From bb4759576827854fe40dcfc43ae9de958c7287c2 Mon Sep 17 00:00:00 2001
From: Emanuele Danovaro <emanuele.danovaro@ecmwf.int>
Date: Thu, 23 Jul 2026 17:36:49 +0200
Subject: [PATCH] fdb-adopt to re-index an existing grib file

---
 src/fdb5/CMakeLists.txt       |   1 +
 src/fdb5/database/Archiver.cc |   4 +-
 src/fdb5/tools/fdb-adopt.cc   | 103 ++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+), 2 deletions(-)
 create mode 100644 src/fdb5/tools/fdb-adopt.cc

diff --git a/src/fdb5/CMakeLists.txt b/src/fdb5/CMakeLists.txt
index 9e2a16560..a894cf131 100644
--- a/src/fdb5/CMakeLists.txt
+++ b/src/fdb5/CMakeLists.txt
@@ -455,6 +455,7 @@ if(HAVE_FDB_BUILD_TOOLS)
 endif()
 
 list( APPEND fdb5_tools
+    fdb-adopt
     fdb-axes
     fdb-write
     fdb-copy
diff --git a/src/fdb5/database/Archiver.cc b/src/fdb5/database/Archiver.cc
index 47051c878..46becf6d5 100644
--- a/src/fdb5/database/Archiver.cc
+++ b/src/fdb5/database/Archiver.cc
@@ -66,8 +66,8 @@ void Archiver::flushDatabase(Database& db) {
 
 void Archiver::flush() {
     std::lock_guard<std::recursive_mutex> lock(flushMutex_);
-    for (auto i = databases_.begin(); i != databases_.end(); ++i) {
-        flushDatabase(i->second);
+    for (auto& kv : databases_) {
+        flushDatabase(kv.second);
     }
 }
 
diff --git a/src/fdb5/tools/fdb-adopt.cc b/src/fdb5/tools/fdb-adopt.cc
new file mode 100644
index 000000000..1b865dfbd
--- /dev/null
+++ b/src/fdb5/tools/fdb-adopt.cc
@@ -0,0 +1,103 @@
+/*
+ * (C) Copyright 1996- ECMWF.
+ *
+ * This software is licensed under the terms of the Apache Licence Version 2.0
+ * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+ * In applying this licence, ECMWF does not waive the privileges and immunities
+ * granted to it by virtue of its status as an intergovernmental organisation nor
+ * does it submit to any jurisdiction.
+ */
+
+#include "eckit/log/Bytes.h"
+#include "eckit/log/Plural.h"
+#include "eckit/log/Progress.h"
+#include "eckit/log/Seconds.h"
+#include "eckit/log/Timer.h"
+#include "eckit/message/Message.h"
+#include "eckit/message/Reader.h"
+#include "eckit/option/CmdArgs.h"
+
+#include "fdb5/api/FDB.h"
+#include "fdb5/database/Key.h"
+#include "fdb5/message/MessageDecoder.h"
+#include "fdb5/toc/TocFieldLocation.h"
+#include "fdb5/tools/FDBTool.h"
+
+//----------------------------------------------------------------------------------------------------------------------
+namespace fdb5::tools {
+
+class FDBAdopt : public fdb5::FDBTool {
+
+    virtual void execute(const eckit::option::CmdArgs& args);
+    virtual void usage(const std::string& tool) const;
+    virtual int minimumPositionalArguments() const { return 1; }
+
+public:
+
+    FDBAdopt(int argc, char** argv) : fdb5::FDBTool(argc, argv) {}
+};
+
+void FDBAdopt::usage(const std::string& tool) const {
+    eckit::Log::info() << std::endl << "Usage: " << tool << " gribfile1 [gribfile2] ..." << std::endl;
+    fdb5::FDBTool::usage(tool);
+}
+
+void FDBAdopt::execute(const eckit::option::CmdArgs& args) {
+
+    FDB fdb(config(args));
+    fdb5::MessageDecoder decoder;
+
+    for (size_t i = 0; i < args.count(); i++) {
+        eckit::PathName path(args(i));
+
+        if (!path.exists()) {
+            throw eckit::UserError("File does not exist: " + args(i), Here());
+        }
+        if (path.isDir()) {
+            throw eckit::UserError("Expected a file but got a directory: " + args(i), Here());
+        }
+        // Index GRIB file
+        eckit::Log::info() << "Processing file " << path << std::endl;
+
+        eckit::message::Reader reader(path);
+        eckit::message::Message msg;
+
+        size_t count = 0;
+        eckit::Length total_size = 0;
+        eckit::Length totalFileSize = path.size();
+        eckit::Timer timer;
+        timer.start();
+
+        eckit::Progress progress("Scanning", 0, totalFileSize);
+
+        eckit::PathName full(path.realName());
+        eckit::URI uri("file", full);
+
+        while ((msg = reader.next())) {
+            fdb5::Key key;
+            decoder.messageToKey(msg, key);
+
+            eckit::Length length = msg.length();
+            eckit::Offset offset = reader.position() - length;
+
+            fdb.reindex(key, fdb5::TocFieldLocation{uri, offset, length, fdb5::Key()});
+            total_size += length;
+            progress(total_size);
+            count++;
+        }
+
+        eckit::Log::info() << "FDB indexed " << eckit::Plural(count, "field") << ","
+                           << " size " << eckit::Bytes(total_size) << ","
+                           << " in " << eckit::Seconds(timer.elapsed()) << " (" << eckit::Bytes(total_size, timer)
+                           << ")" << std::endl;
+    }
+}
+
+}  // namespace fdb5::tools
+
+//----------------------------------------------------------------------------------------------------------------------
+
+int main(int argc, char** argv) {
+    fdb5::tools::FDBAdopt app(argc, argv);
+    return app.start();
+}