Add stdio_logger extension for a minimal logger that Sequel::Database…

… can use

This is mostly taken from the bin/sequel implementation, with
the main change that it should be more thread-safe by using
write instead of puts.

Change bin/sequel to use this extension instead of defining an
anonymous class.  Also have bin/sequel use sync for log files,
as that is what logger does.

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Add stdio_logger extension for a minimal logger that Sequel::Database can use (jeremyevans)
+
 * Simplify Database#inspect output to database_type, host, database, and user (jeremyevans)
 
 === 5.82.0 (2024-07-01)

bin/sequel

@@ -18,21 +18,6 @@ load_dirs = []
 exclusive_options = []
 loggers = []
 
-logger_class = Class.new do
-  def initialize(device)
-    @device = device
-  end
-
-  def debug(msg)
-  end
-
-  [:info, :warn, :error].each do |meth|
-    define_method(meth) do |msg|
-      @device.puts("#{Time.now.strftime('%Y-%m-%d %T')} #{meth.to_s.upcase}: #{msg}")
-    end
-  end
-end
-
 options = OptionParser.new do |opts|
   opts.banner = "Sequel: The Database Toolkit for Ruby"
   opts.define_head "Usage: sequel [options] <uri|path> [file]"
@@ -76,15 +61,17 @@ options = OptionParser.new do |opts|
   end
 
   opts.on("-E", "--echo", "echo SQL statements") do
-    loggers << logger_class.new($stdout)
+    loggers << $stdout
   end
 
   opts.on("-I", "--include dir", "specify $LOAD_PATH directory") do |v|
     $: << v
   end
 
   opts.on("-l", "--log logfile", "log SQL statements to log file") do |v|
-    loggers << logger_class.new(File.open(v, 'a'))
+    file = File.open(v, 'a')
+    file.sync = true
+    loggers << file
   end
 
   opts.on("-L", "--load-dir DIR", "loads all *.rb under specifed directory") do |v|
@@ -168,6 +155,11 @@ begin
     end
   end
 
+  unless loggers.empty?
+    Sequel.extension :stdio_logger
+    loggers.map!{|io| Sequel::StdioLogger.new(io)}
+  end
+
   DB = connect_proc[db]
   load_dirs.each{|d| d.is_a?(Array) ? require(d.first) : Dir["#{d}/**/*.rb"].each{|f| load(f)}}
   if migrate_dir

lib/sequel/extensions/stdio_logger.rb

@@ -0,0 +1,48 @@
+# frozen-string-literal: true
+#
+# The stdio_logger extension exposes a Sequel::StdioLogger class that
+# can be used for logging with Sequel, as a minimal alternative to
+# the logger library.  It exposes debug/info/warn/error methods for the
+# different warning levels.  The debug method is a no-op, so that setting
+# the Database sql_log_level to debug will result in no output for normal
+# queries. The info/warn/error methods log the current time, log level,
+# and the given message.
+# 
+# To use this extension:
+#
+#   Sequel.extension :stdio_logger
+#
+# Then you you can use Sequel::StdioLogger to wrap IO objects that you
+# would like Sequel to log to:
+#
+#   DB.loggers << Sequel::StdioLogger.new($stdout)
+#
+#   log_file = File.open("db_queries.log", 'a')
+#   log_file.sync = true
+#   DB.loggers << Sequel::StdioLogger.new(log_file)
+#
+# This is implemented as a global extension instead of a Database extension
+# because Database loggers must be set before Database extensions are loaded.
+#
+# Related module: Sequel::StdioLogger
+
+#
+module Sequel
+  class StdioLogger
+    def initialize(device)
+      @device = device
+    end
+
+    # Do not log debug messages. This is so setting the Database
+    # sql_log_level to debug will result in no output.
+    def debug(msg)
+    end
+
+    [:info, :warn, :error].each do |meth|
+      define_method(meth) do |msg|
+        @device.write("#{Time.now.strftime('%F %T')} #{meth.to_s.upcase}: #{msg}\n")
+        nil
+      end
+    end
+  end
+end

spec/extensions/stdio_logger_spec.rb

@@ -0,0 +1,25 @@
+require_relative "spec_helper"
+
+require 'stringio'
+
+describe "stdio_logger extension: Sequel::StdioLogger" do
+  before do
+    Sequel.extension :stdio_logger
+    @output = StringIO.new
+    @logger = Sequel::StdioLogger.new(@output)
+  end
+
+  it "#debug should not log" do
+    @logger.debug("foo").must_be_nil
+    @output.rewind
+    @output.read.must_equal ''
+  end
+
+  [:info, :warn, :error].each do |level|
+    it "##{level} should log message with given level" do
+      @logger.send(level, "foo").must_be_nil
+      @output.rewind
+      @output.read.must_match(/ #{level.to_s.upcase}: foo\n\z/)
+    end
+  end
+end