Module: Moose::Inventory::DB

Extended by:
DB
Included in:
DB
Defined in:
lib/moose_inventory/db/db.rb,
lib/moose_inventory/db/models.rb,
lib/moose_inventory/db/exceptions.rb

Overview

Module for DB-related functionality

Defined Under Namespace

Classes: Group, Groupvar, Host, Hostvar, MooseDBException

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Attribute Details

#db ⇒ Object (readonly)

Returns the value of attribute db.



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# File 'lib/moose_inventory/db/db.rb', line 19

def db
  @db
end

#exceptions ⇒ Object (readonly)

Returns the value of attribute exceptions.



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# File 'lib/moose_inventory/db/db.rb', line 21

def exceptions
  @exceptions
end

#models ⇒ Object (readonly)

Returns the value of attribute models.



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# File 'lib/moose_inventory/db/db.rb', line 20

def models
  @models
end

Class Method Details

.init ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 24

def self.init
  # If we allow init more than once, then the db connection is remade,
  # which changes Sequel:DATABASES[0], thereby invalidating the sequel
  # models.  This causes unexpected behavour. That is to say, because
  # of the way Sequel initializes models, this method is not idempotent.
  # In our single-shot application, this shouldn't be a problem. However,
  # our unit tests like to call init multiple times, which borks things.
  # So, we allow init only once, gated by whether @db is nil. In effect,
  # this means we pool the DB connection for the life of the application.
  # Again, not a problem for our one-shot app, but it may be an issue in
  # long-running code. Personally, I don't like this pooling regime - 
  # perhaps I'm not understanding how it's supposed to be used? 
  #
  # QUESTION: can the models be refreshed, to make then again valid? What if
  #       we "load" instead of "require" the models?
  # ANSWER: Nope, still borks even if we use a load.
  #
  # @db = nil            # <- fails for unit tests
  return unless @db.nil? # <- works for unit tests

  Sequel::Model.plugin :json_serializer
  connect
  create_tables

  # Make our models work
  Sequel::DATABASES[0] = @db
  require_relative 'models'
  # load( load_dir = File.join(File.dirname(__FILE__), "models.rb") )

  # For convenience
  @models = {}
  @models[:host]     = Moose::Inventory::DB::Host
  @models[:hostvar]  = Moose::Inventory::DB::Hostvar
  @models[:group]    = Moose::Inventory::DB::Group
  @models[:groupvar] = Moose::Inventory::DB::Groupvar

  @exceptions = {}
  @exceptions[:moose] = Moose::Inventory::DB::MooseDBException

end

.reset ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 119

def self.reset
  fail('Database connection has not been established') if @db.nil?
  # @debug << 'reset'
  purge
  create_tables
end

.transaction ⇒ Object 



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# File 'lib/moose_inventory/db/db.rb', line 66

def self.transaction
  fail('Database connection has not been established') if @db.nil?
  
  tries = 0
  
  begin
    @db.transaction(savepoint: true) do
      yield
    end

  rescue Sequel::DatabaseError => e
  # We want to rescue Sqlite3::BusyException.  But, sequel catches that
  # and re-raises it as Sequel::DatabaseError, with a message referencing
  # the original exception class  
   
  # We look into e, to see whether it is a BusyException.  If not, 
  # we re-raise immediately.  
  raise unless e.message.include?("BusyException")  

  # Looks like a BusyException, so we retry, after a random delay.           
  tries += 1
  case tries
  when 1..10
    if Moose::Inventory::Config._confopts[:trace] == true
      STDERR.puts e.message
    end
    sleep rand()
    retry
  else
    warn('The database appears to be locked by another process, and '\
         " did not become free after #{tries} tries. Giving up. ")

    # TODO: Some useful advice to the user, as to what to do about this error. 
    raise  
  end
      
  rescue @exceptions[:moose] => e
    warn 'An error occurred during a transaction, any changes have been rolled back.'

    if Moose::Inventory::Config._confopts[:trace] == true
      STDERR.puts $!.backtrace    
      abort("ERROR: #{e}")
    else      
      abort("ERROR: #{e.message}")
    end

  rescue Exception => e
    warn 'An error occurred during a transaction, any changes have been rolled back.'
    raise e
  end
end