P4Triggers.rb #2

#--
#-------------------------------------------------------------------------------
#++
#
#= Introduction
#
#== Name:   P4Triggers.rb
#
#== Author: Tony Smith <tony@perforce.com>
#
#== Description
#
#    A library for use when writing Perforce triggers. Methods and classes 
#    common to all my example triggers are to be found in here. The framework
#    for a trigger is very simple:
#
#    1. You derive your trigger class from P4Trigger
#    2. You implement the validate() method to decide whether or not to 
#       allow the submit
#    3. You send output to the user using the message() method
#    4. You raise exceptions to report runtime errors P4Exceptions are
#       already handled for you.
#    5. Your trigger script should call P4Trigger#parse_change() and should use
#       the value returned as its exit status.
#
#    And that's all there is to it!
#
#    The P4Change class merits some familiarisation because objects of this
#    class are what you get when you call P4Trigger#change() and it's a
#    very convenient way to examine the changelist being submitted.
#
#    If you're just getting started with this framework, start by looking at
#    the P4Trigger class and then look at P4Change.
#--
#-------------------------------------------------------------------------------
#++



# A class for holding info about a change. This is intended to be populated
# be the output of "p4 describe" rather than "p4 change -o". The difference
# is mostly in the case of the hash keys, but that's significant enough.
class P4Change

    # Constructor. Pass the hash returned by P4#run_describe( "-s" ) in
    # tagged mode.
    def initialize( hash )
	@change = hash[ "change"  ]
	@user	= hash[ "user"    ]
	@client = hash[ "client"  ]
	@desc	= hash[ "desc"    ]
	@time 	= Time.at( hash[ "time" ].to_i )

	@status	= hash[ "status"  ]
	@files	= Array.new
	@jobs = Hash.new

	if ( hash.has_key?( "depotFile" ) )
	    hash[ "depotFile" ].each_index do
		|i|
		name = hash[ "depotFile" 	][ i ]
		type = hash[ "type"		][ i ]
		rev	 = hash[ "rev"		][ i ]
		act	 = hash[ "action"	][ i ]

		df = P4DepotFile.new( name )
		dr = df.new_revision

		dr.type 	= type
		dr.revno 	= rev.to_i
		dr.action	= act

		@files.push( df )
	    end
	end

	if ( hash.has_key?( "job" ) )
	    hash[ "job" ].each_index do
		|i|
		job 	= hash[ "job" 	  ][ i ]
		status	= hash[ "jobstat" ][ i ]
		@jobs[ job ] = status
	    end
	end
    end

    attr_reader :change, :user, :client, :desc, :time, :status, :files, :jobs

    # Shorthand iterator for looking at the files in the change
    def each_file( &block )
	@files.each { |f| yield( f ) }
    end

    # Shorthand iterator for looking at the jobs fixed by the change
    def each_job( &block )
	@jobs.each { |j| yield( j ) }
    end
end

# A class for encapsulating file types - type checking is quite common in 
# many triggers so it's nice to have it available to all.
class FileType

    # Provide a regexp that the filetype must match and a message for the 
    # types that match the regexp. i.e.
    #
    #   FileType.new( /u?binary/, "binary/ubinary" )
    #
    def initialize( regexp, message )
	@re	= regexp
	@msg	= message
    end

    attr_reader :msg

    # Test to see if the given filetype matches this type using the
    # regexp.
    def match( type )
	@re.match( type ) 
    end
end


# Reopen the P4 class to restructuring the output of "p4 describe -s" into a 
# P4Change object, and to disable any attempt to submit - just in case 
# someone's foolish enough to try
class P4
    def run_describe( *args )
	h = run( "describe", args ).shift
	return h unless h.kind_of?( Hash )
	return P4Change.new( h )
    end

    # Disable the submit_spec interface
    def submit_spec
	raise( "Attempt to submit during trigger execution. Don't do it." )
    end

    # Disable the direct interface to submit
    def run_submit
	raise( "Attempt to submit during trigger execution. Don't do it." )
    end
end

# A class providing a generic framework for all triggers. It provides
# rudimentary error handling so all errors get logged to stderr, and we
# also have a method for reporting a more friendly message to the user.
# It is intended that all trigger scripts will derive their own subclass
# of P4Trigger and override/expand it as necessary.
#
# You must override the validate() method if you want your trigger to
# work. The default implementation accepts *everything* so make sure you
# provide a method to reject bad changes or you will have accomplished
# nothing.
#
class P4Trigger

    # Constructor. 
    def initialize
	@change = nil
	@p4 = P4.new
	@p4.parse_forms
	@p4.exception_level = 1
	begin
	    @p4.connect
	rescue P4Exception
	    error_message()
	    raise
	end
    end

    # Direct access to the P4 object. You can use this for interrogating
    # the Perforce server. It's in parse_forms() mode and has an 
    # exception_level of 1 so exceptions will only be raised on errors, not
    # warnings.
    attr_reader :p4
    
    # Direct access to the changelist in question. Returns a P4Change object
    attr_reader :change

    # The main execution phase of the trigger. We assume since this is a
    # pre-submit trigger that there will be a changelist involved. The
    # steps for most triggers are common:
    #
    # 1. Find out about the changelist
    # 2. Enforce the rules
    #
    # We try to generalise this process so this class calls get_change()
    # for step 1, and validate() for step 2. Subclasses may override these
    # methods to tailor the trigger's behaviour
    #
    # parse_change() returns the correct exit status for the trigger so you
    # would normally use it like this:
    #
    #    exit( trig.parse_change( change_no ) )
    #
    def parse_change( change_no )
	begin
	    if ( ! change_no )
		raise( 	"No changelist number supplied to trigger script.\n" +
			"Please check your trigger configuration."
		     )
	    end
	    get_change( change_no )
	    return ( validate() ? 0 : 1 )
	rescue 
	    # Report errors to stderr, so they go into the Perforce server's
	    # logfile and report a simpler message to stdout
	    $stderr.puts( "\nError during trigger execution:\n\n" )
	    if ( $!.kind_of?( P4Exception ) )
		p4.errors.each { |e| $stderr.puts( e ) }
	    else
		$stderr.puts( $!.to_s )
	    end
	    $stderr.puts( "\nStack Trace:\n" )
	    $stderr.puts( $!.backtrace )
	    $stdout.puts( error_message() )

	    # Now we return false to the caller so they can return with 
	    # the correct exit status
	    return 1
	end
    end

    # The default implementation of get_change. Returns a hash describing
    # the change based on an execution of "p4 describe -s". The hash is
    # also saved in the @change member which subclasses may access in their
    # validate() method.  For most triggers this will be sufficient.
    def get_change( change_no )
	@change = p4.run_describe( "-s", change_no )
    end

    # The default implementation of validate(). Very simple, it accepts
    # everything. You are expected to override this method with one of
    # your own. When you do so, you can use the @change member to get
    # at the details of the change you're validating.
    def validate()
	true
    end

    #
    # Method to send a message to the user. Just writes to stdout, but it's
    # nice to encapsulate that here.
    #
    def message( string )
	$stdout.print( string )
    end

    # Default message for when things go wrong
    def error_message()
	"An error was encountered during trigger execution. Please\n" 	+
	"contact your Perforce administrator and ask them to\n" 	+
	"investigate the cause of this error\n"
    end
end