Joseph Doherty
0868613890
The DL205/DL260 ECOM emits no TCP keepalives, so an idle backend socket can be silently dropped by a middlebox (switch, firewall, NAT) after 2-5 minutes. Enable OS SO_KEEPALIVE on backend and accepted upstream sockets, and drive a periodic synthetic FC03 heartbeat on each idle backend socket so a dead path is detected before a real client request hits it. Controlled by Connection.Keepalive (ON by default). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
250 lines
12 KiB
C#
250 lines
12 KiB
C#
using System.Text;
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namespace Mbproxy.Admin;
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/// <summary>
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/// Renders a <see cref="StatusResponse"/> as a self-contained HTML page.
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///
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/// <para>Constraints (see <c>docs/Operations/StatusPage.md</c>):</para>
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/// <list type="bullet">
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/// <item>No external assets (CSS/JS/fonts/favicons) — firewalled networks only.</item>
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/// <item><c><meta http-equiv="refresh" content="5"></c> for auto-refresh.</item>
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/// <item>Page weight ≤ 50 KB for a 54-PLC fleet.</item>
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/// <item>Listener state colour-coded: bound=green, recovering=orange, stopped=grey.</item>
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/// <item>Connected clients rendered as compact <c>[remote (n PDUs)]</c> list (not nested table).</item>
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/// </list>
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/// </summary>
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internal static class StatusHtmlRenderer
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{
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private const string Css = """
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body{font-family:monospace;font-size:13px;margin:1em}
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h1{font-size:1.1em;margin-bottom:.3em}
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.meta{color:#555;margin-bottom:.8em;font-size:12px}
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table{border-collapse:collapse;width:100%}
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th,td{border:1px solid #ccc;padding:3px 6px;white-space:nowrap}
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th{background:#f0f0f0;text-align:left}
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tr:nth-child(even)td{background:#fafafa}
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.bound{color:green;font-weight:bold}
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.recovering{color:darkorange;font-weight:bold}
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.stopped{color:grey}
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.err{font-size:11px;color:#a00}
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.clients{font-size:11px;color:#333}
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""";
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/// <summary>
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/// Renders the status page as a complete HTML document string.
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/// May allocate; intended for the status-page read path only.
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/// </summary>
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public static string Render(StatusResponse status)
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{
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var sb = new StringBuilder(4096);
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sb.Append("<!DOCTYPE html><html lang=\"en\"><head><meta charset=\"utf-8\">");
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sb.Append("<meta http-equiv=\"refresh\" content=\"5\">");
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sb.Append("<title>mbproxy status</title>");
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sb.Append("<style>").Append(Css).Append("</style>");
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sb.Append("</head><body>");
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// ── Header ────────────────────────────────────────────────────────────
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sb.Append("<h1>mbproxy status</h1>");
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sb.Append("<div class=\"meta\">");
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sb.Append("Version: ").Append(HtmlEncode(status.Service.Version));
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sb.Append(" | Uptime: ").Append(FormatUptime(status.Service.UptimeSeconds));
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sb.Append(" | Listeners: ")
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.Append(status.Listeners.Bound).Append('/').Append(status.Listeners.Configured)
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.Append(" bound");
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if (status.Service.ConfigLastReloadUtc.HasValue)
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{
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sb.Append(" | Last reload: ")
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.Append(HtmlEncode(status.Service.ConfigLastReloadUtc.Value.ToString("yyyy-MM-dd HH:mm:ss") + "Z"));
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}
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sb.Append(" | Reloads: ").Append(status.Service.ConfigReloadCount);
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if (status.Service.ConfigReloadRejectedCount > 0)
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sb.Append(" (").Append(status.Service.ConfigReloadRejectedCount).Append(" rejected)");
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sb.Append("</div>");
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// ── PLC table ─────────────────────────────────────────────────────────
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if (status.Plcs.Count == 0)
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{
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sb.Append("<p><em>No PLCs configured.</em></p>");
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}
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else
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{
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sb.Append("<table>");
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sb.Append("<thead><tr>");
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sb.Append("<th>Name</th><th>Host</th><th>Port</th><th>State</th>");
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sb.Append("<th>Clients</th><th>PDUs fwd</th><th>FC03</th><th>FC04</th>");
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sb.Append("<th>FC06</th><th>FC16</th><th>FC?</th><th>BCD slots</th>");
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sb.Append("<th>Partial BCD</th><th>Invalid BCD</th><th>Ex 01</th><th>Ex 02</th><th>Ex 03</th><th>Ex 04</th><th>Ex ?</th>");
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sb.Append("<th>RTT ms</th><th>Bytes in</th><th>Bytes out</th>");
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// Multiplexer telemetry columns.
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sb.Append("<th>In-flight</th><th>Max in-flight</th><th>TxId wraps</th>");
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sb.Append("<th>Cascades</th><th>Queue</th>");
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// Coalescing column. Single cell carries hit / (hit + miss) ratio as a
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// percentage plus the raw hit count for context. Kept compact (one cell) to
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// stay under the 50 KB page-weight budget.
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sb.Append("<th>Coal</th>");
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// Cache column. Single cell carries hit-ratio percent plus raw hit count;
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// an em-dash when no cache-eligible reads have occurred. Page-weight budget
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// assertion stays under 50 KB for the 54-PLC fleet.
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sb.Append("<th>Cache</th>");
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// Keepalive column — heartbeats sent, with failure / idle-disconnect counts
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// shown only when non-zero.
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sb.Append("<th>Keepalive</th>");
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sb.Append("</tr></thead><tbody>");
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foreach (var plc in status.Plcs)
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{
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sb.Append("<tr>");
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sb.Append("<td>").Append(HtmlEncode(plc.Name)).Append("</td>");
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sb.Append("<td>").Append(HtmlEncode(plc.Host)).Append("</td>");
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sb.Append("<td>").Append(plc.ListenPort).Append("</td>");
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// State cell with colour coding
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string stateClass = plc.Listener.State switch
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{
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"bound" => "bound",
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"recovering" => "recovering",
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_ => "stopped",
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};
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sb.Append("<td><span class=\"").Append(stateClass).Append("\">")
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.Append(HtmlEncode(plc.Listener.State)).Append("</span>");
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if (plc.Listener.State == "recovering" && plc.Listener.LastBindError is { } err)
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{
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sb.Append("<br><span class=\"err\">")
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.Append(HtmlEncode(err))
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.Append(" (attempt ").Append(plc.Listener.RecoveryAttempts).Append(")")
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.Append("</span>");
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}
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sb.Append("</td>");
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// Connected clients
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sb.Append("<td><span class=\"clients\">");
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sb.Append(plc.Clients.Connected);
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if (plc.Clients.RemoteEndpoints.Count > 0)
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{
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sb.Append("<br>");
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bool first = true;
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foreach (var c in plc.Clients.RemoteEndpoints)
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{
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if (!first) sb.Append(", ");
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sb.Append(HtmlEncode(c.Remote))
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.Append(" (").Append(c.PdusForwarded).Append(')');
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first = false;
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}
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}
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sb.Append("</span></td>");
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// Counter cells
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sb.Append("<td>").Append(plc.Pdus.Forwarded).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.ByFc.Fc03).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.ByFc.Fc04).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.ByFc.Fc06).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.ByFc.Fc16).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.ByFc.Other).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.RewrittenSlots).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.PartialBcdWarnings).Append("</td>");
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sb.Append("<td>").Append(plc.Pdus.InvalidBcdWarnings).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.ExceptionsByCode.Code01).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.ExceptionsByCode.Code02).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.ExceptionsByCode.Code03).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.ExceptionsByCode.Code04).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.ExceptionsByCode.CodeOther).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.LastRoundTripMs.ToString("F1")).Append("</td>");
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sb.Append("<td>").Append(plc.Bytes.UpstreamIn).Append("</td>");
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sb.Append("<td>").Append(plc.Bytes.UpstreamOut).Append("</td>");
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// Multiplexer telemetry cells.
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sb.Append("<td>").Append(plc.Backend.InFlight).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.MaxInFlight).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.TxIdWraps).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.DisconnectCascades).Append("</td>");
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sb.Append("<td>").Append(plc.Backend.QueueDepth).Append("</td>");
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// Coalescing ratio cell — "<pct>% (<hit>)". When no coalesced reads have
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// been seen, render an em-dash to keep the cell narrow.
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long coalHit = plc.Backend.CoalescedHitCount;
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long coalMiss = plc.Backend.CoalescedMissCount;
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sb.Append("<td>");
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if (coalHit + coalMiss == 0)
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{
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sb.Append("—");
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}
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else
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{
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int pct = (int)Math.Round(100.0 * coalHit / (coalHit + coalMiss));
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sb.Append(pct).Append("% (").Append(coalHit).Append(')');
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}
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sb.Append("</td>");
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// Cache ratio cell — same pattern as coalescing.
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long cacheHit = plc.Backend.CacheHitCount;
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long cacheMiss = plc.Backend.CacheMissCount;
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sb.Append("<td>");
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if (cacheHit + cacheMiss == 0)
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{
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sb.Append("—");
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}
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else
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{
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int pct = (int)Math.Round(100.0 * cacheHit / (cacheHit + cacheMiss));
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sb.Append(pct).Append("% (").Append(cacheHit).Append(')');
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}
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sb.Append("</td>");
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// Keepalive cell — heartbeats sent; failures + idle-disconnects appended
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// only when non-zero to keep the cell narrow.
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long hbSent = plc.Backend.BackendHeartbeatsSent;
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long hbFailed = plc.Backend.BackendHeartbeatsFailed;
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long hbIdle = plc.Backend.BackendIdleDisconnects;
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sb.Append("<td>");
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if (hbSent == 0 && hbFailed == 0 && hbIdle == 0)
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{
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sb.Append("—");
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}
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else
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{
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sb.Append(hbSent);
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if (hbFailed > 0 || hbIdle > 0)
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sb.Append(" (fail ").Append(hbFailed)
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.Append(", idle-disc ").Append(hbIdle).Append(')');
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}
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sb.Append("</td>");
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sb.Append("</tr>");
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}
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sb.Append("</tbody></table>");
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}
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sb.Append("</body></html>");
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return sb.ToString();
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}
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// ── Helpers ───────────────────────────────────────────────────────────────
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private static string FormatUptime(long seconds)
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{
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var ts = TimeSpan.FromSeconds(seconds);
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if (ts.TotalHours >= 1)
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return $"{(int)ts.TotalHours}h {ts.Minutes:D2}m {ts.Seconds:D2}s";
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if (ts.TotalMinutes >= 1)
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return $"{ts.Minutes}m {ts.Seconds:D2}s";
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return $"{seconds}s";
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}
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private static string HtmlEncode(string s)
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{
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// Fast path: no special chars.
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if (!ContainsHtmlSpecial(s)) return s;
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return s
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.Replace("&", "&")
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.Replace("<", "<")
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.Replace(">", ">")
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.Replace("\"", """);
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}
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private static bool ContainsHtmlSpecial(string s)
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{
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foreach (char c in s)
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if (c is '&' or '<' or '>' or '"') return true;
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return false;
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}
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}
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