Branch imports for masters.

Copied from Perforce
 Change: 23678
 ServerID: perforce.ravenbrook.com

1 files changed, 104 insertions, 0 deletions

diff --git a/mps/code/meter.c b/mps/code/meter.c
new file mode 100644
index 00000000000..fc3b36d7bbd
--- /dev/null
+++ b/mps/code/meter.c
@@ -0,0 +1,104 @@
+/* impl.c.meter: METERS
+ *
+ * $HopeName: MMsrc!meter.c(trunk.9) $
+ * Copyright (C) 1999 Harlequin Limited.  All rights reserved.
+ *
+ * TRANSGRESSIONS
+ *
+ * .trans.label: We label meters with EventLabelAddr, but of course that's
+ * meant for labelling Addr's.  We get away with it as long as the type
+ * Meter is compatible with Addr.
+ */
+
+#include "meter.h"
+#include "mpm.h"
+
+SRCID(meter, "$HopeName$");
+
+
+/* MeterInit -- initialize a meter */
+
+void MeterInit(Meter meter, char *name, void *owner)
+{
+  Word sym;
+
+  meter->name = name;
+  meter->count = 0;
+  meter->total = 0.0;
+  meter->meanSquared = 0.0;
+  meter->max = 0;
+  meter->min = (Size)-1;
+
+  sym = EventInternString(name);
+  EventLabelAddr((Addr)meter, sym); /* see .trans.label */
+  EVENT_PP(MeterInit, meter, owner);
+  UNUSED(owner); /* @@@@ hack */
+}
+
+
+/* MeterAccumulate -- accumulate another data point in the meter */
+
+void MeterAccumulate(Meter meter, Size amount)
+{
+  Count count = meter->count + 1;
+  double total = meter->total;
+  double meanSquared = meter->meanSquared;
+  double dcount = (double)count;
+
+  /* .limitation.variance: This computation accumulates a running
+   * mean^2, minimizing overflow, but sacrificing numerical stablity
+   * for small variances.  For more accuracy, the data set should be
+   * emitted using a telemetry stream and analyzed off-line.
+    .stddev: stddev = sqrt(meanSquared - mean^2).
+   */
+  meter->count = count;
+  meter->total = total + amount;
+  meter->meanSquared =
+    meanSquared / dcount * (dcount - 1.0)
+    + amount / dcount * amount;
+  if (amount > meter->max)
+    meter->max = amount;
+  if (amount < meter->min)
+    meter->min = amount;
+}
+
+
+/* MeterWrite -- describe method for meters */
+
+Res MeterWrite(Meter meter, mps_lib_FILE *stream)
+{
+  Res res = ResOK;
+
+  res = WriteF(stream,
+               "meter $S {", meter->name,
+               "count: $U", meter->count,
+               NULL);
+  if (res != ResOK)
+    return res;
+  if (meter->count > 0) {
+    double mean = meter->total / (double)meter->count;
+    
+    res = WriteF(stream,
+                 ", total: $D", meter->total,
+                 ", max: $U", meter->max,
+                 ", min: $U", meter->min,
+                 ", mean: $D", mean,
+                 ", mean^2: $D", meter->meanSquared,
+                 NULL);
+    if (res != ResOK)
+      return res;
+  }
+  res = WriteF(stream, "}\n", NULL);
+
+  return res;
+}
+
+
+/* MeterEmit -- emit an evnet with the current data from the meter */
+
+void MeterEmit(Meter meter)
+{
+  EVENT_PDDWWW(MeterValues, meter, meter->total, meter->meanSquared,
+               meter->count, meter->max, meter->min);
+  UNUSED(meter); /* @@@@ hack */
+}