Add zstd.

3rdparty/zstd-1.5.0/contrib/pzstd/ErrorHolder.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ */
+#pragma once
+
+#include <atomic>
+#include <cassert>
+#include <stdexcept>
+#include <string>
+
+namespace pzstd {
+
+// Coordinates graceful shutdown of the pzstd pipeline
+class ErrorHolder {
+  std::atomic<bool> error_;
+  std::string message_;
+
+ public:
+  ErrorHolder() : error_(false) {}
+
+  bool hasError() noexcept {
+    return error_.load();
+  }
+
+  void setError(std::string message) noexcept {
+    // Given multiple possibly concurrent calls, exactly one will ever succeed.
+    bool expected = false;
+    if (error_.compare_exchange_strong(expected, true)) {
+      message_ = std::move(message);
+    }
+  }
+
+  bool check(bool predicate, std::string message) noexcept {
+    if (!predicate) {
+      setError(std::move(message));
+    }
+    return !hasError();
+  }
+
+  std::string getError() noexcept {
+    error_.store(false);
+    return std::move(message_);
+  }
+
+  ~ErrorHolder() {
+    assert(!hasError());
+  }
+};
+}