mojo/public/c/system/time.h

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file contains Mojo system time-related declarations/definitions.
//
// Note: This header should be compilable as C.

#ifndef MOJO_PUBLIC_C_SYSTEM_TIME_H_
#define MOJO_PUBLIC_C_SYSTEM_TIME_H_

#include <stdint.h>

// |MojoTimeTicks|: A time delta, in microseconds, the meaning of which is
// source-dependent.

typedef int64_t MojoTimeTicks;

// |MojoDeadline|: Used to specify deadlines (timeouts), in microseconds (except
// for |MOJO_DEADLINE_INDEFINITE|).
//   |MOJO_DEADLINE_INDEFINITE| - Used to indicate "forever".

typedef uint64_t MojoDeadline;

#define MOJO_DEADLINE_INDEFINITE ((MojoDeadline)-1)

#ifdef __cplusplus
extern "C" {
#endif

// Note: Pointer parameters that are labelled "optional" may be null (at least
// under some circumstances). Non-const pointer parameters are also labeled
// "in", "out", or "in/out", to indicate how they are used. (Note that how/if
// such a parameter is used may depend on other parameters or the requested
// operation's success/failure. E.g., a separate |flags| parameter may control
// whether a given "in/out" parameter is used for input, output, or both.)

// Returns the time, in microseconds, since some undefined point in the past.
// The values are only meaningful relative to other values that were obtained
// from the same device without an intervening system restart. Such values are
// guaranteed to be monotonically non-decreasing with the passage of real time.
// Although the units are microseconds, the resolution of the clock may vary and
// is typically in the range of ~1-15 ms.
MojoTimeTicks MojoGetTimeTicksNow(void);

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // MOJO_PUBLIC_C_SYSTEM_TIME_H_