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| 1 // Copyright 2017 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 MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_ |
| 6 #define MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_ |
| 7 |
| 8 #include <stddef.h> |
| 9 |
| 10 #include "mojo/public/c/system/types.h" |
| 11 #include "mojo/public/cpp/system/handle.h" |
| 12 #include "mojo/public/cpp/system/system_export.h" |
| 13 |
| 14 namespace mojo { |
| 15 |
| 16 // Blocks the calling thread, waiting for one or more signals in |signals| to be |
| 17 // become satisfied -- or for all of them to become unsatisfiable -- on the |
| 18 // given Handle. |
| 19 // |
| 20 // If |signals_state| is non-null, |handle| is valid, the wait is not cancelled |
| 21 // (see return values below), the last known signaling state of |handle| is |
| 22 // written to |*signals_state| before returning. |
| 23 // |
| 24 // Return values: |
| 25 // |MOJO_RESULT_OK| if one or more signals in |signals| has been raised on |
| 26 // |handle| . |
| 27 // |MOJO_RESULT_FAILED_PRECONDITION| if the state of |handle| changes such |
| 28 // that no signals in |signals| can ever be raised again. |
| 29 // |MOJO_RESULT_INVALID_ARGUMENT| if |handle| is not a valid handle. |
| 30 // |MOJO_RESULT_CANCELLED| if the wait was cancelled because |handle| was |
| 31 // closed by some other thread while waiting. |
| 32 MOJO_CPP_SYSTEM_EXPORT MojoResult |
| 33 Wait(Handle handle, |
| 34 MojoHandleSignals signals, |
| 35 MojoHandleSignalsState* signals_state = nullptr); |
| 36 |
| 37 // Waits on |handles[0]|, ..., |handles[num_handles-1]| until: |
| 38 // - At least one handle satisfies a signal indicated in its respective |
| 39 // |signals[0]|, ..., |signals[num_handles-1]|. |
| 40 // - It becomes known that no signal in some |signals[i]| will ever be |
| 41 // satisfied. |
| 42 // |
| 43 // This means that |WaitMany()| behaves as if |Wait()| were called on each |
| 44 // handle/signals pair simultaneously, completing when the first |Wait()| would |
| 45 // complete. |
| 46 // |
| 47 // If |signals_states| is non-null, all other arguments are valid, and the wait |
| 48 // is not cancelled (see return values below), the last known signaling state of |
| 49 // each Handle |handles[i]| is written to its corresponding entry in |
| 50 // |signals_states[i]| before returning. |
| 51 // |
| 52 // Returns values: |
| 53 // |MOJO_RESULT_OK| if one of the Handles in |handles| had one or more of its |
| 54 // correpsonding signals satisfied. |*result_index| contains the index |
| 55 // of the Handle in question if |result_index| is non-null. |
| 56 // |MOJO_RESULT_FAILED_PRECONDITION| if one of the Handles in |handles| |
| 57 // changes state such that its corresponding signals become permanently |
| 58 // unsatisfiable. |*result_index| contains the index of the handle in |
| 59 // question if |result_index| is non-null. |
| 60 // |MOJO_RESULT_INVALID_ARGUMENT| if any Handle in |handles| is invalid, |
| 61 // or if either |handles| or |signals| is null. |
| 62 // |MOJO_RESULT_CANCELLED| if the wait was cancelled because a handle in |
| 63 // |handles| was closed by some other thread while waiting. |
| 64 // |*result_index| contains the index of the closed Handle if |
| 65 // |result_index| is non-null. |
| 66 MOJO_CPP_SYSTEM_EXPORT MojoResult |
| 67 WaitMany(const Handle* handles, |
| 68 const MojoHandleSignals* signals, |
| 69 size_t num_handles, |
| 70 size_t* result_index = nullptr, |
| 71 MojoHandleSignalsState* signals_states = nullptr); |
| 72 |
| 73 } // namespace mojo |
| 74 |
| 75 #endif // MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_ |
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