From 536fc539cc36be41a1db2d16458a00d2e5df1c55 Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Fri, 11 Mar 2016 12:36:56 -0800
Subject: [PATCH] Integrate backoff library with subchannel
---
src/core/client_config/subchannel.c | 102 +++++++++-------------------
1 file changed, 31 insertions(+), 71 deletions(-)
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index d91dd116b8..8bd61a7e22 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/transport/connectivity_state.h"
@@ -127,8 +128,8 @@ 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 */
@@ -146,7 +147,6 @@ 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);
@@ -184,8 +184,8 @@ static void connection_destroy(grpc_exec_ctx *exec_ctx, void *arg,
gpr_free(c);
}
-void grpc_connected_subchannel_ref(grpc_connected_subchannel *c
- GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+void grpc_connected_subchannel_ref(
+ grpc_connected_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
GRPC_CHANNEL_STACK_REF(CHANNEL_STACK_FROM_CONNECTION(c), REF_REASON);
}
@@ -226,8 +226,8 @@ static gpr_atm ref_mutate(grpc_subchannel *c, gpr_atm delta,
return old_val;
}
-grpc_subchannel *grpc_subchannel_ref(grpc_subchannel *c
- GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+grpc_subchannel *grpc_subchannel_ref(
+ grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
gpr_atm old_refs;
old_refs = ref_mutate(c, (1 << INTERNAL_REF_BITS),
0 REF_MUTATE_PURPOSE("STRONG_REF"));
@@ -235,8 +235,8 @@ grpc_subchannel *grpc_subchannel_ref(grpc_subchannel *c
return c;
}
-grpc_subchannel *grpc_subchannel_weak_ref(grpc_subchannel *c
- GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+grpc_subchannel *grpc_subchannel_weak_ref(
+ grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
gpr_atm old_refs;
old_refs = ref_mutate(c, 1, 0 REF_MUTATE_PURPOSE("WEAK_REF"));
GPR_ASSERT(old_refs != 0);
@@ -337,6 +337,22 @@ 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);
@@ -348,7 +364,7 @@ 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;
@@ -359,10 +375,8 @@ 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);
}
@@ -579,50 +593,6 @@ static void publish_transport(grpc_exec_ctx *exec_ctx, grpc_subchannel *c) {
gpr_free((void *)filters);
}
-/* 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);
@@ -631,7 +601,8 @@ 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 {
@@ -661,17 +632,6 @@ static void subchannel_connected(grpc_exec_ctx *exec_ctx, void *arg,
}
}
-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
*/
@@ -686,8 +646,8 @@ static void subchannel_call_destroy(grpc_exec_ctx *exec_ctx, void *call,
GPR_TIMER_END("grpc_subchannel_call_unref.destroy", 0);
}
-void grpc_subchannel_call_ref(grpc_subchannel_call *c
- GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+void grpc_subchannel_call_ref(
+ grpc_subchannel_call *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
GRPC_CALL_STACK_REF(SUBCHANNEL_CALL_TO_CALL_STACK(c), REF_REASON);
}
--
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