[RocksDB] allow LDB tool to have customized key formatter

Summary: Currently ldb tool dump keys either in ascii format or hex format - neither is ideal if the key has a binary structure and is not readable in ascii. This diff also allows LDB tool to be customized in ways beyond DB options.

Test Plan: verify that key formatter works with some simple db with binary key.

Reviewers: sdong, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19209

include/rocksdb/ldb_tool.h

@@ -4,13 +4,32 @@
 // of patent rights can be found in the PATENTS file in the same directory.
 #ifndef ROCKSDB_LITE
 #pragma once
+#include <string>
 #include "rocksdb/options.h"
 
 namespace rocksdb {
 
+// An interface for converting a slice to a readable string
+class SliceFormatter {
+ public:
+  virtual ~SliceFormatter() {}
+  virtual std::string Format(const Slice& s) const = 0;
+};
+
+// Options for customizing ldb tool (beyond the DB Options)
+struct LDBOptions {
+  // Create LDBOptions with default values for all fields
+  LDBOptions();
+
+  // Key formatter that converts a slice to a readable string.
+  // Default: Slice::ToString()
+  std::shared_ptr<SliceFormatter> key_formatter;
+};
+
 class LDBTool {
  public:
-  void Run(int argc, char** argv, Options = Options());
+  void Run(int argc, char** argv, Options db_options= Options(),
+           const LDBOptions& ldb_options = LDBOptions());
 };
 
 } // namespace rocksdb

util/ldb_cmd.cc

@@ -50,13 +50,14 @@ const char* LDBCommand::DELIM = " ==> ";
 LDBCommand* LDBCommand::InitFromCmdLineArgs(
   int argc,
   char** argv,
-  const Options& options
+  const Options& options,
+  const LDBOptions& ldb_options
 ) {
   vector<string> args;
   for (int i = 1; i < argc; i++) {
     args.push_back(argv[i]);
   }
-  return InitFromCmdLineArgs(args, options);
+  return InitFromCmdLineArgs(args, options, ldb_options);
 }
 
 /**
@@ -71,7 +72,8 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
  */
 LDBCommand* LDBCommand::InitFromCmdLineArgs(
   const vector<string>& args,
-  const Options& options
+  const Options& options,
+  const LDBOptions& ldb_options
 ) {
   // --x=y command line arguments are added as x->y map entries.
   map<string, string> option_map;
@@ -115,7 +117,8 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
   );
 
   if (command) {
-    command->SetOptions(options);
+    command->SetDBOptions(options);
+    command->SetLDBOptions(ldb_options);
   }
   return command;
 }
@@ -1619,7 +1622,7 @@ void ScanCommand::DoCommand() {
   for ( ;
         it->Valid() && (!end_key_specified_ || it->key().ToString() < end_key_);
         it->Next()) {
-    string key = it->key().ToString();
+    string key = ldb_options_.key_formatter->Format(it->key());
     if (is_db_ttl_) {
       TtlIterator* it_ttl = dynamic_cast<TtlIterator*>(it);
       assert(it_ttl);
@@ -1633,8 +1636,8 @@ void ScanCommand::DoCommand() {
     }
     string value = it->value().ToString();
     fprintf(stdout, "%s : %s\n",
-          (is_key_hex_ ? StringToHex(key) : key).c_str(),
+            (is_key_hex_ ? "0x" + it->key().ToString(true) : key).c_str(),
-          (is_value_hex_ ? StringToHex(value) : value).c_str()
+            (is_value_hex_ ? StringToHex(value) : value).c_str()
         );
     num_keys_scanned++;
     if (max_keys_scanned_ >= 0 && num_keys_scanned >= max_keys_scanned_) {

util/ldb_cmd.h

@@ -13,8 +13,9 @@
 
 #include "db/version_set.h"
 #include "rocksdb/env.h"
-#include "rocksdb/options.h"
 #include "rocksdb/iterator.h"
+#include "rocksdb/ldb_tool.h"
+#include "rocksdb/options.h"
 #include "rocksdb/slice.h"
 #include "util/logging.h"
 #include "util/ldb_cmd_execute_result.h"
@@ -54,23 +55,29 @@ public:
 
   static LDBCommand* InitFromCmdLineArgs(
     const vector<string>& args,
-    const Options& options = Options()
+    const Options& options,
+    const LDBOptions& ldb_options
   );
 
   static LDBCommand* InitFromCmdLineArgs(
     int argc,
     char** argv,
-    const Options& options = Options()
+    const Options& options,
+    const LDBOptions& ldb_options
   );
 
   bool ValidateCmdLineOptions();
 
   virtual Options PrepareOptionsForOpenDB();
 
-  virtual void SetOptions(Options options) {
+  virtual void SetDBOptions(Options options) {
     options_ = options;
   }
 
+  void SetLDBOptions(const LDBOptions& ldb_options) {
+    ldb_options_ = ldb_options;
+  }
+
   virtual bool NoDBOpen() {
     return false;
   }
@@ -291,6 +298,7 @@ protected:
                          const string& option, string* value);
 
   Options options_;
+  LDBOptions ldb_options_;
 
 private:
 

util/ldb_tool.cc

@@ -9,6 +9,17 @@
 
 namespace rocksdb {
 
+class DefaultSliceFormatter : public SliceFormatter {
+ public:
+  virtual std::string Format(const Slice& s) const override {
+    return s.ToString();
+  }
+};
+
+LDBOptions::LDBOptions()
+    : key_formatter(new DefaultSliceFormatter()) {
+}
+
 class LDBCommandRunner {
 public:
 
@@ -71,13 +82,15 @@ public:
     fprintf(stderr, "%s\n", ret.c_str());
   }
 
-  static void RunCommand(int argc, char** argv, Options options) {
+  static void RunCommand(int argc, char** argv, Options options,
+                         const LDBOptions& ldb_options) {
     if (argc <= 2) {
       PrintHelp(argv[0]);
       exit(1);
     }
 
-    LDBCommand* cmdObj = LDBCommand::InitFromCmdLineArgs(argc, argv, options);
+    LDBCommand* cmdObj = LDBCommand::InitFromCmdLineArgs(argc, argv, options,
+                                                         ldb_options);
     if (cmdObj == nullptr) {
       fprintf(stderr, "Unknown command\n");
       PrintHelp(argv[0]);
@@ -99,8 +112,9 @@ public:
 };
 
 
-void LDBTool::Run(int argc, char** argv, Options options) {
+void LDBTool::Run(int argc, char** argv, Options options,
-  LDBCommandRunner::RunCommand(argc, argv, options);
+                  const LDBOptions& ldb_options) {
+  LDBCommandRunner::RunCommand(argc, argv, options, ldb_options);
 }
 } // namespace rocksdb