Initial commit

app/helpers/embed_redis_cache.rb

@@ -0,0 +1,83 @@
+require 'zlib'
+
+class EmbedRedisCache
+  # This needs to be changed whenever there're changes in the code that require invalidation of old keys
+  VERSION = '4'
+
+  def initialize(redis_cache = $tables_metadata)
+    @redis = redis_cache
+  end
+
+  def get(visualization_id, https_request)
+    key = key(visualization_id, https_request)
+    value = redis.get(key)
+    value.present? ? JSON.parse(value, symbolize_names: true) : nil
+  rescue => exception
+    # Captures:
+    # - Redis::BaseError if redis is down
+    # - IO errors due to deploys changing physical path (see read_frontend_version / calculate_embed_template_hash)
+    CartoDB::Logger.error(exception: exception)
+    nil
+  end
+
+  # Only public and public with link
+  def set(visualization_id, https_request, response_headers, response_body)
+    serialized = JSON.generate(headers: response_headers,
+                               body: response_body
+                              )
+    redis.setex(key(visualization_id, https_request), 24.hours.to_i, serialized)
+  rescue => exception
+    # Captures:
+    # - Redis::BaseError if redis is down
+    # - IO errors due to deploys changing physical path (see read_frontend_version / calculate_embed_template_hash)
+    CartoDB::Logger.error(exception: exception)
+    nil
+  end
+
+  def invalidate(visualization_id)
+    redis.del [key(visualization_id, true), key(visualization_id, false)]
+  rescue => exception
+    # Captures:
+    # - Redis::BaseError if redis is down
+    # - IO errors due to deploys changing physical path (see read_frontend_version / calculate_embed_template_hash)
+    CartoDB::Logger.error(exception: exception)
+    nil
+  end
+
+  def key(visualization_id, https_request = false)
+    protocol = https_request ? 'https' : 'http'
+    [
+      "vis",
+      visualization_id,
+      "embed",
+      protocol,
+      VERSION,
+      CartoDB::Application.frontend_version,
+      embed_template_hash
+    ].join(":")
+  end
+
+  def purge(vizs)
+    return unless vizs.count > 0
+    keys = vizs.map { |v| [key(v.id, false), key(v.id, true)] }.flatten
+    redis.del keys
+  end
+
+  private
+
+  def embed_template_hash
+    # INFO: New deploys restart the server, invalidating this value + we want to hit disk as less as possible
+    @@key_fragment_embed_template_hash ||= calculate_embed_template_hash
+  end
+
+  def calculate_embed_template_hash
+    # The alternative Adler-32 is not as reliable as CRC32
+    # and even less with inputs of "few hundred bytes" as is this case
+    Zlib::crc32(File.read(Rails.root.join("app/views/admin/visualizations/embed_map.html.erb")))
+  end
+
+  def redis
+    @redis
+  end
+
+end