Fix NewFileNumber()

Summary: I mistakenly changed the behavior to ++next_file_number_ instead of next_file_number_++, as it should have been: 344edbb044/db/version_set.h (L539)

Test Plan: none. not sure if this would break anything. It's just different behavior, so I'd rather not risk

Reviewers: ljin, rven, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28557

db/db_impl.cc

@@ -3003,8 +3003,6 @@ Status DBImpl::SetNewMemtableAndNewLogFile(ColumnFamilyData* cfd,
   if (!s.ok()) {
     // how do we fail if we're not creating new log?
     assert(creating_new_log);
-    // Avoid chewing through file number space in a tight loop.
-    versions_->ReuseLogFileNumber(new_log_number);
     assert(!new_mem);
     assert(!new_log);
     return s;

db/version_set.h

@@ -535,16 +535,7 @@ class VersionSet {
   uint64_t current_next_file_number() const { return next_file_number_.load(); }
 
   // Allocate and return a new file number
-  uint64_t NewFileNumber() { return next_file_number_.fetch_add(1) + 1; }
-
-  // Arrange to reuse "file_number" unless a newer file number has
-  // already been allocated.
-  // REQUIRES: "file_number" was returned by a call to NewFileNumber().
-  void ReuseLogFileNumber(uint64_t file_number) {
-    auto expected = file_number + 1;
-    std::atomic_compare_exchange_strong(&next_file_number_, &expected,
-                                        file_number);
-  }
+  uint64_t NewFileNumber() { return next_file_number_.fetch_add(1); }
 
   // Return the last sequence number.
   uint64_t LastSequence() const {

include/rocksdb/options.h

@@ -625,14 +625,11 @@ struct DBOptions {
   // Default: false
   bool error_if_exists;
 
-  // If true, the implementation will do aggressive checking of the
-  // data it is processing and will stop early if it detects any
-  // errors.  This may have unforeseen ramifications: for example, a
-  // corruption of one DB entry may cause a large number of entries to
-  // become unreadable or for the entire DB to become unopenable.
-  // If any of the  writes to the database fails (Put, Delete, Merge, Write),
-  // the database will switch to read-only mode and fail all other
+  // If true, RocksDB will aggressively check consistency of the data.
+  // Also, if any of the  writes to the database fails (Put, Delete, Merge,
+  // Write), the database will switch to read-only mode and fail all other
   // Write operations.
+  // In most cases you want this to be set to true.
   // Default: true
   bool paranoid_checks;