std::atomic capacity; std::atomic size; std::atomic num_erases; + std::atomic num_rehashes; std::atomic max_probe_length; std::atomic total_probe_length; std::atomic hashes_bitwise_or; @@ -105,6 +106,11 @@ inline void RecordRehashSlow(HashtablezInfo* info, size_t total_probe_length) { #endif info->total_probe_length.store(total_probe_length, std::memory_order_relaxed); info->num_erases.store(0, std::memory_order_relaxed); + // There is only one concurrent writer, so `load` then `store` is sufficient + // instead of using `fetch_add`. + info->num_rehashes.store( + 1 + info->num_rehashes.load(std::memory_order_relaxed), + std::memory_order_relaxed); } inline void RecordStorageChangedSlow(HashtablezInfo* info, size_t size, @@ -113,7 +119,8 @@ inline void RecordStorageChangedSlow(HashtablezInfo* info, size_t size, info->capacity.store(capacity, std::memory_order_relaxed); if (size == 0) { // This is a clear, reset the total/num_erases too. - RecordRehashSlow(info, 0); + info->total_probe_length.store(0, std::memory_order_relaxed); + info->num_erases.store(0, std::memory_order_relaxed); } } @@ -122,7 +129,11 @@ void RecordInsertSlow(HashtablezInfo* info, size_t hash, inline void RecordEraseSlow(HashtablezInfo* info) { info->size.fetch_sub(1, std::memory_order_relaxed); - info->num_erases.fetch_add(1, std::memory_order_relaxed); + // There is only one concurrent writer, so `load` then `store` is sufficient + // instead of using `fetch_add`. + info->num_erases.store( + 1 + info->num_erases.load(std::memory_order_relaxed), + std::memory_order_relaxed); } HashtablezInfo* SampleSlow(int64_t* next_sample); diff --git a/absl/container/internal/hashtablez_sampler_test.cc b/absl/container/internal/hashtablez_sampler_test.cc index b4c4ff92..04a26cb7 100644 --- a/absl/container/internal/hashtablez_sampler_test.cc +++ b/absl/container/internal/hashtablez_sampler_test.cc @@ -76,6 +76,7 @@ TEST(HashtablezInfoTest, PrepareForSampling) { EXPECT_EQ(info.capacity.load(), 0); EXPECT_EQ(info.size.load(), 0); EXPECT_EQ(info.num_erases.load(), 0); + EXPECT_EQ(info.num_rehashes.load(), 0); EXPECT_EQ(info.max_probe_length.load(), 0); EXPECT_EQ(info.total_probe_length.load(), 0); EXPECT_EQ(info.hashes_bitwise_or.load(), 0); @@ -95,6 +96,7 @@ TEST(HashtablezInfoTest, PrepareForSampling) { EXPECT_EQ(info.capacity.load(), 0); EXPECT_EQ(info.size.load(), 0); EXPECT_EQ(info.num_erases.load(), 0); + EXPECT_EQ(info.num_rehashes.load(), 0); EXPECT_EQ(info.max_probe_length.load(), 0); EXPECT_EQ(info.total_probe_length.load(), 0); EXPECT_EQ(info.hashes_bitwise_or.load(), 0); @@ -167,6 +169,7 @@ TEST(HashtablezInfoTest, RecordRehash) { EXPECT_EQ(info.size.load(), 2); EXPECT_EQ(info.total_probe_length.load(), 3); EXPECT_EQ(info.num_erases.load(), 0); + EXPECT_EQ(info.num_rehashes.load(), 1); } #if defined(ABSL_HASHTABLEZ_SAMPLE) -- cgit v1.2.3