Add time averaged stats for future alarm list work.

This is a trivial C89-ification of the []2 implementation of the same idea.
Indeed the implementation files and tests have been branched from the [] versions.
	Change on 2014/12/15 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82168822

1 files changed, 208 insertions, 0 deletions

diff --git a/test/core/iomgr/time_averaged_stats_test.c b/test/core/iomgr/time_averaged_stats_test.c
new file mode 100644
index 0000000000..7ed2f84f21
--- /dev/null
+++ b/test/core/iomgr/time_averaged_stats_test.c
@@ -0,0 +1,208 @@
+/*
+ *
+ * Copyright 2014, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/iomgr/time_averaged_stats.h"
+
+#include <math.h>
+
+#include <grpc/support/log.h>
+#include "test/core/util/test_config.h"
+
+#define EXPECT_EQ(a, b) GPR_ASSERT((a) == (b))
+#define EXPECT_DOUBLE_EQ(a, b) GPR_ASSERT(fabs((a) - (b)) < 1e-9)
+
+static void no_regress_no_persist_test_1() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0, 0.0);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(0, tas.aggregate_total_weight);
+
+  /* Should have no effect */
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(0, tas.aggregate_total_weight);
+
+  /* Should replace old average */
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(2000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1, tas.aggregate_total_weight);
+}
+
+static void no_regress_no_persist_test_2() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0, 0.0);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  /* Should replace init value */
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(2000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 3000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(3000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1, tas.aggregate_total_weight);
+}
+
+static void no_regress_no_persist_test_3() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0, 0.0);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  /* Should replace init value */
+  grpc_time_averaged_stats_add_sample(&tas, 2500);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(2500, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 3500);
+  grpc_time_averaged_stats_add_sample(&tas, 4500);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(4000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2, tas.aggregate_total_weight);
+}
+
+static void some_regress_no_persist_test() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0.5, 0.0);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(0, tas.aggregate_total_weight);
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  /* (2 * 2000 + 0.5 * 1000) / 2.5 */
+  EXPECT_DOUBLE_EQ(1800, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2.5, tas.aggregate_total_weight);
+}
+
+static void some_decay_test() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 1, 0.0);
+  EXPECT_EQ(1000, tas.aggregate_weighted_avg);
+  /* Should avg with init value */
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(1500, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(1500, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(1500, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2, tas.aggregate_total_weight);
+}
+
+static void no_regress_full_persist_test() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0, 1.0);
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(0, tas.aggregate_total_weight);
+
+  /* Should replace init value */
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_EQ(2000, tas.aggregate_weighted_avg);
+  EXPECT_EQ(1, tas.aggregate_total_weight);
+
+  /* Will result in average of the 3 samples. */
+  grpc_time_averaged_stats_add_sample(&tas, 2300);
+  grpc_time_averaged_stats_add_sample(&tas, 2300);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(2200, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(3, tas.aggregate_total_weight);
+}
+
+static void no_regress_some_persist_test() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0, 0.5);
+  /* Should replace init value */
+  grpc_time_averaged_stats_add_sample(&tas, 2000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(2000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 2500);
+  grpc_time_averaged_stats_add_sample(&tas, 4000);
+  grpc_time_averaged_stats_update_average(&tas);
+  EXPECT_DOUBLE_EQ(3000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2.5, tas.aggregate_total_weight);
+}
+
+static void some_regress_some_persist_test() {
+  grpc_time_averaged_stats tas;
+  grpc_time_averaged_stats_init(&tas, 1000, 0.4, 0.6);
+  /* Sample weight = 0 */
+  EXPECT_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_EQ(0, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_update_average(&tas);
+  /* (0.6 * 0 * 1000 + 0.4 * 1000 / 0.4) */
+  EXPECT_DOUBLE_EQ(1000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(0.4, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 2640);
+  grpc_time_averaged_stats_update_average(&tas);
+  /* (1 * 2640 + 0.6 * 0.4 * 1000 + 0.4 * 1000 / (1 + 0.6 * 0.4 + 0.4) */
+  EXPECT_DOUBLE_EQ(2000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(1.64, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 2876.8);
+  grpc_time_averaged_stats_update_average(&tas);
+  /* (1 * 2876.8 + 0.6 * 1.64 * 2000 + 0.4 * 1000 / (1 + 0.6 * 1.64 + 0.4) */
+  EXPECT_DOUBLE_EQ(2200, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2.384, tas.aggregate_total_weight);
+
+  grpc_time_averaged_stats_add_sample(&tas, 4944.32);
+  grpc_time_averaged_stats_update_average(&tas);
+  /* (1 * 4944.32 + 0.6 * 2.384 * 2200 + 0.4 * 1000) /
+         (1 + 0.6 * 2.384 + 0.4) */
+  EXPECT_DOUBLE_EQ(3000, tas.aggregate_weighted_avg);
+  EXPECT_DOUBLE_EQ(2.8304, tas.aggregate_total_weight);
+}
+
+int main(int argc, char **argv) {
+  grpc_test_init(argc, argv);
+  no_regress_no_persist_test_1();
+  no_regress_no_persist_test_2();
+  no_regress_no_persist_test_3();
+  some_regress_no_persist_test();
+  some_decay_test();
+  no_regress_full_persist_test();
+  no_regress_some_persist_test();
+  some_regress_some_persist_test();
+  return 0;
+}