Merge github.com:grpc/grpc into filter-selection

3 files changed, 159 insertions, 63 deletions

diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index de28437d0c..8f150a8d81 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -45,6 +45,7 @@
 #include "src/core/client_config/subchannel_index.h"
 #include "src/core/iomgr/timer.h"
 #include "src/core/profiling/timers.h"
+#include "src/core/support/backoff.h"
 #include "src/core/surface/channel.h"
 #include "src/core/surface/channel_init.h"
 #include "src/core/transport/connectivity_state.h"
@@ -128,8 +129,8 @@ struct grpc_subchannel {
 
   /** next connect attempt time */
   gpr_timespec next_attempt;
-  /** amount to backoff each failure */
-  gpr_timespec backoff_delta;
+  /** backoff state */
+  gpr_backoff backoff_state;
   /** do we have an active alarm? */
   int have_alarm;
   /** our alarm */
@@ -147,7 +148,6 @@ struct grpc_subchannel_call {
 #define CALLSTACK_TO_SUBCHANNEL_CALL(callstack) \
   (((grpc_subchannel_call *)(callstack)) - 1)
 
-static gpr_timespec compute_connect_deadline(grpc_subchannel *c);
 static void subchannel_connected(grpc_exec_ctx *exec_ctx, void *subchannel,
                                  bool iomgr_success);
 
@@ -338,6 +338,22 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
   grpc_closure_init(&c->connected, subchannel_connected, c);
   grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE,
                                "subchannel");
+  gpr_backoff_init(&c->backoff_state,
+                   GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER,
+                   GRPC_SUBCHANNEL_RECONNECT_JITTER,
+                   GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS * 1000,
+                   GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
+  if (c->args) {
+    for (size_t i = 0; i < c->args->num_args; i++) {
+      if (0 == strcmp(c->args->args[i].key,
+                      "grpc.testing.fixed_reconnect_backoff")) {
+        GPR_ASSERT(c->args->args[i].type == GRPC_ARG_INTEGER);
+        gpr_backoff_init(&c->backoff_state, 1.0, 0.0,
+                         c->args->args[i].value.integer,
+                         c->args->args[i].value.integer);
+      }
+    }
+  }
   gpr_mu_init(&c->mu);
 
   return grpc_subchannel_index_register(exec_ctx, key, c);
@@ -349,7 +365,7 @@ static void continue_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
   args.interested_parties = c->pollset_set;
   args.addr = c->addr;
   args.addr_len = c->addr_len;
-  args.deadline = compute_connect_deadline(c);
+  args.deadline = c->next_attempt;
   args.channel_args = c->args;
   args.initial_connect_string = c->initial_connect_string;
 
@@ -360,10 +376,8 @@ static void continue_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
 }
 
 static void start_connect(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
-  c->backoff_delta = gpr_time_from_seconds(
-      GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS, GPR_TIMESPAN);
   c->next_attempt =
-      gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
+      gpr_backoff_begin(&c->backoff_state, gpr_now(GPR_CLOCK_MONOTONIC));
   continue_connect(exec_ctx, c);
 }
 
@@ -557,50 +571,6 @@ static void publish_transport_locked(grpc_exec_ctx *exec_ctx,
                               "connected");
 }
 
-/* Generate a random number between 0 and 1. */
-static double generate_uniform_random_number(grpc_subchannel *c) {
-  c->random = (1103515245 * c->random + 12345) % ((uint32_t)1 << 31);
-  return c->random / (double)((uint32_t)1 << 31);
-}
-
-/* Update backoff_delta and next_attempt in subchannel */
-static void update_reconnect_parameters(grpc_subchannel *c) {
-  size_t i;
-  int32_t backoff_delta_millis, jitter;
-  int32_t max_backoff_millis =
-      GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000;
-  double jitter_range;
-
-  if (c->args) {
-    for (i = 0; i < c->args->num_args; i++) {
-      if (0 == strcmp(c->args->args[i].key,
-                      "grpc.testing.fixed_reconnect_backoff")) {
-        GPR_ASSERT(c->args->args[i].type == GRPC_ARG_INTEGER);
-        c->next_attempt = gpr_time_add(
-            gpr_now(GPR_CLOCK_MONOTONIC),
-            gpr_time_from_millis(c->args->args[i].value.integer, GPR_TIMESPAN));
-        return;
-      }
-    }
-  }
-
-  backoff_delta_millis =
-      (int32_t)(gpr_time_to_millis(c->backoff_delta) *
-                GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER);
-  if (backoff_delta_millis > max_backoff_millis) {
-    backoff_delta_millis = max_backoff_millis;
-  }
-  c->backoff_delta = gpr_time_from_millis(backoff_delta_millis, GPR_TIMESPAN);
-  c->next_attempt =
-      gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), c->backoff_delta);
-
-  jitter_range = GRPC_SUBCHANNEL_RECONNECT_JITTER * backoff_delta_millis;
-  jitter =
-      (int32_t)((2 * generate_uniform_random_number(c) - 1) * jitter_range);
-  c->next_attempt =
-      gpr_time_add(c->next_attempt, gpr_time_from_millis(jitter, GPR_TIMESPAN));
-}
-
 static void on_alarm(grpc_exec_ctx *exec_ctx, void *arg, bool iomgr_success) {
   grpc_subchannel *c = arg;
   gpr_mu_lock(&c->mu);
@@ -609,7 +579,8 @@ static void on_alarm(grpc_exec_ctx *exec_ctx, void *arg, bool iomgr_success) {
     iomgr_success = 0;
   }
   if (iomgr_success) {
-    update_reconnect_parameters(c);
+    c->next_attempt =
+        gpr_backoff_step(&c->backoff_state, gpr_now(GPR_CLOCK_MONOTONIC));
     continue_connect(exec_ctx, c);
     gpr_mu_unlock(&c->mu);
   } else {
@@ -641,17 +612,6 @@ static void subchannel_connected(grpc_exec_ctx *exec_ctx, void *arg,
   GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, c, "connecting");
 }
 
-static gpr_timespec compute_connect_deadline(grpc_subchannel *c) {
-  gpr_timespec current_deadline =
-      gpr_time_add(c->next_attempt, c->backoff_delta);
-  gpr_timespec min_deadline = gpr_time_add(
-      gpr_now(GPR_CLOCK_MONOTONIC),
-      gpr_time_from_seconds(GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS,
-                            GPR_TIMESPAN));
-  return gpr_time_cmp(current_deadline, min_deadline) > 0 ? current_deadline
-                                                          : min_deadline;
-}
-
 /*
  * grpc_subchannel_call implementation
  */
diff --git a/src/core/support/backoff.c b/src/core/support/backoff.c
new file mode 100644
index 0000000000..7458219645
--- /dev/null
+++ b/src/core/support/backoff.c
@@ -0,0 +1,71 @@
+/*
+ *
+ * Copyright 2016, 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/support/backoff.h"
+
+#include <grpc/support/useful.h>
+
+void gpr_backoff_init(gpr_backoff *backoff, double multiplier, double jitter,
+                      int64_t min_timeout_millis, int64_t max_timeout_millis) {
+  backoff->multiplier = multiplier;
+  backoff->jitter = jitter;
+  backoff->min_timeout_millis = min_timeout_millis;
+  backoff->max_timeout_millis = max_timeout_millis;
+  backoff->rng_state = (uint32_t)gpr_now(GPR_CLOCK_REALTIME).tv_nsec;
+}
+
+gpr_timespec gpr_backoff_begin(gpr_backoff *backoff, gpr_timespec now) {
+  backoff->current_timeout_millis = backoff->min_timeout_millis;
+  return gpr_time_add(
+      now, gpr_time_from_millis(backoff->current_timeout_millis, GPR_TIMESPAN));
+}
+
+/* Generate a random number between 0 and 1. */
+static double generate_uniform_random_number(uint32_t *rng_state) {
+  *rng_state = (1103515245 * *rng_state + 12345) % ((uint32_t)1 << 31);
+  return *rng_state / (double)((uint32_t)1 << 31);
+}
+
+gpr_timespec gpr_backoff_step(gpr_backoff *backoff, gpr_timespec now) {
+  double new_timeout_millis =
+      backoff->multiplier * (double)backoff->current_timeout_millis;
+  double jitter_range = backoff->jitter * new_timeout_millis;
+  double jitter =
+      (2 * generate_uniform_random_number(&backoff->rng_state) - 1) *
+      jitter_range;
+  backoff->current_timeout_millis =
+      GPR_CLAMP((int64_t)(new_timeout_millis + jitter),
+                backoff->min_timeout_millis, backoff->max_timeout_millis);
+  return gpr_time_add(
+      now, gpr_time_from_millis(backoff->current_timeout_millis, GPR_TIMESPAN));
+}
diff --git a/src/core/support/backoff.h b/src/core/support/backoff.h
new file mode 100644
index 0000000000..3234aa214d
--- /dev/null
+++ b/src/core/support/backoff.h
@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2016, 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_SUPPORT_BACKOFF_H
+#define GRPC_INTERNAL_CORE_SUPPORT_BACKOFF_H
+
+#include <grpc/support/time.h>
+
+typedef struct {
+  /// const: multiplier between retry attempts
+  double multiplier;
+  /// const: amount to randomize backoffs
+  double jitter;
+  /// const: minimum time between retries in milliseconds
+  int64_t min_timeout_millis;
+  /// const: maximum time between retries in milliseconds
+  int64_t max_timeout_millis;
+
+  /// random number generator
+  uint32_t rng_state;
+
+  /// current retry timeout in milliseconds
+  int64_t current_timeout_millis;
+} gpr_backoff;
+
+/// Initialize backoff machinery - does not need to be destroyed
+void gpr_backoff_init(gpr_backoff *backoff, double multiplier, double jitter,
+                      int64_t min_timeout_millis, int64_t max_timeout_millis);
+
+/// Begin retry loop: returns a timespec for the NEXT retry
+gpr_timespec gpr_backoff_begin(gpr_backoff *backoff, gpr_timespec now);
+/// Step a retry loop: returns a timespec for the NEXT retry
+gpr_timespec gpr_backoff_step(gpr_backoff *backoff, gpr_timespec now);
+
+#endif  // GRPC_INTERNAL_CORE_SUPPORT_BACKOFF_H