Module: Datadog::RailsCachePatcher

Defined in:

lib/ddtrace/contrib/rails/core_extensions.rb

Overview

RailsCachePatcher contains function to patch Rails caching libraries.

Class Method Summary

• .cache_store_class(k) ⇒ Object
• .patch_cache_store ⇒ Object
• .patch_cache_store_delete ⇒ Object
• .patch_cache_store_fetch ⇒ Object
• .patch_cache_store_read ⇒ Object
• .patch_cache_store_write ⇒ Object

Class Method Details

.cache_store_class(k) ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 173

def cache_store_class(k)
  # When Redis is used, we can't only patch Cache::Store as it is
  # Cache::RedisStore, a sub-class of it that is used, in practice.
  # We need to do a per-method monkey patching as some of them might
  # be redefined, and some of them not. The latest version of redis-activesupport
  # redefines write but leaves untouched read and delete:
  # https://github.com/redis-store/redis-activesupport/blob/master/lib/active_support/cache/redis_store.rb
  c = if defined?(::ActiveSupport::Cache::RedisStore) &&
         ::ActiveSupport::Cache::RedisStore.instance_methods(false).include?(k)
        ::ActiveSupport::Cache::RedisStore
      else
        ::ActiveSupport::Cache::Store
      end
  c
end

.patch_cache_store ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 166

def patch_cache_store
  patch_cache_store_read
  patch_cache_store_fetch
  patch_cache_store_write
  patch_cache_store_delete
end

.patch_cache_store_delete ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 264

def patch_cache_store_delete
  cache_store_class(:delete).class_eval do
    alias_method :delete_without_datadog, :delete
    def delete(*args, &block)
      payload = {
        action: 'DELETE',
        key: args[0],
        tracing_context: {}
      }

      begin
        # process and catch cache exceptions
        Datadog::Contrib::Rails::ActiveSupport.start_trace_cache(payload)
        delete_without_datadog(*args, &block)
      rescue Exception => e
        payload[:exception] = [e.class.name, e.message]
        payload[:exception_object] = e
        raise e
      end
    ensure
      Datadog::Contrib::Rails::ActiveSupport.finish_trace_cache(payload)
    end
  end
end

.patch_cache_store_fetch ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 214

def patch_cache_store_fetch
  cache_store_class(:fetch).class_eval do
    alias_method :fetch_without_datadog, :fetch
    def fetch(*args, &block)
      payload = {
        action: 'GET',
        key: args[0],
        tracing_context: {}
      }

      begin
        # process and catch cache exceptions
        Datadog::Contrib::Rails::ActiveSupport.start_trace_cache(payload)
        fetch_without_datadog(*args, &block)
      rescue Exception => e
        payload[:exception] = [e.class.name, e.message]
        payload[:exception_object] = e
        raise e
      end
    ensure
      Datadog::Contrib::Rails::ActiveSupport.finish_trace_cache(payload)
    end
  end
end

.patch_cache_store_read ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 189

def patch_cache_store_read
  cache_store_class(:read).class_eval do
    alias_method :read_without_datadog, :read
    def read(*args, &block)
      payload = {
        action: 'GET',
        key: args[0],
        tracing_context: {}
      }

      begin
        # process and catch cache exceptions
        Datadog::Contrib::Rails::ActiveSupport.start_trace_cache(payload)
        read_without_datadog(*args, &block)
      rescue Exception => e
        payload[:exception] = [e.class.name, e.message]
        payload[:exception_object] = e
        raise e
      end
    ensure
      Datadog::Contrib::Rails::ActiveSupport.finish_trace_cache(payload)
    end
  end
end

.patch_cache_store_write ⇒ Object

# File 'lib/ddtrace/contrib/rails/core_extensions.rb', line 239

def patch_cache_store_write
  cache_store_class(:write).class_eval do
    alias_method :write_without_datadog, :write
    def write(*args, &block)
      payload = {
        action: 'SET',
        key: args[0],
        tracing_context: {}
      }

      begin
        # process and catch cache exceptions
        Datadog::Contrib::Rails::ActiveSupport.start_trace_cache(payload)
        write_without_datadog(*args, &block)
      rescue Exception => e
        payload[:exception] = [e.class.name, e.message]
        payload[:exception_object] = e
        raise e
      end
    ensure
      Datadog::Contrib::Rails::ActiveSupport.finish_trace_cache(payload)
    end
  end
end