class Aws::S3::ExpressCredentialsCache

def [](bucket_name)
  @mutex.synchronize { @credentials[bucket_name] }
end

def []=(bucket_name, credential_provider)
  @mutex.synchronize do
    @credentials[bucket_name] = credential_provider
  end
end

def clear
  @mutex.synchronize { @credentials = {} }
end

def initialize
  @credentials = {}
  @mutex = Mutex.new
end