Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 1 | // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_ |
| 6 | #define PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_ |
| 7 | |
| 8 | #include <map> |
| 9 | #include <set> |
| 10 | |
| 11 | #include "base/basictypes.h" |
| 12 | #include "base/memory/ref_counted.h" |
| 13 | #include "base/memory/scoped_ptr.h" |
| 14 | #include "base/synchronization/condition_variable.h" |
| 15 | #include "ppapi/c/pp_completion_callback.h" |
| 16 | #include "ppapi/c/pp_instance.h" |
| 17 | #include "ppapi/c/pp_resource.h" |
| 18 | #include "ppapi/shared_impl/ppapi_shared_export.h" |
| 19 | #include "ppapi/shared_impl/ppb_message_loop_shared.h" |
| 20 | |
| 21 | namespace ppapi { |
| 22 | |
| 23 | class CallbackTracker; |
| 24 | class MessageLoopShared; |
| 25 | class Resource; |
| 26 | |
| 27 | namespace thunk { |
| 28 | namespace subtle { |
| 29 | // For a friend declaration below. |
| 30 | class EnterBase; |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | // |TrackedCallback| represents a tracked Pepper callback (from the browser to |
| 35 | // the plugin), typically still pending. Such callbacks have the standard Pepper |
| 36 | // callback semantics. Execution (i.e., completion) of callbacks happens through |
| 37 | // objects of subclasses of |TrackedCallback|. Two things are ensured: (1) that |
| 38 | // the callback is executed at most once, and (2) once a callback is marked to |
| 39 | // be aborted, any subsequent completion is abortive (even if a non-abortive |
| 40 | // completion had previously been scheduled). |
| 41 | // |
| 42 | // The details of non-abortive completion depend on the type of callback (e.g., |
| 43 | // different parameters may be required), but basic abort functionality is core. |
| 44 | // The ability to post aborts is needed in many situations to ensure that the |
| 45 | // plugin is not re-entered into. (Note that posting a task to just run |
| 46 | // |Abort()| is different and not correct; calling |PostAbort()| additionally |
| 47 | // guarantees that all subsequent completions will be abortive.) |
| 48 | // |
| 49 | // This class is reference counted so that different things can hang on to it, |
| 50 | // and not worry too much about ensuring Pepper callback semantics. Note that |
| 51 | // the "owning" |CallbackTracker| will keep a reference until the callback is |
| 52 | // completed. |
| 53 | // |
| 54 | // Subclasses must do several things: |
| 55 | // - They must ensure that the callback is executed at most once (by looking at |
| 56 | // |completed()| before running the callback). |
| 57 | // - They must ensure that the callback is run abortively if it is marked as to |
| 58 | // be aborted (by looking at |aborted()| before running the callback). |
| 59 | // - They must call |MarkAsCompleted()| immediately before actually running the |
| 60 | // callback; see the comment for |MarkAsCompleted()| for a caveat. |
| 61 | class PPAPI_SHARED_EXPORT TrackedCallback |
| 62 | : public base::RefCountedThreadSafe<TrackedCallback> { |
| 63 | public: |
| 64 | // Create a tracked completion callback and register it with the tracker. The |
| 65 | // resource pointer is not stored. If |resource| is NULL, this callback will |
| 66 | // not be added to the callback tracker. |
| 67 | TrackedCallback(Resource* resource, const PP_CompletionCallback& callback); |
| 68 | |
| 69 | // These run the callback in an abortive manner, or post a task to do so (but |
| 70 | // immediately marking the callback as to be aborted). |
| 71 | void Abort(); |
| 72 | void PostAbort(); |
| 73 | |
| 74 | // Run the callback with the given result. If the callback had previously been |
| 75 | // marked as to be aborted (by |PostAbort()|), |result| will be ignored and |
| 76 | // the callback will be run with result |PP_ERROR_ABORTED|. |
| 77 | // |
| 78 | // Run() will invoke the call immediately, if invoked from the target thread |
| 79 | // (as determined by target_loop_). If invoked on a different thread, the |
| 80 | // callback will be scheduled to run later on target_loop_. |
| 81 | void Run(int32_t result); |
| 82 | // PostRun is like Run(), except it guarantees that the callback will be run |
| 83 | // later. In particular, if you invoke PostRun on the same thread on which the |
| 84 | // callback is targeted to run, it will *not* be run immediately. |
| 85 | void PostRun(int32_t result); |
| 86 | |
| 87 | void BlockUntilRun(); |
| 88 | |
| 89 | // Returns the ID of the resource which "owns" the callback, or 0 if the |
| 90 | // callback is not associated with any resource. |
| 91 | PP_Resource resource_id() const { return resource_id_; } |
| 92 | |
| 93 | // Returns true if the callback was completed (possibly aborted). |
| 94 | bool completed() const { return completed_; } |
| 95 | |
| 96 | // Returns true if the callback was or should be aborted; this will be the |
| 97 | // case whenever |Abort()| or |PostAbort()| is called before a non-abortive |
| 98 | // completion. |
| 99 | bool aborted() const { return aborted_; } |
| 100 | |
Ben Murdoch | bb1529c | 2013-08-08 10:24:53 +0100 | [diff] [blame^] | 101 | // Returns true if this is a blocking callback. |
| 102 | bool is_blocking() { |
| 103 | return !callback_.func; |
| 104 | } |
| 105 | |
Ben Murdoch | fb25065 | 2013-07-31 11:42:55 +0100 | [diff] [blame] | 106 | // Determines if the given callback is pending. A callback is pending if it |
| 107 | // has not completed and has not been aborted. When receiving a plugin call, |
| 108 | // use this to detect if |callback| represents an operation in progress. When |
| 109 | // finishing a plugin call, use this to determine whether to write 'out' |
| 110 | // params and Run |callback|. |
| 111 | // NOTE: an aborted callback has not necessarily completed, so a false result |
| 112 | // doesn't imply that the callback has completed. |
| 113 | // As a convenience, if |callback| is null, this returns false. |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 114 | static bool IsPending(const scoped_refptr<TrackedCallback>& callback); |
| 115 | |
Ben Murdoch | 558790d | 2013-07-30 15:19:42 +0100 | [diff] [blame] | 116 | // Helper to determine if the given callback is scheduled to run on another |
| 117 | // message loop. |
| 118 | static bool IsScheduledToRun(const scoped_refptr<TrackedCallback>& callback); |
| 119 | |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 120 | protected: |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 121 | bool is_required() { |
| 122 | return (callback_.func && |
| 123 | !(callback_.flags & PP_COMPLETIONCALLBACK_FLAG_OPTIONAL)); |
| 124 | } |
| 125 | bool is_optional() { |
| 126 | return (callback_.func && |
| 127 | (callback_.flags & PP_COMPLETIONCALLBACK_FLAG_OPTIONAL)); |
| 128 | } |
Torne (Richard Coles) | 868fa2f | 2013-06-11 10:57:03 +0100 | [diff] [blame] | 129 | bool has_null_target_loop() const { return target_loop_.get() == NULL; } |
Torne (Richard Coles) | 5821806 | 2012-11-14 11:43:16 +0000 | [diff] [blame] | 130 | |
| 131 | private: |
| 132 | // TrackedCallback and EnterBase manage dealing with how to invoke callbacks |
| 133 | // appropriately. Pepper interface implementations and proxies should not have |
| 134 | // to check the type of callback, block, or mark them complete explicitly. |
| 135 | friend class ppapi::thunk::subtle::EnterBase; |
| 136 | |
| 137 | // Block until the associated operation has completed. Returns the result. |
| 138 | // This must only be called on a non-main thread on a blocking callback. |
| 139 | int32_t BlockUntilComplete(); |
| 140 | |
| 141 | // Mark this object as complete and remove it from the tracker. This must only |
| 142 | // be called once. Note that running this may result in this object being |
| 143 | // deleted (so keep a reference if it'll still be needed). |
| 144 | void MarkAsCompleted(); |
| 145 | |
| 146 | // This class is ref counted. |
| 147 | friend class base::RefCountedThreadSafe<TrackedCallback>; |
| 148 | virtual ~TrackedCallback(); |
| 149 | |
| 150 | // Flag used by |PostAbort()| and |PostRun()| to check that we don't schedule |
| 151 | // the callback more than once. |
| 152 | bool is_scheduled_; |
| 153 | |
| 154 | scoped_refptr<CallbackTracker> tracker_; |
| 155 | PP_Resource resource_id_; |
| 156 | bool completed_; |
| 157 | bool aborted_; |
| 158 | PP_CompletionCallback callback_; |
| 159 | |
| 160 | // The MessageLoopShared on which this callback should be run. This will be |
| 161 | // NULL if we're in-process. |
| 162 | scoped_refptr<MessageLoopShared> target_loop_; |
| 163 | |
| 164 | int32_t result_for_blocked_callback_; |
| 165 | // Used for pausing/waking the blocked thread if this is a blocking completion |
| 166 | // callback. Note that in-process, there is no lock, blocking callbacks are |
| 167 | // not allowed, and therefore this pointer will be NULL. |
| 168 | scoped_ptr<base::ConditionVariable> operation_completed_condvar_; |
| 169 | |
| 170 | DISALLOW_IMPLICIT_CONSTRUCTORS(TrackedCallback); |
| 171 | }; |
| 172 | |
| 173 | } // namespace ppapi |
| 174 | |
| 175 | #endif // PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_ |