Automatically retry a few times on HTTP errors (#613)

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

.github/workflows/test.yml

@@ -149,4 +149,4 @@ jobs:
       - run: mkdir "$PWD/build"
       - run: TMPDIR="$PWD/build" ./test/lint/fail_lint.sh jsonschema
       - run: TMPDIR="$PWD/build" ./test/bundle/pass_resolve_single.sh jsonschema
-      - run: TMPDIR="$PWD/build" ./test/ci/pass_validate_http_verbose.sh jsonschema
+      - run: TMPDIR="$PWD/build" ./test/ci/pass_validate_http.sh jsonschema

src/resolver.h

@@ -27,6 +27,8 @@
 #include "logger.h"
 
 #include <cassert>     // assert
+#include <chrono>      // std::chrono::seconds
+#include <cstdint>     // std::uint8_t
 #include <filesystem>  // std::filesystem
 #include <functional>  // std::function, std::ref
 #include <iostream>    // std::cerr
@@ -36,10 +38,13 @@
 #include <stdexcept>   // std::runtime_error
 #include <string>      // std::string
 #include <string_view> // std::string_view
+#include <thread>      // std::this_thread::sleep_for
 #include <utility> // std::pair, std::piecewise_construct, std::forward_as_tuple
 
 namespace sourcemeta::jsonschema {
 
+static constexpr std::uint8_t HTTP_MAXIMUM_RETRIES{3};
+
 static inline auto fallback_resolver(const sourcemeta::core::Options &options,
                                      std::string_view identifier)
     -> std::optional<sourcemeta::core::JSON> {
@@ -56,9 +61,24 @@ static inline auto fallback_resolver(const sourcemeta::core::Options &options,
     return std::nullopt;
   }
 
-  LOG_VERBOSE(options) << "Resolving over HTTP: " << identifier << "\n";
-  const cpr::Response response{
-      cpr::Get(cpr::Url{identifier}, cpr::Redirect{true})};
+  cpr::Response response;
+  for (std::uint8_t attempt{1}; attempt <= HTTP_MAXIMUM_RETRIES; ++attempt) {
+    LOG_VERBOSE(options) << "Resolving over HTTP (attempt "
+                         << static_cast<int>(attempt) << "/"
+                         << static_cast<int>(HTTP_MAXIMUM_RETRIES)
+                         << "): " << identifier << "\n";
+    response = cpr::Get(cpr::Url{identifier}, cpr::Redirect{true});
+
+    if (response.status_code == 200) {
+      break;
+    }
+
+    if (attempt < HTTP_MAXIMUM_RETRIES) {
+      LOG_VERBOSE(options) << "Request failed with HTTP "
+                           << response.status_code << ", retrying...\n";
+      std::this_thread::sleep_for(std::chrono::seconds(1));
+    }
+  }
 
   if (response.status_code != 200) {
     std::ostringstream error;

test/CMakeLists.txt

@@ -468,15 +468,10 @@ add_jsonschema_test_unix(decode/fail_no_output)
 # CI specific tests
 add_jsonschema_test_unix_ci(pass_bundle_http)
 add_jsonschema_test_unix_ci(fail_bundle_http_non_200)
-add_jsonschema_test_unix_ci(fail_bundle_http_non_200_verbose)
 add_jsonschema_test_unix_ci(fail_bundle_http_non_schema)
-add_jsonschema_test_unix_ci(fail_bundle_http_non_schema_verbose)
 add_jsonschema_test_unix_ci(fail_validate_http_non_200)
-add_jsonschema_test_unix_ci(fail_validate_http_non_200_verbose)
 add_jsonschema_test_unix_ci(fail_validate_http_non_schema)
-add_jsonschema_test_unix_ci(fail_validate_http_non_schema_verbose)
 add_jsonschema_test_unix_ci(pass_validate_http)
-add_jsonschema_test_unix_ci(pass_validate_http_verbose)
 add_jsonschema_test_unix_ci(precommit_lint)
 
 # TODO: Make this test pass on Linux. It hangs for some reason