Class: Exedb

Inherits:
Object
  • Object
show all
Defined in:
lib/exedb.rb,
lib/exedb/version.rb

Overview

Database-like interface for long-running tasks.

Each instance can run single command (get). If two or more instances with the same command do ‘get’, then only first will really execute command, all others will wait for result (flock is used).

Results of command execution (stdout) is cached. Next ‘get’ will return cached results (unless cache timeout happened).

You can force execution, calling ‘update’ method.

Exit code is available via ‘code’ method

Constant Summary collapse

SLEEP_TIME = 
1
DEF_DIR = 
'/tmp/Exedb'
DEF_CACHE_TIMEOUT = 
60
VERSION = 
"0.1.1"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str = '') ⇒ Exedb

Constructor



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# File 'lib/exedb.rb', line 31

def initialize(str='')
  @update_time=Time.parse("1970-01-01")
  @cache_timeout=DEF_CACHE_TIMEOUT
  @cache_dir=DEF_DIR
  @code=-1
  Dir.mkdir DEF_DIR unless File.directory? DEF_DIR
  self.update_method=(str)
end

Instance Attribute Details

#cache_dir ⇒ Object

Returns the value of attribute cache_dir.



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# File 'lib/exedb.rb', line 25

def cache_dir
  @cache_dir
end

#cache_timeout ⇒ Object

Returns the value of attribute cache_timeout.



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# File 'lib/exedb.rb', line 25

def cache_timeout
  @cache_timeout
end

#update_time ⇒ Object (readonly)

Returns the value of attribute update_time.



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# File 'lib/exedb.rb', line 26

def update_time
  @update_time
end

Instance Method Details

#cache_state ⇒ Object

Returns symbol of cache state:

  • updated = actual

  • need_update = new command execution needed

  • need_reread = just cache file reread is neede



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# File 'lib/exedb.rb', line 131

def cache_state
  if File.exists? @path
    mtime=File.mtime(@path)
    return :need_update if mtime+@cache_timeout<Time.now
    return :need_reread if @update_time<mtime
    return :updated
  end
  :need_update
end

#code ⇒ Object

Get last execution return code. NOTE!!! It is also cached, even on error.



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# File 'lib/exedb.rb', line 108

def code
  actualize
  @code
end

#get ⇒ Object

Get last execution result (stdout), or start new command execution and return result if cache is invalid.



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# File 'lib/exedb.rb', line 99

def get
  actualize
  @content
end

#peek ⇒ Object

Do not execute command - just peek in cache file… Usefull for intermediate command output peeking



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# File 'lib/exedb.rb', line 117

def peek
  begin
    File.read(@path)      
  rescue
    ''
  end
end

#put(str) ⇒ Object

Just alias for update_method=



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# File 'lib/exedb.rb', line 90

def put(str)
  self.update_method=(str)
end

#update ⇒ Object

Force command execution. If another instance with the same command is in progress, no new execution will be started



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# File 'lib/exedb.rb', line 43

def update
  @content=''
  File.open(@path, File::RDWR|File::CREAT, 0644) { |file|
    if file.flock(File::LOCK_EX|File::LOCK_NB)
      begin
        IO.popen(@update_method){|pipe|
          line=pipe.gets
          while line
            file.puts line
            file.flush
            @content = @content+line
            line=pipe.gets
          end
        }
        @code=$?.exitstatus
        #warn "UPDATED: #{@content}/#{@code}"
      rescue
        @content=''
        @code=-1
      end
      file.write @content
      file.flush
      File.open("#{@path}.code",File::RDWR|File::CREAT, 0644){|code_file|
        code_file.puts @code
      }
      file.flock(File::LOCK_UN)
    else
      warn "CANNOT LOCK"
      read_cache
    end
    @update_time=Time.now
  }
  #!!!warn "UPDATED!'"
  @content
end

#update_in_progress? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/exedb.rb', line 141

def update_in_progress?
  if File.exists? @path
    File.open(@path, File::RDONLY) { |file|
      if file.flock(File::LOCK_EX|File::LOCK_NB)
        file.flock(File::LOCK_UN)
        return false
      end
    }
    return true
  end
  return false
end

#update_method=(str) ⇒ Object

Replace executing command



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# File 'lib/exedb.rb', line 82

def update_method=(str)
  @update_method=str
  @key=generate_key str
  @path=File.join(DEF_DIR, @key)
#    warn "key=#{@key}; path=#{@path}; u=#{str}"
end