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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_CDM_PROMISE_H_
#define MEDIA_BASE_CDM_PROMISE_H_
#include <stdint.h>
#include <string>
#include "base/check.h"
#include "base/logging.h"
#include "media/base/cdm_key_information.h"
#include "media/base/media_export.h"
namespace media {
// Interface for promises being resolved/rejected in response to various
// session actions. These may be called synchronously or asynchronously.
// The promise must be resolved or rejected exactly once. It is expected that
// the caller free the promise once it is resolved/rejected.
// These classes are almost generic, except for the parameters to reject(). If
// a generic class for promises is available, this could be changed to use the
// generic class as long as the parameters to reject() can be set appropriately.
// The base class only has a reject() method and GetResolveParameterType() that
// indicates the type of CdmPromiseTemplate. CdmPromiseTemplate<T> adds the
// resolve(T) method that is dependent on the type of promise. This base class
// is specified so that the promises can be easily saved before passing across
// IPC.
class MEDIA_EXPORT CdmPromise {
public:
enum class Exception {
NOT_SUPPORTED_ERROR,
INVALID_STATE_ERROR,
QUOTA_EXCEEDED_ERROR,
TYPE_ERROR,
EXCEPTION_MAX = TYPE_ERROR
};
enum ResolveParameterType {
VOID_TYPE,
INT_TYPE,
STRING_TYPE,
KEY_STATUS_TYPE
};
// These values are reported to UMA. Never change existing values. Only add
// new values at the bottom of the list.
// TODO(xhwang): Make SystemCode an enum class and pass |system_code| as
// SystemCode everywhere.
enum SystemCode : uint32_t {
kMinValue = 1000000, // To avoid conflict with system code reported by CDM.
kOk = kMinValue,
kFailure,
kAborted,
kConnectionError,
kMaxValue = kConnectionError,
};
CdmPromise() = default;
CdmPromise(const CdmPromise&) = delete;
CdmPromise& operator=(const CdmPromise&) = delete;
virtual ~CdmPromise() = default;
// Used to indicate that the operation failed. |exception_code| must be
// specified. |system_code| is a Key System-specific value for the error
// that occurred, or 0 if there is no associated status code or such status
// codes are not supported by the Key System. |error_message| is optional.
virtual void reject(Exception exception_code,
uint32_t system_code,
const std::string& error_message) = 0;
// Used to determine the template type of CdmPromiseTemplate<T> so that
// saved CdmPromise objects can be cast to the correct templated version.
virtual ResolveParameterType GetResolveParameterType() const = 0;
};
template <typename... T>
struct CdmPromiseTraits {};
template <>
struct MEDIA_EXPORT CdmPromiseTraits<> {
static const CdmPromise::ResolveParameterType kType;
};
template <>
struct MEDIA_EXPORT CdmPromiseTraits<int> {
static const CdmPromise::ResolveParameterType kType;
};
template <>
struct MEDIA_EXPORT CdmPromiseTraits<std::string> {
static const CdmPromise::ResolveParameterType kType;
};
template <>
struct MEDIA_EXPORT CdmPromiseTraits<CdmKeyInformation::KeyStatus> {
static const CdmPromise::ResolveParameterType kType;
};
// This class adds the resolve(T) method. This class is still an interface, and
// is used as the type of promise that gets passed around.
template <typename... T>
class CdmPromiseTemplate : public CdmPromise {
public:
CdmPromiseTemplate() : is_settled_(false) {}
CdmPromiseTemplate(const CdmPromiseTemplate&) = delete;
CdmPromiseTemplate& operator=(const CdmPromiseTemplate&) = delete;
virtual ~CdmPromiseTemplate() { DCHECK(is_settled_); }
virtual void resolve(const T&... result) = 0;
// CdmPromise implementation.
ResolveParameterType GetResolveParameterType() const final;
protected:
bool IsPromiseSettled() const { return is_settled_; }
// All implementations must call this method in resolve() and reject() methods
// to indicate that the promise has been settled.
void MarkPromiseSettled() {
// Promise can only be settled once.
DCHECK(!is_settled_);
is_settled_ = true;
}
// Must be called by the concrete destructor if !IsPromiseSettled().
// Note: We can't call reject() in ~CdmPromise() because reject() is virtual.
void RejectPromiseOnDestruction() {
DCHECK(!is_settled_);
std::string message =
"Unfulfilled promise rejected automatically during destruction.";
DVLOG(1) << message;
reject(Exception::INVALID_STATE_ERROR, SystemCode::kAborted, message);
DCHECK(is_settled_);
}
private:
// Keep track of whether the promise has been resolved or rejected yet.
bool is_settled_;
};
// Explicitly defining all variants of GetResolveParameterType().
// Without this component builds on Windows fail due to versions of the same
// method being generated in multiple DLLs.
template <>
MEDIA_EXPORT CdmPromise::ResolveParameterType
CdmPromiseTemplate<>::GetResolveParameterType() const;
template <>
MEDIA_EXPORT CdmPromise::ResolveParameterType
CdmPromiseTemplate<int>::GetResolveParameterType() const;
template <>
MEDIA_EXPORT CdmPromise::ResolveParameterType
CdmPromiseTemplate<std::string>::GetResolveParameterType() const;
template <>
MEDIA_EXPORT CdmPromise::ResolveParameterType CdmPromiseTemplate<
CdmKeyInformation::KeyStatus>::GetResolveParameterType() const;
// A dummy CdmPromise that does nothing. Used for APIs requiring a CdmPromise
// while the result will be ignored.
template <typename... T>
class MEDIA_EXPORT DoNothingCdmPromise : public CdmPromiseTemplate<T...> {
public:
DoNothingCdmPromise() = default;
DoNothingCdmPromise(const DoNothingCdmPromise&) = delete;
DoNothingCdmPromise& operator=(const DoNothingCdmPromise&) = delete;
~DoNothingCdmPromise() override = default;
// CdmPromiseTemplate.
void resolve() final { CdmPromiseTemplate<T...>::MarkPromiseSettled(); }
void reject(CdmPromise::Exception exception_code,
uint32_t system_code,
const std::string& error_message) final {
CdmPromiseTemplate<T...>::MarkPromiseSettled();
}
};
} // namespace media
#endif // MEDIA_BASE_CDM_PROMISE_H_