1 files changed, 110 insertions, 0 deletions
diff --git a/src/core/lib/transport/bdp_estimator.cc b/src/core/lib/transport/bdp_estimator.cc
new file mode 100644
index 0000000000..8b57693413
--- /dev/null
+++ b/src/core/lib/transport/bdp_estimator.cc
@@ -0,0 +1,110 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/transport/bdp_estimator.h"
+
+#include <stdlib.h>
+
+#include <grpc/support/log.h>
+#include <grpc/support/useful.h>
+
+grpc_tracer_flag grpc_bdp_estimator_trace =
+    GRPC_TRACER_INITIALIZER(false, "bdp_estimator");
+
+void grpc_bdp_estimator_init(grpc_bdp_estimator *estimator, const char *name) {
+  estimator->estimate = 65536;
+  estimator->ping_state = GRPC_BDP_PING_UNSCHEDULED;
+  estimator->name = name;
+  estimator->bw_est = 0;
+}
+
+bool grpc_bdp_estimator_get_estimate(const grpc_bdp_estimator *estimator,
+                                     int64_t *estimate) {
+  *estimate = estimator->estimate;
+  return true;
+}
+
+bool grpc_bdp_estimator_get_bw(const grpc_bdp_estimator *estimator,
+                               double *bw) {
+  *bw = estimator->bw_est;
+  return true;
+}
+
+void grpc_bdp_estimator_add_incoming_bytes(grpc_bdp_estimator *estimator,
+                                           int64_t num_bytes) {
+  estimator->accumulator += num_bytes;
+}
+
+bool grpc_bdp_estimator_need_ping(const grpc_bdp_estimator *estimator) {
+  switch (estimator->ping_state) {
+    case GRPC_BDP_PING_UNSCHEDULED:
+      return true;
+    case GRPC_BDP_PING_SCHEDULED:
+      return false;
+    case GRPC_BDP_PING_STARTED:
+      return false;
+  }
+  GPR_UNREACHABLE_CODE(return false);
+}
+
+void grpc_bdp_estimator_schedule_ping(grpc_bdp_estimator *estimator) {
+  if (GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
+    gpr_log(GPR_DEBUG, "bdp[%s]:sched acc=%" PRId64 " est=%" PRId64,
+            estimator->name, estimator->accumulator, estimator->estimate);
+  }
+  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_UNSCHEDULED);
+  estimator->ping_state = GRPC_BDP_PING_SCHEDULED;
+  estimator->accumulator = 0;
+}
+
+void grpc_bdp_estimator_start_ping(grpc_bdp_estimator *estimator) {
+  if (GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
+    gpr_log(GPR_DEBUG, "bdp[%s]:start acc=%" PRId64 " est=%" PRId64,
+            estimator->name, estimator->accumulator, estimator->estimate);
+  }
+  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_SCHEDULED);
+  estimator->ping_state = GRPC_BDP_PING_STARTED;
+  estimator->accumulator = 0;
+  estimator->ping_start_time = gpr_now(GPR_CLOCK_MONOTONIC);
+}
+
+void grpc_bdp_estimator_complete_ping(grpc_bdp_estimator *estimator) {
+  gpr_timespec dt_ts =
+      gpr_time_sub(gpr_now(GPR_CLOCK_MONOTONIC), estimator->ping_start_time);
+  double dt = (double)dt_ts.tv_sec + 1e-9 * (double)dt_ts.tv_nsec;
+  double bw = dt > 0 ? ((double)estimator->accumulator / dt) : 0;
+  if (GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
+    gpr_log(GPR_DEBUG, "bdp[%s]:complete acc=%" PRId64 " est=%" PRId64
+                       " dt=%lf bw=%lfMbs bw_est=%lfMbs",
+            estimator->name, estimator->accumulator, estimator->estimate, dt,
+            bw / 125000.0, estimator->bw_est / 125000.0);
+  }
+  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_STARTED);
+  if (estimator->accumulator > 2 * estimator->estimate / 3 &&
+      bw > estimator->bw_est) {
+    estimator->estimate =
+        GPR_MAX(estimator->accumulator, estimator->estimate * 2);
+    estimator->bw_est = bw;
+    if (GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
+      gpr_log(GPR_DEBUG, "bdp[%s]: estimate increased to %" PRId64,
+              estimator->name, estimator->estimate);
+    }
+  }
+  estimator->ping_state = GRPC_BDP_PING_UNSCHEDULED;
+  estimator->accumulator = 0;
+}