Cleanup DeleteFile API

Summary:
The DeleteFile API was removing files inside the db-lock. This
is now changed to remove files outside the db-lock.
The GetLiveFilesMetadata() returns the smallest and largest
seqnuence number of each file as well.

Test Plan: deletefile_test

Reviewers: emayanke, haobo

Reviewed By: haobo

CC: leveldb

Maniphest Tasks: T63

Differential Revision: https://reviews.facebook.net/D12567

db/db_impl.cc

@@ -2996,9 +2996,11 @@ Status DBImpl::DeleteFile(std::string name) {
   FileMetaData metadata;
   int maxlevel = NumberLevels();
   VersionEdit edit(maxlevel);
+  DeletionState deletion_state;
+  Status status;
+  {
     MutexLock l(&mutex_);
-  Status status =
-    versions_->GetMetadataForFile(number, &level, &metadata);
+    status = versions_->GetMetadataForFile(number, &level, &metadata);
     if (!status.ok()) {
       Log(options_.info_log, "DeleteFile #%lld FAILED. File not found\n",
           static_cast<unsigned long long>(number));
@@ -3025,11 +3027,17 @@ Status DBImpl::DeleteFile(std::string name) {
         return Status::InvalidArgument("File not in last level");
       }
     }
-
     edit.DeleteFile(level, number);
     status = versions_->LogAndApply(&edit, &mutex_);
     if (status.ok()) {
-    DeleteObsoleteFiles();
+      FindObsoleteFiles(deletion_state);
+    }
+  } // lock released here
+
+  if (status.ok()) {
+    // remove files outside the db-lock
+    PurgeObsoleteFiles(deletion_state);
+    EvictObsoleteFiles(deletion_state);
   }
   return status;
 }

db/version_set.cc

@@ -2701,6 +2701,8 @@ void VersionSet::GetLiveFilesMetaData(
       filemetadata.size = files[i]->file_size;
       filemetadata.smallestkey = files[i]->smallest.user_key().ToString();
       filemetadata.largestkey = files[i]->largest.user_key().ToString();
+      filemetadata.smallest_seqno = files[i]->smallest_seqno;
+      filemetadata.largest_seqno = files[i]->largest_seqno;
       metadata->push_back(filemetadata);
     }
   }

include/rocksdb/db.h

@@ -30,16 +30,13 @@ class WriteBatch;
 
 // Metadata associated with each SST file.
 struct LiveFileMetaData {
-  // Name of the file
-  std::string name;
-  // Level at which this file resides.
-  int level;
-  // File size in bytes.
-  size_t size;
-  // Smallest user defined key in the file.
-  std::string smallestkey;
-  // Largest user defined key in the file.
-  std::string largestkey;
+  std::string name;        // Name of the file
+  int level;               // Level at which this file resides.
+  size_t size;             // File size in bytes.
+  std::string smallestkey; // Smallest user defined key in the file.
+  std::string largestkey;  // Largest user defined key in the file.
+  SequenceNumber smallest_seqno; // smallest seqno in file
+  SequenceNumber largest_seqno;  // largest seqno in file
 };
 
 // Abstract handle to particular state of a DB.