Stderr info logger

Summary:
Adapted a stderr logger from the option tests. Moved it to a separate
header so we can reuse it, e.g., from ldb subcommands for faster debugging. This
is especially useful to make errors/warnings more visible when running
"ldb repair", which involves potential data loss.

Test Plan:
ran options_test and "ldb repair"

  $ ./ldb repair --db=./tmp/
  [WARN] **** Repaired rocksdb ./tmp/; recovered 1 files; 588bytes. Some data may have been lost. ****
  OK

Reviewers: IslamAbdelRahman, yhchiang, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D56151

tools/ldb_cmd.cc

@@ -12,19 +12,20 @@
 
 #include <inttypes.h>
 
-#include "db/dbformat.h"
 #include "db/db_impl.h"
-#include "db/log_reader.h"
+#include "db/dbformat.h"
 #include "db/filename.h"
-#include "db/writebuffer.h"
+#include "db/log_reader.h"
 #include "db/write_batch_internal.h"
-#include "rocksdb/write_batch.h"
+#include "db/writebuffer.h"
+#include "port/dirent.h"
 #include "rocksdb/cache.h"
 #include "rocksdb/table_properties.h"
+#include "rocksdb/write_batch.h"
 #include "table/scoped_arena_iterator.h"
-#include "port/dirent.h"
 #include "tools/sst_dump_tool_imp.h"
 #include "util/coding.h"
+#include "util/stderr_logger.h"
 #include "util/string_util.h"
 #include "utilities/ttl/db_ttl_impl.h"
 
@@ -2159,6 +2160,7 @@ void RepairCommand::Help(string& ret) {
 
 void RepairCommand::DoCommand() {
   Options options = PrepareOptionsForOpenDB();
+  options.info_log.reset(new StderrLogger(InfoLogLevel::WARN_LEVEL));
   Status status = RepairDB(db_path_, options);
   if (status.ok()) {
     printf("OK\n");

util/options_test.cc

@@ -24,6 +24,7 @@
 #include "util/options_parser.h"
 #include "util/options_sanity_check.h"
 #include "util/random.h"
+#include "util/stderr_logger.h"
 #include "util/testharness.h"
 #include "util/testutil.h"
 
@@ -37,15 +38,6 @@ DEFINE_bool(enable_print, false, "Print options generated to console.");
 
 namespace rocksdb {
 
-class StderrLogger : public Logger {
- public:
-  using Logger::Logv;
-  virtual void Logv(const char* format, va_list ap) override {
-    vprintf(format, ap);
-    printf("\n");
-  }
-};
-
 Options PrintAndGetOptions(size_t total_write_buffer_limit,
                            int read_amplification_threshold,
                            int write_amplification_threshold,

util/stderr_logger.h

@@ -0,0 +1,31 @@
+//  Copyright (c) 2016-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+
+#pragma once
+
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "rocksdb/env.h"
+
+namespace rocksdb {
+
+// Prints logs to stderr for faster debugging
+class StderrLogger : public Logger {
+ public:
+  explicit StderrLogger(const InfoLogLevel log_level = InfoLogLevel::INFO_LEVEL)
+      : Logger(log_level) {}
+
+  // Brings overloaded Logv()s into scope so they're not hidden when we override
+  // a subset of them.
+  using Logger::Logv;
+
+  virtual void Logv(const char* format, va_list ap) override {
+    vfprintf(stderr, format, ap);
+    fprintf(stderr, "\n");
+  }
+};
+
+}  // namespace rocksdb