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90 lines
4.0 KiB
90 lines
4.0 KiB
// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_
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#define MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_
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#include <stddef.h>
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#include "mojo/public/c/system/trap.h"
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#include "mojo/public/c/system/types.h"
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#include "mojo/public/cpp/system/handle.h"
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#include "mojo/public/cpp/system/system_export.h"
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namespace mojo {
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// Blocks the calling sequence, waiting for one or more signals in |signals| to
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// be become satisfied, not-satisfied, or permanently unsatisfiable on the
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// handle, depending on the |condition| selected.
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//
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// If |signals_state| is non-null, |handle| is valid, the wait is not cancelled
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// (see return values below), the last known signaling state of |handle| is
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// written to |*signals_state| before returning.
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//
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// Return values:
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// |MOJO_RESULT_OK| if one or more signals in |signals| has been raised on
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// |handle| with |condition| set to |MOJO_WATCH_CONDITION_SATISFIED|, or
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// one or more signals in |signals| has been lowered on |handle| with
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// |condition| set to |MOJO_WATCH_CONDITION_NOT_SATISFIED|.
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// |MOJO_RESULT_FAILED_PRECONDITION| if the state of |handle| changes such
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// that no signals in |signals| can ever be raised again and |condition|
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// is |MOJO_WATCH_CONDITION_SATISFIED|.
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// |MOJO_RESULT_INVALID_ARGUMENT| if |handle| is not a valid handle.
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// |MOJO_RESULT_CANCELLED| if the wait was cancelled because |handle| was
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// closed by some other sequence while waiting.
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MOJO_CPP_SYSTEM_EXPORT MojoResult
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Wait(Handle handle,
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MojoHandleSignals signals,
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MojoTriggerCondition condition,
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MojoHandleSignalsState* signals_state = nullptr);
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// A pseudonym for the above Wait() which always waits on
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// |MOJO_TRIGGER_CONDITION_SIGNALS_SATISFIED|.
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inline MojoResult Wait(Handle handle,
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MojoHandleSignals signals,
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MojoHandleSignalsState* signals_state = nullptr) {
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return Wait(handle, signals, MOJO_TRIGGER_CONDITION_SIGNALS_SATISFIED,
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signals_state);
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}
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// Waits on |handles[0]|, ..., |handles[num_handles-1]| until:
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// - At least one handle satisfies a signal indicated in its respective
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// |signals[0]|, ..., |signals[num_handles-1]|.
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// - It becomes known that no signal in some |signals[i]| will ever be
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// satisfied.
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//
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// This means that |WaitMany()| behaves as if |Wait()| were called on each
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// handle/signals pair simultaneously, completing when the first |Wait()| would
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// complete.
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//
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// If |signals_states| is non-null, all other arguments are valid, and the wait
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// is not cancelled (see return values below), the last known signaling state of
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// each Handle |handles[i]| is written to its corresponding entry in
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// |signals_states[i]| before returning.
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//
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// Returns values:
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// |MOJO_RESULT_OK| if one of the Handles in |handles| had one or more of its
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// correpsonding signals satisfied. |*result_index| contains the index
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// of the Handle in question if |result_index| is non-null.
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// |MOJO_RESULT_FAILED_PRECONDITION| if one of the Handles in |handles|
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// changes state such that its corresponding signals become permanently
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// unsatisfiable. |*result_index| contains the index of the handle in
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// question if |result_index| is non-null.
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// |MOJO_RESULT_INVALID_ARGUMENT| if any Handle in |handles| is invalid,
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// or if either |handles| or |signals| is null.
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// |MOJO_RESULT_CANCELLED| if the wait was cancelled because a handle in
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// |handles| was closed by some other sequence while waiting.
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// |*result_index| contains the index of the closed Handle if
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// |result_index| is non-null.
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MOJO_CPP_SYSTEM_EXPORT MojoResult
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WaitMany(const Handle* handles,
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const MojoHandleSignals* signals,
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size_t num_handles,
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size_t* result_index = nullptr,
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MojoHandleSignalsState* signals_states = nullptr);
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} // namespace mojo
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#endif // MOJO_PUBLIC_CPP_SYSTEM_WAIT_H_
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