| /* |
| * Copyright 2017 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #ifndef API_RTC_ERROR_H_ |
| #define API_RTC_ERROR_H_ |
| |
| #ifdef UNIT_TEST |
| #include <ostream> |
| #endif // UNIT_TEST |
| #include <string> |
| #include <utility> // For std::move. |
| |
| #include "absl/strings/string_view.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| |
| namespace webrtc { |
| |
| // Enumeration to represent distinct classes of errors that an application |
| // may wish to act upon differently. These roughly map to DOMExceptions or |
| // RTCError "errorDetailEnum" values in the web API, as described in the |
| // comments below. |
| enum class RTCErrorType { |
| // No error. |
| NONE, |
| |
| // An operation is valid, but currently unsupported. |
| // Maps to OperationError DOMException. |
| UNSUPPORTED_OPERATION, |
| |
| // A supplied parameter is valid, but currently unsupported. |
| // Maps to OperationError DOMException. |
| UNSUPPORTED_PARAMETER, |
| |
| // General error indicating that a supplied parameter is invalid. |
| // Maps to InvalidAccessError or TypeError DOMException depending on context. |
| INVALID_PARAMETER, |
| |
| // Slightly more specific than INVALID_PARAMETER; a parameter's value was |
| // outside the allowed range. |
| // Maps to RangeError DOMException. |
| INVALID_RANGE, |
| |
| // Slightly more specific than INVALID_PARAMETER; an error occurred while |
| // parsing string input. |
| // Maps to SyntaxError DOMException. |
| SYNTAX_ERROR, |
| |
| // The object does not support this operation in its current state. |
| // Maps to InvalidStateError DOMException. |
| INVALID_STATE, |
| |
| // An attempt was made to modify the object in an invalid way. |
| // Maps to InvalidModificationError DOMException. |
| INVALID_MODIFICATION, |
| |
| // An error occurred within an underlying network protocol. |
| // Maps to NetworkError DOMException. |
| NETWORK_ERROR, |
| |
| // Some resource has been exhausted; file handles, hardware resources, ports, |
| // etc. |
| // Maps to OperationError DOMException. |
| RESOURCE_EXHAUSTED, |
| |
| // The operation failed due to an internal error. |
| // Maps to OperationError DOMException. |
| INTERNAL_ERROR, |
| }; |
| |
| // Roughly corresponds to RTCError in the web api. Holds an error type, a |
| // message, and possibly additional information specific to that error. |
| // |
| // Doesn't contain anything beyond a type and message now, but will in the |
| // future as more errors are implemented. |
| class RTCError { |
| public: |
| // Constructors. |
| |
| // Creates a "no error" error. |
| RTCError() {} |
| explicit RTCError(RTCErrorType type) : type_(type) {} |
| |
| RTCError(RTCErrorType type, std::string message) |
| : type_(type), message_(std::move(message)) {} |
| |
| // Delete the copy constructor and assignment operator; there aren't any use |
| // cases where you should need to copy an RTCError, as opposed to moving it. |
| // Can revisit this decision if use cases arise in the future. |
| RTCError(const RTCError& other) = delete; |
| RTCError& operator=(const RTCError& other) = delete; |
| |
| // Move constructor and move-assignment operator. |
| RTCError(RTCError&& other); |
| RTCError& operator=(RTCError&& other); |
| |
| // Identical to default constructed error. |
| // |
| // Preferred over the default constructor for code readability. |
| static RTCError OK(); |
| |
| // Error type. |
| RTCErrorType type() const { return type_; } |
| void set_type(RTCErrorType type) { type_ = type; } |
| |
| // Human-readable message describing the error. Shouldn't be used for |
| // anything but logging/diagnostics, since messages are not guaranteed to be |
| // stable. |
| const char* message() const; |
| |
| void set_message(std::string message); |
| |
| // Convenience method for situations where you only care whether or not an |
| // error occurred. |
| bool ok() const { return type_ == RTCErrorType::NONE; } |
| |
| private: |
| RTCErrorType type_ = RTCErrorType::NONE; |
| std::string message_; |
| }; |
| |
| // Outputs the error as a friendly string. Update this method when adding a new |
| // error type. |
| // |
| // Only intended to be used for logging/diagnostics. The string_view points |
| // to literal string that lives for the whole duration of the program. |
| absl::string_view ToString(RTCErrorType error); |
| |
| #ifdef UNIT_TEST |
| inline std::ostream& operator<<( // no-presubmit-check TODO(webrtc:8982) |
| std::ostream& stream, // no-presubmit-check TODO(webrtc:8982) |
| RTCErrorType error) { |
| return stream << ToString(error); |
| } |
| #endif // UNIT_TEST |
| |
| // Helper macro that can be used by implementations to create an error with a |
| // message and log it. |message| should be a string literal or movable |
| // std::string. |
| #define LOG_AND_RETURN_ERROR_EX(type, message, severity) \ |
| { \ |
| RTC_DCHECK(type != RTCErrorType::NONE); \ |
| RTC_LOG(severity) << message << " (" << ToString(type) << ")"; \ |
| return webrtc::RTCError(type, message); \ |
| } |
| |
| #define LOG_AND_RETURN_ERROR(type, message) \ |
| LOG_AND_RETURN_ERROR_EX(type, message, LS_ERROR) |
| |
| // RTCErrorOr<T> is the union of an RTCError object and a T object. RTCErrorOr |
| // models the concept of an object that is either a usable value, or an error |
| // Status explaining why such a value is not present. To this end RTCErrorOr<T> |
| // does not allow its RTCErrorType value to be RTCErrorType::NONE. This is |
| // enforced by a debug check in most cases. |
| // |
| // The primary use-case for RTCErrorOr<T> is as the return value of a function |
| // which may fail. For example, CreateRtpSender will fail if the parameters |
| // could not be successfully applied at the media engine level, but if |
| // successful will return a unique_ptr to an RtpSender. |
| // |
| // Example client usage for a RTCErrorOr<std::unique_ptr<T>>: |
| // |
| // RTCErrorOr<std::unique_ptr<Foo>> result = FooFactory::MakeNewFoo(arg); |
| // if (result.ok()) { |
| // std::unique_ptr<Foo> foo = result.ConsumeValue(); |
| // foo->DoSomethingCool(); |
| // } else { |
| // RTC_LOG(LS_ERROR) << result.error(); |
| // } |
| // |
| // Example factory implementation returning RTCErrorOr<std::unique_ptr<T>>: |
| // |
| // RTCErrorOr<std::unique_ptr<Foo>> FooFactory::MakeNewFoo(int arg) { |
| // if (arg <= 0) { |
| // return RTCError(RTCErrorType::INVALID_RANGE, "Arg must be positive"); |
| // } else { |
| // return std::unique_ptr<Foo>(new Foo(arg)); |
| // } |
| // } |
| // |
| template <typename T> |
| class RTCErrorOr { |
| // Used to convert between RTCErrorOr<Foo>/RtcErrorOr<Bar>, when an implicit |
| // conversion from Foo to Bar exists. |
| template <typename U> |
| friend class RTCErrorOr; |
| |
| public: |
| typedef T element_type; |
| |
| // Constructs a new RTCErrorOr with RTCErrorType::INTERNAL_ERROR error. This |
| // is marked 'explicit' to try to catch cases like 'return {};', where people |
| // think RTCErrorOr<std::vector<int>> will be initialized with an empty |
| // vector, instead of a RTCErrorType::INTERNAL_ERROR error. |
| RTCErrorOr() : error_(RTCErrorType::INTERNAL_ERROR) {} |
| |
| // Constructs a new RTCErrorOr with the given non-ok error. After calling |
| // this constructor, calls to value() will DCHECK-fail. |
| // |
| // NOTE: Not explicit - we want to use RTCErrorOr<T> as a return |
| // value, so it is convenient and sensible to be able to do 'return |
| // RTCError(...)' when the return type is RTCErrorOr<T>. |
| // |
| // REQUIRES: !error.ok(). This requirement is DCHECKed. |
| RTCErrorOr(RTCError&& error) : error_(std::move(error)) { // NOLINT |
| RTC_DCHECK(!error.ok()); |
| } |
| |
| // Constructs a new RTCErrorOr with the given value. After calling this |
| // constructor, calls to value() will succeed, and calls to error() will |
| // return a default-constructed RTCError. |
| // |
| // NOTE: Not explicit - we want to use RTCErrorOr<T> as a return type |
| // so it is convenient and sensible to be able to do 'return T()' |
| // when the return type is RTCErrorOr<T>. |
| RTCErrorOr(const T& value) : value_(value) {} // NOLINT |
| RTCErrorOr(T&& value) : value_(std::move(value)) {} // NOLINT |
| |
| // Delete the copy constructor and assignment operator; there aren't any use |
| // cases where you should need to copy an RTCErrorOr, as opposed to moving |
| // it. Can revisit this decision if use cases arise in the future. |
| RTCErrorOr(const RTCErrorOr& other) = delete; |
| RTCErrorOr& operator=(const RTCErrorOr& other) = delete; |
| |
| // Move constructor and move-assignment operator. |
| // |
| // Visual Studio doesn't support "= default" with move constructors or |
| // assignment operators (even though they compile, they segfault), so define |
| // them explicitly. |
| RTCErrorOr(RTCErrorOr&& other) |
| : error_(std::move(other.error_)), value_(std::move(other.value_)) {} |
| RTCErrorOr& operator=(RTCErrorOr&& other) { |
| error_ = std::move(other.error_); |
| value_ = std::move(other.value_); |
| return *this; |
| } |
| |
| // Conversion constructor and assignment operator; T must be copy or move |
| // constructible from U. |
| template <typename U> |
| RTCErrorOr(RTCErrorOr<U> other) // NOLINT |
| : error_(std::move(other.error_)), value_(std::move(other.value_)) {} |
| template <typename U> |
| RTCErrorOr& operator=(RTCErrorOr<U> other) { |
| error_ = std::move(other.error_); |
| value_ = std::move(other.value_); |
| return *this; |
| } |
| |
| // Returns a reference to our error. If this contains a T, then returns |
| // default-constructed RTCError. |
| const RTCError& error() const { return error_; } |
| |
| // Moves the error. Can be useful if, say "CreateFoo" returns an |
| // RTCErrorOr<Foo>, and internally calls "CreateBar" which returns an |
| // RTCErrorOr<Bar>, and wants to forward the error up the stack. |
| RTCError MoveError() { return std::move(error_); } |
| |
| // Returns this->error().ok() |
| bool ok() const { return error_.ok(); } |
| |
| // Returns a reference to our current value, or DCHECK-fails if !this->ok(). |
| // |
| // Can be convenient for the implementation; for example, a method may want |
| // to access the value in some way before returning it to the next method on |
| // the stack. |
| const T& value() const { |
| RTC_DCHECK(ok()); |
| return value_; |
| } |
| T& value() { |
| RTC_DCHECK(ok()); |
| return value_; |
| } |
| |
| // Moves our current value out of this object and returns it, or DCHECK-fails |
| // if !this->ok(). |
| T MoveValue() { |
| RTC_DCHECK(ok()); |
| return std::move(value_); |
| } |
| |
| private: |
| RTCError error_; |
| T value_; |
| }; |
| |
| } // namespace webrtc |
| |
| #endif // API_RTC_ERROR_H_ |