lib/zfs_mgmt.rb in zfs_mgmt-0.4.7 vs lib/zfs_mgmt.rb in zfs_mgmt-0.4.8

@@ -6,10 +6,11 @@
 require 'date'
 require 'logger'
 require 'text-table'
 require 'open3'
 require 'filesize'
+require 'timeout'
 
 $logger = Logger.new(STDERR, progname: 'zfs_mgmt')
 
 $date_patterns = {
   'hourly' => '%F Hour %H',
@@ -35,10 +36,12 @@
 $properties_xlate = {
   'userrefs' => ->(x) { x.to_i },
   'creation' => ->(x) { x.to_i },
 }
 
+$lock = nil
+
 module ZfsMgmt
   class << self
     attr_accessor :global_options
   end
   class ZfsGetError < StandardError
@@ -684,8 +687,44 @@
       unless props['zfsmgmt:destination']
         $logger.error("#{zfs}: you must specify a destination zfs path via the user property zfsmgmt:destination, even if using --destination on the command line, skipping")
         next
       end
       zfs_send(options,zfs,props,snaps)
+    end
+  end
+  def self.lock(options)
+    # open lock file, try to lock file until lock_wait has expired or
+    # lock is obtained, write pid?
+    return nil unless options[:lock]
+    begin
+      lock = File.open(options[:lock_file], File::RDWR|File::CREAT, 0644)
+    rescue Errno::ENOENT => error
+      $logger.error("unable to open lock file (#{options[:lock_file]}), possibly the directory doesn't exist")
+      raise
+    end
+    if options[:lock_wait] > 0
+      begin
+        status = Timeout::timeout(options[:lock_wait]) do
+          return lock if lock.flock(File::LOCK_EX)
+          $logger.error("flock of #{options[:lock_file]} failed")
+          raise "flock failed"
+        end
+      rescue Timeout::Error => error
+        $logger.error("timed out waiting to lock")
+        raise
+      end
+    else
+      # zero is wait forever!
+      return lock if lock.flock(File::LOCK_EX)
+      $logger.error("flock of #{options[:lock_file]} failed")
+      raise "flock failed"
+    end
+    $logger.error("unable to obtain lock")
+    raise "unknown failure in locking file"
+  end
+  def self.unlock(lock)
+    unless lock.nil?
+      lock.flock(File::LOCK_UN)
+      lock.close()
     end
   end
 end