X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/24e38a335377c878955e302cd11b2097cd7c5e07..42c20b25e1325124b88e3b9b285544dc41122b56:/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 cc89228832..c95ebdc255 100644
--- a/apps/workbench/app/controllers/keep_disks_controller.rb
+++ b/apps/workbench/app/controllers/keep_disks_controller.rb
@@ -1,7 +1,59 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
 class KeepDisksController < ApplicationController
   def create
     defaults = { is_readable: true, is_writable: true }
     @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.
+
+    @cache_age_histogram = []
+    @histogram_pretty_date = nil
+    histogram_log = Log.
+      filter([[:event_type, '=', 'block-age-free-space-histogram']]).
+      order(:created_at => :desc).
+      with_count('none').
+      limit(1)
+    histogram_log.each do |log_entry|
+      # We expect this block to only execute at most once since we
+      # specified limit(1)
+      @cache_age_histogram = log_entry['properties'][:histogram]
+      # Javascript wants dates in milliseconds.
+      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_ms - x[0]*1000,
+          :cache => total_free_cache - x[1],
+          :persisted => persisted_storage} }
+    end
+
+    # Do the regular control work needed.
+    super
+  end
 end