MINOR: samples: add xx-hash functions

This patch adds the support of xx-hash 32 and 64-bits functions.

doc/configuration.txt

@@ -12806,6 +12806,24 @@ xor(<value>)
   This prefix is followed by a name. The separator is a '.'. The name may only
   contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.
 
+xxh32([<seed>])
+  Hashes a binary input sample into an unsigned 32-bit quantity using the 32-bit
+  variant of the XXHash hash function. This hash supports a seed which defaults
+  to zero but a different value maybe passed as the <seed> argument. This hash
+  is known to be very good and very fast so it can be used to hash URLs and/or
+  URL parameters for use as stick-table keys to collect statistics with a low
+  collision rate, though care must be taken as the algorithm is not considered
+  as cryptographically secure.
+
+xxh64([<seed>])
+  Hashes a binary input sample into a signed 64-bit quantity using the 64-bit
+  variant of the XXHash hash function. This hash supports a seed which defaults
+  to zero but a different value maybe passed as the <seed> argument. This hash
+  is known to be very good and very fast so it can be used to hash URLs and/or
+  URL parameters for use as stick-table keys to collect statistics with a low
+  collision rate, though care must be taken as the algorithm is not considered
+  as cryptographically secure.
+
 
 7.3.2. Fetching samples from internal states
 --------------------------------------------

src/sample.c

@@ -33,6 +33,8 @@
 #include <proto/stick_table.h>
 #include <proto/vars.h>
 
+#include <import/xxhash.h>
+
 /* sample type names */
 const char *smp_to_type[SMP_TYPES] = {
 	[SMP_T_ANY]  = "any",
@@ -1617,6 +1619,41 @@ static int sample_conv_wt6(const struct arg *arg_p, struct sample *smp, void *pr
 	return 1;
 }
 
+/* hashes the binary input into a 32-bit unsigned int using xxh.
+ * The seed of the hash defaults to 0 but can be changd in argument 1.
+ */
+static int sample_conv_xxh32(const struct arg *arg_p, struct sample *smp, void *private)
+{
+	unsigned int seed;
+
+	if (arg_p && arg_p->data.sint)
+		seed = arg_p->data.sint;
+	else
+		seed = 0;
+	smp->data.u.sint = XXH32(smp->data.u.str.str, smp->data.u.str.len, seed);
+	smp->data.type = SMP_T_SINT;
+	return 1;
+}
+
+/* hashes the binary input into a 64-bit unsigned int using xxh.
+ * In fact, the function returns a 64 bit unsigned, but the sample
+ * storage of haproxy only proposes 64-bits signed, so the value is
+ * cast as signed. This cast doesn't impact the hash repartition.
+ * The seed of the hash defaults to 0 but can be changd in argument 1.
+ */
+static int sample_conv_xxh64(const struct arg *arg_p, struct sample *smp, void *private)
+{
+	unsigned long long int seed;
+
+	if (arg_p && arg_p->data.sint)
+		seed = (unsigned long long int)arg_p->data.sint;
+	else
+		seed = 0;
+	smp->data.u.sint = (long long int)XXH64(smp->data.u.str.str, smp->data.u.str.len, seed);
+	smp->data.type = SMP_T_SINT;
+	return 1;
+}
+
 /* hashes the binary input into a 32-bit unsigned int */
 static int sample_conv_crc32(const struct arg *arg_p, struct sample *smp, void *private)
 {
@@ -2680,6 +2717,8 @@ static struct sample_conv_kw_list sample_conv_kws = {ILH, {
 	{ "djb2",   sample_conv_djb2,      ARG1(0,SINT), NULL, SMP_T_BIN,  SMP_T_SINT  },
 	{ "sdbm",   sample_conv_sdbm,      ARG1(0,SINT), NULL, SMP_T_BIN,  SMP_T_SINT  },
 	{ "wt6",    sample_conv_wt6,       ARG1(0,SINT), NULL, SMP_T_BIN,  SMP_T_SINT  },
+	{ "xxh32",  sample_conv_xxh32,     ARG1(0,SINT), NULL, SMP_T_BIN,  SMP_T_SINT  },
+	{ "xxh64",  sample_conv_xxh64,     ARG1(0,SINT), NULL, SMP_T_BIN,  SMP_T_SINT  },
 	{ "json",   sample_conv_json,      ARG1(1,STR),  sample_conv_json_check, SMP_T_STR,  SMP_T_STR },
 	{ "bytes",  sample_conv_bytes,     ARG2(1,SINT,SINT), NULL, SMP_T_BIN,  SMP_T_BIN },
 	{ "field",  sample_conv_field,     ARG2(2,SINT,STR), sample_conv_field_check, SMP_T_STR,  SMP_T_STR },