diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/core/ext/client_channel/retry_throttle.c | 36 | ||||
-rw-r--r-- | src/core/lib/support/atm.c | 47 | ||||
-rw-r--r-- | src/python/grpcio/grpc_core_dependencies.py | 1 |
3 files changed, 54 insertions, 30 deletions
diff --git a/src/core/ext/client_channel/retry_throttle.c b/src/core/ext/client_channel/retry_throttle.c index 7b813c33df..8926c3d782 100644 --- a/src/core/ext/client_channel/retry_throttle.c +++ b/src/core/ext/client_channel/retry_throttle.c @@ -73,20 +73,9 @@ bool grpc_server_retry_throttle_data_record_failure( // First, check if we are stale and need to be replaced. get_replacement_throttle_data_if_needed(&throttle_data); // We decrement milli_tokens by 1000 (1 token) for each failure. - const int delta = -1000; - const int old_value = (int)gpr_atm_full_fetch_add( - &throttle_data->milli_tokens, (gpr_atm)delta); - // If the above change takes us below 0, then re-add the excess. Note - // that between these two atomic operations, the value will be - // artificially low by as much as 1000, but this window should be - // brief. - int new_value = old_value - 1000; - if (new_value < 0) { - const int excess_value = new_value - (old_value < 0 ? old_value : 0); - gpr_atm_full_fetch_add(&throttle_data->milli_tokens, - (gpr_atm)-excess_value); - new_value = 0; - } + const int new_value = (int)gpr_atm_no_barrier_clamped_add( + &throttle_data->milli_tokens, (gpr_atm)-1000, (gpr_atm)0, + (gpr_atm)throttle_data->max_milli_tokens); // Retries are allowed as long as the new value is above the threshold // (max_milli_tokens / 2). return new_value > throttle_data->max_milli_tokens / 2; @@ -97,22 +86,9 @@ void grpc_server_retry_throttle_data_record_success( // First, check if we are stale and need to be replaced. get_replacement_throttle_data_if_needed(&throttle_data); // We increment milli_tokens by milli_token_ratio for each success. - const int delta = throttle_data->milli_token_ratio; - const int old_value = (int)gpr_atm_full_fetch_add( - &throttle_data->milli_tokens, (gpr_atm)delta); - // If the above change takes us over max_milli_tokens, then subtract - // the excess. Note that between these two atomic operations, the - // value will be artificially high by as much as milli_token_ratio, - // but this window should be brief. - const int new_value = old_value + throttle_data->milli_token_ratio; - if (new_value > throttle_data->max_milli_tokens) { - const int excess_value = - new_value - (old_value > throttle_data->max_milli_tokens - ? old_value - : throttle_data->max_milli_tokens); - gpr_atm_full_fetch_add(&throttle_data->milli_tokens, - (gpr_atm)-excess_value); - } + gpr_atm_no_barrier_clamped_add( + &throttle_data->milli_tokens, (gpr_atm)throttle_data->milli_token_ratio, + (gpr_atm)0, (gpr_atm)throttle_data->max_milli_tokens); } grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_ref( diff --git a/src/core/lib/support/atm.c b/src/core/lib/support/atm.c new file mode 100644 index 0000000000..06e8432caf --- /dev/null +++ b/src/core/lib/support/atm.c @@ -0,0 +1,47 @@ +/* + * + * Copyright 2017, 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 <grpc/support/atm.h> +#include <grpc/support/useful.h> + +gpr_atm gpr_atm_no_barrier_clamped_add(gpr_atm *value, gpr_atm delta, + gpr_atm min, gpr_atm max) { + gpr_atm current; + gpr_atm new; + do { + current = gpr_atm_no_barrier_load(value); + new = GPR_CLAMP(current + delta, min, max); + if (new == current) break; + } while (!gpr_atm_no_barrier_cas(value, current, new)); + return new; +} diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py index 94d6e46cae..da0dba7dfe 100644 --- a/src/python/grpcio/grpc_core_dependencies.py +++ b/src/python/grpcio/grpc_core_dependencies.py @@ -33,6 +33,7 @@ CORE_SOURCE_FILES = [ 'src/core/lib/profiling/basic_timers.c', 'src/core/lib/profiling/stap_timers.c', 'src/core/lib/support/alloc.c', + 'src/core/lib/support/atm.c', 'src/core/lib/support/avl.c', 'src/core/lib/support/backoff.c', 'src/core/lib/support/cmdline.c', |