From 20fb601aa9f68ff0aa147df22524b7d01758552b Mon Sep 17 00:00:00 2001 From: Richard Cole Date: Sun, 24 Jan 2016 18:10:16 -0800 Subject: [PATCH] Fix snapshot compaction bug Closes google/leveldb#320 During compaction it was possible that records from a block b1=(l1,u1) would be pushed down from level i to level i+1. If there is a block b2=(l2,u2) at level i with k1 = user_key(u1) = user_key(l2) then a subsequent search for k1 will yield the record l2 which has a smaller sequence number than u1 because the sort order for records sorts increasing by user key but decreaing by sequence number. This change add a call to a new function AddBoundaryInputs to SetupOtherInputs. AddBoundaryInputs searches for a block b2 matching the criteria above and adds it to the set of files to be compacted. Whenever AddBoundaryInputs is called it is important that the compaction fileset in level i+1 (known as c->inputs_[1] in the code) be recomputed. Each call to AddBoundaryInputs is followed by a call to GetOverlappingInputs. SetupOtherInputs is called on both manual and automated compaction passes. It is called for both level zero and for levels greater than 0. The original change posted in https://github.com/google/leveldb/pull/339 has been modified to also include changed made by Chris Mumford in https://github.com/cmumford/leveldb/commit/4b72cb14f8da2aab12451c24b8e205aff686e9dc 1. Releasing snapshots during test cleanup to avoid memory leak warnings. 2. Refactored test to use testutil.h to be in line with other issue tests and to create the test database in the correct temporary location. 3. Added copyright banner. Otherwise, just minor formatting and limiting character width to 80 characters. Additionally the change was rebased on top of current master and changes previously made to the Makefile were ported to the CMakeLists.txt. Testing Done: A test program (issue320_test) was constructed that performs mutations while snapshots are active. issue320_test fails without this bug fix after 64k writes. It passes with this bug fix. It was run with 200M writes and passed. Unit tests were written for the new function that was added to the code. Make test was run and seen to pass. Signed-off-by: Richard Cole --- CMakeLists.txt | 1 + db/version_set.cc | 79 ++++++++++++++++++++++++++ db/version_set_test.cc | 148 +++++++++++++++++++++++++++++++++++++++++++++++- issues/issue320_test.cc | 139 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 366 insertions(+), 1 deletion(-) create mode 100644 issues/issue320_test.cc diff --git a/CMakeLists.txt b/CMakeLists.txt index 934f15a..aada6b7 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -296,6 +296,7 @@ if(LEVELDB_BUILD_TESTS) leveldb_test("${PROJECT_SOURCE_DIR}/issues/issue178_test.cc") leveldb_test("${PROJECT_SOURCE_DIR}/issues/issue200_test.cc") + leveldb_test("${PROJECT_SOURCE_DIR}/issues/issue320_test.cc") leveldb_test("${PROJECT_SOURCE_DIR}/util/env_test.cc") leveldb_test("${PROJECT_SOURCE_DIR}/util/status_test.cc") diff --git a/db/version_set.cc b/db/version_set.cc index 156a007..7891dfc 100644 --- a/db/version_set.cc +++ b/db/version_set.cc @@ -1347,9 +1347,87 @@ Compaction* VersionSet::PickCompaction() { return c; } +// find the largest key in a vector of files. returns true if files it not empty +bool FindLargestKey(const InternalKeyComparator & icmp, const std::vector & files, InternalKey *largestKey) { + if (files.empty()) { + return false; + } + *largestKey = files[0]->largest; + for (size_t i = 1; i < files.size(); ++i) { + FileMetaData* f = files[i]; + if (icmp.Compare(f->largest, *largestKey) > 0) { + *largestKey = f->largest; + } + } + return true; +} + +// find minimum file b2=(l2, u2) in level file for which l2 > u1 and user_key(l2) = user_key(u1) +FileMetaData* FindSmallestBoundaryFile(const InternalKeyComparator & icmp, + const std::vector & levelFiles, + const InternalKey & largestKey) { + const Comparator* user_cmp = icmp.user_comparator(); + FileMetaData* smallestBoundaryFile = NULL; + for (size_t i = 0; i < levelFiles.size(); ++i) { + FileMetaData* f = levelFiles[i]; + if (icmp.Compare(f->smallest, largestKey) > 0 && + user_cmp->Compare(f->smallest.user_key(), largestKey.user_key()) == 0) { + if (smallestBoundaryFile == NULL || + icmp.Compare(f->smallest, smallestBoundaryFile->smallest) < 0) { + smallestBoundaryFile = f; + } + } + } + return smallestBoundaryFile; +} + +// If there are two blocks, b1=(l1, u1) and b2=(l2, u2) and +// user_key(u1) = user_key(l2), and if we compact b1 but not +// b2 then a subsequent get operation will yield an incorrect +// result because it will return the record from b2 in level +// i rather than from b1 because it searches level by level +// for records matching the supplied user key. +// +// This function extracts the largest file b1 from compactionFiles +// and then searches for a b2 in levelFiles for which user_key(u1) = +// user_key(l2). If it finds such a file b2 (known as a boundary file) +// it adds it to compactionFiles and then searches again using this +// new upper bound. +// +// parameters: +// in levelFiles: list of files to search for boundary files +// in/out compactionFiles: list of files to extend by adding boundary files +void AddBoundaryInputs(const InternalKeyComparator& icmp, + const std::vector& levelFiles, + std::vector* compactionFiles) { + InternalKey largestKey; + + // find largestKey in compactionFiles, quick return if compactionFiles is + // empty + if (!FindLargestKey(icmp, *compactionFiles, &largestKey)) { + return; + } + + bool continueSearching = true; + while (continueSearching) { + FileMetaData* smallestBoundaryFile = + FindSmallestBoundaryFile(icmp, levelFiles, largestKey); + + // if a boundary file was found advance largestKey, otherwise we're done + if (smallestBoundaryFile != NULL) { + compactionFiles->push_back(smallestBoundaryFile); + largestKey = smallestBoundaryFile->largest; + } else { + continueSearching = false; + } + } +} + void VersionSet::SetupOtherInputs(Compaction* c) { const int level = c->level(); InternalKey smallest, largest; + + AddBoundaryInputs(icmp_, current_->files_[level], &c->inputs_[0]); GetRange(c->inputs_[0], &smallest, &largest); current_->GetOverlappingInputs(level+1, &smallest, &largest, &c->inputs_[1]); @@ -1363,6 +1441,7 @@ void VersionSet::SetupOtherInputs(Compaction* c) { if (!c->inputs_[1].empty()) { std::vector expanded0; current_->GetOverlappingInputs(level, &all_start, &all_limit, &expanded0); + AddBoundaryInputs(icmp_, current_->files_[level], &expanded0); const int64_t inputs0_size = TotalFileSize(c->inputs_[0]); const int64_t inputs1_size = TotalFileSize(c->inputs_[1]); const int64_t expanded0_size = TotalFileSize(expanded0); diff --git a/db/version_set_test.cc b/db/version_set_test.cc index d21433e..090f115 100644 --- a/db/version_set_test.cc +++ b/db/version_set_test.cc @@ -172,7 +172,153 @@ TEST(FindFileTest, OverlappingFiles) { ASSERT_TRUE(Overlaps("600", "700")); } -} // namespace leveldb +void AddBoundaryInputs(const InternalKeyComparator &icmp, + const std::vector &levelFiles, + std::vector *compactionFiles); + +class AddBoundaryInputsTest { + public: + std::vector levelFiles_; + std::vector compactionFiles_; + std::vector allFiles_; + InternalKeyComparator icmp_; + + AddBoundaryInputsTest() : icmp_(BytewiseComparator()){}; + + ~AddBoundaryInputsTest() { + for (size_t i = 0; i < allFiles_.size(); ++i) { + delete allFiles_[i]; + } + allFiles_.clear(); + }; + + FileMetaData *CreateFileMetaData(uint64_t number, InternalKey smallest, + InternalKey largest) { + FileMetaData *f = new FileMetaData(); + f->number = number; + f->smallest = smallest; + f->largest = largest; + allFiles_.push_back(f); + return f; + } +}; + +TEST(AddBoundaryInputsTest, TestEmptyFileSets) { + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_TRUE(compactionFiles_.empty()); + ASSERT_TRUE(levelFiles_.empty()); +} + +TEST(AddBoundaryInputsTest, TestEmptyLevelFiles) { + FileMetaData *f1 = + CreateFileMetaData(1, InternalKey("100", 2, kTypeValue), + InternalKey(InternalKey("100", 1, kTypeValue))); + compactionFiles_.push_back(f1); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_EQ(1, compactionFiles_.size()); + ASSERT_EQ(f1, compactionFiles_[0]); + ASSERT_TRUE(levelFiles_.empty()); +} + +TEST(AddBoundaryInputsTest, TestEmptyCompactionFiles) { + FileMetaData *f1 = + CreateFileMetaData(1, InternalKey("100", 2, kTypeValue), + InternalKey(InternalKey("100", 1, kTypeValue))); + levelFiles_.push_back(f1); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_TRUE(compactionFiles_.empty()); + ASSERT_EQ(1, levelFiles_.size()); + ASSERT_EQ(f1, levelFiles_[0]); +} + +TEST(AddBoundaryInputsTest, TestNoBoundaryFiles) { + FileMetaData *f1 = + CreateFileMetaData(1, InternalKey("100", 2, kTypeValue), + InternalKey(InternalKey("100", 1, kTypeValue))); + FileMetaData *f2 = + CreateFileMetaData(1, InternalKey("200", 2, kTypeValue), + InternalKey(InternalKey("200", 1, kTypeValue))); + FileMetaData *f3 = + CreateFileMetaData(1, InternalKey("300", 2, kTypeValue), + InternalKey(InternalKey("300", 1, kTypeValue))); + + levelFiles_.push_back(f3); + levelFiles_.push_back(f2); + levelFiles_.push_back(f1); + compactionFiles_.push_back(f2); + compactionFiles_.push_back(f3); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_EQ(2, compactionFiles_.size()); +} + +TEST(AddBoundaryInputsTest, TestOneBoundaryFiles) { + FileMetaData *f1 = + CreateFileMetaData(1, InternalKey("100", 3, kTypeValue), + InternalKey(InternalKey("100", 2, kTypeValue))); + FileMetaData *f2 = + CreateFileMetaData(1, InternalKey("100", 1, kTypeValue), + InternalKey(InternalKey("200", 3, kTypeValue))); + FileMetaData *f3 = + CreateFileMetaData(1, InternalKey("300", 2, kTypeValue), + InternalKey(InternalKey("300", 1, kTypeValue))); + + levelFiles_.push_back(f3); + levelFiles_.push_back(f2); + levelFiles_.push_back(f1); + compactionFiles_.push_back(f1); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_EQ(2, compactionFiles_.size()); + ASSERT_EQ(f1, compactionFiles_[0]); + ASSERT_EQ(f2, compactionFiles_[1]); +} + +TEST(AddBoundaryInputsTest, TestTwoBoundaryFiles) { + FileMetaData *f1 = + CreateFileMetaData(1, InternalKey("100", 6, kTypeValue), + InternalKey(InternalKey("100", 5, kTypeValue))); + FileMetaData *f2 = + CreateFileMetaData(1, InternalKey("100", 2, kTypeValue), + InternalKey(InternalKey("300", 1, kTypeValue))); + FileMetaData *f3 = + CreateFileMetaData(1, InternalKey("100", 4, kTypeValue), + InternalKey(InternalKey("100", 3, kTypeValue))); + + levelFiles_.push_back(f2); + levelFiles_.push_back(f3); + levelFiles_.push_back(f1); + compactionFiles_.push_back(f1); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_EQ(3, compactionFiles_.size()); + ASSERT_EQ(f1, compactionFiles_[0]); + ASSERT_EQ(f3, compactionFiles_[1]); + ASSERT_EQ(f2, compactionFiles_[2]); +} + +TEST(AddBoundaryInputsTest, TestDisjoinFilePointers) { + FileMetaData *f1 = CreateFileMetaData(1, InternalKey("100", 6, kTypeValue), InternalKey(InternalKey("100", 5, kTypeValue))); + FileMetaData *f2 = CreateFileMetaData(1, InternalKey("100", 6, kTypeValue), InternalKey(InternalKey("100", 5, kTypeValue))); + FileMetaData *f3 = CreateFileMetaData(1, InternalKey("100", 2, kTypeValue), InternalKey(InternalKey("300", 1, kTypeValue))); + FileMetaData *f4 = CreateFileMetaData(1, InternalKey("100", 4, kTypeValue), InternalKey(InternalKey("100", 3, kTypeValue))); + + levelFiles_.push_back(f2); + levelFiles_.push_back(f3); + levelFiles_.push_back(f4); + + compactionFiles_.push_back(f1); + + AddBoundaryInputs(icmp_, levelFiles_, &compactionFiles_); + ASSERT_EQ(3, compactionFiles_.size()); + ASSERT_EQ(f1, compactionFiles_[0]); + ASSERT_EQ(f4, compactionFiles_[1]); + ASSERT_EQ(f3, compactionFiles_[2]); +} + +} // namespace leveldb int main(int argc, char** argv) { return leveldb::test::RunAllTests(); diff --git a/issues/issue320_test.cc b/issues/issue320_test.cc new file mode 100644 index 0000000..619ddb5 --- /dev/null +++ b/issues/issue320_test.cc @@ -0,0 +1,139 @@ +// Copyright (c) 2019 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. +#include +#include +#include +#include +#include +#include + +#include + +#include +#include +#include + +using namespace std; + +namespace leveldb { + +namespace { + +unsigned int random(unsigned int max) { + return std::rand() % max; +} + +string newString(int32_t index) { + const unsigned int len = 1024; + char bytes[len]; + unsigned int i = 0; + while (i < 8) { + bytes[i] = 'a' + ((index >> (4 * i)) & 0xf); + ++i; + } + while (i < sizeof(bytes)) { + bytes[i] = 'a' + random(26); + ++i; + } + return string(bytes, sizeof(bytes)); +} + +} // namespace + +class Issue320 { }; + +TEST(Issue320, Test) { + std::srand(0); + + bool delete_before_put = false; + bool keep_snapshots = true; + + vector*> test_map(10000, nullptr); + vector snapshots(100, nullptr); + + DB* db; + Options options; + options.create_if_missing = true; + + std::string dbpath = test::TmpDir() + "/leveldb_issue320_test"; + ASSERT_OK(DB::Open(options, dbpath, &db)); + + unsigned int target_size = 10000; + unsigned int num_items = 0; + unsigned long count = 0; + string key; + string value, old_value; + + WriteOptions writeOptions; + ReadOptions readOptions; + while (count < 200000) { + if ((++count % 1000) == 0) { + cout << "count: " << count << endl; + } + + unsigned int index = random(test_map.size()); + WriteBatch batch; + + if (test_map[index] == nullptr) { + num_items++; + test_map[index] = + new pair(newString(index), newString(index)); + batch.Put(test_map[index]->first, test_map[index]->second); + } else { + ASSERT_OK(db->Get(readOptions, test_map[index]->first, &old_value)); + if (old_value != test_map[index]->second) { + cout << "ERROR incorrect value returned by Get" << endl; + cout << " count=" << count << endl; + cout << " old value=" << old_value << endl; + cout << " test_map[index]->second=" << test_map[index]->second << endl; + cout << " test_map[index]->first=" << test_map[index]->first << endl; + cout << " index=" << index << endl; + ASSERT_EQ(old_value, test_map[index]->second); + } + + if (num_items >= target_size && random(100) > 30) { + batch.Delete(test_map[index]->first); + delete test_map[index]; + test_map[index] = nullptr; + --num_items; + } else { + test_map[index]->second = newString(index); + if (delete_before_put) batch.Delete(test_map[index]->first); + batch.Put(test_map[index]->first, test_map[index]->second); + } + } + + ASSERT_OK(db->Write(writeOptions, &batch)); + + if (keep_snapshots && random(10) == 0) { + unsigned int i = random(snapshots.size()); + if (snapshots[i] != nullptr) { + db->ReleaseSnapshot(snapshots[i]); + } + snapshots[i] = db->GetSnapshot(); + } + } + + for (Snapshot const* snapshot : snapshots) { + if (snapshot) { + db->ReleaseSnapshot(snapshot); + } + } + + for (size_t i = 0; i < test_map.size(); ++i) { + if (test_map[i] != nullptr) { + delete test_map[i]; + test_map[i] = nullptr; + } + } + + delete db; + DestroyDB(dbpath, options); +} + +} // namespace leveldb + +int main(int argc, char** argv) { + return leveldb::test::RunAllTests(); +}