IndexedDB: Reusing leveldb logs when opening database

This change activates a new open mode in leveldb which reuses logs & manifest
to reduce time to open database.

This affects only Indexed DB databases, not other leveldb's opened elsewhere.

BUG=402980,395799

Review URL: https://codereview.chromium.org/803603004

Cr-Commit-Position: refs/heads/master@{#308493}

content/browser/indexed_db/leveldb/leveldb_database.cc

@@ -103,6 +103,7 @@ static leveldb::Status OpenDB(
   options.create_if_missing = true;
   options.paranoid_checks = true;
   options.filter_policy = filter_policy->get();
+  options.reuse_logs = true;
   options.compression = leveldb::kSnappyCompression;
 
   // For info about the troubles we've run into with this parameter, see:

third_party/leveldatabase/env_chromium.cc

@@ -358,6 +358,8 @@ const char* MethodIDToString(MethodID method) {
       return "NewRandomAccessFile";
     case kNewWritableFile:
       return "NewWritableFile";
+    case kNewAppendableFile:
+      return "NewAppendableFile";
     case kDeleteFile:
       return "DeleteFile";
     case kCreateDir:
@@ -904,6 +906,22 @@ Status ChromiumEnv::NewWritableFile(const std::string& fname,
   }
 }
 
+Status ChromiumEnv::NewAppendableFile(const std::string& fname,
+                                      leveldb::WritableFile** result) {
+  *result = NULL;
+  FilePath path = FilePath::FromUTF8Unsafe(fname);
+  scoped_ptr<base::File> f(new base::File(
+      path, base::File::FLAG_OPEN_ALWAYS | base::File::FLAG_APPEND));
+  if (!f->IsValid()) {
+    RecordErrorAt(kNewAppendableFile);
+    return MakeIOError(fname, "Unable to create appendable file",
+                       kNewAppendableFile, f->error_details());
+  }
+  *result =
+      new ChromiumWritableFile(fname, f.release(), this, this, make_backup_);
+  return Status::OK();
+}
+
 uint64_t ChromiumEnv::NowMicros() {
   return base::TimeTicks::Now().ToInternalValue();
 }

third_party/leveldatabase/env_chromium.h

@@ -19,6 +19,8 @@
 
 namespace leveldb_env {
 
+// These entries map to values in tools/metrics/histograms/histograms.xml. New
+// values should be appended at the end.
 enum MethodID {
   kSequentialFileRead,
   kSequentialFileSkip,
@@ -41,6 +43,7 @@ enum MethodID {
   kNewLogger,
   kSyncParent,
   kGetChildren,
+  kNewAppendableFile,
   kNumEntries
 };
 
@@ -129,6 +132,8 @@ class ChromiumEnv : public leveldb::Env,
       leveldb::RandomAccessFile** result);
   virtual leveldb::Status NewWritableFile(const std::string& fname,
                                           leveldb::WritableFile** result);
+  virtual leveldb::Status NewAppendableFile(const std::string& fname,
+                                            leveldb::WritableFile** result);
   virtual leveldb::Status NewLogger(const std::string& fname,
                                     leveldb::Logger** result);
 

tools/metrics/histograms/histograms.xml

@@ -49274,6 +49274,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="18" label="NewLogger"/>
   <int value="19" label="SyncParent"/>
   <int value="20" label="GetChildren"/>
+  <int value="21" label="NewAppendableFile"/>
 </enum>
 
 <enum name="LevelDBPrefStoreErrorCodes" type="int">
@@ -58942,6 +58943,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <suffix name="GetChildren" label="ChromiumEnv::GetChildren"/>
   <suffix name="GetFileSize" label="ChromiumEnv::GetFileSize"/>
   <suffix name="LockFile" label="ChromiumEnv::LockFile"/>
+  <suffix name="NewAppendableFile" label="ChromiumEnv::NewAppendableFile"/>
   <suffix name="NewRandomAccessFile" label="ChromiumEnv::NewRandomAccessFile"/>
   <suffix name="RandomAccessFileRead" label="ChromiumRandomAccessFile::Read"/>
   <suffix name="RenameFile" label="ChromiumEnv::RenameFile"/>