From ac6fe90a8cce7257e0e9941a3db31430f9f99a70 Mon Sep 17 00:00:00 2001
From: Adam Cooke <adam@krystal.io>
Date: Mon, 16 Sep 2024 11:08:01 +0100
Subject: [PATCH] feat: adds Logger#with_destination to log blocks to custom
 destinations

---
 README.md                        |  7 ++++++-
 lib/klogger/logger.rb            | 10 +++++++++-
 spec/helpers/fake_destination.rb | 15 +++++++++++++++
 spec/specs/logger_spec.rb        | 19 +++++++++++++++++++
 4 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 spec/helpers/fake_destination.rb

diff --git a/README.md b/README.md
index 6b9873e..cb83819 100644
--- a/README.md
+++ b/README.md
@@ -78,7 +78,7 @@ logger.info { "Hello world!" }
 logger.info('Result of 1 + 1') { 1 + 1 } # Logs with a message of "Result: 2"
 ```
 
-### Loggging exceptions
+### Logging exceptions
 
 Exceptions happen and when they do, you want to know about them. Klogger provides a helper method to log exceptions. These will automatically be logged with the `error` severity.
 
@@ -197,4 +197,9 @@ end
 # Create a logger and add the destination
 logger = Klogger.new(name)
 logger.add_destination(GraylogDestination.new('graylog.example.com', 12201))
+
+# If you only want to send certain data to another block, you can do so
+logger.with_destination(other_destination) do
+  # ...
+end
 ```
diff --git a/lib/klogger/logger.rb b/lib/klogger/logger.rb
index 953848d..a1dd4a0 100644
--- a/lib/klogger/logger.rb
+++ b/lib/klogger/logger.rb
@@ -36,6 +36,7 @@ def initialize(name = nil,
       @destinations = []
       @group_set = GroupSet.new
       @silenced = Concurrent::ThreadLocalVar.new { false }
+      @block_destinations = Concurrent::ThreadLocalVar.new { [] }
       @include_group_ids = include_group_ids
       super(destination)
       self.formatter = FORMATTERS[formatter].new(highlight: highlight)
@@ -98,6 +99,13 @@ def remove_destination(destination)
       @destinations.delete(destination)
     end
 
+    def with_destination(destination)
+      @block_destinations.value << destination
+      yield
+    ensure
+      @block_destinations.value.delete(destination)
+    end
+
     def create_tagged_logger(**tags)
       TaggedLogger.new(self, **tags)
     end
@@ -142,7 +150,7 @@ def create_payload(severity, message, tags)
     end
 
     def call_destinations(payload, group_ids)
-      @destinations.each do |destination|
+      (@destinations + @block_destinations.value).each do |destination|
         destination.call(self, payload.dup, group_ids)
       rescue StandardError => e
         # If something goes wrong in here, we don't want to break the application
diff --git a/spec/helpers/fake_destination.rb b/spec/helpers/fake_destination.rb
new file mode 100644
index 0000000..f38f87f
--- /dev/null
+++ b/spec/helpers/fake_destination.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class FakeDestination
+
+  attr_reader :lines
+
+  def initialize
+    @lines = []
+  end
+
+  def call(logger, payload, group_ids)
+    @lines << [logger, payload, group_ids]
+  end
+
+end
diff --git a/spec/specs/logger_spec.rb b/spec/specs/logger_spec.rb
index f8ae10b..a7b29fd 100644
--- a/spec/specs/logger_spec.rb
+++ b/spec/specs/logger_spec.rb
@@ -3,6 +3,7 @@
 require 'spec_helper'
 require 'klogger'
 require 'klogger/logger'
+require_relative '../helpers/fake_destination'
 
 module Klogger
 
@@ -394,6 +395,24 @@ module Klogger
         expect(logger.destinations).to_not include destination
       end
     end
+
+    describe '#with_destination' do
+      subject(:logger) { described_class.new('example', destination: output) }
+      let(:fake_destination) { FakeDestination.new }
+
+      it 'sends log output to the given destination for the duration of the block' do
+        logger.info 'line1'
+        logger.with_destination(fake_destination) do
+          logger.info 'line2'
+          logger.info 'line3'
+        end
+        logger.info 'line4'
+        expect(fake_destination.lines).to match [
+          [logger, hash_including(message: 'line2'), []],
+          [logger, hash_including(message: 'line3'), []]
+        ]
+      end
+    end
   end
 
 end