From da08be02858a6a0c2d895683ae8d05b5c89e9361 Mon Sep 17 00:00:00 2001
From: Bel LaPointe <breel@qualtrics.com>
Date: Fri, 26 Feb 2021 23:02:05 -0600
Subject: [PATCH] Create deltas class, mature multiwrite for retries

---
 nullboard.html | 127 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 116 insertions(+), 11 deletions(-)
diff --git a/nullboard.html b/nullboard.html
index 3ce9c98..cd5c853 100644
--- a/nullboard.html
+++ b/nullboard.html
@@ -1106,7 +1106,7 @@
 </head>
 <body>
 	<div class=logo>
-		<a href=https://nullboard.io>Nullboard</a>
+		<a href=https://nullboard.io>Nullboard <span id="pending"></span></a>
 		<div class=bulk>
 			<a href=# class=view-about>About</a>
 			<a href=# class=view-license>License</a>
@@ -1237,6 +1237,38 @@
       }
    }
 
+   class Deltas {
+      constructor(database)
+      {
+         this.database = new NamespacedDatabase("deltas", database);
+      }
+
+      length()
+      {
+         var n = 0;
+         this.database.forEach((k) => { n += 1; });
+         return n;
+      }
+
+      push(key)
+      {
+         this.database.set(key, 1);
+      }
+
+      pop(key)
+      {
+         this.database.del(key);
+      }
+
+      popEach(foo)
+      {
+         this.database.forEach((key) => {
+            foo(key);
+            this.database.del(key);
+         });
+      }
+   }
+
    class MultiDatabase extends Database {
       constructor()
       {
@@ -1250,24 +1282,97 @@
          {
             this.databases.push(arguments[i]);
          }
+         this.deltas = new Deltas(this.primary());
+         this.scheduleSync();
+      }
+
+      primary()
+      {
+         return this.databases[0];
+      }
+
+      replicas()
+      {
+         return this.databases.slice(1);
+      }
+
+      scheduleSync()
+      {
+         setInterval(() => { this.sync(); }, 15 * 1000);
+      }
+
+      sync()
+      {
+         console.log("syncing to replicas: " + this.pendingSyncCount());
+         this.deltas.popEach((k) => {
+            console.log("syncing to replicas: " + k);
+            this.replicate(k);
+         });
+         console.log("synced to replicas: " + this.pendingSyncCount());
+         this.writePendingSyncCount();
+      }
+
+      pendingSyncCount()
+      {
+         return this.deltas.length();
+      }
+
+      writePendingSyncCount()
+      {
+         var n = this.pendingSyncCount();
+         var s = "(" + n + ")";
+         if (! n)
+            s = ""
+         document.getElementById("pending").innerHTML = s;
+      }
+
+      replicate(k)
+      {
+         var v = this.primary().get(k);
+         this.replicas().forEach((database) => {
+            if (v)
+               database.set(k, v);
+            else
+               database.del(k, v);
+         });
       }
 
       get(key) {
-         return this.databases[0].get(key);
+         return this.primary().get(key);
       }
 
       set(key, value)
       {
-         this.databases.forEach((database) => {
-            database.set(key, value);
-         });
+         this.primary().set(key, value);
+         this.deltas.push(key);
+         try
+         {
+            this.replicas().forEach((database) => {
+               database.set(key, value);
+            });
+            this.deltas.pop(key);
+         }
+         catch (e)
+         {
+            console.log("failed to replicate set: " + e);
+         }
       }
 
       del(key)
       {
-         this.databases.forEach((database) => {
-            database.del(key, value);
-         });
+         this.primary().del(key);
+         this.deltas.push(key);
+         try
+         {
+            this.replicas().forEach((database) => {
+               database.del(key);
+            });
+            this.deltas.pop(key);
+         }
+         catch (e)
+         {
+            console.log("failed to replicate del: " + e);
+         }
       }
 
       forEach(foo)
@@ -1290,7 +1395,7 @@
       {
          if (key.startsWith(this.namespace + "."))
             return key.slice(this.namespace.length + 1);
-         return key;
+         return null;
       }
 
       prefix(key)
@@ -1319,7 +1424,8 @@
       {
          this.database.forEach((key) => {
             var k = this.deprefix(key);
-            foo(k);
+            if (k)
+               foo(k);
          });
       }
    }
@@ -1367,7 +1473,6 @@
       new NamespacedDatabase("A", new Local()),
       new NamespacedDatabase("B", new Local()),
    );
-   globalStorage = new NamespacedDatabase("B", new Local());
 
 	/*
 	 *	poor man's error handling -- $fixme
