From f533dda4935d69c1de3124667b435e6384b8243b Mon Sep 17 00:00:00 2001
From: Marcos Bento <Marcos.Bento@ecmwf.int>
Date: Mon, 11 Nov 2024 16:39:27 +0000
Subject: [PATCH] Enable reloading of Mirror configuration

Mirror attribute is reset with the latest configuration when "reload" is used as
value on a Alter Mirror command

Re ECFLOW-1986
---
 libs/base/src/ecflow/base/cts/user/AlterCmd.cpp |  2 +-
 libs/node/src/ecflow/node/MirrorAttr.cpp        | 15 ++++++++++++---
 libs/node/src/ecflow/node/MirrorAttr.hpp        |  9 +++++++++
 libs/node/src/ecflow/node/NodeChange.cpp        | 14 +++++++++-----
 4 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/libs/base/src/ecflow/base/cts/user/AlterCmd.cpp b/libs/base/src/ecflow/base/cts/user/AlterCmd.cpp
index 517c736cc..6b4c64b2a 100644
--- a/libs/base/src/ecflow/base/cts/user/AlterCmd.cpp
+++ b/libs/base/src/ecflow/base/cts/user/AlterCmd.cpp
@@ -613,7 +613,7 @@ const char* AlterCmd::desc() {
            "       For change:\n"
            "         [ variable | clock_type | clock_gain | clock_date | clock_sync  | event | meter | label |\n"
            "           trigger  | complete   | repeat     | limit_max  | limit_value | defstatus | late | time |\n"
-           "           today, aviso, mirror ]\n"
+           "           today | aviso | mirror ]\n"
            "         *NOTE* If the clock is changed, then the suite will need to be re-queued in order for\n"
            "         the change to take effect fully.\n"
            "       For add:\n"
diff --git a/libs/node/src/ecflow/node/MirrorAttr.cpp b/libs/node/src/ecflow/node/MirrorAttr.cpp
index bce3abbcd..d8c3134c6 100644
--- a/libs/node/src/ecflow/node/MirrorAttr.cpp
+++ b/libs/node/src/ecflow/node/MirrorAttr.cpp
@@ -74,6 +74,14 @@ void MirrorAttr::reset() {
     start_controller();
 }
 
+void MirrorAttr::reload() {
+    if (controller_) {
+        state_change_no_ = Ecf::incr_state_change_no();
+        stop_controller();
+        start_controller();
+    }
+}
+
 void MirrorAttr::finish() {
     stop_controller();
 }
@@ -190,7 +198,7 @@ std::string MirrorAttr::resolve_cfg(const std::string& value,
 }
 
 void MirrorAttr::start_controller() {
-    if (controller_ == nullptr) {
+    if (!controller_) {
 
         // Resolve variables in configuration
         // In the case of the 'remote_host', we have to resolve the configuration
@@ -217,7 +225,8 @@ void MirrorAttr::start_controller() {
 
         SLOG(D,
              "MirrorAttr: start polling Mirror attribute '" << absolute_name() << "', from " << remote_path_ << " @ "
-                                                            << remote_host << ':' << remote_port << ")");
+                                                            << remote_host << ':' << remote_port << ") using polling: "
+                                                            << polling << " s");
 
         std::uint32_t polling_value;
         try {
@@ -247,7 +256,7 @@ void MirrorAttr::start_controller() {
 }
 
 void MirrorAttr::stop_controller() {
-    if (controller_ != nullptr) {
+    if (controller_) {
         SLOG(D,
              "MirrorAttr: finishing polling for Mirror attribute \"" << parent_->absNodePath() << ":" << name_
                                                                      << "\", from host: " << remote_host_
diff --git a/libs/node/src/ecflow/node/MirrorAttr.hpp b/libs/node/src/ecflow/node/MirrorAttr.hpp
index 45786fa7f..199bc73a3 100644
--- a/libs/node/src/ecflow/node/MirrorAttr.hpp
+++ b/libs/node/src/ecflow/node/MirrorAttr.hpp
@@ -59,6 +59,8 @@ class MirrorAttr {
     static constexpr const char* fallback_polling     = "120";
     static constexpr const char* fallback_remote_auth = "";
 
+    static constexpr const char* reload_option_value = "reload";
+
     static bool is_valid_name(const std::string& name);
 
     /**
@@ -104,8 +106,15 @@ class MirrorAttr {
 
     /**
      * Initialises the Mirror procedure, which effectively starts the background polling mechanism.
+     * Typically, called when traversing the tree -- does nothing if Mirror service is already set up.
      */
     void reset();
+    /**
+     * Restarts the Mirror procedure, which effectively stops before restarting the background polling mechanism.
+     * Typicallly, called explicitly via Alter command -- forces the reinitialisation of the Mirror service,
+     * guaranteeing that parameters, given as ECF variables, are reevaluated.
+     */
+    void reload();
     void finish();
 
     /**
diff --git a/libs/node/src/ecflow/node/NodeChange.cpp b/libs/node/src/ecflow/node/NodeChange.cpp
index 8abbe8e4d..8befadb15 100644
--- a/libs/node/src/ecflow/node/NodeChange.cpp
+++ b/libs/node/src/ecflow/node/NodeChange.cpp
@@ -201,11 +201,15 @@ void Node::changeMirror(const std::string& name, const std::string& value) {
         throw std::runtime_error("Node::changeMirror: Could not find mirror " + name);
     }
 
-    auto attr = MirrorParser::parse_mirror_line(value, name, this);
-
-    // The following delete/add enforces the reconfiguration of the attribute backend thread
-    this->deleteMirror(name); // delete the mirror if it exists (to avoid duplicates
-    this->addMirror(attr);
+    if (value == MirrorAttr::reload_option_value) {
+        found->reload();
+    } else { 
+        auto attr = MirrorParser::parse_mirror_line(value, name, this);
+
+        // The following delete/add enforces the reconfiguration of the attribute backend thread
+        this->deleteMirror(name); // delete the mirror if it exists (to avoid duplicates
+        this->addMirror(attr);
+    }
 
     state_change_no_ = Ecf::incr_state_change_no();
 }