ldb: Add compression and bloom filter options.

Summary:
Added the following two options:
[--bloom_bits=<int,e.g.:14>]
[--compression_type=<no|snappy|zlib|bzip2>]

These options will be used when ldb opens the leveldb database.

Test Plan: Tried by hand for both success and failure cases. We do need a test framework.

Reviewers: dhruba, emayanke, sheki

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7197

util/ldb_cmd.cc

@@ -11,6 +11,59 @@
 
 namespace leveldb {
 
+const char* LDBCommand::BLOOM_ARG = "--bloom_bits=";
+const char* LDBCommand::COMPRESSION_TYPE_ARG = "--compression_type=";
+
+void LDBCommand::parse_open_args(std::vector<std::string>& args) {
+  std::vector<std::string> rest_of_args;
+  for (unsigned int i = 0; i < args.size(); i++) {
+    std::string& arg = args.at(i);
+    if (arg.find(BLOOM_ARG) == 0
+        || arg.find(COMPRESSION_TYPE_ARG) == 0) {
+      open_args_.push_back(arg);
+    } else {
+      rest_of_args.push_back(arg);
+    }
+  }
+  swap(args, rest_of_args);
+}
+
+leveldb::Options LDBCommand::PrepareOptionsForOpenDB() {
+  leveldb::Options opt;
+  opt.create_if_missing = false;
+  for (unsigned int i = 0; i < open_args_.size(); i++) {
+    std::string& arg = open_args_.at(i);
+    if (arg.find(BLOOM_ARG) == 0) {
+      std::string bits_string = arg.substr(strlen(BLOOM_ARG));
+      int bits = atoi(bits_string.c_str());
+      if (bits == 0) {
+        // Badly-formatted bits.
+        exec_state_ = LDBCommandExecuteResult::FAILED(
+          std::string("Badly-formatted bits: ") + bits_string);
+      }
+      opt.filter_policy = leveldb::NewBloomFilterPolicy(bits);
+    } else if (arg.find(COMPRESSION_TYPE_ARG) == 0) {
+      std::string comp = arg.substr(strlen(COMPRESSION_TYPE_ARG));
+      if (comp == "no") {
+        opt.compression = leveldb::kNoCompression;
+      } else if (comp == "snappy") {
+        opt.compression = leveldb::kSnappyCompression;
+      } else if (comp == "zlib") {
+        opt.compression = leveldb::kZlibCompression;
+      } else if (comp == "bzip2") {
+        opt.compression = leveldb::kBZip2Compression;
+      } else {
+        // Unknown compression.
+        exec_state_ = LDBCommandExecuteResult::FAILED(
+          "Unknown compression level: " + comp);
+      }
+    }
+  }
+
+  return opt;
+}
+
+
 const char* LDBCommand::FROM_ARG = "--from=";
 const char* LDBCommand::END_ARG = "--to=";
 const char* LDBCommand::HEX_ARG = "--hex";

util/ldb_cmd.h

@@ -95,18 +95,16 @@ public:
   LDBCommand(std::string& db_name, std::vector<std::string>& args) :
     db_path_(db_name),
     db_(NULL) {
+    parse_open_args(args);
   }
 
   LDBCommand(std::vector<std::string>& args) :
     db_path_(""),
     db_(NULL) {
+    parse_open_args(args);
   }
 
-  virtual leveldb::Options PrepareOptionsForOpenDB()  {
-    leveldb::Options opt;
-    opt.create_if_missing = false;
-    return opt;
-  }
+  virtual leveldb::Options PrepareOptionsForOpenDB();
 
   virtual bool NoDBOpen() {
     return false;
@@ -121,7 +119,11 @@ public:
 
   /* Print the help message */
   static void Help(std::string& ret) {
-    ret.append("--db=DB_PATH ");
+    ret.append("--db=DB_PATH [");
+    ret.append(LDBCommand::BLOOM_ARG);
+    ret.append("<int,e.g.:14>] [");
+    ret.append(LDBCommand::COMPRESSION_TYPE_ARG);
+    ret.append("<no|snappy|zlib|bzip2>] ");
   }
 
   /* Run the command, and return the execute result. */
@@ -130,8 +132,11 @@ public:
       return;
     }
 
-   if (db_ == NULL && !NoDBOpen()) {
+    if (db_ == NULL && !NoDBOpen()) {
       OpenDB();
+      if (!exec_state_.IsNotStarted()) {
+        return;
+      }
     }
     
     DoCommand();
@@ -169,6 +174,9 @@ protected:
 
   void OpenDB() {
     leveldb::Options opt = PrepareOptionsForOpenDB();
+    if (!exec_state_.IsNotStarted()) {
+      return;
+    }
     // Open the DB.
     leveldb::Status st = leveldb::DB::Open(opt, db_path_, &db_);
     if (!st.ok()) {
@@ -190,6 +198,13 @@ protected:
   LDBCommandExecuteResult exec_state_;
   std::string db_path_;
   leveldb::DB* db_;
+
+private:
+
+  static const char* BLOOM_ARG;
+  static const char* COMPRESSION_TYPE_ARG;
+  std::vector<std::string> open_args_;
+  void parse_open_args(std::vector<std::string>& args);
 };
 
 class Compactor: public LDBCommand {