72 lines
1.9 KiB
Ruby
72 lines
1.9 KiB
Ruby
module Gitlab
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module EtagCaching
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class Middleware
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def initialize(app)
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@app = app
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end
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def call(env)
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request = Rack::Request.new(env)
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route = Gitlab::EtagCaching::Router.match(request)
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return @app.call(env) unless route
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track_event(:etag_caching_middleware_used, route)
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etag, cached_value_present = get_etag(request)
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if_none_match = env['HTTP_IF_NONE_MATCH']
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if if_none_match == etag
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handle_cache_hit(etag, route)
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else
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track_cache_miss(if_none_match, cached_value_present, route)
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status, headers, body = @app.call(env)
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headers['ETag'] = etag
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[status, headers, body]
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end
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end
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private
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def get_etag(request)
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cache_key = request.path
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store = Gitlab::EtagCaching::Store.new
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current_value = store.get(cache_key)
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cached_value_present = current_value.present?
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unless cached_value_present
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current_value = store.touch(cache_key, only_if_missing: true)
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end
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[weak_etag_format(current_value), cached_value_present]
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end
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def weak_etag_format(value)
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%Q{W/"#{value}"}
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end
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def handle_cache_hit(etag, route)
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track_event(:etag_caching_cache_hit, route)
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status_code = Gitlab::PollingInterval.polling_enabled? ? 304 : 429
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[status_code, { 'ETag' => etag }, []]
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end
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def track_cache_miss(if_none_match, cached_value_present, route)
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if if_none_match.blank?
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track_event(:etag_caching_header_missing, route)
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elsif !cached_value_present
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track_event(:etag_caching_key_not_found, route)
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else
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track_event(:etag_caching_resource_changed, route)
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end
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end
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def track_event(name, route)
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Gitlab::Metrics.add_event(name, endpoint: route.name)
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end
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end
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end
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end
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