Class: AvroTurf::DiskCache

Inherits:
Object
  • Object
show all
Defined in:
lib/avro_turf/disk_cache.rb

Overview

A cache for the CachedConfluentSchemaRegistry. Extends the InMemoryCache to provide a write-thru to disk for persistent cache.

Instance Method Summary collapse

Constructor Details

#initialize(disk_path, logger: Logger.new($stdout)) ⇒ DiskCache

Returns a new instance of DiskCache.



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# File 'lib/avro_turf/disk_cache.rb', line 5

def initialize(disk_path, logger: Logger.new($stdout))
  @logger = logger

  # load the write-thru cache on startup, if it exists
  @schemas_by_id_path = File.join(disk_path, 'schemas_by_id.json')
  hash = read_from_disk_cache(@schemas_by_id_path)
  @schemas_by_id = hash || {}

  @ids_by_schema_path = File.join(disk_path, 'ids_by_schema.json')
  hash = read_from_disk_cache(@ids_by_schema_path)
  @ids_by_schema = hash || {}

  @schemas_by_subject_version_path = File.join(disk_path, 'schemas_by_subject_version.json')
  @schemas_by_subject_version = {}

  @data_by_schema_path = File.join(disk_path, 'data_by_schema.json')
  hash = read_from_disk_cache(@data_by_schema_path)
  @data_by_schema = hash || {}
end

Instance Method Details

#lookup_by_id(id) ⇒ Object

override the write-thru cache (json) does not store keys in numeric format so, convert id to a string for caching purposes



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# File 'lib/avro_turf/disk_cache.rb', line 28

def lookup_by_id(id)
  @schemas_by_id[id.to_s]
end

#lookup_by_schema(subject, schema) ⇒ Object

override to use a json serializable cache key



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# File 'lib/avro_turf/disk_cache.rb', line 42

def lookup_by_schema(subject, schema)
  key = "#{subject}#{schema}"
  @ids_by_schema[key]
end

#lookup_by_version(subject, version) ⇒ Object

checks instance var (in-memory cache) for schema checks disk cache if in-memory cache doesn’t exists if file exists but no in-memory cache, read from file and sync in-memory cache finally, if file doesn’t exist return nil



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# File 'lib/avro_turf/disk_cache.rb', line 75

def lookup_by_version(subject, version)
  key = "#{subject}#{version}"
  schema = @schemas_by_subject_version[key]

  return schema unless schema.nil?

  hash = read_from_disk_cache(@schemas_by_subject_version_path)
  if hash
    @schemas_by_subject_version = hash
    @schemas_by_subject_version[key]
  end
end

#lookup_data_by_schema(subject, schema) ⇒ Object

override to use a json serializable cache key



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# File 'lib/avro_turf/disk_cache.rb', line 48

def lookup_data_by_schema(subject, schema)
  key = "#{subject}#{schema}"
  @data_by_schema[key]
end

#store_by_id(id, schema) ⇒ Object

override to include write-thru cache after storing result from upstream



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# File 'lib/avro_turf/disk_cache.rb', line 33

def store_by_id(id, schema)
  # must return the value from storing the result (i.e. do not return result from file write)
  @schemas_by_id[id.to_s] = schema
  write_to_disk_cache(@schemas_by_id_path, @schemas_by_id)

  schema
end

#store_by_schema(subject, schema, id) ⇒ Object

override to use a json serializable cache key and update the file cache



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# File 'lib/avro_turf/disk_cache.rb', line 54

def store_by_schema(subject, schema, id)
  key = "#{subject}#{schema}"
  @ids_by_schema[key] = id

  write_to_disk_cache(@ids_by_schema_path, @ids_by_schema)
  id
end

#store_by_version(subject, version, schema) ⇒ Object

check if file exists and parse json into a hash if file exists take json and overwite/insert schema at key if file doesn’t exist create new hash write the new/updated hash to file update instance var (in memory-cache) to match



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# File 'lib/avro_turf/disk_cache.rb', line 93

def store_by_version(subject, version, schema)
  key = "#{subject}#{version}"
  hash = read_from_disk_cache(@schemas_by_subject_version_path)
  hash = if hash
           hash[key] = schema
           hash
         else
           { key => schema }
         end

  write_to_disk_cache(@schemas_by_subject_version_path, hash)

  @schemas_by_subject_version = hash
  @schemas_by_subject_version[key]
end

#store_data_by_schema(subject, schema, data) ⇒ Object 



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# File 'lib/avro_turf/disk_cache.rb', line 62

def store_data_by_schema(subject, schema, data)
  return unless data

  key = "#{subject}#{schema}"
  @data_by_schema[key] = data
  write_to_disk_cache(@data_by_schema_path, @data_by_schema)
  data
end