Class: Aptly::Mutex

Inherits:
Object
  • Object
show all
Defined in:
lib/aptly/mutex.rb

Constant Summary collapse

@@mutex_path = 
'/tmp/aptly.lock'

Class Method Summary collapse

Class Method Details

.lock ⇒ Object

Attempts to acquire the aptly mutex. This method will wait if the mutex is already locked elsewhere, and check back every 5 seconds to see if it has been freed. On each check where the mutex is determined to be in use, we check if the process which originally acquired the lock is still running so we can acquire a stale mutex should we need to.

Returns:

True, once the lock is acquired.



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# File 'lib/aptly/mutex.rb', line 37

def self.lock
  while self.locked?
    self.running? && sleep(5) || self.unlock
  end
  File.open(@@mutex_path, 'w') {|f| f.write Process.pid}
end

.locked? ⇒ Boolean

Checks if the mutex is in use. This is done via a simple file check.

Returns:

True if locked, else false

Returns:

  • (Boolean) 


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# File 'lib/aptly/mutex.rb', line 49

def self.locked?
  File.exist? @@mutex_path
end

.mutex_path ⇒ Object

Static attribute accessor for mutex path

Returns:

The path to the aptly mutex file



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# File 'lib/aptly/mutex.rb', line 12

def self.mutex_path
  @@mutex_path
end

.mutex_path=(path) ⇒ Object

Alter the mutex path. This should be set to the same path in all places where ruby-aptly will be used on the same host, since the mutex is meant to be system-wide.

Parameters:

path

The desired path for the mutex



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# File 'lib/aptly/mutex.rb', line 24

def self.mutex_path= path
  @@mutex_path = path
end

.running? ⇒ Boolean

Checks if the process which originally acquired the mutex is still running. This is useful to determine staleness of a locked mutex.

Returns:

True if running, else false

Returns:

  • (Boolean) 


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# File 'lib/aptly/mutex.rb', line 59

def self.running?
  begin
    pid = File.open(@@mutex_path).read.to_i
    Process.kill(0, pid)
    return true
  rescue Errno::ESRCH, Errno::ENOENT
    return false
  end
end

.unlock ⇒ Object

Unlocks the mutex so that other processes may acquire it.

Returns:

True if unlock happens, else false



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# File 'lib/aptly/mutex.rb', line 74

def self.unlock
  File.delete @@mutex_path if self.locked?
end