From b16e56baf28bdb987c1a48924a2a510d4bb095ab Mon Sep 17 00:00:00 2001
From: dakkar <dakkar@thenautilus.net>
Date: Sat, 25 Jan 2020 16:00:05 +0000
Subject: speed-up Bayes predictions

this is *probably* correct
---
 lib/MaildirIndexer/Index/ByAddresses.rakumod | 32 +++++++++++++++++++---------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/lib/MaildirIndexer/Index/ByAddresses.rakumod b/lib/MaildirIndexer/Index/ByAddresses.rakumod
index c6cc412..3e7dc9d 100644
--- a/lib/MaildirIndexer/Index/ByAddresses.rakumod
+++ b/lib/MaildirIndexer/Index/ByAddresses.rakumod
@@ -15,7 +15,10 @@ has BagHash $!count-by-address-and-mailbox .= new;
 has BagHash $!known-addresses .= new;
 has BagHash $!count-by-mailbox .= new;
 has Hash $!p-address-given-mailbox .= new;
-has $!total-count;
+has Int $!total-count;
+
+has Hash $!cached-p-given-mailbox .= new;
+has Instant $!last-cached-at .= from-posix(0);
 
 method dump() {
 }
@@ -38,6 +41,21 @@ submethod account-for(Str @addresses,Str $mailbox,Int $step) {
             $!p-address-given-mailbox{$pair} :delete;
         }
     }
+
+    # update the cache every 10 seconds
+    if ((now - $!last-cached-at) > 10) {
+        for $!count-by-mailbox.keys -> Str $mailbox {
+            my $p = $!count-by-mailbox{$mailbox} / $!total-count;
+
+            for $!known-addresses.keys -> Str $addr {
+                my $addr-p = $!p-address-given-mailbox{$addr => $mailbox} // 1e-15;
+                $p *= 1 - $addr-p;
+            }
+
+            $!cached-p-given-mailbox{$mailbox} = $p;
+        }
+        $!last-cached-at = now;
+    }
 }
 
 method add-mail(MaildirIndexer::Email:D $email, Str:D $mailbox --> Nil) {
@@ -71,19 +89,13 @@ method del-path(IO:D $file, Str:D $mailbox --> Nil) {
 
 submethod predict-mailbox-given-addresses(@addresses) {
     my %prediction;
-    my Bag $addr-bag .= new(|@addresses);
 
     for $!count-by-mailbox.keys -> Str $mailbox {
-        my $p = $!count-by-mailbox{$mailbox} / $!total-count;
+        my $p = $!cached-p-given-mailbox{$mailbox};
 
-        for $!known-addresses.keys -> Str $addr {
+        for @addresses -> Str $addr {
             my $addr-p = $!p-address-given-mailbox{$addr => $mailbox} // 1e-15;
-            if ($addr-bag{$addr}) {
-                $p *= $addr-p;
-            }
-            else {
-                $p *= 1 - $addr-p;
-            }
+            $p *= $addr-p / ( 1- $addr-p );
         }
 
         %prediction{$mailbox} = $p;
-- 
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