blob: 9ab3ff45feab792f790974e79d70a6d01a4cdbe0 [file] [log] [blame]
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <string>
#include "base/basictypes.h"
#include "base/logging.h"
#include "cobalt/media/base/media_export.h"
#include "cobalt/media/base/media_keys.h"
#include "starboard/types.h"
namespace cobalt {
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
// the pepper interface.
class MEDIA_EXPORT CdmPromise {
enum ResolveParameterType {
virtual ~CdmPromise();
// 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(MediaKeys::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;
// For some reason the Windows compiler is not happy with the implementation
// of CdmPromiseTemplate being in the .cc file, so moving it here.
template <typename... T>
struct CdmPromiseTraits {};
template <>
struct CdmPromiseTraits<> {
static const CdmPromise::ResolveParameterType kType = CdmPromise::VOID_TYPE;
template <>
struct CdmPromiseTraits<int> {
static const CdmPromise::ResolveParameterType kType = CdmPromise::INT_TYPE;
template <>
struct CdmPromiseTraits<std::string> {
static const CdmPromise::ResolveParameterType kType = CdmPromise::STRING_TYPE;
// 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 MEDIA_EXPORT CdmPromiseTemplate : public CdmPromise {
CdmPromiseTemplate() : is_settled_(false) {}
virtual ~CdmPromiseTemplate() { DCHECK(is_settled_); }
virtual void resolve(const T&... result) = 0;
// CdmPromise implementation.
virtual void reject(MediaKeys::Exception exception_code, uint32_t system_code,
const std::string& error_message) = 0;
ResolveParameterType GetResolveParameterType() const override {
return CdmPromiseTraits<T...>::kType;
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.
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() {
std::string message =
"Unfulfilled promise rejected automatically during destruction.";
DVLOG(1) << message;
reject(MediaKeys::INVALID_STATE_ERROR, 0, message);
// Keep track of whether the promise has been resolved or rejected yet.
bool is_settled_;
} // namespace media
} // namespace cobalt