Bug 1708643 - Add QM_OR_ELSE_WARN_IF/QM_OR_ELSE_NOTE_IF/QM_OR_ELSE_LOG_IF macros; r=dom-storage-reviewers,asuth

Differential Revision: https://phabricator.services.mozilla.com/D114844

dom/quota/QuotaCommon.h

@@ -894,6 +894,69 @@ class NotNull;
  */
 #define QM_OR_ELSE_LOG(...) QM_OR_ELSE_REPORT(Log, __VA_ARGS__)
 
+namespace mozilla::dom::quota {
+
+// XXX Support orElseIf directly in mozilla::Result
+template <typename V, typename E, typename P, typename F>
+auto OrElseIf(Result<V, E>&& aResult, P&& aPred, F&& aFunc) -> Result<V, E> {
+  return MOZ_UNLIKELY(aResult.isErr())
+             ? (std::forward<P>(aPred)(aResult.inspectErr()))
+                   ? std::forward<F>(aFunc)(aResult.unwrapErr())
+                   : aResult.propagateErr()
+             : aResult.unwrap();
+}
+
+}  // namespace mozilla::dom::quota
+
+// QM_OR_ELSE_REPORT_IF macro is an implementation detail of
+// QM_OR_ELSE_WARN_IF/QM_OR_ELSE_NOTE_IF/QM_OR_ELSE_LOG_IF and shouldn't be
+// used directly.
+
+#define QM_OR_ELSE_REPORT_IF(severity, expr, predicate, fallback) \
+  mozilla::dom::quota::OrElseIf(                                  \
+      (expr),                                                     \
+      [&](const auto& firstRes) {                                 \
+        bool res = predicate(firstRes);                           \
+        mozilla::dom::quota::QM_HANDLE_ERROR(                     \
+            #expr, firstRes,                                      \
+            res ? mozilla::dom::quota::Severity::severity         \
+                : mozilla::dom::quota::Severity::Error);          \
+        return res;                                               \
+      },                                                          \
+      fallback)
+
+/*
+ * QM_OR_ELSE_WARN_IF(expr, predicate, fallback) evaluates expr first, which
+ * must produce a Result value. On Success, it just moves the success over.
+ * On error, it calls a predicate function (passed as the second argument) and
+ * then it either calls HandleError (with the Warning severity) and a fallback
+ * function (passed as the third argument) which produces a new result if the
+ * predicate returned true. Or it calls HandleError (with the Error severity)
+ * and propagates the error result if the predicate returned false. So failed
+ * expr can be reported as a warning or as an error depending on the predicate.
+ * QM_OR_ELSE_WARN_IF is a sub macro and is intended to be used along with one
+ * of the main macros such as QM_TRY.
+ */
+#define QM_OR_ELSE_WARN_IF(...) QM_OR_ELSE_REPORT_IF(Warning, __VA_ARGS__)
+
+/**
+ * QM_OR_ELSE_NOTE_IF is like QM_OR_ELSE_WARN_IF. The only difference is that
+ * failures are reported using a lower level of severity relative to failures
+ * reported by QM_OR_ELSE_WARN_IF.
+ */
+#define QM_OR_ELSE_NOTE_IF(...) QM_OR_ELSE_REPORT_IF(Note, __VA_ARGS__)
+
+/**
+ * QM_OR_ELSE_LOG_IF is like QM_OR_ELSE_WARN_IF. The only difference is that
+ * failures are reported using the lowest severity which is currently ignored
+ * in LogError, so nothing goes to the console, browser console and telemetry.
+ * Since nothing goes to the telemetry, the macro can't signal the end of the
+ * underlying error stack or change the type of the error stack in the
+ * telemetry. For that reason, the expression shouldn't contain nested QM_TRY
+ * macro uses.
+ */
+#define QM_OR_ELSE_LOG_IF(...) QM_OR_ELSE_REPORT_IF(Log, __VA_ARGS__)
+
 // Telemetry probes to collect number of failure during the initialization.
 #ifdef NIGHTLY_BUILD
 #  define RECORD_IN_NIGHTLY(_recorder, _status) \

dom/quota/test/gtest/TestQuotaCommon.cpp

@@ -1244,6 +1244,118 @@ TEST(QuotaCommon_OrElseWarn, Failure_MappedToError)
   EXPECT_FALSE(tryContinued);
 }
 
+TEST(QuotaCommon_OrElseWarnIf, Success)
+{
+  bool predicateRun = false;
+  bool fallbackRun = false;
+  bool tryContinued = false;
+
+  const auto res = [&]() -> mozilla::Result<mozilla::Ok, NotOk> {
+    QM_TRY(QM_OR_ELSE_WARN_IF(
+        OkIf(true),
+        [&predicateRun](const NotOk) {
+          predicateRun = true;
+          return false;
+        },
+        ([&fallbackRun](const NotOk) {
+          fallbackRun = true;
+          return mozilla::Result<mozilla::Ok, NotOk>{mozilla::Ok{}};
+        })));
+
+    tryContinued = true;
+    return mozilla::Ok{};
+  }();
+
+  EXPECT_TRUE(res.isOk());
+  EXPECT_FALSE(predicateRun);
+  EXPECT_FALSE(fallbackRun);
+  EXPECT_TRUE(tryContinued);
+}
+
+TEST(QuotaCommon_OrElseWarnIf, Failure_PredicateReturnsFalse)
+{
+  bool predicateRun = false;
+  bool fallbackRun = false;
+  bool tryContinued = false;
+
+  const auto res = [&]() -> mozilla::Result<mozilla::Ok, NotOk> {
+    QM_TRY(QM_OR_ELSE_WARN_IF(
+        OkIf(false),
+        [&predicateRun](const NotOk) {
+          predicateRun = true;
+          return false;
+        },
+        ([&fallbackRun](const NotOk) {
+          fallbackRun = true;
+          return mozilla::Result<mozilla::Ok, NotOk>{mozilla::Ok{}};
+        })));
+
+    tryContinued = true;
+    return mozilla::Ok{};
+  }();
+
+  EXPECT_TRUE(res.isErr());
+  EXPECT_TRUE(predicateRun);
+  EXPECT_FALSE(fallbackRun);
+  EXPECT_FALSE(tryContinued);
+}
+
+TEST(QuotaCommon_OrElseWarnIf, Failure_PredicateReturnsTrue_MappedToSuccess)
+{
+  bool predicateRun = false;
+  bool fallbackRun = false;
+  bool tryContinued = false;
+
+  const auto res = [&]() -> mozilla::Result<mozilla::Ok, NotOk> {
+    QM_TRY(QM_OR_ELSE_WARN_IF(
+        OkIf(false),
+        [&predicateRun](const NotOk) {
+          predicateRun = true;
+          return true;
+        },
+        ([&fallbackRun](const NotOk) {
+          fallbackRun = true;
+          return mozilla::Result<mozilla::Ok, NotOk>{mozilla::Ok{}};
+        })));
+
+    tryContinued = true;
+    return mozilla::Ok{};
+  }();
+
+  EXPECT_TRUE(res.isOk());
+  EXPECT_TRUE(predicateRun);
+  EXPECT_TRUE(fallbackRun);
+  EXPECT_TRUE(tryContinued);
+}
+
+TEST(QuotaCommon_OrElseWarnIf, Failure_PredicateReturnsTrue_MappedToError)
+{
+  bool predicateRun = false;
+  bool fallbackRun = false;
+  bool tryContinued = false;
+
+  const auto res = [&]() -> mozilla::Result<mozilla::Ok, NotOk> {
+    QM_TRY(QM_OR_ELSE_WARN_IF(
+        OkIf(false),
+        [&predicateRun](const NotOk) {
+          predicateRun = true;
+          return true;
+        },
+        ([&fallbackRun](const NotOk) {
+          fallbackRun = true;
+          return mozilla::Result<mozilla::Ok, NotOk>{mozilla::NotOk{}};
+        })));
+
+    tryContinued = true;
+    return mozilla::Ok{};
+  }();
+
+  EXPECT_TRUE(res.isErr());
+  EXPECT_TRUE(predicateRun);
+  EXPECT_TRUE(fallbackRun);
+  EXPECT_FALSE(tryContinued);
+}
+
 TEST(QuotaCommon_OkIf, True)
 {
   auto res = OkIf(true);