Class: ExceptionCatcher

Inherits:
Object show all
Defined in:
lib/util/exception_catcher.rb

Overview

ExceptionCatcher makes it easy to execute multiple operations even though any might fail with exception

  • executed tasks can be named to make it easier to identify which tasks failed

  • collects result and exceptions for each executed task

  • raises a MultipleExceptions exception if there were more than one exception

    catcher = ExceptionCatcher.new
catcher.catch(1){raise "1"}
catcher.catch(2){raise "2"}
catcher.catch(3){"ok!"}
catcher.exception(1) # -> exception object raised by the task 1
catcher.exception(2) # -> exception object raise by the task 2
catcher.result(3) # -> "ok!"
catcher.check # raises a MultipleExceptions exception

Defined Under Namespace

Classes: MultipleExceptions

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ExceptionCatcher

Returns a new instance of ExceptionCatcher.



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# File 'lib/util/exception_catcher.rb', line 36

def initialize
  @mutex = Mutex.new
  @results = {}
  @exceptions = {}
  @tasks = []
end

Instance Attribute Details

#exceptions ⇒ Object (readonly)

Returns the value of attribute exceptions.



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# File 'lib/util/exception_catcher.rb', line 34

def exceptions
  @exceptions
end

#mutex ⇒ Object (readonly)

Returns the value of attribute mutex.



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# File 'lib/util/exception_catcher.rb', line 34

def mutex
  @mutex
end

#results ⇒ Object (readonly)

Returns the value of attribute results.



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# File 'lib/util/exception_catcher.rb', line 34

def results
  @results
end

#tasks ⇒ Object (readonly)

Returns the value of attribute tasks.



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# File 'lib/util/exception_catcher.rb', line 34

def tasks
  @tasks
end

Instance Method Details

#catch(task = nil, &block) ⇒ Object?

Catches exceptions thrown by block

Parameters:

  • task (Object, nil) (defaults to: nil) —

    if task is defined, results can be checked per task

  • block, (Proc) —

    block which is executed

Returns:

  • (Object, nil) —

    returns block’s result or nil if block raised an exception



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# File 'lib/util/exception_catcher.rb', line 47

def catch(task=nil, &block)
  if task.nil?
    task = block
  end
  @mutex.synchronize do
    @tasks << task
  end
  begin
    result = block.call
    @mutex.synchronize do
      @results[task]=result
    end
    result
  rescue Exception => e
    @mutex.synchronize do
      @exceptions[task]=e
    end
    nil
  end
end

#check ⇒ Object

Checks if there has been exceptions and raises the original exception if there has been one exception and MultipleExceptions if there has been many exceptions



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# File 'lib/util/exception_catcher.rb', line 90

def check
  @mutex.synchronize do
    if @exceptions.size == 1
      e = @exceptions.values.first
      raise e.class, e.message, e.backtrace
    elsif @exceptions.size > 1
      raise MultipleExceptions.new("Caught #{@exceptions.size} exceptions!").catcher(self)
    end
  end
end

#exception(task) ⇒ Object?

Returns block’s exception or nil if the block did not raise an exception.

Parameters:

  • task (Object) —

    identifies the executed task

Returns:

  • (Object, nil) —

    block’s exception or nil if the block did not raise an exception



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# File 'lib/util/exception_catcher.rb', line 78

def exception(task)
  @mutex.synchronize do
    @exceptions[task]
  end
end

#exceptions? ⇒ bool

Returns exceptions? returns true if there has been exceptions.

Returns:

  • (bool) —

    exceptions? returns true if there has been exceptions



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# File 'lib/util/exception_catcher.rb', line 85

def exceptions?
  @exceptions.size > 0
end

#result(task) ⇒ Object?

Returns result for the named block or nil if the block ended in exception.

Parameters:

  • task (Object) —

    identifies the executed task

Returns:

  • (Object, nil) —

    result for the named block or nil if the block ended in exception



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# File 'lib/util/exception_catcher.rb', line 70

def result(task)
  @mutex.synchronize do
    @results[task]
  end
end