Remove unused steno features - Round 2 (deep cleanup)

After deeper analysis, removed ~180 lines of additional unused code:

Removed features:
- Fluentd sink - never configured or used (~60 lines)
- TaggedLogger class and Logger#tag() - never called (~64 lines)
- Logger#log_exception() - never called (4 lines)
- Context::FiberLocal - only ThreadLocal used (~15 lines + Fiber patches)
- Steno.set_logger_regexp() - dynamic level adjustment, unused (~20 lines)
- Steno.clear_logger_regexp() - unused (~15 lines)
- Steno.logger_level_snapshot() - unused (~10 lines)

Modified files:
- lib/steno/config.rb - Removed Fluentd sink configuration
- lib/steno/context.rb - Removed FiberLocal class and Fiber monkey patches
- lib/steno/logger.rb - Removed tag() and log_exception() methods
- lib/steno/sink.rb - Removed require for fluentd
- lib/steno/steno.rb - Removed regexp methods, simplified logger()
- Removed requires for tagged_logger from steno.rb
- Updated tests to remove tests for deleted features

Kept (used or needed):
- Codec::Json - Backward compatibility fallback
- Context::Null - Default fallback
- All log levels - debug2 is actively used

Total code reduction:
- Round 1: ~240 lines
- Round 2: ~180 lines
- Total: ~420 lines removed

Tests: 64 examples passing (was 78, removed 14 test examples)

Updated README.md with complete documentation of Round 2 removals.

Author: johha

lib/steno/README.md

@@ -78,7 +78,7 @@ Syslog.close if Syslog.opened?
 - Windows conditionals from config.rb, syslog.rb, test files
 - `WINDOWS` constant from sink/base.rb
 
-### 6. Unused Features Removal
+### 6. Unused Features Removal (Round 1)
 **Rationale**: Remove dead code not used by CCNG
 
 **Removed**:
@@ -94,6 +94,31 @@ Syslog.close if Syslog.opened?
 - `Logger#log_exception()` - Useful utility method
 - `Context::FiberLocal` - Valid alternative context type, minimal code
 
+### 7. Unused Features Removal (Round 2)
+**Rationale**: Deeper analysis revealed more unused code
+
+**Removed**:
+- `lib/steno/sink/fluentd.rb` - Fluentd sink, never configured or used (~60 lines)
+- `lib/steno/tagged_logger.rb` - TaggedLogger class, never used (~60 lines)
+- `Logger#tag()` method - Never called in CCNG (4 lines)
+- `Logger#log_exception()` method - Never called in CCNG (4 lines)
+- `Steno::Context::FiberLocal` - Fiber context, only ThreadLocal is used (~15 lines)
+- `Steno.set_logger_regexp()` - Dynamic logger level adjustment, unused (~20 lines)
+- `Steno.clear_logger_regexp()` - Counterpart method, unused (~15 lines)
+- `Steno.logger_level_snapshot()` - Logger level inspection, unused (~10 lines)
+- Removed Fluentd config line from config.rb
+- Removed `require 'steno/tagged_logger'` from steno.rb
+- Removed `require 'steno/sink/fluentd'` from sink.rb
+- Removed Fiber monkey patches from context.rb
+- Test files for removed features
+
+**Total code reduction**: ~240 lines (Round 1) + ~175 lines (Round 2) = **~415 lines removed**
+
+**What's kept**:
+- `Steno::Codec::Json` - Backward compatibility fallback for timestamp='deprecated'
+- `Steno::Context::Null` - Default fallback context
+- All log levels including debug1, debug2 - debug2 is actively used
+
 ---
 
 ## Making Future Modifications

lib/steno/config.rb

@@ -53,8 +53,6 @@ def to_config_hash(hash)
         opts[:sinks] << Steno::Sink::Syslog.instance
       end
 
-      opts[:sinks] << Steno::Sink::Fluentd.new(hash[:fluentd]) if hash[:fluentd]
-
       opts[:sinks] << Steno::Sink::IO.new($stdout) if opts[:sinks].empty?
 
       opts

lib/steno/context.rb

@@ -1,13 +1,3 @@
-class Fiber
-  def __steno_context_data__
-    @__steno_context_data__ ||= {}
-  end
-
-  def __steno_clear_context_data__
-    @__steno_context_data__ = {}
-  end
-end
-
 module Steno
 end
 
@@ -43,14 +33,4 @@ def clear
       Thread.current[THREAD_LOCAL_KEY] = {}
     end
   end
-
-  class FiberLocal < Base
-    def data
-      Fiber.current.__steno_context_data__
-    end
-
-    def clear
-      Fiber.current.__steno_clear_context_data__
-    end
-  end
 end

lib/steno/logger.rb

@@ -101,15 +101,6 @@ def level_active?(level_name)
     @min_level_lock.synchronize { level <= @min_level }
   end
 
-  # Convenience method for logging an exception, along with its backtrace.
-  #
-  # @param [Exception] exception
-
-  # @return [nil]
-  def log_exception(exception, user_data={})
-    warn("Caught exception: #{exception}", user_data.merge(backtrace: exception.backtrace))
-  end
-
   # Adds a record to the configured sinks.
   #
   # @param [Symbol] level_name    The level associated with the record
@@ -134,16 +125,6 @@ def log(level_name, message=nil, user_data=nil)
     nil
   end
 
-  # Returns a proxy that will emit the supplied user data along with each
-  # log record.
-  #
-  # @param [Hash] user_data
-  #
-  # @return [Steno::TaggedLogger]
-  def tag(user_data={})
-    Steno::TaggedLogger.new(self, user_data)
-  end
-
   private
 
   def parse_record_loc(callstack)

lib/steno/sink.rb

@@ -1,5 +1,4 @@
 require 'steno/sink/base'
 require 'steno/sink/io'
 require 'steno/sink/syslog'
-require 'steno/sink/fluentd'
 require 'steno/sink/counter'

lib/steno/sink/fluentd.rb

@@ -4,13 +4,12 @@
 require 'steno/errors'
 require 'steno/log_level'
 require 'steno/logger'
-require 'steno/tagged_logger'
 require 'steno/record'
 require 'steno/sink'
 
 module Steno
   class << self
-    attr_reader :config, :logger_regexp
+    attr_reader :config
 
     # Initializes the logging system. This must be called exactly once before
     # attempting to use any Steno class methods.
@@ -24,9 +23,6 @@ def init(config)
       @loggers = {}
       @loggers_lock = Mutex.new
 
-      @logger_regexp = nil
-      @logger_regexp_level = nil
-
       nil
     end
 
@@ -40,10 +36,8 @@ def logger(name)
         logger = @loggers[name]
 
         if logger.nil?
-          level = compute_level(name)
-
           logger = Steno::Logger.new(name, @config.sinks,
-                                     level: level,
+                                     level: @config.default_log_level,
                                      context: @config.context)
 
           @loggers[name] = logger
@@ -52,71 +46,6 @@ def logger(name)
         logger
       end
     end
-
-    # Sets all loggers whose name matches _regexp_ to _level_. Resets any
-    # loggers whose name matches the previous regexp but not the supplied regexp.
-    #
-    # @param [Regexp] regexp
-    # @param [Symbol] level
-    #
-    # @return [nil]
-    def set_logger_regexp(regexp, level)
-      @loggers_lock.synchronize do
-        @loggers.each do |name, logger|
-          if name =~ regexp
-            logger.level = level
-          elsif @logger_regexp && (name =~ @logger_regexp)
-            # Reset loggers affected by the old regexp but not by the new
-            logger.level = @config.default_log_level
-          end
-        end
-
-        @logger_regexp = regexp
-        @logger_regexp_level = level
-
-        nil
-      end
-    end
-
-    # Clears the logger regexp, if set. Resets the level of any loggers matching
-    # the regex to the default log level.
-    #
-    # @return [nil]
-    def clear_logger_regexp
-      @loggers_lock.synchronize do
-        return if @logger_regexp.nil?
-
-        @loggers.each do |name, logger|
-          logger.level = @config.default_log_level if name =~ @logger_regexp
-        end
-
-        @logger_regexp = nil
-        @logger_regexp_level = nil
-      end
-
-      nil
-    end
-
-    # @return [Hash] Map of logger name => level
-    def logger_level_snapshot
-      @loggers_lock.synchronize do
-        snapshot = {}
-
-        @loggers.each { |name, logger| snapshot[name] = logger.level }
-
-        snapshot
-      end
-    end
-
-    private
-
-    def compute_level(name)
-      if @logger_regexp && name =~ @logger_regexp
-        @logger_regexp_level
-      else
-        @config.default_log_level
-      end
-    end
   end
 end
 

lib/steno/steno.rb

@@ -42,25 +42,4 @@
       t2.join
     end
   end
-
-  describe Steno::Context::FiberLocal do
-    include_context 'steno context'
-
-    let(:context) { described_class.new }
-
-    it 'stores data local to fibers' do
-      f2 = Fiber.new do
-        expect(context.data['fiber']).to be_nil
-        context.data['fiber'] = 'f2'
-      end
-
-      f1 = Fiber.new do
-        context.data['fiber'] = 'f1'
-        f2.resume
-        expect(context.data['fiber']).to eq('f1')
-      end
-
-      f1.resume
-    end
-  end
 end

lib/steno/tagged_logger.rb

@@ -90,12 +90,4 @@
       logger.debugf('test %d %0.2f', 1, 2.2)
     end
   end
-
-  describe '#tag' do
-    it 'returns a tagged logger' do
-      tagged_logger = logger.tag('foo' => 'bar')
-      expect(tagged_logger).not_to be_nil
-      expect(tagged_logger.user_data).to eq({ 'foo' => 'bar' })
-    end
-  end
 end