1 //===-- Timeout.h -----------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLDB_UTILITY_TIMEOUT_H
10 #define LLDB_UTILITY_TIMEOUT_H
11 
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/Support/Chrono.h"
14 #include "llvm/Support/FormatProviders.h"
15 
16 namespace lldb_private {
17 
18 // A general purpose class for representing timeouts for various APIs. It's
19 // basically an llvm::Optional<std::chrono::duration<int64_t, Ratio>>, but we
20 // customize it a bit to enable the standard chrono implicit conversions (e.g.
21 // from Timeout<std::milli> to Timeout<std::micro>.
22 //
23 // The intended meaning of the values is:
24 // - llvm::None - no timeout, the call should wait forever - 0 - poll, only
25 // complete the call if it will not block - >0 - wait for a given number of
26 // units for the result
27 template <typename Ratio>
28 class Timeout : public llvm::Optional<std::chrono::duration<int64_t, Ratio>> {
29 private:
30   template <typename Ratio2> using Dur = std::chrono::duration<int64_t, Ratio2>;
31   template <typename Rep2, typename Ratio2>
32   using EnableIf = std::enable_if<
33       std::is_convertible<std::chrono::duration<Rep2, Ratio2>,
34                           std::chrono::duration<int64_t, Ratio>>::value>;
35 
36   using Base = llvm::Optional<Dur<Ratio>>;
37 
38 public:
39   Timeout(llvm::NoneType none) : Base(none) {}
40 
41   template <typename Ratio2,
42             typename = typename EnableIf<int64_t, Ratio2>::type>
43   Timeout(const Timeout<Ratio2> &other)
44       : Base(other ? Base(Dur<Ratio>(*other)) : llvm::None) {}
45 
46   template <typename Rep2, typename Ratio2,
47             typename = typename EnableIf<Rep2, Ratio2>::type>
48   Timeout(const std::chrono::duration<Rep2, Ratio2> &other)
49       : Base(Dur<Ratio>(other)) {}
50 };
51 
52 } // namespace lldb_private
53 
54 namespace llvm {
55 template<typename Ratio>
56 struct format_provider<lldb_private::Timeout<Ratio>, void> {
57   static void format(const lldb_private::Timeout<Ratio> &timeout,
58                      raw_ostream &OS, StringRef Options) {
59     typedef typename lldb_private::Timeout<Ratio>::value_type Dur;
60 
61     if (!timeout)
62       OS << "<infinite>";
63     else
64       format_provider<Dur>::format(*timeout, OS, Options);
65   }
66 };
67 }
68 
69 #endif // LLDB_UTILITY_TIMEOUT_H
70