[TESTS] added a trivial program to benchmark hash algos
The uri_hash.c program makes it very easy to benchmark the
distribution of hash algos. Pass it one word per line, and
it will show the distribution per server for 1 to 10 servers.
diff --git a/tests/uri_hash.c b/tests/uri_hash.c
new file mode 100644
index 0000000..4fc1f9f
--- /dev/null
+++ b/tests/uri_hash.c
@@ -0,0 +1,228 @@
+#include <stdio.h>
+
+#define NSERV 10
+#define MAXLINE 1000
+
+char line[MAXLINE];
+
+int counts_gd1[NSERV][NSERV];
+static unsigned long hash_gd1(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++)
+ hash = c + (hash << 6) + (hash << 16) - hash;
+
+ return hash;
+}
+
+int counts_gd2[NSERV][NSERV];
+static unsigned long hash_gd2(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++) {
+ if (c == '?' || c == '\n')
+ break;
+ hash = c + (hash << 6) + (hash << 16) - hash;
+ }
+
+ return hash;
+}
+
+
+int counts_gd3[NSERV][NSERV];
+static unsigned long hash_gd3(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++) {
+ if (c == '?' || c == '\n')
+ break;
+ hash = c - (hash << 3) + (hash << 15) - hash;
+ }
+
+ return hash;
+}
+
+
+int counts_gd4[NSERV][NSERV];
+static unsigned long hash_gd4(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++) {
+ if (c == '?' || c == '\n')
+ break;
+ hash = hash + (hash << 6) - (hash << 15) - c;
+ }
+
+ return hash;
+}
+
+
+int counts_gd5[NSERV][NSERV];
+static unsigned long hash_gd5(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++) {
+ if (c == '?' || c == '\n')
+ break;
+ hash = hash + (hash << 2) - (hash << 19) - c;
+ }
+
+ return hash;
+}
+
+
+int counts_gd6[NSERV][NSERV];
+static unsigned long hash_gd6(char *uri)
+{
+ unsigned long hash = 0;
+ int c;
+
+ while (c = *uri++) {
+ if (c == '?' || c == '\n')
+ break;
+ hash = hash + (hash << 2) - (hash << 22) - c;
+ }
+
+ return hash;
+}
+
+
+int counts_wt1[NSERV][NSERV];
+static unsigned long hash_wt1(int hsize, char *string) {
+ int bits;
+ unsigned long data, val;
+
+ bits = val = data = 0;
+ while (*string) {
+ if (*string == '?' || *string == '\n')
+ break;
+ data |= ((unsigned long)(unsigned char)*string) << bits;
+ bits += 8;
+ while (bits >= hsize) {
+ val ^= data - (val >> hsize);
+ bits -= hsize;
+ data >>= hsize;
+ }
+ string++;
+ }
+ val ^= data;
+ while (val > ((1 << hsize) - 1)) {
+ val = (val & ((1 << hsize) - 1)) ^ (val >> hsize);
+ }
+ return val;
+}
+
+/*
+ * efficient hash : no duplicate on the first 65536 values of 2 bytes.
+ * less than 0.1% duplicates for the first 1.6 M values of 3 bytes.
+ */
+int counts_wt2[NSERV][NSERV];
+typedef unsigned int u_int32_t;
+
+static inline u_int32_t shl32(u_int32_t i, int count) {
+ if (count == 32)
+ return 0;
+ return i << count;
+}
+
+static inline u_int32_t shr32(u_int32_t i, int count) {
+ if (count == 32)
+ return 0;
+ return i >> count;
+}
+
+static unsigned int rev32(unsigned int c) {
+ c = ((c & 0x0000FFFF) << 16)| ((c & 0xFFFF0000) >> 16);
+ c = ((c & 0x00FF00FF) << 8) | ((c & 0xFF00FF00) >> 8);
+ c = ((c & 0x0F0F0F0F) << 4) | ((c & 0xF0F0F0F0) >> 4);
+ c = ((c & 0x33333333) << 2) | ((c & 0xCCCCCCCC) >> 2);
+ c = ((c & 0x55555555) << 1) | ((c & 0xAAAAAAAA) >> 1);
+ return c;
+}
+
+int hash_wt2(const char *src, int len) {
+ unsigned int i = 0x3C964BA5; /* as many ones as zeroes */
+ unsigned int j, k;
+ unsigned int ih, il;
+ int bit;
+
+ while (len--) {
+ j = (unsigned char)*src++;
+ if (j == '?' || j == '\n')
+ break;
+ bit = rev32(j - i);
+ bit = bit - (bit >> 3) + (bit >> 16) - j;
+
+ bit &= 0x1f;
+ ih = shr32(i, bit);
+ il = i & (shl32(1, bit) - 1);
+ i = shl32(il, 32-bit) - ih - ~j;
+ }
+ return i;
+}
+
+void count_hash_results(unsigned long hash, int counts[NSERV][NSERV]) {
+ int srv, nsrv;
+
+ for (nsrv = 0; nsrv < NSERV; nsrv++) {
+ srv = hash % (nsrv + 1);
+ counts[nsrv][srv]++;
+ }
+}
+
+void dump_hash_results(char *name, int counts[NSERV][NSERV]) {
+ int srv, nsrv;
+
+ printf("%s:\n", name);
+ for (nsrv = 0; nsrv < NSERV; nsrv++) {
+ printf("%02d srv: ", nsrv+1);
+ for (srv = 0; srv <= nsrv; srv++) {
+ //printf("%6d ", counts[nsrv][srv]);
+ //printf("%3.1f ", (100.0*counts[nsrv][srv]) / (double)counts[0][0]);
+ printf("%3.1f ", 100.0*(counts[nsrv][srv] - (double)counts[0][0]/(nsrv+1)) / (double)counts[0][0]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+}
+
+main() {
+ memset(counts_gd1, 0, sizeof(counts_gd1));
+ memset(counts_gd2, 0, sizeof(counts_gd2));
+ memset(counts_gd3, 0, sizeof(counts_gd3));
+ memset(counts_gd4, 0, sizeof(counts_gd4));
+ memset(counts_gd5, 0, sizeof(counts_gd5));
+ memset(counts_gd6, 0, sizeof(counts_gd6));
+ memset(counts_wt1, 0, sizeof(counts_wt1));
+ memset(counts_wt2, 0, sizeof(counts_wt2));
+
+ while (fgets(line, MAXLINE, stdin) != NULL) {
+ count_hash_results(hash_gd1(line), counts_gd1);
+ count_hash_results(hash_gd2(line), counts_gd2);
+ count_hash_results(hash_gd3(line), counts_gd3);
+ count_hash_results(hash_gd4(line), counts_gd4);
+ count_hash_results(hash_gd5(line), counts_gd5);
+ count_hash_results(hash_gd6(line), counts_gd6);
+ count_hash_results(hash_wt1(31, line), counts_wt1);
+ count_hash_results(hash_wt2(line, strlen(line)), counts_wt2);
+ }
+
+ dump_hash_results("hash_gd1", counts_gd1);
+ dump_hash_results("hash_gd2", counts_gd2);
+ dump_hash_results("hash_gd3", counts_gd3);
+ dump_hash_results("hash_gd4", counts_gd4);
+ dump_hash_results("hash_gd5", counts_gd5);
+ dump_hash_results("hash_gd6", counts_gd6);
+ dump_hash_results("hash_wt1", counts_wt1);
+ dump_hash_results("hash_wt2", counts_wt2);
+}