Merge branch 'master' into performance

Conflicts:
	db/db_impl.cc
	db/db_impl.h

db/db_impl.cc

@@ -86,6 +86,22 @@ struct DBImpl::CompactionState {
   }
 };
 
+struct DBImpl::DeletionState {
+
+  // the set of all live files that cannot be deleted
+  std::set<uint64_t> live;
+
+  // a list of all siles that exists in the db directory
+  std::vector<std::string> allfiles;
+
+  // the current filenumber, lognumber and prevlognumber
+  // that corresponds to the set of files in 'live'.
+  uint64_t filenumber, lognumber, prevlognumber;
+
+  // the list of all files to be evicted from the table cahce
+  std::vector<uint64_t> files_to_evict;
+};
+
 // Fix user-supplied options to be reasonable
 template <class T,class V>
 static void ClipToRange(T* ptr, V minvalue, V maxvalue) {
@@ -249,7 +265,11 @@ void DBImpl::MaybeIgnoreError(Status* s) const {
   }
 }
 
-void DBImpl::DeleteObsoleteFiles() {
+// Returns the list of live files in 'live' and the list
+// of all files in the filesystem in 'allfiles'.
+void DBImpl::FindObsoleteFiles(DeletionState& deletion_state) {
+  mutex_.AssertHeld();
+
   // if deletion is disabled, do nothing
   if (disable_delete_obsolete_files_) {
     return;
@@ -268,39 +288,51 @@ void DBImpl::DeleteObsoleteFiles() {
   }
 
   // Make a set of all of the live files
-  std::set<uint64_t> live = pending_outputs_;
-  versions_->AddLiveFiles(&live);
+  deletion_state.live = pending_outputs_;
+  versions_->AddLiveFiles(&deletion_state.live);
 
-  std::vector<std::string> filenames;
-  env_->GetChildren(dbname_, &filenames); // Ignoring errors on purpose
+  // set of all files in the directory
+  env_->GetChildren(dbname_, &deletion_state.allfiles); // Ignore errors
+
+  // store the current filenum, lognum, etc
+  deletion_state.filenumber = versions_->ManifestFileNumber();
+  deletion_state.lognumber = versions_->LogNumber();
+  deletion_state.prevlognumber = versions_->PrevLogNumber();
+}
+
+// Diffs the files listed in filenames and those that do not
+// belong to live files are posibly removed. If the removed file
+// is a sst file, then it returns the file number in files_to_evict.
+// It is not necesary to hold the mutex when invoking this method.
+void DBImpl::PurgeObsoleteFiles(DeletionState& state) {
   uint64_t number;
   FileType type;
   std::vector<std::string> old_log_files;
-  for (size_t i = 0; i < filenames.size(); i++) {
-    if (ParseFileName(filenames[i], &number, &type)) {
+  for (size_t i = 0; i < state.allfiles.size(); i++) {
+    if (ParseFileName(state.allfiles[i], &number, &type)) {
       bool keep = true;
       switch (type) {
         case kLogFile:
-          keep = ((number >= versions_->LogNumber()) ||
-                  (number == versions_->PrevLogNumber()));
+          keep = ((number >= state.lognumber) ||
+                  (number == state.prevlognumber));
           break;
         case kDescriptorFile:
           // Keep my manifest file, and any newer incarnations'
           // (in case there is a race that allows other incarnations)
-          keep = (number >= versions_->ManifestFileNumber());
+          keep = (number >= state.filenumber);
           break;
         case kTableFile:
-          keep = (live.find(number) != live.end());
+          keep = (state.live.find(number) != state.live.end());
           break;
         case kTempFile:
           // Any temp files that are currently being written to must
           // be recorded in pending_outputs_, which is inserted into "live"
-          keep = (live.find(number) != live.end());
+          keep = (state.live.find(number) != state.live.end());
           break;
         case kInfoLogFile:
           keep = true;
           if (number != 0) {
-            old_log_files.push_back(filenames[i]);
+            old_log_files.push_back(state.allfiles[i]);
           }
           break;
         case kCurrentFile:
@@ -311,12 +343,13 @@ void DBImpl::DeleteObsoleteFiles() {
 
       if (!keep) {
         if (type == kTableFile) {
-          table_cache_->Evict(number);
+          // record the files to be evicted from the cache
+          state.files_to_evict.push_back(number);
         }
         Log(options_.info_log, "Delete type=%d #%lld\n",
             int(type),
             static_cast<unsigned long long>(number));
-        Status st = env_->DeleteFile(dbname_ + "/" + filenames[i]);
+        Status st = env_->DeleteFile(dbname_ + "/" + state.allfiles[i]);
         if(!st.ok()) {
           Log(options_.info_log, "Delete type=%d #%lld FAILED\n",
               int(type),
@@ -333,13 +366,32 @@ void DBImpl::DeleteObsoleteFiles() {
     std::sort(old_log_files.begin(), old_log_files.end());
     for (int i = 0; i >= (old_log_file_count - KEEP_LOG_FILE_NUM); i++) {
       std::string& to_delete = old_log_files.at(i);
-      Log(options_.info_log, "Delete type=%d %s\n",
-          int(kInfoLogFile), to_delete.c_str());
+      // Log(options_.info_log, "Delete type=%d %s\n",
+      //     int(kInfoLogFile), to_delete.c_str());
       env_->DeleteFile(dbname_ + "/" + to_delete);
     }
   }
 }
 
+void DBImpl::EvictObsoleteFiles(DeletionState& state) {
+  mutex_.AssertHeld();
+  for (unsigned int i = 0; i < state.files_to_evict.size(); i++) {
+    table_cache_->Evict(state.files_to_evict[i]);
+  }
+}
+
+void DBImpl::DeleteObsoleteFiles() {
+  mutex_.AssertHeld();
+  DeletionState deletion_state;
+  std::set<uint64_t> live;
+  std::vector<std::string> allfiles;
+  std::vector<uint64_t> files_to_evict;
+  uint64_t filenumber, lognumber, prevlognumber;
+  FindObsoleteFiles(deletion_state);
+  PurgeObsoleteFiles(deletion_state);
+  EvictObsoleteFiles(deletion_state);
+}
+
 Status DBImpl::Recover(VersionEdit* edit) {
   mutex_.AssertHeld();
 
@@ -828,11 +880,12 @@ void DBImpl::BGWork(void* db) {
 
 void DBImpl::BackgroundCall() {
   bool madeProgress;
+  DeletionState deletion_state;
   MutexLock l(&mutex_);
   // Log(options_.info_log, "XXX BG Thread %llx process new work item", pthread_self());
   assert(bg_compaction_scheduled_);
   if (!shutting_down_.Acquire_Load()) {
-    Status s = BackgroundCompaction(&madeProgress);
+    Status s = BackgroundCompaction(&madeProgress, deletion_state);
     if (!s.ok()) {
       // Wait a little bit before retrying background compaction in
       // case this is an environmental problem and we do not want to
@@ -847,6 +900,14 @@ void DBImpl::BackgroundCall() {
     }
   }
 
+  // delete unnecessary files if any, this is done outside the mutex
+  if (!deletion_state.live.empty()) {
+    mutex_.Unlock();
+    PurgeObsoleteFiles(deletion_state);
+    mutex_.Lock();
+  }
+  EvictObsoleteFiles(deletion_state);
+
   bg_compaction_scheduled_--;
 
   MaybeScheduleLogDBDeployStats();
@@ -860,7 +921,8 @@ void DBImpl::BackgroundCall() {
   bg_cv_.SignalAll();
 }
 
-Status DBImpl::BackgroundCompaction(bool* madeProgress) {
+Status DBImpl::BackgroundCompaction(bool* madeProgress, 
+  DeletionState& deletion_state) {
   *madeProgress = false;
   mutex_.AssertHeld();
 
@@ -924,7 +986,7 @@ Status DBImpl::BackgroundCompaction(bool* madeProgress) {
     CleanupCompaction(compact);
     versions_->ReleaseCompactionFiles(c);
     c->ReleaseInputs();
-    DeleteObsoleteFiles();
+    FindObsoleteFiles(deletion_state);
     *madeProgress = true;
   }
   delete c;