Updated mcollective.init according to OSCI-658

[packages/precise/mcollective.git] / lib / mcollective / facts / base.rb

diff --git a/lib/mcollective/facts/base.rb b/lib/mcollective/facts/base.rb
new file mode 100644 (file)
index 0000000..c5cb4bb
--- /dev/null
+++ b/lib/mcollective/facts/base.rb
@@ -0,0 +1,86 @@
+module MCollective
+  module Facts
+    # A base class for fact providers, to make a new fully functional fact provider
+    # inherit from this and simply provide a self.get_facts method that returns a
+    # hash like:
+    #
+    #  {"foo" => "bar",
+    #   "bar" => "baz"}
+    class Base
+      def initialize
+        @facts = {}
+        @last_good_facts = {}
+        @last_facts_load = 0
+      end
+
+      # Registers new fact sources into the plugin manager
+      def self.inherited(klass)
+        PluginManager << {:type => "facts_plugin", :class => klass.to_s}
+      end
+
+      # Returns the value of a single fact
+      def get_fact(fact=nil)
+        config = Config.instance
+
+        cache_time = config.fact_cache_time || 300
+
+        Thread.exclusive do
+          begin
+            if (Time.now.to_i - @last_facts_load > cache_time.to_i ) || force_reload?
+              Log.debug("Resetting facter cache, now: #{Time.now.to_i} last-known-good: #{@last_facts_load}")
+
+              tfacts = load_facts_from_source
+
+              # Force reset to last known good state on empty facts
+              raise "Got empty facts" if tfacts.empty?
+
+              @facts.clear
+
+              tfacts.each_pair do |key,value|
+                @facts[key.to_s] = value.to_s
+              end
+
+              @last_good_facts = @facts.clone
+              @last_facts_load = Time.now.to_i
+            else
+              Log.debug("Using cached facts now: #{Time.now.to_i} last-known-good: #{@last_facts_load}")
+            end
+          rescue Exception => e
+            Log.error("Failed to load facts: #{e.class}: #{e}")
+
+            # Avoid loops where failing fact loads cause huge CPU
+            # loops, this way it only retries once every cache_time
+            # seconds
+            @last_facts_load = Time.now.to_i
+
+            # Revert to last known good state
+            @facts = @last_good_facts.clone
+          end
+        end
+
+
+        # If you do not supply a specific fact all facts will be returned
+        if fact.nil?
+          return @facts
+        else
+          @facts.include?(fact) ? @facts[fact] : nil
+        end
+      end
+
+      # Returns all facts
+      def get_facts
+        get_fact(nil)
+      end
+
+      # Returns true if we know about a specific fact, false otherwise
+      def has_fact?(fact)
+        get_fact(nil).include?(fact)
+      end
+
+      # Plugins can override this to provide forced fact invalidation
+      def force_reload?
+        false
+      end
+    end
+  end
+end