Class: SDBTools::Transaction

Inherits:
Object
  • Object
show all
Defined in:
lib/sdbtools/transaction.rb

Overview

SimpleDB is not remotely transactional. A Transaction in this context is just a way to group together a series of SimpleDB requests for the purpose of benchmarking.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(description, on_close_action = self.class.on_close) ⇒ Transaction

Returns a new instance of Transaction.



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# File 'lib/sdbtools/transaction.rb', line 73

def initialize(description, on_close_action=self.class.on_close)
  @description   = description
  @box_usage     = 0.0
  @request_count = 0
  @item_count    = 0
  @on_close      = on_close_action
  @times         = Benchmark::Tms.new
  @nesting_level = self.class.transaction_stack.size
end

Instance Attribute Details

#box_usage ⇒ Object (readonly)

Returns the value of attribute box_usage.



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# File 'lib/sdbtools/transaction.rb', line 66

def box_usage
  @box_usage
end

#description ⇒ Object (readonly)

Returns the value of attribute description.



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# File 'lib/sdbtools/transaction.rb', line 65

def description
  @description
end

#item_count ⇒ Object (readonly)

Returns the value of attribute item_count.



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# File 'lib/sdbtools/transaction.rb', line 68

def item_count
  @item_count
end

#nesting_level ⇒ Object (readonly)

Returns the value of attribute nesting_level.



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# File 'lib/sdbtools/transaction.rb', line 71

def nesting_level
  @nesting_level
end

#on_close ⇒ Object (readonly)

Returns the value of attribute on_close.



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# File 'lib/sdbtools/transaction.rb', line 70

def on_close
  @on_close
end

#request_count ⇒ Object (readonly)

Returns the value of attribute request_count.



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# File 'lib/sdbtools/transaction.rb', line 67

def request_count
  @request_count
end

#times ⇒ Object (readonly)

Returns the value of attribute times.



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# File 'lib/sdbtools/transaction.rb', line 69

def times
  @times
end

Class Method Details

.add_stats(box_usage, request_count, item_count, times) ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 53

def self.add_stats(box_usage, request_count, item_count, times)
  current and current.add_stats(box_usage, request_count, item_count, times)
end

.current ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 57

def self.current
  transaction_stack.last
end

.log_transaction_close(logger, cutoff_level = :none) ⇒ Object

Usage:

Transaction.on_close = Transaction.log_transaction_close(logger)



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# File 'lib/sdbtools/transaction.rb', line 36

def self.log_transaction_close(logger, cutoff_level=:none)
  pattern = "%s \"%s\" (User %0.6u; System %0.6y; CPU %0.6t; Clock %0.6r; Box %0.6f; Reqs %d; Items %d)"
  lambda do |t|
    if cutoff_level == :none || cutoff_level <= t.nesting_level
      prefix = "*" * (t.nesting_level + 1)
      logger.info(
        t.times.format(
          pattern,
          prefix, 
          t.description,
          t.box_usage, 
          t.request_count, 
          t.item_count))
    end
  end
end

.on_close ⇒ Object

Get the default on_close action



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# File 'lib/sdbtools/transaction.rb', line 26

def self.on_close
  if current
    current.on_close
  else
    @on_close_action ||= lambda{|t|}
  end
end

.on_close=(action) ⇒ Object

Set the default on_close action. An on_close action receives a Transaction object which is being closed



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# File 'lib/sdbtools/transaction.rb', line 21

def self.on_close=(action)
  @on_close_action = action
end

.open(description, on_close = self.on_close) ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 10

def self.open(description, on_close=self.on_close)
  transaction = self.new(description, on_close)
  transaction_stack.push(transaction)
  yield(transaction)
ensure
  transaction = transaction_stack.pop
  transaction.close
end

.transaction_stack ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 61

def self.transaction_stack
  Thread.current[:sdbtools_transaction_stack] ||= []
end

Instance Method Details

#add_stats(box_usage, request_count, item_count, times = Benchmark::Tms.new) ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 89

def add_stats(box_usage, request_count, item_count, times=Benchmark::Tms.new)
  @request_count += request_count.to_i
  @box_usage     += box_usage.to_f
  @item_count    += item_count
  @times         += times
end

#add_stats_from_aws_response(response) ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 96

def add_stats_from_aws_response(response)
  response   = response.nil? ? {} : response
  box_usage  = response[:box_usage].to_f
  item_count = Array(response[:items]).size + Array(response[:domains]).size
  item_count += 1 if response.key?(:attributes)
  add_stats(box_usage, 1, item_count)
  response
end

#close ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 83

def close
  self.class.add_stats(@box_usage, @request_count, @item_count, @times)
  @on_close.call(self)
  self
end

#measure_aws_call ⇒ Object 



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# File 'lib/sdbtools/transaction.rb', line 105

def measure_aws_call
  add_stats_from_aws_response(time{yield})
end

#time ⇒ Object

Benchmark the block and add its times to the transaction



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# File 'lib/sdbtools/transaction.rb', line 110

def time
  result = nil
  self.times.add! do 
    result = yield 
  end
  result
end