Move the file copy out of the mutex.

Summary:
We now release the mutex before copying the files in the case
of the trivial move. This path does not use the compaction job.

Test Plan: DBTest.LevelCompactionThirdPath

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30381

HISTORY.md

@@ -3,6 +3,10 @@
 ### Unreleased Features
 * Changed the LRU caching algorithm so that referenced blocks (by iterators) are never evicted
 * By default we now optimize the compilation for the compilation platform (using -march=native). If you want to build portable binary, use 'PORTABLE=1' before the make command.
+* We now allow level-compaction to place files in different paths by
+  specifying them in db_paths along with the target_size.
+  Lower numbered levels will be placed earlier in the db_paths and higher
+  numbered levels will be placed later in the db_paths vector.
 
 ### 3.9.0 (12/8/2014)
 
@@ -17,10 +21,6 @@
 * New API LinkFile added to Env. If you implement your own Env class, an
   implementation of the API LinkFile will have to be provided.
 * MemTableRep takes MemTableAllocator instead of Arena
-* We now allow level-compaction to place files in different paths by
-  specifying them in db_paths along with the target_size.
-  Lower numbered levels will be placed earlier in the db_paths and higher
-  numbered levels will be placed later in the db_paths vector.
 
 ### Improvements
 * RocksDBLite library now becomes smaller and will be compiled with -fno-exceptions flag.

db/compaction.cc

@@ -140,6 +140,7 @@ bool Compaction::IsTrivialMove() const {
           num_input_levels() == 2 &&
           num_input_files(0) == 1 &&
           num_input_files(1) == 0 &&
+          input(0, 0)->fd.GetPathId() == GetOutputPathId() &&
           TotalFileSize(grandparents_) <= max_grandparent_overlap_bytes_);
 }
 

db/compaction.h

@@ -119,7 +119,7 @@ class Compaction {
   // moving a single input file to the next level (no merging or splitting)
   bool IsTrivialMove() const;
 
-  // If true, then the comaction can be done by simply deleting input files.
+  // If true, then the compaction can be done by simply deleting input files.
   bool IsDeletionCompaction() const {
     return deletion_compaction_;
   }

db/db_impl.cc

@@ -2060,31 +2060,10 @@ Status DBImpl::BackgroundCompaction(bool* madeProgress, JobContext* job_context,
     // Move file to next level
     assert(c->num_input_files(0) == 1);
     FileMetaData* f = c->input(0, 0);
-    FileMetaData ftemp;
-    uint64_t fdnum = f->fd.GetNumber();
-    uint32_t fdpath = f->fd.GetPathId();
     c->edit()->DeleteFile(c->level(), f->fd.GetNumber());
-    // Need to move file if file is to be stored in a new path
-    if (c->GetOutputPathId() != f->fd.GetPathId()) {
-      fdnum = versions_->NewFileNumber();
-      std::string source = TableFileName(db_options_.db_paths,
-                                         f->fd.GetNumber(), f->fd.GetPathId());
-      std::string destination =
-          TableFileName(db_options_.db_paths, fdnum, c->GetOutputPathId());
-      Status s = CopyFile(env_, source, destination, 0);
-      if (s.ok()) {
-        fdpath = c->GetOutputPathId();
-      } else {
-        fdnum = f->fd.GetNumber();
-        if (!s.IsShutdownInProgress()) {
-          Log(InfoLogLevel::WARN_LEVEL, db_options_.info_log,
-              "Compaction error: %s", s.ToString().c_str());
-        }
-      }
-    }
-    c->edit()->AddFile(c->level() + 1, fdnum, fdpath, f->fd.GetFileSize(),
-                       f->smallest, f->largest, f->smallest_seqno,
-                       f->largest_seqno);
+    c->edit()->AddFile(c->level() + 1, f->fd.GetNumber(), f->fd.GetPathId(),
+                       f->fd.GetFileSize(), f->smallest, f->largest,
+                       f->smallest_seqno, f->largest_seqno);
     status = versions_->LogAndApply(c->column_family_data(),
                                     *c->mutable_cf_options(),
                                     c->edit(), &mutex_, db_directory_.get());