提交 fe244589 编写于 作者: A antirez

Yet another version of the double saving code, with comments explaining what's happening there

上级 5107436c
......@@ -3513,7 +3513,18 @@ static int rdbSaveDoubleValue(FILE *fp, double val) {
len = 1;
buf[0] = (val < 0) ? 255 : 254;
} else {
if (val > LLONG_MAX && val < LLONG_MIN && val == ((long long)val))
/* Check if the float is in a safe range to be casted into a
* long long. We are assuming that long long is 64 bit here.
* Also we are assuming that there are no implementations around where
* double has precision < 52 bit.
*
* Under this assumptions we test if a double is inside an interval
* where casting to long long is safe. Then using two castings we
* make sure the decimal part is zero. If all this is true we use
* integer printing function that is much faster. */
double min = -4503599627370495;
double max = 4503599627370496;
if (val > min && val < max && val == ((double)((long long)val)))
ll2string((char*)buf+1,sizeof(buf),(long long)val);
else
snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val);
......
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