1 files changed, 124 insertions, 70 deletions

diff --git a/src/leveldb/db/db_impl.cc b/src/leveldb/db/db_impl.cc
index 49b95953b4..60f4e66e55 100644
--- a/src/leveldb/db/db_impl.cc
+++ b/src/leveldb/db/db_impl.cc
@@ -125,7 +125,7 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname)
       db_lock_(NULL),
       shutting_down_(NULL),
       bg_cv_(&mutex_),
-      mem_(new MemTable(internal_comparator_)),
+      mem_(NULL),
       imm_(NULL),
       logfile_(NULL),
       logfile_number_(0),
@@ -134,7 +134,6 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname)
       tmp_batch_(new WriteBatch),
       bg_compaction_scheduled_(false),
       manual_compaction_(NULL) {
-  mem_->Ref();
   has_imm_.Release_Store(NULL);
 
   // Reserve ten files or so for other uses and give the rest to TableCache.
@@ -271,7 +270,7 @@ void DBImpl::DeleteObsoleteFiles() {
   }
 }
 
-Status DBImpl::Recover(VersionEdit* edit) {
+Status DBImpl::Recover(VersionEdit* edit, bool *save_manifest) {
   mutex_.AssertHeld();
 
   // Ignore error from CreateDir since the creation of the DB is
@@ -301,66 +300,69 @@ Status DBImpl::Recover(VersionEdit* edit) {
     }
   }
 
-  s = versions_->Recover();
-  if (s.ok()) {
-    SequenceNumber max_sequence(0);
-
-    // Recover from all newer log files than the ones named in the
-    // descriptor (new log files may have been added by the previous
-    // incarnation without registering them in the descriptor).
-    //
-    // Note that PrevLogNumber() is no longer used, but we pay
-    // attention to it in case we are recovering a database
-    // produced by an older version of leveldb.
-    const uint64_t min_log = versions_->LogNumber();
-    const uint64_t prev_log = versions_->PrevLogNumber();
-    std::vector<std::string> filenames;
-    s = env_->GetChildren(dbname_, &filenames);
+  s = versions_->Recover(save_manifest);
+  if (!s.ok()) {
+    return s;
+  }
+  SequenceNumber max_sequence(0);
+
+  // Recover from all newer log files than the ones named in the
+  // descriptor (new log files may have been added by the previous
+  // incarnation without registering them in the descriptor).
+  //
+  // Note that PrevLogNumber() is no longer used, but we pay
+  // attention to it in case we are recovering a database
+  // produced by an older version of leveldb.
+  const uint64_t min_log = versions_->LogNumber();
+  const uint64_t prev_log = versions_->PrevLogNumber();
+  std::vector<std::string> filenames;
+  s = env_->GetChildren(dbname_, &filenames);
+  if (!s.ok()) {
+    return s;
+  }
+  std::set<uint64_t> expected;
+  versions_->AddLiveFiles(&expected);
+  uint64_t number;
+  FileType type;
+  std::vector<uint64_t> logs;
+  for (size_t i = 0; i < filenames.size(); i++) {
+    if (ParseFileName(filenames[i], &number, &type)) {
+      expected.erase(number);
+      if (type == kLogFile && ((number >= min_log) || (number == prev_log)))
+        logs.push_back(number);
+    }
+  }
+  if (!expected.empty()) {
+    char buf[50];
+    snprintf(buf, sizeof(buf), "%d missing files; e.g.",
+             static_cast<int>(expected.size()));
+    return Status::Corruption(buf, TableFileName(dbname_, *(expected.begin())));
+  }
+
+  // Recover in the order in which the logs were generated
+  std::sort(logs.begin(), logs.end());
+  for (size_t i = 0; i < logs.size(); i++) {
+    s = RecoverLogFile(logs[i], (i == logs.size() - 1), save_manifest, edit,
+                       &max_sequence);
     if (!s.ok()) {
       return s;
     }
-    std::set<uint64_t> expected;
-    versions_->AddLiveFiles(&expected);
-    uint64_t number;
-    FileType type;
-    std::vector<uint64_t> logs;
-    for (size_t i = 0; i < filenames.size(); i++) {
-      if (ParseFileName(filenames[i], &number, &type)) {
-        expected.erase(number);
-        if (type == kLogFile && ((number >= min_log) || (number == prev_log)))
-          logs.push_back(number);
-      }
-    }
-    if (!expected.empty()) {
-      char buf[50];
-      snprintf(buf, sizeof(buf), "%d missing files; e.g.",
-               static_cast<int>(expected.size()));
-      return Status::Corruption(buf, TableFileName(dbname_, *(expected.begin())));
-    }
-
-    // Recover in the order in which the logs were generated
-    std::sort(logs.begin(), logs.end());
-    for (size_t i = 0; i < logs.size(); i++) {
-      s = RecoverLogFile(logs[i], edit, &max_sequence);
 
-      // The previous incarnation may not have written any MANIFEST
-      // records after allocating this log number.  So we manually
-      // update the file number allocation counter in VersionSet.
-      versions_->MarkFileNumberUsed(logs[i]);
-    }
+    // The previous incarnation may not have written any MANIFEST
+    // records after allocating this log number.  So we manually
+    // update the file number allocation counter in VersionSet.
+    versions_->MarkFileNumberUsed(logs[i]);
+  }
 
-    if (s.ok()) {
-      if (versions_->LastSequence() < max_sequence) {
-        versions_->SetLastSequence(max_sequence);
-      }
-    }
+  if (versions_->LastSequence() < max_sequence) {
+    versions_->SetLastSequence(max_sequence);
   }
 
-  return s;
+  return Status::OK();
 }
 
-Status DBImpl::RecoverLogFile(uint64_t log_number,
-                              VersionEdit* edit,
+Status DBImpl::RecoverLogFile(uint64_t log_number, bool last_log,
+                              bool* save_manifest, VersionEdit* edit,
                               SequenceNumber* max_sequence) {
   struct LogReporter : public log::Reader::Reporter {
     Env* env;
@@ -405,6 +407,7 @@ Status DBImpl::RecoverLogFile(uint64_t log_number,
   std::string scratch;
   Slice record;
   WriteBatch batch;
+  int compactions = 0;
   MemTable* mem = NULL;
   while (reader.ReadRecord(&record, &scratch) &&
          status.ok()) {
@@ -432,25 +435,52 @@ Status DBImpl::RecoverLogFile(uint64_t log_number,
     }
 
     if (mem->ApproximateMemoryUsage() > options_.write_buffer_size) {
+      compactions++;
+      *save_manifest = true;
       status = WriteLevel0Table(mem, edit, NULL);
+      mem->Unref();
+      mem = NULL;
       if (!status.ok()) {
         // Reflect errors immediately so that conditions like full
         // file-systems cause the DB::Open() to fail.
         break;
       }
-      mem->Unref();
-      mem = NULL;
     }
   }
 
-  if (status.ok() && mem != NULL) {
-    status = WriteLevel0Table(mem, edit, NULL);
-    // Reflect errors immediately so that conditions like full
-    // file-systems cause the DB::Open() to fail.
+  delete file;
+
+  // See if we should keep reusing the last log file.
+  if (status.ok() && options_.reuse_logs && last_log && compactions == 0) {
+    assert(logfile_ == NULL);
+    assert(log_ == NULL);
+    assert(mem_ == NULL);
+    uint64_t lfile_size;
+    if (env_->GetFileSize(fname, &lfile_size).ok() &&
+        env_->NewAppendableFile(fname, &logfile_).ok()) {
+      Log(options_.info_log, "Reusing old log %s \n", fname.c_str());
+      log_ = new log::Writer(logfile_, lfile_size);
+      logfile_number_ = log_number;
+      if (mem != NULL) {
+        mem_ = mem;
+        mem = NULL;
+      } else {
+        // mem can be NULL if lognum exists but was empty.
+        mem_ = new MemTable(internal_comparator_);
+        mem_->Ref();
+      }
+    }
+  }
+
+  if (mem != NULL) {
+    // mem did not get reused; compact it.
+    if (status.ok()) {
+      *save_manifest = true;
+      status = WriteLevel0Table(mem, edit, NULL);
+    }
+    mem->Unref();
   }
 
-  if (mem != NULL) mem->Unref();
-  delete file;
   return status;
 }
 
@@ -821,8 +851,9 @@ Status DBImpl::FinishCompactionOutputFile(CompactionState* compact,
     delete iter;
     if (s.ok()) {
       Log(options_.info_log,
-          "Generated table #%llu: %lld keys, %lld bytes",
+          "Generated table #%llu@%d: %lld keys, %lld bytes",
           (unsigned long long) output_number,
+          compact->compaction->level(),
           (unsigned long long) current_entries,
           (unsigned long long) current_bytes);
     }
@@ -1395,6 +1426,19 @@ bool DBImpl::GetProperty(const Slice& property, std::string* value) {
   } else if (in == "sstables") {
     *value = versions_->current()->DebugString();
     return true;
+  } else if (in == "approximate-memory-usage") {
+    size_t total_usage = options_.block_cache->TotalCharge();
+    if (mem_) {
+      total_usage += mem_->ApproximateMemoryUsage();
+    }
+    if (imm_) {
+      total_usage += imm_->ApproximateMemoryUsage();
+    }
+    char buf[50];
+    snprintf(buf, sizeof(buf), "%llu",
+             static_cast<unsigned long long>(total_usage));
+    value->append(buf);
+    return true;
   }
 
   return false;
@@ -1449,8 +1493,11 @@ Status DB::Open(const Options& options, const std::string& dbname,
   DBImpl* impl = new DBImpl(options, dbname);
   impl->mutex_.Lock();
   VersionEdit edit;
-  Status s = impl->Recover(&edit); // Handles create_if_missing, error_if_exists
-  if (s.ok()) {
+  // Recover handles create_if_missing, error_if_exists
+  bool save_manifest = false;
+  Status s = impl->Recover(&edit, &save_manifest);
+  if (s.ok() && impl->mem_ == NULL) {
+    // Create new log and a corresponding memtable.
     uint64_t new_log_number = impl->versions_->NewFileNumber();
     WritableFile* lfile;
     s = options.env->NewWritableFile(LogFileName(dbname, new_log_number),
@@ -1460,15 +1507,22 @@ Status DB::Open(const Options& options, const std::string& dbname,
       impl->logfile_ = lfile;
       impl->logfile_number_ = new_log_number;
       impl->log_ = new log::Writer(lfile);
-      s = impl->versions_->LogAndApply(&edit, &impl->mutex_);
-    }
-    if (s.ok()) {
-      impl->DeleteObsoleteFiles();
-      impl->MaybeScheduleCompaction();
+      impl->mem_ = new MemTable(impl->internal_comparator_);
+      impl->mem_->Ref();
     }
   }
+  if (s.ok() && save_manifest) {
+    edit.SetPrevLogNumber(0);  // No older logs needed after recovery.
+    edit.SetLogNumber(impl->logfile_number_);
+    s = impl->versions_->LogAndApply(&edit, &impl->mutex_);
+  }
+  if (s.ok()) {
+    impl->DeleteObsoleteFiles();
+    impl->MaybeScheduleCompaction();
+  }
   impl->mutex_.Unlock();
   if (s.ok()) {
+    assert(impl->mem_ != NULL);
     *dbptr = impl;
   } else {
     delete impl;