Thread: [etch-devel] SF.net SVN: etch:[129] trunk/server/lib/etch.rb

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Revision: 129
          http://etch.svn.sourceforge.net/etch/?rev=129&view=rev
Author:   jheiss
Date:     2009-10-29 20:41:05 +0000 (Thu, 29 Oct 2009)

Log Message:
-----------
Add support for files that depend on commands and vice-versa.

Add featuring allowing the server to tell the client to retry certain
commands on the next request. The "need sum" mechanism is used to do the
same thing for files, but as commands have no original content saving
mechanism we have to have an explicit feature for retries. The server
needs this if it is unable to generate all of the prerequisites for the
command, usually because the command depends on a file for which the
server needs original content info.

Modify generate_file and generate_commands methods to return a value
indicating the status of the generation. Thus if either is called due to
a dependency the caller knows whether it should proceed with its own
generation, or tell the client to retry next time if one or more
dependencies fail to generate due to a need for original content info.
generate_file previously pulled this info out of the @generation_status
hash, but it seems preferable to use a return value.

In generate_file, if a dependency fails to generate don't explicitly go
through the dependency tree and filter/need_orig each dependency. Each
file where that is necessary has already handled itself, and it's fine
if the client goes ahead and writes out other parts of the tree.

Fix bug in generate_file, we need to return the (filtered) config for
files which failed to generate due to a dependency failure, as the
config may contain setup entries.

Fix bug in xmlremove where it was calling the wrong REXML method if
asked to remove an element from a document (as opposed to another
element). The method call that was being used didn't generate an error,
but also didn't do anything. This in turn meant that
filter_xml_completely! was a no-op, which meant we were sending back
unfiltered configs when we meant to send back just depend and setup
entries.

Modified Paths:
--------------
    trunk/server/lib/etch.rb

Modified: trunk/server/lib/etch.rb
===================================================================

--- trunk/server/lib/etch.rb	2009-10-29 20:40:41 UTC (rev 128)
+++ trunk/server/lib/etch.rb	2009-10-29 20:41:05 UTC (rev 129)
@@ -43,7 +43,7 @@
   # if Logger didn't immediately blow up we'd probably end up with scrambled
   # logs as simultaneous connections tried to write at the same time.  Or
   # maybe that would work, depending on how Ruby and the OS buffer writes to
-  # the file.
+  # the file?
   def initialize(logger, debug_logger)
     @logger = logger
     @dlogger = debug_logger
@@ -178,7 +178,9 @@
     @generation_status = {}
     @configs = {}
     @need_orig = {}
-
+    @allcommands = {}
+    @retrycommands = {}
+    
     filelist.each do |file|
       @dlogger.debug "Generating #{file}"
       generate_file(file, request)
@@ -188,8 +190,6 @@
     # Generate configuration commands
     #
     
-    @allcommands = {}
-    
     commandnames = []
     if request.empty?
       @dlogger.debug "Building complete configuration commands for request from #{@fqdn}"
@@ -214,7 +214,8 @@
     
     {:configs => @configs,
      :need_orig => @need_orig,
-     :allcommands => @allcommands}
+     :allcommands => @allcommands,
+     :retrycommands => @retrycommands}
   end
 
   #
@@ -234,13 +235,16 @@
     end
     parentshash.keys.sort
   end
-
+  
+  # Returns the value of the generation_status variable, see comments in
+  # method for possible values.
   def generate_file(file, request)
     # Skip files we've already generated in response to <depend>
     # statements.
     if @already_generated[file]
       @dlogger.debug "Skipping already generated #{file}"
-      return
+      # Return the status of that previous generation
+      return @generation_status[file]
     end
 
     # Check for circular dependencies, otherwise we're vulnerable
@@ -274,46 +278,43 @@
     # As we go through the process of generating the file we'll end up with
     # four possible outcomes:
     # fatal error: raise an exception
-    # failure: we're missing needed data, generally the original file
+    # failure: we're missing needed data for this file or a dependency,
+    #          generally the original file
     # success: we successfully processed a valid configuration
     # unknown: no valid configuration nor errors encountered, probably because
-    #          filtering removed everything from the config.xml file
+    #          filtering removed everything from the config.xml file.  This
+    #          should be considered a successful outcome, it indicates the
+    #          caller/client provided us with all required data and our result
+    #          is that no action needs to be taken.
     # We keep track of which of the failure, success or unknown states we end
     # up in via the generation_status variable.  We initialize it to :unknown.
     # If we encounter either failure or success we set it to false or :success.
     catch :generate_done do
       # Generate any other files that this file depends on
       depends = []
+      proceed = true
       Etch.xmleach(config_xml, '/config/depend') do |depend|
         @dlogger.debug "Generating dependency #{Etch.xmltext(depend)}"
         depends << Etch.xmltext(depend)
-        generate_file(Etch.xmltext(depend), request)
+        r = generate_file(Etch.xmltext(depend), request)
+        proceed = proceed && r
       end
-      # If any dependency failed to generate (due to a need for orig contents
-      # from the client) then we need to unroll the whole dependency tree and
-      # punt it back to the client
-      dependency_status = depends.all? { |depend| @generation_status[depend] }
-      if !dependency_status
-        depends.each do |depend|
-          # Make sure any configuration we're returning is just the basics
-          # needed to supply orig data
-          if @configs[depend]
-            filter_xml_completely!(@configs[depend], ['depend', 'setup'])
-          end
-          # And if we weren't already planning to request orig contents for this
-          # file then stick it into the orig request list so that the client
-          # knows it needs to ask for this file again next time.
-          if !@need_orig.has_key?(depend)
-            @need_orig[depend] = true
-          end
-        end
-        # Lastly make sure that this file gets sent back appropriately
+      # Also generate any commands that this file depends on
+      Etch.xmleach(config_xml, '/config/dependcommand') do |dependcommand|
+        @dlogger.debug "Generating command dependency #{Etch.xmltext(dependcommand)}"
+        r = generate_commands(Etch.xmltext(dependcommand), request)
+        proceed = proceed && r
+      end
+      if !proceed
+        @dlogger.debug "One or more dependencies of #{file} need data from client"
+        # Tell the client to request this file again
         @need_orig[file] = true
+        # Strip this file's config down to the bare necessities
         filter_xml_completely!(config_xml, ['depend', 'setup'])
         generation_status = false
         throw :generate_done
       end
-    
+      
       # Change into the corresponding directory so that the user can
       # refer to source files and scripts by their relative pathnames.
       Dir::chdir "#{@sourcebase}/#{file}"
@@ -346,6 +347,7 @@
       if request[:files] && request[:files][file] && request[:files][file][:orig]
         original_file = request[:files][file][:orig]
       else
+        @dlogger.debug "Need original contents of #{file} from client"
         @need_orig[file] = true
         # If there are setup commands defined for this file we need to
         # pass those back along with our request for the original file,
@@ -777,8 +779,11 @@
         end
       end
     end
-  
-    if generation_status && generation_status != :unknown &&
+    
+    # In addition to successful configs return configs for files that need
+    # orig data (generation_status==false) because any setup commands might be
+    # needed to create the original file.
+    if generation_status != :unknown &&
        Etch.xmlfindfirst(config_xml, '/config/*')
       # The client needs this attribute to know to which file
       # this chunk of XML refers
@@ -789,8 +794,12 @@
     @already_generated[file] = true
     @filestack.delete(file)
     @generation_status[file] = generation_status
+    
+    generation_status
   end
   
+  # Returns the value of the generation_status variable, see comments in
+  # method for possible values.
   def generate_commands(command, request)
     # Skip commands we've already generated in response to <depend>
     # statements.
@@ -826,31 +835,67 @@
       raise "Filtered commands.xml for #{command} fails validation"
     end
     
-    # Generate any other files that this file depends on
-    Etch.xmleach(commands_xml, '/commands/depend') do |depend|
-      @dlogger.debug "Generating command dependency #{Etch.xmltext(depend)}"
-      generate_commands(Etch.xmltext(depend), request)
-    end
-    
-    # Change into the corresponding directory so that the user can
-    # refer to source files and scripts by their relative pathnames.
-    Dir::chdir "#{@commandsbase}/#{command}"
-    
-    # Check that the resulting document is consistent after filtering
-    Etch.xmleach(commands_xml, '/commands/step') do |step|
-      guard_exec_elements = Etch.xmlarray(step, 'guard/exec')
-      if check_for_inconsistency(guard_exec_elements)
-        raise "Inconsistent guard 'exec' entries for #{command}"
+    generation_status = :unknown
+    # As we go through the process of generating the command we'll end up with
+    # four possible outcomes:
+    # fatal error: raise an exception
+    # failure: we're missing needed data for this command or a dependency,
+    #          generally the original file for a file this command depends on
+    # success: we successfully processed a valid configuration
+    # unknown: no valid configuration nor errors encountered, probably because
+    #          filtering removed everything from the commands.xml file.  This
+    #          should be considered a successful outcome, it indicates the
+    #          caller/client provided us with all required data and our result
+    #          is that no action needs to be taken.
+    # We keep track of which of the failure, success or unknown states we end
+    # up in via the generation_status variable.  We initialize it to :unknown.
+    # If we encounter either failure or success we set it to false or :success.
+    catch :generate_done do
+      # Generate any other commands that this command depends on
+      proceed = true
+      Etch.xmleach(commands_xml, '/commands/depend') do |depend|
+        @dlogger.debug "Generating command dependency #{Etch.xmltext(depend)}"
+        r = generate_commands(Etch.xmltext(depend), request)
+        proceed = proceed && r
       end
-      command_exec_elements = Etch.xmlarray(step, 'command/exec')
-      if check_for_inconsistency(command_exec_elements)
-        raise "Inconsistent command 'exec' entries for #{command}"
+      # Also generate any files that this command depends on
+      Etch.xmleach(commands_xml, '/commands/dependfile') do |dependfile|
+        @dlogger.debug "Generating file dependency #{Etch.xmltext(dependfile)}"
+        r = generate_file(Etch.xmltext(dependfile), request)
+        proceed = proceed && r
       end
+      if !proceed
+        # Try again next time
+        @retrycommands[command] = true
+        generation_status = false
+        throw :generate_done
+      end
+      
+      # Change into the corresponding directory so that the user can
+      # refer to source files and scripts by their relative pathnames.
+      Dir::chdir "#{@commandsbase}/#{command}"
+      
+      # Check that the resulting document is consistent after filtering
+      Etch.xmleach(commands_xml, '/commands/step') do |step|
+        guard_exec_elements = Etch.xmlarray(step, 'guard/exec')
+        if check_for_inconsistency(guard_exec_elements)
+          raise "Inconsistent guard 'exec' entries for #{command}"
+        end
+        command_exec_elements = Etch.xmlarray(step, 'command/exec')
+        if check_for_inconsistency(command_exec_elements)
+          raise "Inconsistent command 'exec' entries for #{command}"
+        end
+      end
+      
+      # I'm not sure if we'd benefit from further checking the XML for
+      # validity.  For now we declare success if we got this far.
+      generation_status = :success
     end
     
     # If filtering didn't remove all the content then add this to the list of
     # commands to be returned to the client.
-    if Etch.xmlfindfirst(commands_xml, '/commands/*')
+    if generation_status && generation_status != :unknown &&
+       Etch.xmlfindfirst(commands_xml, '/commands/*')
       # Include the commands directory name to aid troubleshooting on the
       # client side.
       Etch.xmlattradd(Etch.xmlroot(commands_xml), 'commandname', command)
@@ -859,6 +904,9 @@
     
     @already_generated[command] = true
     @filestack.delete(command)
+    @generation_status[command] = generation_status
+    
+    generation_status
   end
   
   ALWAYS_KEEP = ['depend', 'setup', 'pre', 'test_before_post', 'post', 'test']
@@ -1198,7 +1246,11 @@
     when :libxml
       element.remove!
     when :rexml
-      xmldoc.elements.delete(element)
+      if xmldoc.node_type == :document
+        xmldoc.root.elements.delete(element)
+      else
+        xmldoc.elements.delete(element)
+      end
     else
       raise "Unknown @xmllib #{@xmllib}"
     end


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