1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef INCLUDE_PERFETTO_BASE_STATUS_H_
18 #define INCLUDE_PERFETTO_BASE_STATUS_H_
19
20 #include <optional>
21 #include <string>
22 #include <string_view>
23 #include <vector>
24
25 #include "perfetto/base/compiler.h"
26 #include "perfetto/base/export.h"
27 #include "perfetto/base/logging.h"
28
29 namespace perfetto {
30 namespace base {
31
32 // Represents either the success or the failure message of a function.
33 // This can used as the return type of functions which would usually return an
34 // bool for success or int for errno but also wants to add some string context
35 // (ususally for logging).
36 //
37 // Similar to absl::Status, an optional "payload" can also be included with more
38 // context about the error. This allows passing additional metadata about the
39 // error (e.g. location of errors, potential mitigations etc).
40 class PERFETTO_EXPORT_COMPONENT Status {
41 public:
Status()42 Status() : ok_(true) {}
Status(std::string msg)43 explicit Status(std::string msg) : ok_(false), message_(std::move(msg)) {
44 PERFETTO_CHECK(!message_.empty());
45 }
46
47 // Copy operations.
48 Status(const Status&) = default;
49 Status& operator=(const Status&) = default;
50
51 // Move operations. The moved-from state is valid but unspecified.
52 Status(Status&&) noexcept = default;
53 Status& operator=(Status&&) = default;
54
ok()55 bool ok() const { return ok_; }
56
57 // When ok() is false this returns the error message. Returns the empty string
58 // otherwise.
message()59 const std::string& message() const { return message_; }
c_message()60 const char* c_message() const { return message_.c_str(); }
61
62 //////////////////////////////////////////////////////////////////////////////
63 // Payload Management APIs
64 //////////////////////////////////////////////////////////////////////////////
65
66 // Payloads can be attached to error statuses to provide additional context.
67 //
68 // Payloads are (key, value) pairs, where the key is a string acting as a
69 // unique "type URL" and the value is an opaque string. The "type URL" should
70 // be unique, follow the format of a URL and, ideally, documentation on how to
71 // interpret its associated data should be available.
72 //
73 // To attach a payload to a status object, call `Status::SetPayload()`.
74 // Similarly, to extract the payload from a status, call
75 // `Status::GetPayload()`.
76 //
77 // Note: the payload APIs are only meaningful to call when the status is an
78 // error. Otherwise, all methods are noops.
79
80 // Gets the payload for the given |type_url| if one exists.
81 //
82 // Will always return std::nullopt if |ok()|.
83 std::optional<std::string_view> GetPayload(std::string_view type_url) const;
84
85 // Sets the payload for the given key. The key should
86 //
87 // Will always do nothing if |ok()|.
88 void SetPayload(std::string_view type_url, std::string value);
89
90 // Erases the payload for the given string and returns true if the payload
91 // existed and was erased.
92 //
93 // Will always do nothing if |ok()|.
94 bool ErasePayload(std::string_view type_url);
95
96 private:
97 struct Payload {
98 std::string type_url;
99 std::string payload;
100 };
101
102 bool ok_ = false;
103 std::string message_;
104 std::vector<Payload> payloads_;
105 };
106
107 // Returns a status object which represents the Ok status.
OkStatus()108 inline Status OkStatus() {
109 return Status();
110 }
111
112 Status ErrStatus(const char* format, ...) PERFETTO_PRINTF_FORMAT(1, 2);
113
114 } // namespace base
115 } // namespace perfetto
116
117 #endif // INCLUDE_PERFETTO_BASE_STATUS_H_
118