dtracy: add support for aggregations

1 files changed, 138 insertions, 0 deletions

diff --git a/sys/src/libdtracy/agg.c b/sys/src/libdtracy/agg.c
new file mode 100644
index 000000000..d374ed913
--- /dev/null
+++ b/sys/src/libdtracy/agg.c
@@ -0,0 +1,138 @@
+#include <u.h>
+#include <libc.h>
+#include <dtracy.h>
+
+int
+dtaunpackid(DTAgg *a)
+{
+	a->type = a->id >> 28 & 15;
+	a->keysize = a->id >> 13 & 0x7ff8;
+	switch(a->type){
+	case AGGCNT:
+	case AGGSUM:
+	case AGGMIN:
+	case AGGMAX:
+		a->recsize = 8 + a->keysize + 8;
+		return 0;
+	case AGGAVG:
+		a->recsize = 8 + a->keysize + 16;
+		return 0;
+	case AGGSTD:
+		a->recsize = 8 + a->keysize + 32;
+		return 0;
+	default:
+		return -1;
+	}
+}
+
+static u64int
+hash(uchar *s, int n, int m)
+{
+	u64int h;
+	int i;
+	
+	h = 0xcbf29ce484222325ULL;
+	for(i = 0; i < n; i++){
+		h ^= s[i];
+		h *= 0x100000001b3ULL;
+	}
+	for(; i < m; i++)
+		h *= 0x100000001b3ULL;
+	return h;
+}
+
+static int
+keyeq(uchar *a, uchar *b, int n, int m)
+{
+	int i;
+	
+	for(i = 0; i < n; i++)
+		if(a[i] != b[i])
+			return 0;
+	for(; i < m; i++)
+		if(a[i] != 0)
+			return 0;
+	return 1;
+}
+
+/* calculate v*v with 128 bits precision and add it to the 128-bit word at q */
+static void
+addsquare(u64int *q, s64int v)
+{
+	u32int v0;
+	s32int v1;
+	s64int s0, s1, s2;
+	u64int r;
+	
+	v0 = v;
+	v1 = v>>32;
+	s0 = (s64int)v0 * (s64int)v0;
+	s1 = (s64int)v0 * (s64int)v1;
+	s2 = (s64int)v1 * (s64int)v1;
+	r = s0 + (s1<<33);
+	if(r < (u64int)s0) q[1]++;
+	q[0] += r;
+	if(q[0] < r) q[1]++;
+	q[1] += s2 + (s1>>31);
+}
+
+static void
+updaterecord(int type, u64int *q, s64int val)
+{
+	switch(type){
+	case AGGCNT: q[0] += 1; break;
+	case AGGSUM: q[0] += val; break;
+	case AGGAVG: q[0] += val; q[1]++; break;
+	case AGGMIN: if(val < q[0]) q[0] = val; break;
+	case AGGMAX: if(val > q[0]) q[0] = val; break;
+	case AGGSTD: q[0] += val; q[1]++; addsquare(&q[2], val); break;
+	}
+}
+
+static void
+createrecord(int type, u64int *q, s64int val)
+{
+	switch(type){
+	case AGGCNT: q[0] = 1; break;
+	case AGGSUM: case AGGMIN: case AGGMAX: q[0] = val; break;
+	case AGGAVG: q[0] = val; q[1] = 1; break;
+	case AGGSTD: q[0] = val; q[1] = 1; q[2] = 0; q[3] = 0; addsquare(&q[2], val); break;
+	}
+}
+
+/* runs in probe context */
+void
+dtarecord(DTChan *ch, int mach, DTAgg *a, uchar *key, int nkey, s64int val)
+{
+	u64int h;
+	u32int *p, *q;
+	DTBuf *c;
+	
+	c = ch->aggwrbufs[mach];
+	h = hash(key, nkey, a->keysize);
+	p = (u32int*)(c->data + DTABUCKETS + (h % DTANUMBUCKETS) * 4);
+	while(*p != DTANIL){
+		assert((uint)*p < DTABUCKETS);
+		q = (u32int*)(c->data + *p);
+		if(q[1] == a->id && keyeq((uchar*)(q + 2), key, nkey, a->keysize) == 0){
+			updaterecord(a->type, (u64int*)(q + 2 + a->keysize / 4), val);
+			return;
+		}
+		p = q;
+	}
+	if(c->wr + a->recsize > DTABUCKETS)
+		return;
+	*p = c->wr;
+	q = (u32int*)(c->data + c->wr);
+	q[0] = DTANIL;
+	q[1] = a->id;
+	if(nkey == a->keysize)
+		memmove(&q[2], key, nkey);
+	else if(nkey > a->keysize){
+		memmove(&q[2], key, nkey);
+		memset((uchar*)q + 8 + nkey, 0, a->keysize - nkey);
+	}else
+		memmove(&q[2], key, a->keysize);
+	createrecord(a->type, (u64int*)(q + 2 + a->keysize / 4), val);
+	c->wr += a->recsize;
+}