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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
3 // found in the LICENSE file.
4 
5 // This file contains basic functions common to different Mojo system APIs.
6 //
7 // Note: This header should be compilable as C.
8 
9 #ifndef MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_
10 #define MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_
11 
12 #include <stddef.h>
13 #include <stdint.h>
14 
15 #include "mojo/public/c/system/system_export.h"
16 #include "mojo/public/c/system/types.h"
17 
18 #ifdef __cplusplus
19 extern "C" {
20 #endif
21 
22 // Initializes Mojo in the calling application.
23 //
24 // With the exception of Mojo Core embedders, applications using Mojo APIs must
25 // call this function before any others.
26 //
27 // |options| may be null.
28 //
29 // Returns:
30 //   |MOJO_RESULT_OK| if Mojo intiailization was successful.
31 //   |MOJO_RESULT_INVALID_ARGUMENT| if |options| was null or invalid.
32 //   |MOJO_RESULT_FAILED_PRECONDITION| if |MojoInitialize()| was already called
33 //       once or if the application already explicitly initialized a Mojo Core
34 //       environment as an embedder.
35 MOJO_SYSTEM_EXPORT MojoResult
36 MojoInitialize(const struct MojoInitializeOptions* options);
37 
38 // Returns the time, in microseconds, since some undefined point in the past.
39 // The values are only meaningful relative to other values that were obtained
40 // from the same device without an intervening system restart. Such values are
41 // guaranteed to be monotonically non-decreasing with the passage of real time.
42 // Although the units are microseconds, the resolution of the clock may vary and
43 // is typically in the range of ~1-15 ms.
44 MOJO_SYSTEM_EXPORT MojoTimeTicks MojoGetTimeTicksNow(void);
45 
46 // Closes the given |handle|.
47 //
48 // Returns:
49 //   |MOJO_RESULT_OK| on success.
50 //   |MOJO_RESULT_INVALID_ARGUMENT| if |handle| is not a valid handle.
51 //
52 // Concurrent operations on |handle| may succeed (or fail as usual) if they
53 // happen before the close, be cancelled with result |MOJO_RESULT_CANCELLED| if
54 // they properly overlap (this is likely the case with traps), or fail with
55 // |MOJO_RESULT_INVALID_ARGUMENT| if they happen after.
56 MOJO_SYSTEM_EXPORT MojoResult MojoClose(MojoHandle handle);
57 
58 // Queries the last known signals state of a handle.
59 //
60 // Note that no guarantees can be made about the accuracy of the returned
61 // signals state by the time this returns, as other threads in the system may
62 // change the handle's state at any time. Use with appropriate discretion.
63 //
64 // Returns:
65 //   |MOJO_RESULT_OK| on success. |*signals_state| is populated with the
66 //       last known signals state of |handle|.
67 //   |MOJO_RESULT_INVALID_ARGUMENT| if |handle| is not a valid handle or
68 //       |signals_state| is null.
69 MOJO_SYSTEM_EXPORT MojoResult
70 MojoQueryHandleSignalsState(MojoHandle handle,
71                             struct MojoHandleSignalsState* signals_state);
72 
73 #ifdef __cplusplus
74 }  // extern "C"
75 #endif
76 
77 #endif  // MOJO_PUBLIC_C_SYSTEM_FUNCTIONS_H_
78