1 files changed, 40 insertions, 0 deletions
diff --git a/tools/update-verify/release/common/cached_download.sh b/tools/update-verify/release/common/cached_download.sh
new file mode 100644
index 0000000000..7cb3c42f8d
--- /dev/null
+++ b/tools/update-verify/release/common/cached_download.sh
@@ -0,0 +1,40 @@
+# this library works like a wrapper around wget, to allow downloads to be cached
+# so that if later the same url is retrieved, the entry from the cache will be
+# returned.
+
+pushd `dirname $0` &>/dev/null
+cache_dir="$(pwd)/cache"
+popd &>/dev/null
+
+# Deletes all files in the cache directory
+# We don't support folders or .dot(hidden) files
+# By not deleting the cache directory, it allows us to use Docker tmpfs mounts,
+# which are the only workaround to poor mount r/w performance on MacOS
+# Reference: https://forums.docker.com/t/file-access-in-mounted-volumes-extremely-slow-cpu-bound/8076/288
+clear_cache () {
+    rm -rf "${cache_dir}/*"
+}
+
+# download method - you pass a filename to save the file under, and the url to call
+cached_download () {
+    local output_file="${1}"
+    local url="${2}"
+
+    if fgrep -x "${url}" "${cache_dir}/urls.list" >/dev/null; then
+        echo "Retrieving '${url}' from cache..."
+        local line_number="$(fgrep -nx  "${url}" "${cache_dir}/urls.list" | sed 's/:.*//')"
+        cp "${cache_dir}/obj_$(printf "%05d\n" "${line_number}").cache" "${output_file}"
+    else
+        echo "Downloading '${url}' and placing in cache..."
+        rm -f "${output_file}"
+        $retry wget -O "${output_file}" --progress=dot:giga --server-response "${url}" 2>&1
+        local exit_code=$?
+        if [ "${exit_code}" == 0 ]; then
+            echo "${url}" >> "${cache_dir}/urls.list"
+            local line_number="$(fgrep -nx  "${url}" "${cache_dir}/urls.list" | sed 's/:.*//')"
+            cp "${output_file}" "${cache_dir}/obj_$(printf "%05d\n" "${line_number}").cache"
+        else
+            return "${exit_code}"
+        fi
+    fi
+}