Integrate the manifest_dump command with ldb

Summary:
Syntax:

   manifest_dump [--verbose] --num=<manifest_num>

e.g.

$ ./ldb --db=/home/smarlow/tmp/testdb manifest_dump --num=12
manifest_file_number 13 next_file_number 14 last_sequence 3 log_number
11  prev_log_number 0
--- level 0 --- version# 0 ---
 6:116['a1' @ 1 : 1 .. 'a1' @ 1 : 1]
 10:130['a3' @ 2 : 1 .. 'a4' @ 3 : 1]
--- level 1 --- version# 0 ---
--- level 2 --- version# 0 ---
--- level 3 --- version# 0 ---
--- level 4 --- version# 0 ---
--- level 5 --- version# 0 ---
--- level 6 --- version# 0 ---

Test Plan: - Tested on an example DB (see output in summary)

Reviewers: sheki, dhruba

Reviewed By: sheki

CC: leveldb, heyongqiang

Differential Revision: https://reviews.facebook.net/D9609

tools/ldb.cc

@@ -56,6 +56,7 @@ public:
     ReduceDBLevelsCommand::Help(ret);
     DBDumperCommand::Help(ret);
     DBLoaderCommand::Help(ret);
+    ManifestDumpCommand::Help(ret);
 
     fprintf(stderr, "%s\n", ret.c_str());
   }

tools/manifest_dump.cc

@@ -1,81 +0,0 @@
-// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file. See the AUTHORS file for names of contributors.
-
-#include "db/version_set.h"
-
-#include <algorithm>
-#include <stdio.h>
-#include "db/filename.h"
-#include "db/log_reader.h"
-#include "db/log_writer.h"
-#include "db/memtable.h"
-#include "db/table_cache.h"
-#include "leveldb/env.h"
-#include "leveldb/table_builder.h"
-#include "table/merger.h"
-#include "table/two_level_iterator.h"
-#include "util/coding.h"
-#include "util/logging.h"
-#include "util/storage_options.h"
-
-static int verbose = 0;
-static int output_hex = 0;
-
-using namespace leveldb;
-
-//
-// Takes a manifest file and dumps out all metedata
-//
-int main(int argc, char** argv) {
-
-  // parse command line options
-  size_t n;
-  char junk;
-  int foundfile = 0;
-  std::string manifestfile;
-  for (int i = 1; i < argc; i++) {
-    std::string param(argv[i]);
-    if ((n = param.find("--file=")) != std::string::npos) {
-      manifestfile = param.substr(strlen("--file="));
-      foundfile = 1;
-    } else if (sscanf(argv[i], "--verbose=%ld%c", &n, &junk) == 1 &&
-        (n == 0 || n == 1)) {
-      verbose = n;
-    } else if (param == "--output_hex") {
-      output_hex = n;
-    } else {
-      fprintf(stderr, "Unknown or badly-formatted option: %s\n",
-              argv[i]);
-      abort();
-    }
-  }
-  if (!foundfile) {
-    fprintf(stderr,
-      "%s [--verbose=0|1] [--output_hex] [--file=pathname of manifest file]\n",
-      argv[0]);
-    abort();
-  }
-
-  if (verbose) {
-    printf("Processing Manifest file %s\n", manifestfile.c_str());
-  }
-
-  Options options;
-  StorageOptions sopt;
-  std::string file(manifestfile);
-  std::string dbname("dummy");
-  TableCache* tc = new TableCache(dbname, &options, sopt, 10);
-  const InternalKeyComparator* cmp = new InternalKeyComparator(options.comparator);
-
-  VersionSet* versions = new VersionSet(dbname, &options, sopt,
-                                   tc, cmp);
-  Status s = versions->DumpManifest(options, file, verbose, output_hex);
-  if (!s.ok()) {
-    printf("Error in processing file %s %s\n", manifestfile.c_str(),
-           s.ToString().c_str());
-  }
-  if (verbose) {
-    printf("Processing Manifest file %s done\n", manifestfile.c_str());
-  }
-}