From bd34d9f689f71fda0bed01de476839ff99dda7df Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Mon, 11 Apr 2016 19:54:56 +0200
Subject: [PATCH] btrbk: change preserve logic: keep FIRST present of
 hour/day/... instead of LAST

---
 btrbk            | 46 +++++++++++++++++++++++-----------------------
 doc/btrbk.conf.5 | 10 +++++-----
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/btrbk b/btrbk
index 65250e6..d97a6e9 100755
--- a/btrbk
+++ b/btrbk
@@ -2634,11 +2634,11 @@ sub schedule(@)
     $href->{preserve} ||= $preserve_latest;
   }
 
-  my %last_in_delta_hours;
-  my %last_in_delta_days;
+  my %first_in_delta_hours;
+  my %first_in_delta_days;
   my %first_in_delta_weeks;
-  my %last_weekly_in_delta_months;
-  my %last_monthly_in_delta_years;
+  my %first_weekly_in_delta_months;
+  my %first_monthly_in_delta_years;
 
   # filter "preserve all within N days/weeks/..."
   foreach my $href (@sorted_schedule) {
@@ -2657,21 +2657,21 @@ sub schedule(@)
         $href->{preserve} ||= "preserve all: $href->{delta_years} years ago"   if($href->{delta_years}  <= $preserve_all_n);
       }
     }
-    $last_in_delta_hours{$href->{delta_hours}} = $href;
+    $first_in_delta_hours{$href->{delta_hours}} //= $href;
   }
 
   # filter hourly, daily, weekly, monthly, yearly
-  foreach (sort {$b <=> $a} keys %last_in_delta_hours) {
-    my $href = $last_in_delta_hours{$_} || die;
+  foreach (sort {$b <=> $a} keys %first_in_delta_hours) {
+    my $href = $first_in_delta_hours{$_} || die;
     if($preserve_hourly && (($preserve_hourly eq 'all') || $href->{delta_hours} <= $preserve_hourly)) {
-      $href->{preserve} ||= "preserved hourly: last present of hour, $href->{delta_hours} hours ago";
+      $href->{preserve} ||= "preserved hourly: first present of hour, $href->{delta_hours} hours ago";
     }
-    $last_in_delta_days{$href->{delta_days}} = $href;
+    $first_in_delta_days{$href->{delta_days}} //= $href;
   }
-  foreach (sort {$b <=> $a} keys %last_in_delta_days) {
-    my $href = $last_in_delta_days{$_} || die;
+  foreach (sort {$b <=> $a} keys %first_in_delta_days) {
+    my $href = $first_in_delta_days{$_} || die;
     if($preserve_daily && (($preserve_daily eq 'all') || ($href->{delta_days} <= $preserve_daily))) {
-      $href->{preserve} ||= "preserved daily: last present of day, $href->{delta_days} days ago";
+      $href->{preserve} ||= "preserved daily: first present of day, $href->{delta_days} days ago";
     }
     $first_in_delta_weeks{$href->{delta_weeks}} //= $href;
   }
@@ -2681,19 +2681,19 @@ sub schedule(@)
     if($preserve_weekly && (($preserve_weekly eq 'all') || ($href->{delta_weeks} <= $preserve_weekly))) {
       $href->{preserve} ||= "preserved weekly: $href->{delta_weeks} weeks ago, $href->{err_days_text}";
     }
-    $last_weekly_in_delta_months{$href->{delta_months}} = $href;
+    $first_weekly_in_delta_months{$href->{delta_months}} //= $href;
   }
-  foreach (sort {$b <=> $a} keys %last_weekly_in_delta_months) {
-    my $href = $last_weekly_in_delta_months{$_} || die;
+  foreach (sort {$b <=> $a} keys %first_weekly_in_delta_months) {
+    my $href = $first_weekly_in_delta_months{$_} || die;
     if($preserve_monthly && (($preserve_monthly eq 'all') || ($href->{delta_months} <= $preserve_monthly))) {
-      $href->{preserve} ||= "preserved monthly: last present weekly of month $href->{month} ($href->{delta_months} months ago, $href->{err_days_text})";
+      $href->{preserve} ||= "preserved monthly: first present weekly of month $href->{month} ($href->{delta_months} months ago, $href->{err_days_text})";
     }
-    $last_monthly_in_delta_years{$href->{delta_years}} = $href;
+    $first_monthly_in_delta_years{$href->{delta_years}} //= $href;
   }
-  foreach (sort {$b <=> $a} keys %last_monthly_in_delta_years) {
-    my $href = $last_monthly_in_delta_years{$_} || die;
+  foreach (sort {$b <=> $a} keys %first_monthly_in_delta_years) {
+    my $href = $first_monthly_in_delta_years{$_} || die;
     if($preserve_yearly && (($preserve_yearly eq 'all') || ($href->{delta_years} <= $preserve_yearly))) {
-      $href->{preserve} ||= "preserved yearly: last present weekly of year $href->{year} ($href->{delta_years} years ago, $href->{err_days_text})";
+      $href->{preserve} ||= "preserved yearly: first present weekly of year $href->{year} ($href->{delta_years} years ago, $href->{err_days_text})";
     }
   }
 
@@ -2747,13 +2747,13 @@ sub format_preserve_matrix($@)
     }
     else {
       push @out, "preserving all within $preserve->{all_n} $trans{$preserve->{all_q}}" if($preserve->{all_n} && $preserve->{all_q});
-      push @out, "last present daily for $preserve->{d} days" if($preserve->{d});
+      push @out, "first present daily for $preserve->{d} days" if($preserve->{d});
       unless($preserve->{d} && ($preserve->{d} eq 'all')) {
         push @out, "first daily in week (starting on $preserve->{dow}) for $preserve->{w} weeks" if($preserve->{w});
         unless($preserve->{w} && ($preserve->{w} eq 'all')) {
-          push @out, "last weekly of month for $preserve->{m} months" if($preserve->{m});
+          push @out, "first weekly of month for $preserve->{m} months" if($preserve->{m});
           unless($preserve->{m} && ($preserve->{m} eq 'all')) {
-            push @out, "last weekly of year for $preserve->{y} years" if($preserve->{y});
+            push @out, "first weekly of year for $preserve->{y} years" if($preserve->{y});
           }
         }
       }
diff --git a/doc/btrbk.conf.5 b/doc/btrbk.conf.5
index 1c18716..79da6ec 100644
--- a/doc/btrbk.conf.5
+++ b/doc/btrbk.conf.5
@@ -1,4 +1,4 @@
-.TH "btrbk.conf" "5" "2016-03-31" "btrbk v0.23.0-dev" ""
+.TH "btrbk.conf" "5" "2016-04-12" "btrbk v0.23.0-dev" ""
 .\" disable hyphenation
 .nh
 .\" disable justification (adjust text to left margin only)
@@ -247,7 +247,7 @@ With the following semantics:
 .B hourly
 .RS 4
 Defines how many hours back hourly backups should be preserved. The
-last backup of an hour is considered an hourly backup. Note that if
+first backup of an hour is considered an hourly backup. Note that if
 you use <hourly> scheduling, make sure to also set
 \fItimestamp_format\fR to \[lq]long\[rq], or the scheduler will
 interpret the time as "00:00" (midnight).
@@ -256,7 +256,7 @@ interpret the time as "00:00" (midnight).
 .B daily
 .RS 4
 Defines how many days back daily backups should be preserved. The
-last backup of a day is considered a daily backup.
+first backup of a day is considered a daily backup.
 .RE
 .PP
 .B weekly
@@ -270,14 +270,14 @@ as a weekly backup.
 .B monthly
 .RS 4
 Defines how many months back monthly backups should be
-preserved. Every last weekly backup in a month is considered a
+preserved. Every first weekly backup in a month is considered a
 monthly backup.
 .RE
 .PP
 .B yearly
 .RS 4
 Defines for how many years back yearly backups should be
-preserved. Every last monthly backup in a year is considered a yearly
+preserved. Every first monthly backup in a year is considered a yearly
 backup.
 .RE
 .PP