include/grpc/impl/codegen/time.h

/*
 *
 * Copyright 2015-2016, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef GRPC_IMPL_CODEGEN_TIME_H
#define GRPC_IMPL_CODEGEN_TIME_H
/* Time support.
   We use gpr_timespec, which is analogous to struct timespec.  On some
   machines, absolute times may be in local time.  */

#include <grpc/impl/codegen/port_platform.h>
#include <stddef.h>
#include <time.h>

#ifdef __cplusplus
extern "C" {
#endif

/* The clocks we support. */
typedef enum {
  /* Monotonic clock. Epoch undefined. Always moves forwards. */
  GPR_CLOCK_MONOTONIC = 0,
  /* Realtime clock. May jump forwards or backwards. Settable by
     the system administrator. Has its epoch at 0:00:00 UTC 1 Jan 1970. */
  GPR_CLOCK_REALTIME,
  /* CPU cycle time obtained by rdtsc instruction on x86 platforms. Epoch
     undefined. Degrades to GPR_CLOCK_REALTIME on other platforms. */
  GPR_CLOCK_PRECISE,
  /* Unmeasurable clock type: no base, created by taking the difference
     between two times */
  GPR_TIMESPAN
} gpr_clock_type;

typedef struct gpr_timespec {
  int64_t tv_sec;
  int32_t tv_nsec;
  /** Against which clock was this time measured? (or GPR_TIMESPAN if
      this is a relative time meaure) */
  gpr_clock_type clock_type;
} gpr_timespec;

/* Time constants. */
GPR_API gpr_timespec gpr_time_0(gpr_clock_type type);     /* The zero time interval. */
GPR_API gpr_timespec gpr_inf_future(gpr_clock_type type); /* The far future */
GPR_API gpr_timespec gpr_inf_past(gpr_clock_type type);   /* The far past. */

#define GPR_MS_PER_SEC 1000
#define GPR_US_PER_SEC 1000000
#define GPR_NS_PER_SEC 1000000000
#define GPR_NS_PER_MS 1000000
#define GPR_NS_PER_US 1000
#define GPR_US_PER_MS 1000

/* initialize time subsystem */
GPR_API void gpr_time_init(void);

/* Return the current time measured from the given clocks epoch. */
GPR_API gpr_timespec gpr_now(gpr_clock_type clock);

/* Convert a timespec from one clock to another */
GPR_API gpr_timespec gpr_convert_clock_type(gpr_timespec t,
                                    gpr_clock_type target_clock);

/* Return -ve, 0, or +ve according to whether a < b, a == b, or a > b
   respectively.  */
GPR_API int gpr_time_cmp(gpr_timespec a, gpr_timespec b);

GPR_API gpr_timespec gpr_time_max(gpr_timespec a, gpr_timespec b);
GPR_API gpr_timespec gpr_time_min(gpr_timespec a, gpr_timespec b);

/* Add and subtract times.  Calculations saturate at infinities. */
GPR_API gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b);
GPR_API gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b);

/* Return a timespec representing a given number of time units. LONG_MIN is
   interpreted as gpr_inf_past, and LONG_MAX as gpr_inf_future.  */
GPR_API gpr_timespec gpr_time_from_micros(long x, gpr_clock_type clock_type);
GPR_API gpr_timespec gpr_time_from_nanos(long x, gpr_clock_type clock_type);
GPR_API gpr_timespec gpr_time_from_millis(long x, gpr_clock_type clock_type);
GPR_API gpr_timespec gpr_time_from_seconds(long x, gpr_clock_type clock_type);
GPR_API gpr_timespec gpr_time_from_minutes(long x, gpr_clock_type clock_type);
GPR_API gpr_timespec gpr_time_from_hours(long x, gpr_clock_type clock_type);

GPR_API int32_t gpr_time_to_millis(gpr_timespec timespec);

/* Return 1 if two times are equal or within threshold of each other,
   0 otherwise */
GPR_API int gpr_time_similar(gpr_timespec a, gpr_timespec b, gpr_timespec threshold);

/* Sleep until at least 'until' - an absolute timeout */
GPR_API void gpr_sleep_until(gpr_timespec until);

GPR_API double gpr_timespec_to_micros(gpr_timespec t);

#ifdef __cplusplus
}
#endif

#endif /* GRPC_IMPL_CODEGEN_TIME_H */