Add update-ament-vendor.sh maintainer script

This script automatically updates (or generates) all
vendored-source.json files.

maintainers/scripts/ament-vendor-update-order.nix

@@ -0,0 +1,8 @@
+{ candidates }:
+with import ../../. {};
+let
+  updatable = lib.filter (pkg: if pkg ? updateAmentVendor then true else lib.warn "${pkg.pname} not updatable" false) candidates;
+  isDependent = a: b: builtins.elem a (b.buildInputs ++ b.propagatedBuildInputs ++ b.nativeBuildInputs);
+  sorted = (lib.toposort isDependent updatable).result;
+in
+map (p: let name = lib.removePrefix "ros-${p.rosDistro}-" p.pname; in "${p.rosDistro}.${name}") sorted

maintainers/scripts/update-ament-vendor.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash --pure --keep NIX_PATH
+#! nix-shell -p nix-eval-jobs jq nix rush-parallel
+
+set -euo pipefail
+
+# Scrip to generate/update vendored-source.json files needed by
+# patchAmentVendorGit.
+#
+# Run it from the top-level directory of this repo, i.e.,
+# ./maintainers/scripts/update-ament-vendor.sh
+
+# Find potential candidates for updating
+candidates=$(
+    # Extract all rosPackages (ignoring eval errors)
+    nix-eval-jobs --expr '(import ./. {}).rosPackages' |
+        # Select only packages that depend on ament-cmake-vendor-package
+        jq -r 'select(.inputDrvs|objects|keys|any(contains("ament-cmake-vendor-package"))).attr')
+
+# Some *-vendor packages depend on others. For the update to work,
+# dependencies must be updated first followed by dependent packages.
+update_order=$(
+    nix-instantiate \
+        --eval --strict --json \
+        --arg candidates "with (import ./. {}).rosPackages; [ $candidates ]" \
+        "$(dirname $0)/ament-vendor-update-order.nix" | jq -r '.[]')
+
+ok_cmds=$(mktemp)
+trap "rm $ok_cmds" EXIT
+
+# First try updating all packages in parallel. This is the fast path,
+# which is sufficient if there are no updates or updates in just a few
+# root packages in the dependency tree.
+if ! rush --keep-order --verbose -c --succ-cmd-file $ok_cmds -- \
+     bash -c '$(nix-build -A rosPackages.{}.updateAmentVendor) 2>&1' <<<"$update_order"
+then
+    # If the parallel update fails, it's likely due to the update
+    # deeper in the dependency tree. Then it is usually more efficient
+    # to run all updates serially in the topologic order, which is
+    # guaranteed not to fail due to dependencies between to-be-updated
+    # packages.
+    printf "\nFalling back to serial execution\n"
+    rush -j1 --verbose --continue --succ-cmd-file $ok_cmds -- \
+         bash -c '$(nix-build -A rosPackages.{}.updateAmentVendor) 2>&1' <<<"$update_order"
+fi