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Side by Side Diff: ppapi/c/pp_completion_callback.h

Issue 7241024: Mostly minor changes such as adding <code></code> around elements, a little rewriting, and a few ... (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src/
Patch Set: '' Created 9 years, 5 months ago
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1 /* Copyright (c) 2011 The Chromium Authors. All rights reserved. 1 /* Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 * Use of this source code is governed by a BSD-style license that can be 2 * Use of this source code is governed by a BSD-style license that can be
3 * found in the LICENSE file. 3 * found in the LICENSE file.
4 */ 4 */
5 #ifndef PPAPI_C_PP_COMPLETION_CALLBACK_H_ 5 #ifndef PPAPI_C_PP_COMPLETION_CALLBACK_H_
6 #define PPAPI_C_PP_COMPLETION_CALLBACK_H_ 6 #define PPAPI_C_PP_COMPLETION_CALLBACK_H_
7 7
8 /** 8 /**
9 * @file 9 * @file
10 * This file defines the API to create and run a callback. 10 * This file defines the API to create and run a callback.
11 */ 11 */
12 12
13 #include <stdlib.h> 13 #include <stdlib.h>
14 14
15 #include "ppapi/c/pp_macros.h" 15 #include "ppapi/c/pp_macros.h"
16 #include "ppapi/c/pp_stdint.h" 16 #include "ppapi/c/pp_stdint.h"
17 17
18 /** 18 /**
19 * @addtogroup Typedefs 19 * @addtogroup Typedefs
20 * @{ 20 * @{
21 */ 21 */
22 22
23 /** 23 /**
24 * PP_CompletionCallback_Func defines the signature that you implement to 24 * This typedef defines the signature that you implement to
25 * receive callbacks on asynchronous completion. 25 * receive callbacks on asynchronous completion.
26 *
27 * @param[in] user_data A pointer to user data passed to a callback function.
28 * @param[in] result If result is 0 (PP_OK), the operation succeeded. Negative
29 * values, other than -1, indicate error and are specified in pp_errors.h.
dmichael (off chromium) 2011/06/30 10:03:48 nit: Those commas don't seem necessary to me. Pare
jond 2011/06/30 16:24:16 Done.
jond 2011/06/30 16:24:16 Done.
30 * Positive values for result usually indicate success and have some
31 * operation-dependent meaning (such as bytes read).
26 */ 32 */
27 typedef void (*PP_CompletionCallback_Func)(void* user_data, int32_t result); 33 typedef void (*PP_CompletionCallback_Func)(void* user_data, int32_t result);
28 /** 34 /**
29 * @} 35 * @}
30 */ 36 */
31 37
32 /** 38 /**
33 * @addtogroup Structs 39 * @addtogroup Structs
34 * @{ 40 * @{
35 */ 41 */
36 42
37 /** 43 /**
38 * Any method that takes a PP_CompletionCallback has the option of completing 44 * Any method that takes a <code>PP_CompletionCallback</code> has the option of
39 * asynchronously if the operation would block. Such a method should return 45 * completing asynchronously if the operation would block. Such a method
40 * PP_OK_COMPLETIONPENDING to indicate that the method will complete 46 * should return <code>PP_OK_COMPLETIONPENDING</code> to indicate that the
41 * asynchronously and will always be invoked from the main thread of PPAPI 47 * method will complete asynchronously and will always be invoked from the main
42 * execution. If the completion callback is NULL, then the operation will 48 * thread of PPAPI execution. If the completion callback is NULL, then the
43 * block if necessary to complete its work. PP_BlockUntilComplete() provides a 49 * operation will block if necessary to complete its work.
44 * convenient way to specify blocking behavior. Refer to PP_BlockUntilComplete 50 * <code>PP_BlockUntilComplete()</code> provides a convenient way to specify
45 * for more information. 51 * blocking behavior. Refer to <code>PP_BlockUntilComplete</code> for more
52 * information.
46 * 53 *
47 * The result parameter passes an int32_t that, if negative or equal to 0, 54 * The result parameter passes an int32_t that, if negative or equal to 0,
48 * indicate if the call will completely asynchronously (the callback will be 55 * indicate if the call will complete asynchronously (the callback will be
49 * called with a status code). A value greater than zero indicates additional 56 * called with a status code). A value greater than zero indicates additional
50 * information such as bytes read. 57 * information such as bytes read.
51 */ 58 */
52 struct PP_CompletionCallback { 59 struct PP_CompletionCallback {
60 /**
61 * This value is a callback function that will be called.
62 */
53 PP_CompletionCallback_Func func; 63 PP_CompletionCallback_Func func;
64
65 /**
66 * This value is a pointer to user data passed to a callback function.
67 */
54 void* user_data; 68 void* user_data;
55 }; 69 };
56 /** 70 /**
57 * @} 71 * @}
58 */ 72 */
59 73
60 /** 74 /**
61 * @addtogroup Functions 75 * @addtogroup Functions
62 * @{ 76 * @{
63 */ 77 */
64 78
65 /** 79 /**
66 * PP_MakeCompletionCallback() is used to create a PP_CompletionCallback. 80 * PP_MakeCompletionCallback() is used to create a
81 * <code>PP_CompletionCallback</code>.
67 * 82 *
68 * @param[in] func A PP_CompletionCallback_Func that will be called. 83 * @param[in] func A <code>PP_CompletionCallback_Func</code> that will be
84 * called.
69 * @param[in] user_data A pointer to user data passed to your callback 85 * @param[in] user_data A pointer to user data passed to your callback
70 * function. This is optional and is typically used to help track state 86 * function. This is optional and is typically used to help track state
71 * when you may have multiple callbacks pending. 87 * when you may have multiple callbacks pending.
72 * @return A PP_CompletionCallback structure. 88 * @return A <code>PP_CompletionCallback</code> structure.
73 */ 89 */
74 PP_INLINE struct PP_CompletionCallback PP_MakeCompletionCallback( 90 PP_INLINE struct PP_CompletionCallback PP_MakeCompletionCallback(
75 PP_CompletionCallback_Func func, 91 PP_CompletionCallback_Func func,
76 void* user_data) { 92 void* user_data) {
77 struct PP_CompletionCallback cc; 93 struct PP_CompletionCallback cc;
78 cc.func = func; 94 cc.func = func;
79 cc.user_data = user_data; 95 cc.user_data = user_data;
80 return cc; 96 return cc;
81 } 97 }
82 /** 98 /**
83 * @} 99 * @}
84 */ 100 */
85 101
86 /** 102 /**
87 * @addtogroup Functions 103 * @addtogroup Functions
88 * @{ 104 * @{
89 */ 105 */
90 106
91 /** 107 /**
92 * PP_RunCompletionCallback() is used to run a callback. 108 * PP_RunCompletionCallback() is used to run a callback.
93 * 109 *
94 * @param[in] cc A pointer to a PP_CompletionCallback that will be run. 110 * @param[in] cc A pointer to a <code>PP_CompletionCallback</code> that will be
111 * run.
95 * @param[in] res The result parameter that, if negative or equal to 0, 112 * @param[in] res The result parameter that, if negative or equal to 0,
96 * indicate if the call will completely asynchronously (the callback will be 113 * indicate if the call will completely asynchronously (the callback will be
97 * called with a status code). A value greater than zero indicates additional 114 * called with a status code). A value greater than zero indicates additional
98 * information such as bytes read. 115 * information such as bytes read.
99 */ 116 */
100 PP_INLINE void PP_RunCompletionCallback(struct PP_CompletionCallback* cc, 117 PP_INLINE void PP_RunCompletionCallback(struct PP_CompletionCallback* cc,
101 int32_t res) { 118 int32_t res) {
102 cc->func(cc->user_data, res); 119 cc->func(cc->user_data, res);
103 } 120 }
104 121
105 /** 122 /**
106 * @} 123 * @}
107 */ 124 */
108 125
109 /** 126 /**
110 * @addtogroup Functions 127 * @addtogroup Functions
111 * @{ 128 * @{
112 */ 129 */
113 130
114 /** 131 /**
115 * PP_BlockUntilComplete() is used in place of an actual completion callback 132 * PP_BlockUntilComplete() is used in place of an actual completion callback
116 * to request blocking behavior. If specified, the calling thread will block 133 * to request blocking behavior. If specified, the calling thread will block
117 * until the function completes. Blocking completion callbacks are only usable 134 * until the function completes. Blocking completion callbacks are only usable
118 * from background threads. 135 * from background threads.
119 * 136 *
120 * @return A PP_CompletionCallback structure. 137 * @return A <code>PP_CompletionCallback</code> structure.
121 */ 138 */
122 PP_INLINE struct PP_CompletionCallback PP_BlockUntilComplete() { 139 PP_INLINE struct PP_CompletionCallback PP_BlockUntilComplete() {
123 return PP_MakeCompletionCallback(NULL, NULL); 140 return PP_MakeCompletionCallback(NULL, NULL);
124 } 141 }
125 142
126 /** 143 /**
127 * Runs a callback and clears the reference to it. 144 * PP_RunAndClearCompletionCallback() runs a callback and clears the reference
145 * to that callback.
128 * 146 *
129 * This is used when the null-ness of a completion callback is used as a signal 147 * This function is used when the null-ness of a completion callback is used as
130 * for whether a completion callback has been registered. In this case, after 148 * a signal for whether a completion callback has been registered. In this
131 * the execution of the callback, it should be cleared. 149 * case, after the execution of the callback, it should be cleared. However,
132 * 150 * this introduces a conflict if the completion callback wants to schedule more
133 * However, this introduces a conflict if the completion callback wants to 151 * work that involves the same completion callback again (for example, when
134 * schedule more work that involves the same completion callback again (for 152 * reading data from an URLLoader, one would typically queue up
135 * example, when reading data from an URLLoader, one would typically queue up
136 * another read callback). As a result, this function clears the pointer 153 * another read callback). As a result, this function clears the pointer
137 * *before* the given callback is executed. 154 * before the provided callback is executed.
138 */ 155 */
139 PP_INLINE void PP_RunAndClearCompletionCallback( 156 PP_INLINE void PP_RunAndClearCompletionCallback(
140 struct PP_CompletionCallback* cc, 157 struct PP_CompletionCallback* cc,
141 int32_t res) { 158 int32_t res) {
142 struct PP_CompletionCallback temp = *cc; 159 struct PP_CompletionCallback temp = *cc;
143 *cc = PP_BlockUntilComplete(); 160 *cc = PP_BlockUntilComplete();
144 PP_RunCompletionCallback(&temp, res); 161 PP_RunCompletionCallback(&temp, res);
145 } 162 }
146 /** 163 /**
147 * @} 164 * @}
148 */ 165 */
149 166
150 #endif /* PPAPI_C_PP_COMPLETION_CALLBACK_H_ */ 167 #endif /* PPAPI_C_PP_COMPLETION_CALLBACK_H_ */
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