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authorAdam Niedzielski <adamsunday@gmail.com>2017-02-07 18:06:08 +0100
committerAdam Niedzielski <adamsunday@gmail.com>2017-03-01 16:48:01 +0100
commit61c9604721dbda53eb4a7111d16c1b19292f9766 (patch)
tree5cdce583a6c0f8984efbaf3a0b6a3fab33c0b113 /lib
parent0a31efb57768345e2b3350a493021a26b54994a3 (diff)
downloadgitlab-ce-61c9604721dbda53eb4a7111d16c1b19292f9766.tar.gz
Add middleware for ETag caching with Redis
Diffstat (limited to 'lib')
-rw-r--r--lib/gitlab/etag_caching/middleware.rb66
-rw-r--r--lib/gitlab/etag_caching/store.rb32
2 files changed, 98 insertions, 0 deletions
diff --git a/lib/gitlab/etag_caching/middleware.rb b/lib/gitlab/etag_caching/middleware.rb
new file mode 100644
index 00000000000..0f24f9bbfde
--- /dev/null
+++ b/lib/gitlab/etag_caching/middleware.rb
@@ -0,0 +1,66 @@
+module Gitlab
+ module EtagCaching
+ class Middleware
+ RESERVED_WORDS = ProjectPathValidator::RESERVED.map { |word| "/#{word}/" }.join('|')
+ ROUTE_REGEXP = Regexp.union(
+ %r(^(?!.*(#{RESERVED_WORDS})).*/noteable/issue/\d+/notes\z)
+ )
+
+ def initialize(app)
+ @app = app
+ end
+
+ def call(env)
+ return @app.call(env) unless enabled_for_current_route?(env)
+ Gitlab::Metrics.add_event(:etag_caching_middleware_used)
+
+ etag, cached_value_present = get_etag(env)
+ if_none_match = env['HTTP_IF_NONE_MATCH']
+
+ if if_none_match == etag
+ Gitlab::Metrics.add_event(:etag_caching_cache_hit)
+ [304, { 'ETag' => etag }, ['']]
+ else
+ track_cache_miss(if_none_match, cached_value_present)
+
+ status, headers, body = @app.call(env)
+ headers['ETag'] = etag
+ [status, headers, body]
+ end
+ end
+
+ private
+
+ def enabled_for_current_route?(env)
+ ROUTE_REGEXP.match(env['PATH_INFO'])
+ end
+
+ def get_etag(env)
+ cache_key = env['PATH_INFO']
+ store = Store.new
+ current_value = store.get(cache_key)
+ cached_value_present = current_value.present?
+
+ unless cached_value_present
+ current_value = store.touch(cache_key, only_if_missing: true)
+ end
+
+ [weak_etag_format(current_value), cached_value_present]
+ end
+
+ def weak_etag_format(value)
+ %Q{W/"#{value}"}
+ end
+
+ def track_cache_miss(if_none_match, cached_value_present)
+ if if_none_match.blank?
+ Gitlab::Metrics.add_event(:etag_caching_header_missing)
+ elsif !cached_value_present
+ Gitlab::Metrics.add_event(:etag_caching_key_not_found)
+ else
+ Gitlab::Metrics.add_event(:etag_caching_resource_changed)
+ end
+ end
+ end
+ end
+end
diff --git a/lib/gitlab/etag_caching/store.rb b/lib/gitlab/etag_caching/store.rb
new file mode 100644
index 00000000000..9532e432f78
--- /dev/null
+++ b/lib/gitlab/etag_caching/store.rb
@@ -0,0 +1,32 @@
+module Gitlab
+ module EtagCaching
+ class Store
+ EXPIRY_TIME = 10.minutes
+ REDIS_NAMESPACE = 'etag:'.freeze
+
+ def get(key)
+ Gitlab::Redis.with { |redis| redis.get(redis_key(key)) }
+ end
+
+ def touch(key, only_if_missing: false)
+ etag = generate_etag
+
+ Gitlab::Redis.with do |redis|
+ redis.set(redis_key(key), etag, ex: EXPIRY_TIME, nx: only_if_missing)
+ end
+
+ etag
+ end
+
+ private
+
+ def generate_etag
+ SecureRandom.hex
+ end
+
+ def redis_key(key)
+ "#{REDIS_NAMESPACE}#{key}"
+ end
+ end
+ end
+end