Make "make analyze" happy

Summary:
"make analyze" is reporting some errors. It's complicated to look but it seems to me that they are all false positive. Anyway, I think cleaning them up is a good idea. Some of the changes are hacky but I don't know a better way.
Closes https://github.com/facebook/rocksdb/pull/2508

Differential Revision: D5341710

Pulled By: siying

fbshipit-source-id: 6070e430e0e41a080ef441e05e8ec827d45efab6

db/db_impl_write.cc

@@ -142,7 +142,7 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
   WriteContext write_context;
   WriteThread::WriteGroup write_group;
   bool in_parallel_group = false;
-  uint64_t last_sequence;
+  uint64_t last_sequence = kMaxSequenceNumber;
   if (!concurrent_prepare_) {
     last_sequence = versions_->LastSequence();
   }
@@ -247,6 +247,7 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
         last_sequence = versions_->FetchAddLastToBeWrittenSequence(total_count);
       }
     }
+    assert(last_sequence != kMaxSequenceNumber);
     const SequenceNumber current_sequence = last_sequence + 1;
     last_sequence += total_count;
 

db/db_iter.cc

@@ -644,6 +644,7 @@ void DBIter::ReverseToBackward() {
     while (iter_->Valid() &&
            user_comparator_->Compare(ikey.user_key, saved_key_.GetUserKey()) >
                0) {
+      assert(ikey.sequence != kMaxSequenceNumber);
       if (ikey.sequence > sequence_) {
         PERF_COUNTER_ADD(internal_recent_skipped_count, 1);
       } else {
@@ -956,6 +957,7 @@ void DBIter::FindPrevUserKey() {
         ++num_skipped;
       }
     }
+    assert(ikey.sequence != kMaxSequenceNumber);
     if (ikey.sequence > sequence_) {
       PERF_COUNTER_ADD(internal_recent_skipped_count, 1);
     } else {

db/dbformat.h

@@ -80,7 +80,9 @@ struct ParsedInternalKey {
   SequenceNumber sequence;
   ValueType type;
 
-  ParsedInternalKey() { }  // Intentionally left uninitialized (for speed)
+  ParsedInternalKey()
+      : sequence(kMaxSequenceNumber)  // Make code analyzer happy
+  {}  // Intentionally left uninitialized (for speed)
   ParsedInternalKey(const Slice& u, const SequenceNumber& seq, ValueType t)
       : user_key(u), sequence(seq), type(t) { }
   std::string DebugString(bool hex = false) const;

utilities/blob_db/blob_db_impl.cc

@@ -1230,7 +1230,7 @@ Status BlobDBImpl::CommonGet(const ColumnFamilyData* cfd, const Slice& key,
   }
 
   // 0 - size
-  if (!handle.size()) {
+  if (!handle.size() && value != nullptr) {
     value->clear();
     return Status::OK();
   }

utilities/blob_db/blob_db_test.cc

@@ -35,17 +35,7 @@ class BlobDBTest : public testing::Test {
   void Open(BlobDBOptionsImpl bdb_options = BlobDBOptionsImpl(),
             Options options = Options()) {
     options.create_if_missing = true;
-    Reopen(bdb_options, options);
-  }
-
-  void Reopen(BlobDBOptionsImpl bdb_options = BlobDBOptionsImpl(),
-              Options options = Options()) {
-    if (blob_db_) {
-      delete blob_db_;
-      blob_db_ = nullptr;
-    }
     ASSERT_OK(BlobDB::Open(options, bdb_options, dbname_, &blob_db_));
-    ASSERT_TRUE(blob_db_);
   }
 
   void Destroy() {