Added resize method to Base. Fixed lastupdate to work with 1.3

CHANGELOG.rdoc

@@ -11,7 +11,7 @@
 
 * Added graph! to RRD
 * Added bang methods to base
-* Added dump, last_update methods to RRD::Base instance (TODO: tune, resize)
+* Added dump, last_update, resize methods to RRD::Base instance (TODO: tune)
 * Added dump, tune, resize, last_update methods to RRD::Wrapper
 * Escape ':' on graph label
 * Added flags to be used on RRD::Base instances and for building graphs

README.rdoc

@@ -6,7 +6,7 @@ You may use it in the raw format, as many rrd libs in languages like perl or pyt
 
 rrd-ffi uses ffi to wrap the librrd C bindings, not system calls.
 
-IMPORTANT: You need librrd installed in your system for this gem to work
+IMPORTANT: You need librrd installed (version 1.3.1 or above) in your system for this gem to work
 
 = Basics 
 
@@ -28,7 +28,7 @@ or
 
   export LD_LIBRARY_PATH=/opt/local/lib
 
-If you are not using MAC OS and still have problems, export the RRD_PATH variable with the path to your librrd file.
+If you are not using MAC OS and still having problems, export the RRD_PATH variable with the path to your librrd file.
 
 === Installing librrd
 
@@ -38,6 +38,12 @@ Fedora/Red Hat: <tt>yum install rrdtool-devel</tt>
 
 Mac: <tt>port install rrdtool</tt>
 
+From source:
+  cd rrdtool-${rrdtool_version}
+  ./configure --disable-ruby --prefix=/usr/local
+  make
+  make install
+
 == Example Usage
   require "rrd"
   rrd = RRD::Base.new("myrrd.rrd")

lib/rrd/base.rb

@@ -56,6 +56,16 @@ def last_update
       Wrapper.last_update(rrd_file)
     end
 
+    # Writes a new file 'resize.rrd'
+    def resize(rra_num, options)
+      info = self.info
+      step = info["step"]
+      rra_step = info["rra[#{rra_num}].pdp_per_row"]
+      action = options.keys.first.to_s.upcase
+      delta = (options.values.first / (step * rra_step)).to_i # Force an integer
+      Wrapper.resize(rrd_file, rra_num.to_s, action, delta.to_s)
+    end
+
     # See RRD::Wrapper.restore
     def restore(xml_file, options = {})
       options = options.clone

lib/rrd/wrapper.rb

@@ -41,6 +41,8 @@ class << self
       extend FFI::Library
 
       ffi_lib RRD::Wrapper.detect_rrd_lib
+      attach_function :rrd_strversion, [], :string
+
       attach_function :rrd_create, [:int, :pointer], :int
       attach_function :rrd_dump, [:int, :pointer], :int
       attach_function :rrd_fetch, [:int, :pointer, :pointer, :pointer, :pointer, :pointer, :pointer, :pointer], :int
@@ -49,10 +51,11 @@ class << self
       attach_function :rrd_info, [:int, :pointer], :pointer
       attach_function :rrd_last, [:int, :pointer], :time_t
 
-      begin
+      if rrd_strversion >= "1.4"
         attach_function :rrd_lastupdate_r, [:string, :pointer, :pointer, :pointer, :pointer], :int
-      rescue Exception => e
-        puts "Please upgrade your rrdtool version to use last_update method"
+        alias :rrd_lastupdate :rrd_lastupdate_r
+      else
+        attach_function :rrd_lastupdate, [:string, :pointer, :pointer, :pointer, :pointer], :int
       end
 
       attach_function :rrd_resize, [:int, :pointer], :int
@@ -173,13 +176,12 @@ def last(*args)
       #    [1266933900, "0.9", "253"   ]]
       # 
       def last_update(file)
-        raise "Please upgrade your rrdtool version before using last_updae method" unless respond_to?(:rrd_lastupdate_r)
         update_time_ptr = empty_pointer
         ds_count_ptr = empty_pointer
         ds_names_ptr = empty_pointer
         values_ptr = FFI::MemoryPointer.new(:pointer)
 
-        return false if rrd_lastupdate_r(file, update_time_ptr, ds_count_ptr, ds_names_ptr, values_ptr) == -1
+        return false if rrd_lastupdate(file, update_time_ptr, ds_count_ptr, ds_names_ptr, values_ptr) == -1
         update_time = update_time_ptr.get_ulong(0)
         ds_count = ds_count_ptr.get_ulong(0)
         ds_names = ds_names_ptr.get_pointer(0).get_array_of_string(0, ds_count)
@@ -190,6 +192,8 @@ def last_update(file)
       end
 
       # Used to modify the number of rows in an RRA
+      # 
+      # Creates a new file in the same directory, called 'resize.rrd'
       def resize(*args)
         argv = to_pointer(["resize"] + args)
         rrd_resize(args.size+1, argv) == 0

spec/rrd/base_spec.rb

@@ -56,6 +56,12 @@
     @rrd.restore(XML_FILE, :force_overwrite => true).should be_true
   end
 
+  it "should resize a RRA from rrd file" do
+    RRD::Wrapper.should_receive(:info).and_return({"step" => 5, "rra[1].pdp_per_row" => 12}) # step of 1 minute on RRA
+    RRD::Wrapper.should_receive(:resize).with(RRD_FILE, "1", "GROW", "60").and_return(true)
+    @rrd.resize(1, :grow => 1.hour)
+  end
+
   it "should return the last update made" do
     RRD::Wrapper.should_receive(:last_update).with(RRD_FILE).and_return([])
     @rrd.last_update

spec/rrd/wrapper_spec.rb

@@ -71,7 +71,6 @@
     end
 
     it "should return the last entered values" do
-      pending unless RRD::Wrapper.respond_to?(:rrd_lastupdate_r)
       result = RRD::Wrapper.last_update(RRD_FILE)
       result.should have(2).lines
       result[1][0].should == 1266945375