Module: Common::Client::Concerns::MhvLockedSessionClient

Extended by:
ActiveSupport::Concern
Includes:
SentryLogging
Included in:
MHVJwtSessionClient
Defined in:
lib/common/client/concerns/mhv_locked_session_client.rb

Overview

Module mixin for overriding session logic when making session-based client connections that should lock during session creation, to prevent threads from making simultaneous authentication API calls.

All refrences to “session” in this module refer to the upstream MHV session.

See Also:

Constant Summary collapse

LOCK_RETRY_DELAY =

Number of seconds to wait between attempts to acquire a session lock

1
RETRY_ATTEMPTS =

How many times to attempt to acquire a session lock

10

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from SentryLogging

#log_exception_to_sentry, #log_message_to_sentry, #non_nil_hash?, #normalize_level, #rails_logger

Instance Attribute Details

#session ⇒ Hash (readonly)

Returns a hash containing session information.

Returns:

  • (Hash) —

    a hash containing session information



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# File 'lib/common/client/concerns/mhv_locked_session_client.rb', line 18

module MhvLockedSessionClient
  extend ActiveSupport::Concern
  include SentryLogging

  LOCK_RETRY_DELAY = 1 # Number of seconds to wait between attempts to acquire a session lock
  RETRY_ATTEMPTS = 10 # How many times to attempt to acquire a session lock

  attr_reader :session

  ##
  # @param session [Hash] a hash containing a key with which the session will be found or built
  #
  def initialize(session:)
    refresh_session(session)
  end

  ##
  # Ensure the upstream MHV session is not expired or incomplete.
  #
  # @return [MhvFhirSessionClient] instance of `self`
  #
  def authenticate
    raise 'ICN is required for session creation' unless user_key

    iteration = 0

    # Loop unless a complete, valid MHV session exists, or until max_iterations is reached
    while invalid?(session) && iteration < RETRY_ATTEMPTS
      break if lock_and_get_session # Break out of the loop once a new session is created.

      sleep(LOCK_RETRY_DELAY)

      # Refresh the MHV session reference in case another thread has updated it.
      refresh_session(session)
      iteration += 1
    end
    if invalid?(session) && iteration >= RETRY_ATTEMPTS
      Rails.logger.info("Failed to create #{@client_session} after #{iteration} attempts to acquire lock")
    end

    self
  end

  ##
  # Override client_session method to use extended ::ClientSession classes
  #
  class_methods do
    ##
    # @return [MedicalRecords::ClientSession] if a MR (Medical Records) client session
    #
    def client_session(klass = nil)
      @client_session ||= klass
    end
  end

  protected

  def refresh_session(session)
    @session = self.class.client_session.find_or_build(session)
  end

  def invalid?(session)
    session.expired?
  end

  private

  ##
  # Attempt to acquire a redis lock, then create a new MHV session. Once the session is created,
  # release the lock.
  #
  # return [Boolean] true if a session was created, otherwise false
  #
  def lock_and_get_session
    redis_lock = obtain_redis_lock
    if redis_lock
      begin
        @session = get_session
        return true
      ensure
        release_redis_lock(redis_lock)
      end
    end
    false
  end

  def obtain_redis_lock
    lock_key = "mhv_fhir_session_lock:#{user_key}"
    redis_lock = Redis::Namespace.new(REDIS_CONFIG[session_config_key][:namespace], redis: $redis)
    success = redis_lock.set(lock_key, 1, nx: true, ex: REDIS_CONFIG[session_config_key][:each_ttl])

    return redis_lock if success

    nil
  end

  def release_redis_lock(redis_lock)
    lock_key = "mhv_fhir_session_lock:#{user_key}"
    redis_lock.del(lock_key)
  end
end

Instance Method Details

#authenticate ⇒ MhvFhirSessionClient

Ensure the upstream MHV session is not expired or incomplete.

Returns:



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# File 'lib/common/client/concerns/mhv_locked_session_client.rb', line 39

def authenticate
  raise 'ICN is required for session creation' unless user_key

  iteration = 0

  # Loop unless a complete, valid MHV session exists, or until max_iterations is reached
  while invalid?(session) && iteration < RETRY_ATTEMPTS
    break if lock_and_get_session # Break out of the loop once a new session is created.

    sleep(LOCK_RETRY_DELAY)

    # Refresh the MHV session reference in case another thread has updated it.
    refresh_session(session)
    iteration += 1
  end
  if invalid?(session) && iteration >= RETRY_ATTEMPTS
    Rails.logger.info("Failed to create #{@client_session} after #{iteration} attempts to acquire lock")
  end

  self
end

#initialize(session:) ⇒ Object

Parameters:

  • session (Hash) —

    a hash containing a key with which the session will be found or built



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# File 'lib/common/client/concerns/mhv_locked_session_client.rb', line 30

def initialize(session:)
  refresh_session(session)
end

#invalid?(session) ⇒ Boolean (protected)

Returns:

  • (Boolean) 


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# File 'lib/common/client/concerns/mhv_locked_session_client.rb', line 79

def invalid?(session)
  session.expired?
end

#refresh_session(session) ⇒ Object (protected) 



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# File 'lib/common/client/concerns/mhv_locked_session_client.rb', line 75

def refresh_session(session)
  @session = self.class.client_session.find_or_build(session)
end