100 lines
3.6 KiB
C
100 lines
3.6 KiB
C
// calogTime.c -- calog time library (see calogTime.h). Three stateless natives over the
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// POSIX clocks: a wall-clock read, a monotonic read, and a millisecond sleep. No shared
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// state and no timers/threads -- each native is a pure function of its arguments (or a
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// plain block of the calling context thread).
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#define _POSIX_C_SOURCE 200809L
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#include "calogTime.h"
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#include <errno.h>
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#include <time.h>
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// Conversion factors shared by timeSleepNative and timeToSeconds.
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#define TIME_NS_PER_MS 1000000.0
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#define TIME_NS_PER_SEC 1000000000
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static int32_t timeMonotonicNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
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static int32_t timeNowNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
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static int32_t timeSleepNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData);
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static double timeToSeconds(const struct timespec *ts);
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int32_t calogTimeRegister(CalogT *calog) {
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calogRegisterInline(calog, "timeNow", timeNowNative, NULL);
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calogRegisterInline(calog, "timeMonotonic", timeMonotonicNative, NULL);
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calogRegisterInline(calog, "timeSleep", timeSleepNative, NULL);
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return calogOkE;
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}
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static int32_t timeMonotonicNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
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struct timespec ts;
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(void)args;
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(void)userData;
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calogValueNil(result);
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if (argCount != 0) {
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return calogFail(result, calogErrArgE, "timeMonotonic expects ()");
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}
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if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0) {
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return calogFail(result, calogErrUnsupportedE, "timeMonotonic: clock_gettime failed");
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}
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calogValueReal(result, timeToSeconds(&ts));
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return calogOkE;
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}
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static int32_t timeNowNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
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struct timespec ts;
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(void)args;
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(void)userData;
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calogValueNil(result);
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if (argCount != 0) {
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return calogFail(result, calogErrArgE, "timeNow expects ()");
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}
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if (clock_gettime(CLOCK_REALTIME, &ts) != 0) {
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return calogFail(result, calogErrUnsupportedE, "timeNow: clock_gettime failed");
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}
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calogValueReal(result, timeToSeconds(&ts));
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return calogOkE;
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}
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static int32_t timeSleepNative(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
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struct timespec request;
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struct timespec remaining;
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double ms;
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int64_t nanos;
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(void)userData;
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calogValueNil(result);
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if (argCount != 1 || (args[0].type != calogIntE && args[0].type != calogRealE)) {
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return calogFail(result, calogErrArgE, "timeSleep expects (milliseconds)");
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}
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ms = (args[0].type == calogIntE) ? (double)args[0].as.i : args[0].as.r;
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if (!(ms >= 0.0)) {
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return calogFail(result, calogErrRangeE, "timeSleep: milliseconds must be non-negative");
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}
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// Reject ms large enough that ms * TIME_NS_PER_MS would overflow int64_t --
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// the cast below is UB otherwise (C11 6.3.1.4p1).
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if (ms > (double)INT64_MAX / TIME_NS_PER_MS) {
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return calogFail(result, calogErrRangeE, "timeSleep: milliseconds out of range");
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}
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nanos = (int64_t)(ms * TIME_NS_PER_MS);
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request.tv_sec = (time_t)(nanos / TIME_NS_PER_SEC);
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request.tv_nsec = (long)(nanos % TIME_NS_PER_SEC);
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while (nanosleep(&request, &remaining) != 0) {
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if (errno != EINTR) {
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return calogFail(result, calogErrUnsupportedE, "timeSleep: nanosleep failed");
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}
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request = remaining;
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}
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return calogOkE;
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}
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static double timeToSeconds(const struct timespec *ts) {
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return (double)ts->tv_sec + (double)ts->tv_nsec / TIME_NS_PER_SEC;
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}
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