First comments for Retries and RobustServer.
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1 changed files with 47 additions and 2 deletions
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@ -4,6 +4,7 @@ def Signal.signame s
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when String then s
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when Symbol then s.to_s
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when Fixnum then list.invert[s]
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else raise ArgumentError, "String, Symbol or Fixnum expected, not #{s.class}"
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end
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end
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@ -12,6 +13,7 @@ def Signal.sig s
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when Fixnum then s
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when String then list[s]
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when Symbol then list[s.to_s]
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else raise ArgumentError, "String, Symbol or Fixnum expected, not #{s.class}"
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end
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end
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@ -25,25 +27,58 @@ def Signal.[] s
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when String then list[s]
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when Symbol then list[s.to_s]
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when Fixnum then list.invert[s]
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else raise ArgumentError
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else raise ArgumentError, "String, Symbol or Fixnum expected, not #{s.class}"
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end
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end
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# Counts retries ot something. If the retries are to often in a short time,
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# you shouldn't retry again.
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#
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# Example:
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# retries = Retry.new 5, 1
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# begin
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# array_of_ints_and_some_strings.each do |i|
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# puts 2*i
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# end
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# rescue TypeError
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# retries.retry? and retry
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# raise $!
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# end
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#
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# Retry.new( 10, 30).run( ConnectionLost) do
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# try_to_connect_to_db
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# try_query
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# end
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class Retries
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attr_accessor :max, :range
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attr_reader :count, :last
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# max: How many retries in range-time are allowed maximal.
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# range: In which time-range are these retries are allowed
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def initialize max = nil, range = nil
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@max, @range, @count, @last = max || 10, range || 10, 0, Time.now
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end
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# Counts retries on every call.
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# If these retries are to often - max times in range - it will return false
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# else true.
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# Now you can say: "I give up, to many retries, it seems it doesn't work."
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def retry?
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@count = @last + @range > Time.now ? @count + 1 : 1
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@last = Time.now
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@count < @max
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end
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def run ex, &e
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# Automatical retrieing on raised exceptions in block.
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# ex: Your expected Esception you will rescue. Default: Object, so realy everything.
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#
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# Example:
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# Retries.new( 10, 30).run ArgumentError do something_do_which_could_raise_exception ArgumentError end
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#
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# This will retry maximal 10 times in 30 seconds to Call this block. But only rescues ArgumentError!
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# Every other Error it will ignore and throws Exception. No retry.
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def run ex = nil, &e
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ex ||= Object
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begin e.call *args
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rescue ex
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retries.retry? and retry
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@ -51,6 +86,16 @@ class Retries
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end
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end
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# Easy problem-handler for your Server.
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#
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# A Server should never crash.
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# If an Exception raised, which is not rescued, your program will shutdown abnormaly.
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# Or if a signal tries to "kill" your program, your program will shutdown abnormaly too.
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#
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# With RobustServer these errors will be a more unimportant problem and It'll be easier to handle.
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#
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# Subclasses should implements *#run*, which will be your main-worker.
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# For initializing, you can override **#initialize**, but doen't forget to call **super**.
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class RobustServer
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attr_reader :signals
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