X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/638d136057f4d9ed19f132075079da396217d6fd..d455c8373cf39f4310d2b0e13e7a9d02aca0b2ab:/apps/workbench/app/controllers/keep_disks_controller.rb

diff --git a/apps/workbench/app/controllers/keep_disks_controller.rb b/apps/workbench/app/controllers/keep_disks_controller.rb
index b7bc7c06dc..f57455b37f 100644
--- a/apps/workbench/app/controllers/keep_disks_controller.rb
+++ b/apps/workbench/app/controllers/keep_disks_controller.rb
@@ -4,11 +4,31 @@ class KeepDisksController < ApplicationController
     @object = KeepDisk.new defaults.merge(params[:keep_disk] || {})
     super
   end
+
   def index
+    # Retrieve cache age histogram info from logs.
+
+    # In the logs we expect to find it in an ordered list with entries
+    # of the form (mtime, disk proportion free).
+
+    # An entry of the form (1388747781, 0.52) means that if we deleted
+    # the oldest non-presisted blocks until we had 52% of the disk
+    # free, then all blocks with an mtime greater than 1388747781
+    # would be preserved.
+
+    # The chart we want to produce, will tell us how much of the disk
+    # will be free if we use a cache age of x days. Therefore we will
+    # produce output specifying the age, cache and persisted. age is
+    # specified in milliseconds. cache is the size of the cache if we
+    # delete all blocks older than age. persistent is the size of the
+    # persisted blocks. It is constant regardless of age, but it lets
+    # us show a stacked graph.
+
+    # Finally each entry in cache_age_histogram is a dictionary,
+    # because that's what our charting package wats.
 
-    # Retrieve cache age histogram info
     @cache_age_histogram = []
-    @histogram_date = 0
+    @histogram_pretty_date = nil
     histogram_log = Log.
       filter([[:event_type, '=', 'block-age-free-space-histogram']]).
       order(:created_at => :desc).
@@ -18,14 +38,17 @@ class KeepDisksController < ApplicationController
       # specified limit(1)
       @cache_age_histogram = log_entry['properties'][:histogram]
       # Javascript wants dates in milliseconds.
-      @histogram_date = log_entry['event_at'].to_i * 1000
+      histogram_date_ms = log_entry['event_at'].to_i * 1000
+      @histogram_pretty_date = log_entry['event_at'].strftime('%b %-d, %Y')
 
       total_free_cache = @cache_age_histogram[-1][1]
       persisted_storage = 1 - total_free_cache
-      @cache_age_histogram.map! { |x| {:age => @histogram_date - x[0]*1000,
+      @cache_age_histogram.map! { |x| {:age => histogram_date_ms - x[0]*1000,
           :cache => total_free_cache - x[1],
           :persisted => persisted_storage} }
     end
+
+    # Do the regular control work needed.
     super
   end
 end