Allow user to specify log level for info_log

Summary:
Currently, there is no easy way for user to change log level of info log. Add a parameter in options to specify that.
Also make the default level to INFO level. Removing the [INFO] tag if it is INFO level as I don't want to cause performance regression. (add [LOG] means another mem-copy and string formatting).

Test Plan:
make all check
manual check the levels work as expected.

Reviewers: dhruba, yhchiang

Reviewed By: yhchiang

CC: dhruba, igor, i.am.jin.lei, ljin, haobo, leveldb

Differential Revision: https://reviews.facebook.net/D16563

include/rocksdb/env.h

@@ -513,7 +513,7 @@ class Directory {
   virtual Status Fsync() = 0;
 };
 
-enum InfoLogLevel {
+enum InfoLogLevel : unsigned char {
   DEBUG = 0,
   INFO,
   WARN,
@@ -526,7 +526,7 @@ enum InfoLogLevel {
 class Logger {
  public:
   enum { DO_NOT_SUPPORT_GET_LOG_FILE_SIZE = -1 };
-  explicit Logger(const InfoLogLevel log_level = InfoLogLevel::ERROR)
+  explicit Logger(const InfoLogLevel log_level = InfoLogLevel::INFO)
       : log_level_(log_level) {}
   virtual ~Logger();
 
@@ -543,10 +543,20 @@ class Logger {
     if (log_level < log_level_) {
       return;
     }
-    char new_format[500];
-    snprintf(new_format, sizeof(new_format) - 1, "[%s] %s",
-             kInfoLogLevelNames[log_level], format);
-    Logv(new_format, ap);
+
+    if (log_level == INFO) {
+      // Doesn't print log level if it is INFO level.
+      // This is to avoid unexpected performance regression after we add
+      // the feature of log level. All the logs before we add the feature
+      // are INFO level. We don't want to add extra costs to those existing
+      // logging.
+      Logv(format, ap);
+    } else {
+      char new_format[500];
+      snprintf(new_format, sizeof(new_format) - 1, "[%s] %s",
+               kInfoLogLevelNames[log_level], format);
+      Logv(new_format, ap);
+    }
   }
   virtual size_t GetLogFileSize() const {
     return DO_NOT_SUPPORT_GET_LOG_FILE_SIZE;

include/rocksdb/options.h

@@ -24,6 +24,7 @@ class CompactionFilter;
 class CompactionFilterFactory;
 class Comparator;
 class Env;
+enum InfoLogLevel : unsigned char;
 class FilterPolicy;
 class Logger;
 class MergeOperator;
@@ -152,6 +153,8 @@ struct Options {
   // Default: nullptr
   shared_ptr<Logger> info_log;
 
+  InfoLogLevel info_log_level;
+
   // -------------------
   // Parameters that affect performance
 

util/auto_roll_logger.cc

@@ -88,7 +88,7 @@ Status CreateLoggerFromOptions(
     AutoRollLogger* result = new AutoRollLogger(
         env, dbname, db_log_dir,
         options.max_log_file_size,
-        options.log_file_time_to_roll);
+        options.log_file_time_to_roll, options.info_log_level);
     Status s = result->GetStatus();
     if (!s.ok()) {
       delete result;
@@ -101,7 +101,11 @@ Status CreateLoggerFromOptions(
     env->CreateDir(dbname);  // In case it does not exist
     env->RenameFile(fname, OldInfoLogFileName(dbname, env->NowMicros(),
                                               db_absolute_path, db_log_dir));
-    return env->NewLogger(fname, logger);
+    auto s = env->NewLogger(fname, logger);
+    if (logger->get() != nullptr) {
+      (*logger)->SetInfoLogLevel(options.info_log_level);
+    }
+    return s;
   }
 }
 

util/auto_roll_logger.h

@@ -19,7 +19,7 @@ class AutoRollLogger : public Logger {
   AutoRollLogger(Env* env, const std::string& dbname,
                  const std::string& db_log_dir, size_t log_max_size,
                  size_t log_file_time_to_roll,
-                 const InfoLogLevel log_level = InfoLogLevel::ERROR)
+                 const InfoLogLevel log_level = InfoLogLevel::INFO)
       : Logger(log_level),
         dbname_(dbname),
         db_log_dir_(db_log_dir),

util/env.cc

@@ -40,7 +40,7 @@ void Log(Logger* info_log, const char* format, ...) {
   if (info_log) {
     va_list ap;
     va_start(ap, format);
-    info_log->Logv(format, ap);
+    info_log->Logv(InfoLogLevel::INFO, format, ap);
     va_end(ap);
   }
 }
@@ -163,7 +163,7 @@ void Log(const shared_ptr<Logger>& info_log, const char* format, ...) {
   if (info_log) {
     va_list ap;
     va_start(ap, format);
-    info_log->Logv(format, ap);
+    info_log->Logv(InfoLogLevel::INFO, format, ap);
     va_end(ap);
   }
 }

util/options.cc

@@ -38,6 +38,7 @@ Options::Options()
       paranoid_checks(false),
       env(Env::Default()),
       info_log(nullptr),
+      info_log_level(INFO),
       write_buffer_size(4<<20),
       max_write_buffer_number(2),
       min_write_buffer_number_to_merge(1),