OLD | NEW |
1 // Copyright 2014 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 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 // This file contains basic functions common to different Mojo system APIs. | 5 // This file contains basic functions common to different Mojo system APIs. |
6 // | 6 // |
7 // Note: This header should be compilable as C. | 7 // Note: This header should be compilable as C. |
8 | 8 |
9 #ifndef MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ | 9 #ifndef MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ |
10 #define MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ | 10 #define MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ |
11 | 11 |
| 12 #include <stddef.h> |
12 #include <stdint.h> | 13 #include <stdint.h> |
13 | 14 |
14 #include "mojo/public/c/system/system_export.h" | 15 #include "mojo/public/c/system/system_export.h" |
15 #include "mojo/public/c/system/types.h" | 16 #include "mojo/public/c/system/types.h" |
16 | 17 |
17 #ifdef __cplusplus | 18 #ifdef __cplusplus |
18 extern "C" { | 19 extern "C" { |
19 #endif | 20 #endif |
20 | 21 |
| 22 // A callback used to notify watchers registered via |MojoWatch()|. Called when |
| 23 // some watched signals are satisfied or become unsatisfiable. See the |
| 24 // documentation for |MojoWatch()| for more details. |
| 25 typedef void (*MojoWatchCallback)(uintptr_t context, |
| 26 MojoResult result, |
| 27 struct MojoHandleSignalsState signals_state); |
| 28 |
21 // Note: Pointer parameters that are labelled "optional" may be null (at least | 29 // Note: Pointer parameters that are labelled "optional" may be null (at least |
22 // under some circumstances). Non-const pointer parameters are also labeled | 30 // under some circumstances). Non-const pointer parameters are also labeled |
23 // "in", "out", or "in/out", to indicate how they are used. (Note that how/if | 31 // "in", "out", or "in/out", to indicate how they are used. (Note that how/if |
24 // such a parameter is used may depend on other parameters or the requested | 32 // such a parameter is used may depend on other parameters or the requested |
25 // operation's success/failure. E.g., a separate |flags| parameter may control | 33 // operation's success/failure. E.g., a separate |flags| parameter may control |
26 // whether a given "in/out" parameter is used for input, output, or both.) | 34 // whether a given "in/out" parameter is used for input, output, or both.) |
27 | 35 |
28 // Returns the time, in microseconds, since some undefined point in the past. | 36 // Returns the time, in microseconds, since some undefined point in the past. |
29 // The values are only meaningful relative to other values that were obtained | 37 // The values are only meaningful relative to other values that were obtained |
30 // from the same device without an intervening system restart. Such values are | 38 // from the same device without an intervening system restart. Such values are |
(...skipping 91 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
122 // |MOJO_RESULT_FAILED_PRECONDITION| if it is or becomes impossible that SOME | 130 // |MOJO_RESULT_FAILED_PRECONDITION| if it is or becomes impossible that SOME |
123 // |handle[i]| will ever satisfy any of the signals in |signals[i]|. | 131 // |handle[i]| will ever satisfy any of the signals in |signals[i]|. |
124 MOJO_SYSTEM_EXPORT MojoResult | 132 MOJO_SYSTEM_EXPORT MojoResult |
125 MojoWaitMany(const MojoHandle* handles, | 133 MojoWaitMany(const MojoHandle* handles, |
126 const MojoHandleSignals* signals, | 134 const MojoHandleSignals* signals, |
127 uint32_t num_handles, | 135 uint32_t num_handles, |
128 MojoDeadline deadline, | 136 MojoDeadline deadline, |
129 uint32_t* result_index, // Optional out | 137 uint32_t* result_index, // Optional out |
130 struct MojoHandleSignalsState* signals_states); // Optional out | 138 struct MojoHandleSignalsState* signals_states); // Optional out |
131 | 139 |
| 140 // Watches the given handle for one of the following events to happen: |
| 141 // - A signal indicated by |signals| is satisfied. |
| 142 // - It becomes known that no signal indicated by |signals| will ever be |
| 143 // satisfied. (See the description of the |MOJO_RESULT_CANCELLED| and |
| 144 // |MOJO_RESULT_FAILED_PRECONDITION| return values below.) |
| 145 // - The handle is closed. |
| 146 // |
| 147 // |handle|: The handle to watch. Must be an open message pipe or data pipe |
| 148 // handle. |
| 149 // |signals|: The signals to watch for. |
| 150 // |callback|: A function to be called any time one of the above events happens. |
| 151 // The function must be safe to call from any thread at any time. |
| 152 // |context|: User-provided context passed to |callback| when called. |context| |
| 153 // is used to uniquely identify a registered watch and can be used to cancel |
| 154 // the watch later using |MojoCancelWatch()|. |
| 155 // |
| 156 // Returns: |
| 157 // |MOJO_RESULT_OK| if the watch has been successfully registered. Note that |
| 158 // if the signals are already satisfied this may synchronously invoke |
| 159 // |callback| before returning. |
| 160 // |MOJO_RESULT_CANCELLED| if the watch was cancelled. In this case it is not |
| 161 // necessary to explicitly call |MojoCancelWatch()|, and in fact it may be |
| 162 // an error to do so as the handle may have been closed. |
| 163 // |MOJO_RESULT_INVALID_ARGUMENT| if |handle| is not an open message pipe |
| 164 // handle. |
| 165 // |MOJO_RESULT_FAILED_PRECONDITION| if it is already known that |signals| can |
| 166 // never be satisfied. |
| 167 // |MOJO_RESULT_ALREADY_EXISTS| if there is already a watch registered for |
| 168 // the same combination of |handle| and |context|. |
| 169 // |
| 170 // Callback result codes: |
| 171 // The callback may be called at any time on any thread with one of the |
| 172 // following result codes to indicate various events: |
| 173 // |
| 174 // |MOJO_RESULT_OK| indicates that some signal in |signals| has been |
| 175 // satisfied. |
| 176 // |MOJO_RESULT_FAILED_PRECONDITION| indicates that no signals in |signals| |
| 177 // can ever be satisfied again. |
| 178 // |MOJO_RESULT_CANCELLED| indicates that the handle has been closed. In this |
| 179 // case the watch is implicitly cancelled and there is no need to call |
| 180 // |MojoCancelWatch()|. |
| 181 MOJO_SYSTEM_EXPORT MojoResult |
| 182 MojoWatch(MojoHandle handle, |
| 183 MojoHandleSignals signals, |
| 184 MojoWatchCallback callback, |
| 185 uintptr_t context); |
| 186 |
| 187 // Cancels a handle watch corresponding to some prior call to |MojoWatch()|. |
| 188 // |
| 189 // NOTE: If the watch callback corresponding to |context| is currently running |
| 190 // this will block until the callback completes execution. It is therefore |
| 191 // illegal to call |MojoCancelWatch()| on a given |handle| and |context| from |
| 192 // within the associated callback itself, as this will always deadlock. |
| 193 // |
| 194 // After |MojoCancelWatch()| function returns, the watch's associated callback |
| 195 // will NEVER be called again by Mojo. |
| 196 // |
| 197 // |context|: The same user-provided context given to some prior call to |
| 198 // |MojoWatch()|. Only the watch corresponding to this context will be |
| 199 // cancelled. |
| 200 // |
| 201 // Returns: |
| 202 // |MOJO_RESULT_OK| if the watch corresponding to |context| was cancelled. |
| 203 // |MOJO_RESULT_INVALID_ARGUMENT| if no watch was registered with |context| |
| 204 // for the given |handle|, or if |handle| is invalid. |
| 205 MOJO_SYSTEM_EXPORT MojoResult |
| 206 MojoCancelWatch(MojoHandle handle, uintptr_t context); |
| 207 |
132 #ifdef __cplusplus | 208 #ifdef __cplusplus |
133 } // extern "C" | 209 } // extern "C" |
134 #endif | 210 #endif |
135 | 211 |
136 #endif // MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ | 212 #endif // MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_ |
OLD | NEW |