Class: Fbe::Middleware::SqliteStore

Inherits:
Object
  • Object
show all
Defined in:
lib/fbe/middleware/sqlite_store.rb

Overview

Persisted SQLite store for Faraday::HttpCache

This class provides a persistent cache store backed by SQLite for use with Faraday::HttpCache middleware. It’s designed to cache HTTP responses from GitHub API calls to reduce API rate limit consumption and improve performance.

Key features:

  • Automatic version management to invalidate cache on version changes

  • Size-based cache eviction (configurable, defaults to 10MB)

  • Thread-safe SQLite transactions

  • JSON serialization for cached values

  • Filtering of non-cacheable requests (non-GET, URLs with query parameters)

Usage example:

store = Fbe::Middleware::SqliteStore.new(
  '/path/to/cache.db',
  '1.0.0',
  loog: logger,
  maxsize: '50Mb'
)
# Use with Faraday
Faraday.new do |builder|
  builder.use Faraday::HttpCache, store: store
end

The store automatically manages the SQLite database schema and handles cleanup operations when the database grows too large. Old entries are deleted based on their last access time to maintain the configured size limit.

Author

Yegor Bugayenko ([email protected])

Copyright

Copyright © 2024-2025 Zerocracy

License

MIT

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path, version, loog: Loog::NULL, maxsize: '10Mb', maxvsize: '10Kb', ttl: nil, cache_min_age: nil) ⇒ SqliteStore

Initialize the SQLite store. or ttl is not nil or not Integer or not positive

Raises:

  • (ArgumentError) —

    If path is nil/empty, directory doesn’t exist, version is nil/empty,



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# File 'lib/fbe/middleware/sqlite_store.rb', line 60

def initialize(path, version, loog: Loog::NULL, maxsize: '10Mb', maxvsize: '10Kb', ttl: nil, cache_min_age: nil)
  raise ArgumentError, 'Database path cannot be nil or empty' if path.nil? || path.empty?
  dir = File.dirname(path)
  raise ArgumentError, "Directory #{dir} does not exist" unless File.directory?(dir)
  raise ArgumentError, 'Version cannot be nil or empty' if version.nil? || version.empty?
  @path = File.absolute_path(path)
  @version = version
  @loog = loog
  @maxsize = Filesize.from(maxsize.to_s).to_i
  @maxvsize = Filesize.from(maxvsize.to_s).to_i
  raise ArgumentError, 'TTL can be nil or Integer > 0' if !ttl.nil? && !(ttl.is_a?(Integer) && ttl.positive?)
  @ttl = ttl
  if !cache_min_age.nil? && !(cache_min_age.is_a?(Integer) && cache_min_age.positive?)
    raise ArgumentError, 'Cache min age can be nil or Integer > 0'
  end
  @cache_min_age = cache_min_age
end

Instance Attribute Details

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 48

def path
  @path
end

Instance Method Details

#all ⇒ Array<Array>

Get all entries from the cache.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 157

def all
  perform { _1.execute('SELECT key, value FROM cache') }
end

#clear ⇒ void

This method returns an undefined value.

Clear all entries from the cache.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 147

def clear
  perform do |t|
    t.execute 'DELETE FROM cache;'
    t.execute "UPDATE meta SET value = ? WHERE key = 'version';", [@version]
  end
  @db.execute 'VACUUM;'
end

#delete(key) ⇒ nil

Delete a key from the cache.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 98

def delete(key)
  perform { _1.execute('DELETE FROM cache WHERE key = ?', [key]) }
  nil
end

#read(key) ⇒ Object?

Read a value from the cache.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 81

def read(key)
  value = perform do |t|
    t.execute('UPDATE cache SET touched_at = ?2 WHERE key = ?1;', [key, Time.now.utc.iso8601])
    t.execute('SELECT value FROM cache WHERE key = ? LIMIT 1;', [key])
  end.dig(0, 0)
  return unless value
  begin
    JSON.parse(Zlib::Inflate.inflate(value))
  rescue Zlib::Error => e
    @loog.info("Failed to decompress cached value for key: #{key}, error: #{e.message}, the key will be deleted")
    delete(key)
  end
end

#write(key, value) ⇒ nil

Note:

Values larger than 10KB are not cached

Note:

Non-GET requests and URLs with query parameters are not cached

Write a value to the cache.



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# File 'lib/fbe/middleware/sqlite_store.rb', line 109

def write(key, value)
  return if value.is_a?(Array) && value.any? do |vv|
    req = JSON.parse(vv[0])
    req['method'] != 'get'
  end
  if @cache_min_age && value.is_a?(Array) && value[0].is_a?(Array) && value[0].size > 1
    begin
      resp = JSON.parse(value[0][1])
    rescue TypeError, JSON::ParserError => e
      @loog.info("Failed to parse response to rewrite the cache age: #{e.message}")
      resp = nil
    end
    cache_control = resp.dig('response_headers', 'cache-control') if resp.is_a?(Hash)
    if cache_control && !cache_control.empty?
      %w[max-age s-maxage].each do |key|
        age = cache_control.scan(/#{key}=(\d+)/i).first&.first&.to_i
        if age
          age = [age, @cache_min_age].max
          cache_control = cache_control.sub(/#{key}=(\d+)/, "#{key}=#{age}")
        end
      end
      resp['response_headers']['cache-control'] = cache_control
      value[0][1] = JSON.dump(resp)
    end
  end
  value = Zlib::Deflate.deflate(JSON.dump(value))
  return if value.bytesize > @maxvsize
  perform do |t|
    t.execute("      INSERT INTO cache(key, value, touched_at, created_at) VALUES(?1, ?2, ?3, ?3)\n      ON CONFLICT(key) DO UPDATE SET value = ?2, touched_at = ?3, created_at = ?3\n    SQL\n  end\n  nil\nend\n", [key, value, Time.now.utc.iso8601])