Fix clang analyzer errors

Summary:
Fixing erros reported by clang static analyzer.
* Removing some unused variables.
* Adding assertions to fix false positives reported by clang analyzer.
* Adding `__clang_analyzer__` macro to suppress false positive warnings.

Test Plan:
    USE_CLANG=1 OPT=-g make analyze -j64

Reviewers: andrewkr, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D60549

db/flush_job.cc

@@ -292,9 +292,6 @@ Status FlushJob::WriteLevel0Table(const autovector<MemTable*>& mems,
   }
   base->Unref();
 
-  // re-acquire the most current version
-  base = cfd_->current();
-
   // Note that if file_size is zero, the file has been deleted and
   // should not be added to the manifest.
   if (s.ok() && meta->fd.GetFileSize() > 0) {

db/flush_scheduler.cc

@@ -20,6 +20,8 @@ void FlushScheduler::ScheduleFlush(ColumnFamilyData* cfd) {
   }
 #endif  // NDEBUG
   cfd->Ref();
+// Suppress false positive clang analyzer warnings.
+#ifndef __clang_analyzer__
   Node* node = new Node{cfd, head_.load(std::memory_order_relaxed)};
   while (!head_.compare_exchange_strong(
       node->next, node, std::memory_order_relaxed, std::memory_order_relaxed)) {
@@ -28,6 +30,7 @@ void FlushScheduler::ScheduleFlush(ColumnFamilyData* cfd) {
     // inter-thread synchronization, so we don't even need release
     // semantics for this CAS
   }
+#endif  // __clang_analyzer__
 }
 
 ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {

db/log_reader.cc

@@ -91,7 +91,7 @@ bool Reader::ReadRecord(Slice* record, std::string* scratch,
   Slice fragment;
   while (true) {
     uint64_t physical_record_offset = end_of_buffer_offset_ - buffer_.size();
-    size_t drop_size;
+    size_t drop_size = 0;
     const unsigned int record_type = ReadPhysicalRecord(&fragment, &drop_size);
     switch (record_type) {
       case kFullType:
@@ -199,10 +199,11 @@ bool Reader::ReadRecord(Slice* record, std::string* scratch,
           scratch->clear();
           return false;
         }
-	if (record_type == kBadRecordLen)
+        if (record_type == kBadRecordLen) {
-	  ReportCorruption(drop_size, "bad record length");
+          ReportCorruption(drop_size, "bad record length");
-	else
+        } else {
-	  ReportCorruption(drop_size, "checksum mismatch");
+          ReportCorruption(drop_size, "checksum mismatch");
+        }
         if (in_fragmented_record) {
           ReportCorruption(scratch->size(), "error in middle of record");
           in_fragmented_record = false;
@@ -343,7 +344,7 @@ unsigned int Reader::ReadPhysicalRecord(Slice* result, size_t* drop_size) {
     if (buffer_.size() < (size_t)kHeaderSize) {
       int r;
       if (!ReadMore(drop_size, &r)) {
-	return r;
+        return r;
       }
       continue;
     }
@@ -362,11 +363,11 @@ unsigned int Reader::ReadPhysicalRecord(Slice* result, size_t* drop_size) {
       header_size = kRecyclableHeaderSize;
       // We need enough for the larger header
       if (buffer_.size() < (size_t)kRecyclableHeaderSize) {
-	int r;
+        int r;
-	if (!ReadMore(drop_size, &r)) {
+        if (!ReadMore(drop_size, &r)) {
           return r;
         }
-	continue;
+        continue;
       }
       const uint32_t log_num = DecodeFixed32(header + 7);
       if (log_num != log_number_) {

db/merge_helper.cc

@@ -26,6 +26,7 @@ Status MergeHelper::TimedFullMerge(const MergeOperator* merge_operator,
   assert(merge_operator != nullptr);
 
   if (operands.size() == 0) {
+    assert(value != nullptr && result != nullptr);
     result->assign(value->data(), value->size());
     return Status::OK();
   }

db/version_set.cc

@@ -2746,7 +2746,7 @@ Status VersionSet::Recover(
     }
   }
 
-  for (auto builder : builders) {
+  for (auto& builder : builders) {
     delete builder.second;
   }
 

table/block.cc

@@ -73,7 +73,7 @@ void BlockIter::Prev() {
     const CachedPrevEntry& current_prev_entry =
         prev_entries_[prev_entries_idx_];
 
-    const char* key_ptr = current_prev_entry.key_ptr;
+    const char* key_ptr = nullptr;
     if (current_prev_entry.key_ptr != nullptr) {
       // The key is not delta encoded and stored in the data block
       key_ptr = current_prev_entry.key_ptr;

table/block_based_table_reader.cc

@@ -1052,6 +1052,7 @@ InternalIterator* BlockBasedTable::NewIndexIterator(
     Status s;
     s = CreateIndexReader(&index_reader);
     if (s.ok()) {
+      assert(index_reader != nullptr);
       s = block_cache->Insert(key, index_reader, index_reader->usable_size(),
                               &DeleteCachedIndexEntry, &cache_handle);
     }
@@ -1062,6 +1063,9 @@ InternalIterator* BlockBasedTable::NewIndexIterator(
       RecordTick(statistics, BLOCK_CACHE_BYTES_WRITE, usable_size);
       RecordTick(statistics, BLOCK_CACHE_INDEX_BYTES_INSERT, usable_size);
     } else {
+      if (index_reader != nullptr) {
+        delete index_reader;
+      }
       RecordTick(statistics, BLOCK_CACHE_ADD_FAILURES);
       // make sure if something goes wrong, index_reader shall remain intact.
       if (input_iter != nullptr) {
@@ -1189,7 +1193,8 @@ InternalIterator* BlockBasedTable::NewDataBlockIterator(
   }
 
   InternalIterator* iter;
-  if (s.ok() && block.value != nullptr) {
+  if (s.ok()) {
+    assert(block.value != nullptr);
     iter = block.value->NewIterator(&rep->internal_comparator, input_iter);
     if (block.cache_handle != nullptr) {
       iter->RegisterCleanup(&ReleaseCachedEntry, block_cache,
@@ -1198,6 +1203,7 @@ InternalIterator* BlockBasedTable::NewDataBlockIterator(
       iter->RegisterCleanup(&DeleteHeldResource<Block>, block.value, nullptr);
     }
   } else {
+    assert(block.value == nullptr);
     if (input_iter != nullptr) {
       input_iter->SetStatus(s);
       iter = input_iter;

table/block_prefix_index.cc

@@ -136,6 +136,7 @@ class BlockPrefixIndex::Builder {
         assert(prefixes_per_bucket[i]->next == nullptr);
         buckets[i] = prefixes_per_bucket[i]->start_block;
       } else {
+        assert(total_block_array_entries > 0);
         assert(prefixes_per_bucket[i] != nullptr);
         buckets[i] = EncodeIndex(offset);
         block_array_buffer[offset] = num_blocks;

table/table_test.cc

@@ -1765,7 +1765,6 @@ TEST_F(BlockBasedTableTest, FilterBlockInBlockCache) {
     ASSERT_GT(props.GetCacheBytesRead(), last_cache_bytes_read);
     ASSERT_EQ(props.GetCacheBytesWrite(),
               table_options.block_cache->GetUsage());
-    last_cache_bytes_read = props.GetCacheBytesRead();
   }
   // release the iterator so that the block cache can reset correctly.
   iter.reset();

third-party/gtest-1.7.0/fused-src/gtest/gtest-all.cc

@@ -34,6 +34,9 @@
 // Sometimes it's desirable to build Google Test by compiling a single file.
 // This file serves this purpose.
 
+// Suppress clang analyzer warnings.
+#ifndef __clang_analyzer__
+
 // This line ensures that gtest.h can be compiled on its own, even
 // when it's fused.
 #include "gtest/gtest.h"
@@ -109,7 +112,6 @@
 #ifndef GTEST_INCLUDE_GTEST_GTEST_SPI_H_
 #define GTEST_INCLUDE_GTEST_GTEST_SPI_H_
 
-
 namespace testing {
 
 // This helper class can be used to mock out Google Test failure reporting
@@ -10255,3 +10257,5 @@ const char* TypedTestCasePState::VerifyRegisteredTestNames(
 
 }  // namespace internal
 }  // namespace testing
+
+#endif  // __clang_analyzer__

tools/db_sanity_test.cc

@@ -230,6 +230,9 @@ class SanityTestBloomFilter : public SanityTest {
 
 namespace {
 bool RunSanityTests(const std::string& command, const std::string& path) {
+  bool result = true;
+// Suppress false positive clang static anaylzer warnings.
+#ifndef __clang_analyzer__
   std::vector<SanityTest*> sanity_tests = {
       new SanityTestBasic(path),
       new SanityTestSpecialComparator(path),
@@ -248,7 +251,6 @@ bool RunSanityTests(const std::string& command, const std::string& path) {
   } else {
     fprintf(stderr, "Verifying...\n");
   }
-  bool result = true;
   for (auto sanity_test : sanity_tests) {
     Status s;
     fprintf(stderr, "%s -- ", sanity_test->Name().c_str());
@@ -266,6 +268,7 @@ bool RunSanityTests(const std::string& command, const std::string& path) {
 
     delete sanity_test;
   }
+#endif  // __clang_analyzer__
   return result;
 }
 }  // namespace

util/dynamic_bloom_test.cc

@@ -201,6 +201,7 @@ TEST_F(DynamicBloomTest, perf) {
     }
     ASSERT_EQ(count, num_keys);
     elapsed = timer.ElapsedNanos();
+    assert(count > 0);
     fprintf(stderr, "standard bloom, avg query latency %" PRIu64 "\n",
             elapsed / count);
 
@@ -227,6 +228,7 @@ TEST_F(DynamicBloomTest, perf) {
     }
 
     elapsed = timer.ElapsedNanos();
+    assert(count > 0);
     fprintf(stderr,
             "blocked bloom(enable locality), avg query latency %" PRIu64 "\n",
             elapsed / count);

util/options_parser.cc

@@ -756,6 +756,7 @@ Status RocksDBOptionsParser::VerifyBlockBasedTableFactory(
   if (base_tf == nullptr) {
     return Status::OK();
   }
+  assert(file_tf != nullptr);
 
   const auto& base_opt = base_tf->table_options();
   const auto& file_opt = file_tf->table_options();

util/thread_local_test.cc

@@ -57,6 +57,8 @@ class IDChecker : public ThreadLocalPtr {
 
 }  // anonymous namespace
 
+// Suppress false positive clang analyzer warnings.
+#ifndef __clang_analyzer__
 TEST_F(ThreadLocalTest, UniqueIdTest) {
   port::Mutex mu;
   port::CondVar cv(&mu);
@@ -103,6 +105,7 @@ TEST_F(ThreadLocalTest, UniqueIdTest) {
   // After exit, id sequence in queue:
   // 3, 1, 2, 0
 }
+#endif  // __clang_analyzer__
 
 TEST_F(ThreadLocalTest, SequentialReadWriteTest) {
   // global id list carries over 3, 1, 2, 0

utilities/write_batch_with_index/write_batch_with_index.cc

@@ -226,6 +226,8 @@ class BaseDeltaIterator : public Iterator {
   bool BaseValid() const { return base_iterator_->Valid(); }
   bool DeltaValid() const { return delta_iterator_->Valid(); }
   void UpdateCurrent() {
+// Suppress false positive clang analyzer warnings.
+#ifndef __clang_analyzer__
     while (true) {
       WriteEntry delta_entry;
       if (DeltaValid()) {
@@ -275,6 +277,7 @@ class BaseDeltaIterator : public Iterator {
     }
 
     AssertInvariants();
+#endif  // __clang_analyzer__
   }
 
   bool forward_;