Merging upstream version 1.35.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 52 insertions, 42 deletions

diff --git a/libnetdata/storage_number/storage_number.c b/libnetdata/storage_number/storage_number.c
index 3e6a9f45c..ba7a66874 100644
--- a/libnetdata/storage_number/storage_number.c
+++ b/libnetdata/storage_number/storage_number.c
@@ -91,48 +91,21 @@ RET_SN:
     return r;
 }
 
-calculated_number unpack_storage_number(storage_number value) {
-    if(!value) return 0;
-
-    int sign = 0, exp = 0;
-    int factor = 10;
-
-    // bit 32 = 0:positive, 1:negative
-    if(unlikely(value & (1 << 31)))
-        sign = 1;
-
-    // bit 31 = 0:divide, 1:multiply
-    if(unlikely(value & (1 << 30)))
-        exp = 1;
-
-    // bit 27 SN_EXISTS_100
-    if(unlikely(value & (1 << 26)))
-        factor = 100;
-
-    // bit 26 SN_EXISTS_RESET
-    // bit 25 SN_ANOMALY_BIT
-
-    // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
-    int mul = (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));
-
-    calculated_number 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);
-
-    if(exp) {
-        for(; mul; mul--)
-            n *= factor;
+// Lookup table to make storage number unpacking efficient.
+calculated_number 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
     }
-    else {
-        for( ; mul ; mul--)
-            n /= 10;
-    }
-
-    if(sign) n = -n;
-    return n;
 }
 
 /*
diff --git a/libnetdata/storage_number/storage_number.h b/libnetdata/storage_number/storage_number.h
index 4101f69e0..7e7b511b0 100644
--- a/libnetdata/storage_number/storage_number.h
+++ b/libnetdata/storage_number/storage_number.h
@@ -80,7 +80,7 @@ typedef uint32_t storage_number;
 #define did_storage_number_reset(value)  ((((storage_number) (value)) & SN_EXISTS_RESET) != 0)
 
 storage_number pack_storage_number(calculated_number value, uint32_t flags);
-calculated_number unpack_storage_number(storage_number value);
+static inline calculated_number unpack_storage_number(storage_number value) __attribute__((const));
 
 int print_calculated_number(char *str, calculated_number value);
 
@@ -98,4 +98,41 @@ int print_calculated_number(char *str, calculated_number value);
 // period of at least every other 10 samples.
 #define MAX_INCREMENTAL_PERCENT_RATE 10
 
+
+static inline calculated_number unpack_storage_number(storage_number value) {
+    extern calculated_number unpack_storage_number_lut10x[4 * 8];
+
+    if(!value) return 0;
+
+    int sign = 1, exp = 0;
+    int factor = 0;
+
+    // bit 32 = 0:positive, 1:negative
+    if(unlikely(value & (1 << 31)))
+        sign = -1;
+
+    // bit 31 = 0:divide, 1:multiply
+    if(unlikely(value & (1 << 30)))
+        exp = 1;
+
+    // bit 27 SN_EXISTS_100
+    if(unlikely(value & (1 << 26)))
+        factor = 1;
+
+    // bit 26 SN_EXISTS_RESET
+    // bit 25 SN_ANOMALY_BIT
+
+    // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
+    int mul = (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));
+
+    calculated_number 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;
+}
+
 #endif /* NETDATA_STORAGE_NUMBER_H */