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-rw-r--r--libnetdata/storage_number/Makefile.am12
-rw-r--r--libnetdata/storage_number/README.md21
-rw-r--r--libnetdata/storage_number/storage_number.c233
-rw-r--r--libnetdata/storage_number/storage_number.h178
-rw-r--r--libnetdata/storage_number/tests/Makefile.am4
-rw-r--r--libnetdata/storage_number/tests/test_storage_number.c52
6 files changed, 500 insertions, 0 deletions
diff --git a/libnetdata/storage_number/Makefile.am b/libnetdata/storage_number/Makefile.am
new file mode 100644
index 00000000..c5f84504
--- /dev/null
+++ b/libnetdata/storage_number/Makefile.am
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+SUBDIRS = \
+ tests \
+ $(NULL)
+
+dist_noinst_DATA = \
+ README.md \
+ $(NULL)
diff --git a/libnetdata/storage_number/README.md b/libnetdata/storage_number/README.md
new file mode 100644
index 00000000..2dd6df6c
--- /dev/null
+++ b/libnetdata/storage_number/README.md
@@ -0,0 +1,21 @@
+<!--
+title: "Netdata storage number"
+custom_edit_url: https://github.com/netdata/netdata/edit/master/libnetdata/storage_number/README.md
+sidebar_label: "Storage number"
+learn_status: "Published"
+learn_topic_type: "Tasks"
+learn_rel_path: "Developers/libnetdata"
+-->
+
+# Netdata storage number
+
+Although `netdata` does all its calculations using `long double`, it stores all values using
+a **custom-made 32-bit number**.
+
+This custom-made number can store in 29 bits values from `-167772150000000.0` to `167772150000000.0`
+with a precision of 0.00001 (yes, it's a floating point number, meaning that higher integer values
+have less decimal precision) and 3 bits for flags.
+
+This provides an extremely optimized memory footprint with just 0.0001% max accuracy loss.
+
+
diff --git a/libnetdata/storage_number/storage_number.c b/libnetdata/storage_number/storage_number.c
new file mode 100644
index 00000000..6468951b
--- /dev/null
+++ b/libnetdata/storage_number/storage_number.c
@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+bool is_system_ieee754_double(void) {
+ static bool logged = false;
+
+ struct {
+ NETDATA_DOUBLE original;
+
+ union {
+ uint64_t i;
+ NETDATA_DOUBLE d;
+ };
+ } tests[] = {
+ { .original = 1.25, .i = 0x3FF4000000000000 },
+ { .original = 1.0, .i = 0x3FF0000000000000 },
+ { .original = 2.0, .i = 0x4000000000000000 },
+ { .original = 4.0, .i = 0x4010000000000000 },
+ { .original = 8.8, .i = 0x402199999999999A },
+ { .original = 16.16, .i = 0x403028F5C28F5C29 },
+ { .original = 32.32, .i = 0x404028F5C28F5C29 },
+ { .original = 64.64, .i = 0x405028F5C28F5C29 },
+ { .original = 128.128, .i = 0x406004189374BC6A },
+ { .original = 32768.32768, .i = 0x40E0000A7C5AC472 },
+ { .original = 65536.65536, .i = 0x40F0000A7C5AC472 },
+ { .original = -65536.65536, .i = 0xC0F0000A7C5AC472 },
+ { .original = 65535.65535, .i = 0x40EFFFF4F8A0902E },
+ { .original = -65535.65535, .i = 0xC0EFFFF4F8A0902E },
+ { .original = 4.503599627e15, .i = 0x432FFFFFFFF4B180 },
+ { .original = -4.503599627e15, .i = 0xC32FFFFFFFF4B180 },
+ { .original = 1.25e25, .i = 0x4524ADF4B7320335 },
+ { .original = 1.25e307, .i = 0x7FB1CCF385EBC8A0 },
+ { .original = 1.25e-25, .i = 0x3AC357C299A88EA7 },
+ { .original = 1.25e-100, .i = 0x2B317F7D4ED8C33E },
+ { .original = NAN, .i = 0x7FF8000000000000 },
+ { .original = -INFINITY, .i = 0xFFF0000000000000 },
+ { .original = INFINITY, .i = 0x7FF0000000000000 },
+ { .original = 1.25e-132, .i = 0x248C6463225AB7EC },
+ { .original = 0.0, .i = 0x0000000000000000 },
+ { .original = -0.0, .i = 0x8000000000000000 },
+ { .original = DBL_MIN, .i = 0x0010000000000000 },
+ { .original = DBL_MAX, .i = 0x7FEFFFFFFFFFFFFF },
+ { .original = -DBL_MIN, .i = 0x8010000000000000 },
+ { .original = -DBL_MAX, .i = 0xFFEFFFFFFFFFFFFF },
+ };
+
+ size_t errors = 0;
+ size_t elements = sizeof(tests) / sizeof(tests[0]);
+ for(size_t i = 0; i < elements ; i++) {
+ uint64_t *ptr = (uint64_t *)&tests[i].original;
+
+ if(*ptr != tests[i].i && (tests[i].original == tests[i].d || (isnan(tests[i].original) && isnan(tests[i].d)))) {
+ if(!logged)
+ netdata_log_info("IEEE754: test #%zu, value " NETDATA_DOUBLE_FORMAT_G " is represented in this system as %lX, but it was expected as %lX",
+ i+1, tests[i].original, *ptr, tests[i].i);
+ errors++;
+ }
+ }
+
+ if(!errors && sizeof(NETDATA_DOUBLE) == sizeof(uint64_t)) {
+ if(!logged)
+ netdata_log_info("IEEE754: system is using IEEE754 DOUBLE PRECISION values");
+
+ logged = true;
+ return true;
+ }
+ else {
+ if(!logged)
+ netdata_log_info("IEEE754: system is NOT compatible with IEEE754 DOUBLE PRECISION values");
+
+ logged = true;
+ return false;
+ }
+}
+
+storage_number pack_storage_number(NETDATA_DOUBLE value, SN_FLAGS flags) {
+ // bit 32 = sign 0:positive, 1:negative
+ // bit 31 = 0:divide, 1:multiply
+ // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
+ // bit 27 SN_EXISTS_100
+ // bit 26 SN_EXISTS_RESET
+ // bit 25 SN_ANOMALY_BIT = 0: anomalous, 1: not anomalous
+ // bit 24 to bit 1 = the value
+
+ if(unlikely(fpclassify(value) == FP_NAN || fpclassify(value) == FP_INFINITE))
+ return SN_EMPTY_SLOT;
+
+ storage_number r = flags & SN_USER_FLAGS;
+
+ if(unlikely(fpclassify(value) == FP_ZERO || fpclassify(value) == FP_SUBNORMAL))
+ return r;
+
+ int m = 0;
+ NETDATA_DOUBLE n = value, factor = 10;
+
+ // if the value is negative
+ // add the sign bit and make it positive
+ if(n < 0) {
+ r += SN_FLAG_NEGATIVE; // the sign bit 32
+ n = -n;
+ }
+
+ if(n / 10000000.0 > 0x00ffffff) {
+ factor = 100;
+ r |= SN_FLAG_NOT_EXISTS_MUL100;
+ }
+
+ // make its integer part fit in 0x00ffffff
+ // by dividing it by 10 up to 7 times
+ // and increasing the multiplier
+ while(m < 7 && n > (NETDATA_DOUBLE)0x00ffffff) {
+ n /= factor;
+ m++;
+ }
+
+ if(m) {
+ // the value was too big, and we divided it
+ // so, we add a multiplier to unpack it
+ r += SN_FLAG_MULTIPLY + (m << 27); // the multiplier m
+
+ if(n > (NETDATA_DOUBLE)0x00ffffff) {
+ #ifdef NETDATA_INTERNAL_CHECKS
+ netdata_log_error("Number " NETDATA_DOUBLE_FORMAT " is too big.", value);
+ #endif
+ r += 0x00ffffff;
+ return r;
+ }
+ }
+ else {
+ // 0x0019999e is the number that can be multiplied
+ // by 10 to give 0x00ffffff
+ // while the value is below 0x0019999e we can
+ // multiply it by 10, up to 7 times, increasing
+ // the multiplier
+ while(m < 7 && n < (NETDATA_DOUBLE)0x0019999e) {
+ n *= 10;
+ m++;
+ }
+
+ if (unlikely(n > (NETDATA_DOUBLE)0x00ffffff)) {
+ n /= 10;
+ m--;
+ }
+ // the value was small enough, and we multiplied it
+ // so, we add a divider to unpack it
+ r += (m << 27); // the divider m
+ }
+
+#ifdef STORAGE_WITH_MATH
+ // without this there are rounding problems
+ // example: 0.9 becomes 0.89
+ r += lrint((double) n);
+#else
+ r += (storage_number)n;
+#endif
+
+ return r;
+}
+
+// Lookup table to make storage number unpacking efficient.
+NETDATA_DOUBLE unpack_storage_number_lut10x[4 * 8];
+
+__attribute__((constructor)) void initialize_lut(void) {
+ // The lookup table is partitioned in 4 subtables based on the
+ // values of the factor and exp bits.
+ for (int i = 0; i < 8; i++) {
+ // factor = 0
+ unpack_storage_number_lut10x[0 * 8 + i] = 1 / pow(10, i); // exp = 0
+ unpack_storage_number_lut10x[1 * 8 + i] = pow(10, i); // exp = 1
+
+ // factor = 1
+ unpack_storage_number_lut10x[2 * 8 + i] = 1 / pow(100, i); // exp = 0
+ unpack_storage_number_lut10x[3 * 8 + i] = pow(100, i); // exp = 1
+ }
+}
+
+/*
+int print_netdata_double(char *str, NETDATA_DOUBLE value)
+{
+ char *wstr = str;
+
+ int sign = (value < 0) ? 1 : 0;
+ if(sign) value = -value;
+
+#ifdef STORAGE_WITH_MATH
+ // without llrintl() there are rounding problems
+ // for example 0.9 becomes 0.89
+ unsigned long long uvalue = (unsigned long long int) llrintl(value * (NETDATA_DOUBLE)100000);
+#else
+ unsigned long long uvalue = value * (NETDATA_DOUBLE)100000;
+#endif
+
+ wstr = print_number_llu_r_smart(str, uvalue);
+
+ // make sure we have 6 bytes at least
+ while((wstr - str) < 6) *wstr++ = '0';
+
+ // put the sign back
+ if(sign) *wstr++ = '-';
+
+ // reverse it
+ char *begin = str, *end = --wstr, aux;
+ while (end > begin) aux = *end, *end-- = *begin, *begin++ = aux;
+ // wstr--;
+ // strreverse(str, wstr);
+
+ // remove trailing zeros
+ int decimal = 5;
+ while(decimal > 0 && *wstr == '0') {
+ *wstr-- = '\0';
+ decimal--;
+ }
+
+ // terminate it, one position to the right
+ // to let space for a dot
+ wstr[2] = '\0';
+
+ // make space for the dot
+ int i;
+ for(i = 0; i < decimal ;i++) {
+ wstr[1] = wstr[0];
+ wstr--;
+ }
+
+ // put the dot
+ if(wstr[2] == '\0') { wstr[1] = '\0'; decimal--; }
+ else wstr[1] = '.';
+
+ // return the buffer length
+ return (int) ((wstr - str) + 2 + decimal );
+}
+*/
diff --git a/libnetdata/storage_number/storage_number.h b/libnetdata/storage_number/storage_number.h
new file mode 100644
index 00000000..82c870d6
--- /dev/null
+++ b/libnetdata/storage_number/storage_number.h
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_STORAGE_NUMBER_H
+#define NETDATA_STORAGE_NUMBER_H 1
+
+#include <math.h>
+#include "../libnetdata.h"
+
+#ifdef NETDATA_WITH_LONG_DOUBLE
+
+typedef long double NETDATA_DOUBLE;
+#define NETDATA_DOUBLE_FORMAT "%0.7Lf"
+#define NETDATA_DOUBLE_FORMAT_ZERO "%0.0Lf"
+#define NETDATA_DOUBLE_FORMAT_AUTO "%Lf"
+#define NETDATA_DOUBLE_MODIFIER "Lf"
+#define NETDATA_DOUBLE_FORMAT_G "%0.19Le"
+
+#define NETDATA_DOUBLE_MAX LDBL_MAX
+
+#define strtondd(s, endptr) strtold(s, endptr)
+#define powndd(x, y) powl(x, y)
+#define llrintndd(x) llrintl(x)
+#define roundndd(x) roundl(x)
+#define sqrtndd(x) sqrtl(x)
+#define copysignndd(x, y) copysignl(x, y)
+#define modfndd(x, y) modfl(x, y)
+#define fabsndd(x) fabsl(x)
+#define floorndd(x) floorl(x)
+#define ceilndd(x) ceill(x)
+#define log10ndd(x) log10l(x)
+
+#else // NETDATA_WITH_LONG_DOUBLE
+
+typedef double NETDATA_DOUBLE;
+#define NETDATA_DOUBLE_FORMAT "%0.7f"
+#define NETDATA_DOUBLE_FORMAT_ZERO "%0.0f"
+#define NETDATA_DOUBLE_FORMAT_AUTO "%f"
+#define NETDATA_DOUBLE_MODIFIER "f"
+#define NETDATA_DOUBLE_FORMAT_G "%0.19e"
+
+#define NETDATA_DOUBLE_MAX DBL_MAX
+
+#define strtondd(s, endptr) strtod(s, endptr)
+#define powndd(x, y) pow(x, y)
+#define llrintndd(x) llrint(x)
+#define roundndd(x) round(x)
+#define sqrtndd(x) sqrt(x)
+#define copysignndd(x, y) copysign(x, y)
+#define modfndd(x, y) modf(x, y)
+#define fabsndd(x) fabs(x)
+#define floorndd(x) floor(x)
+#define ceilndd(x) ceil(x)
+#define log10ndd(x) log10(x)
+
+#endif // NETDATA_WITH_LONG_DOUBLE
+
+typedef long long collected_number;
+#define COLLECTED_NUMBER_FORMAT "%lld"
+
+#define epsilonndd (NETDATA_DOUBLE)0.0000001
+#define considered_equal_ndd(a, b) (fabsndd((a) - (b)) < epsilonndd)
+
+#if defined(HAVE_ISFINITE) || defined(isfinite)
+// The isfinite() macro shall determine whether its argument has a
+// finite value (zero, subnormal, or normal, and not infinite or NaN).
+#define netdata_double_isnumber(a) (isfinite(a))
+#elif defined(HAVE_FINITE) || defined(finite)
+#define netdata_double_isnumber(a) (finite(a))
+#else
+#define netdata_double_isnumber(a) (fpclassify(a) != FP_NAN && fpclassify(a) != FP_INFINITE)
+#endif
+
+#define netdata_double_is_zero(a) (!netdata_double_isnumber(a) || considered_equal_ndd(a, 0.0))
+#define netdata_double_is_nonzero(a) (!netdata_double_is_zero(a))
+
+typedef uint32_t storage_number;
+
+typedef struct storage_number_tier1 {
+ float sum_value;
+ float min_value;
+ float max_value;
+ uint16_t count;
+ uint16_t anomaly_count;
+} storage_number_tier1_t;
+
+#define STORAGE_NUMBER_FORMAT "%u"
+
+typedef enum {
+ SN_FLAG_NONE = 0,
+ SN_FLAG_NOT_ANOMALOUS = (1 << 24), // the anomaly bit of the value (0:anomalous, 1:not anomalous)
+ SN_FLAG_RESET = (1 << 25), // the value has been overflown
+ SN_FLAG_NOT_EXISTS_MUL100 = (1 << 26), // very large value (multiplier is 100 instead of 10)
+ SN_FLAG_MULTIPLY = (1 << 30), // multiply, else divide
+ SN_FLAG_NEGATIVE = (1 << 31), // negative, else positive
+} SN_FLAGS;
+
+#define SN_USER_FLAGS (SN_FLAG_NOT_ANOMALOUS | SN_FLAG_RESET)
+
+// default flags for all storage numbers
+// anomaly bit is reversed, so we set it by default
+#define SN_DEFAULT_FLAGS SN_FLAG_NOT_ANOMALOUS
+
+// When the calculated number is zero and the value is anomalous (ie. it's bit
+// is zero) we want to return a storage_number representation that is
+// different from the empty slot. We achieve this by mapping zero to
+// SN_EXISTS_100. Unpacking the SN_EXISTS_100 value will return zero because
+// its fraction field (as well as its exponent factor field) will be zero.
+#define SN_EMPTY_SLOT SN_FLAG_NOT_EXISTS_MUL100
+
+// checks
+#define does_storage_number_exist(value) (((storage_number)(value)) != SN_EMPTY_SLOT)
+#define did_storage_number_reset(value) ((((storage_number)(value)) & SN_FLAG_RESET))
+#define is_storage_number_anomalous(value) (does_storage_number_exist(value) && !(((storage_number)(value)) & SN_FLAG_NOT_ANOMALOUS))
+
+storage_number pack_storage_number(NETDATA_DOUBLE value, SN_FLAGS flags) __attribute__((const));
+static inline NETDATA_DOUBLE unpack_storage_number(storage_number value) __attribute__((const));
+
+// sign div/mul <--- multiplier / divider ---> 10/100 RESET EXISTS VALUE
+#define STORAGE_NUMBER_POSITIVE_MAX_RAW (storage_number)( (0 << 31) | (1 << 30) | (1 << 29) | (1 << 28) | (1 << 27) | (1 << 26) | (0 << 25) | (1 << 24) | 0x00ffffff )
+#define STORAGE_NUMBER_POSITIVE_MIN_RAW (storage_number)( (0 << 31) | (0 << 30) | (1 << 29) | (1 << 28) | (1 << 27) | (0 << 26) | (0 << 25) | (1 << 24) | 0x00000001 )
+#define STORAGE_NUMBER_NEGATIVE_MAX_RAW (storage_number)( (1 << 31) | (0 << 30) | (1 << 29) | (1 << 28) | (1 << 27) | (0 << 26) | (0 << 25) | (1 << 24) | 0x00000001 )
+#define STORAGE_NUMBER_NEGATIVE_MIN_RAW (storage_number)( (1 << 31) | (1 << 30) | (1 << 29) | (1 << 28) | (1 << 27) | (1 << 26) | (0 << 25) | (1 << 24) | 0x00ffffff )
+
+// accepted accuracy loss
+#define ACCURACY_LOSS_ACCEPTED_PERCENT 0.0001
+#define accuracy_loss(t1, t2) (((t1) == (t2) || (t1) == 0.0 || (t2) == 0.0) ? 0.0 : (100.0 - (((t1) > (t2)) ? ((t2) * 100.0 / (t1) ) : ((t1) * 100.0 / (t2)))))
+
+// Maximum acceptable rate of increase for counters. With a rate of 10% netdata can safely detect overflows with a
+// period of at least every other 10 samples.
+#define MAX_INCREMENTAL_PERCENT_RATE 10
+
+
+static inline NETDATA_DOUBLE unpack_storage_number(storage_number value) {
+ extern NETDATA_DOUBLE unpack_storage_number_lut10x[4 * 8];
+
+ if(unlikely(value == SN_EMPTY_SLOT))
+ return NAN;
+
+ int sign = 1, exp = 0;
+ int factor = 0;
+
+ // bit 32 = 0:positive, 1:negative
+ if(unlikely(value & SN_FLAG_NEGATIVE))
+ sign = -1;
+
+ // bit 31 = 0:divide, 1:multiply
+ if(unlikely(value & SN_FLAG_MULTIPLY))
+ exp = 1;
+
+ // bit 27 SN_FLAG_NOT_EXISTS_MUL100
+ if(unlikely(value & SN_FLAG_NOT_EXISTS_MUL100))
+ factor = 1;
+
+ // bit 26 SN_FLAG_RESET
+ // bit 25 SN_FLAG_NOT_ANOMALOUS
+
+ // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
+ int mul = (int)((value & ((1<<29)|(1<<28)|(1<<27))) >> 27);
+
+ // bit 24 to bit 1 = the value, so remove all other bits
+ value ^= value & ((1<<31)|(1<<30)|(1<<29)|(1<<28)|(1<<27)|(1<<26)|(1<<25)|(1<<24));
+
+ NETDATA_DOUBLE n = value;
+
+ // fprintf(stderr, "UNPACK: %08X, sign = %d, exp = %d, mul = %d, factor = %d, n = " CALCULATED_NUMBER_FORMAT "\n", value, sign, exp, mul, factor, n);
+
+ return sign * unpack_storage_number_lut10x[(factor * 16) + (exp * 8) + mul] * n;
+}
+
+// all these prefixes should use characters that are not allowed in the numbers they represent
+#define HEX_PREFIX "0x" // we check 2 characters when parsing
+#define IEEE754_UINT64_B64_PREFIX "#" // we check the 1st character during parsing
+#define IEEE754_DOUBLE_B64_PREFIX "@" // we check the 1st character during parsing
+#define IEEE754_DOUBLE_HEX_PREFIX "%" // we check the 1st character during parsing
+
+bool is_system_ieee754_double(void);
+
+#endif /* NETDATA_STORAGE_NUMBER_H */
diff --git a/libnetdata/storage_number/tests/Makefile.am b/libnetdata/storage_number/tests/Makefile.am
new file mode 100644
index 00000000..babdcf0d
--- /dev/null
+++ b/libnetdata/storage_number/tests/Makefile.am
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
diff --git a/libnetdata/storage_number/tests/test_storage_number.c b/libnetdata/storage_number/tests/test_storage_number.c
new file mode 100644
index 00000000..19309e5c
--- /dev/null
+++ b/libnetdata/storage_number/tests/test_storage_number.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../../libnetdata.h"
+#include "../../required_dummies.h"
+#include <setjmp.h>
+#include <cmocka.h>
+
+static void test_number_printing(void **state)
+{
+ (void)state;
+
+ char value[50];
+
+ print_netdata_double(value, 0);
+ assert_string_equal(value, "0");
+
+ print_netdata_double(value, 0.0000001);
+ assert_string_equal(value, "0.0000001");
+
+ print_netdata_double(value, 0.00000009);
+ assert_string_equal(value, "0.0000001");
+
+ print_netdata_double(value, 0.000000001);
+ assert_string_equal(value, "0");
+
+ print_netdata_double(value, 99.99999999999999999);
+ assert_string_equal(value, "100");
+
+ print_netdata_double(value, -99.99999999999999999);
+ assert_string_equal(value, "-100");
+
+ print_netdata_double(value, 123.4567890123456789);
+ assert_string_equal(value, "123.456789");
+
+ print_netdata_double(value, 9999.9999999);
+ assert_string_equal(value, "9999.9999999");
+
+ print_netdata_double(value, -9999.9999999);
+ assert_string_equal(value, "-9999.9999999");
+
+ print_netdata_double(value, unpack_storage_number(pack_storage_number(16.777218L, SN_DEFAULT_FLAGS)));
+ assert_string_equal(value, "16.77722");
+}
+
+int main(void)
+{
+ const struct CMUnitTest tests[] = {
+ cmocka_unit_test(test_number_printing)
+ };
+
+ return cmocka_run_group_tests_name("storage_number", tests, NULL, NULL);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-22 19:49:34 +0000