diff options
author | Yash Tibrewal <yashkt@google.com> | 2017-09-21 18:56:08 -0700 |
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committer | Yash Tibrewal <yashkt@google.com> | 2017-10-02 16:29:41 -0700 |
commit | 83062842c3601faeddcae8f901c515e3c78f3661 (patch) | |
tree | 58536b25350a5f2b3123161ab4ca9b8ce01a43a5 /src/core/ext/filters/client_channel/retry_throttle.cc | |
parent | 1c9b584a153ff592c92b6cf6baa620d8602a37cd (diff) |
Changes for C to C++. Adding extern C to header files for compatibility.
Also converting to .cc
Diffstat (limited to 'src/core/ext/filters/client_channel/retry_throttle.cc')
-rw-r--r-- | src/core/ext/filters/client_channel/retry_throttle.cc | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/retry_throttle.cc b/src/core/ext/filters/client_channel/retry_throttle.cc new file mode 100644 index 0000000000..09dcade089 --- /dev/null +++ b/src/core/ext/filters/client_channel/retry_throttle.cc @@ -0,0 +1,202 @@ +/* + * + * Copyright 2017 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/ext/filters/client_channel/retry_throttle.h" + +#include <limits.h> +#include <string.h> + +#include <grpc/support/alloc.h> +#include <grpc/support/atm.h> +#include <grpc/support/avl.h> +#include <grpc/support/string_util.h> +#include <grpc/support/sync.h> + +// +// server_retry_throttle_data +// + +struct grpc_server_retry_throttle_data { + gpr_refcount refs; + int max_milli_tokens; + int milli_token_ratio; + gpr_atm milli_tokens; + // A pointer to the replacement for this grpc_server_retry_throttle_data + // entry. If non-NULL, then this entry is stale and must not be used. + // We hold a reference to the replacement. + gpr_atm replacement; +}; + +static void get_replacement_throttle_data_if_needed( + grpc_server_retry_throttle_data** throttle_data) { + while (true) { + grpc_server_retry_throttle_data* new_throttle_data = + (grpc_server_retry_throttle_data*)gpr_atm_acq_load( + &(*throttle_data)->replacement); + if (new_throttle_data == NULL) return; + *throttle_data = new_throttle_data; + } +} + +bool grpc_server_retry_throttle_data_record_failure( + grpc_server_retry_throttle_data* throttle_data) { + // 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 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; +} + +void grpc_server_retry_throttle_data_record_success( + grpc_server_retry_throttle_data* throttle_data) { + // 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. + 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( + grpc_server_retry_throttle_data* throttle_data) { + gpr_ref(&throttle_data->refs); + return throttle_data; +} + +void grpc_server_retry_throttle_data_unref( + grpc_server_retry_throttle_data* throttle_data) { + if (gpr_unref(&throttle_data->refs)) { + grpc_server_retry_throttle_data* replacement = + (grpc_server_retry_throttle_data*)gpr_atm_acq_load( + &throttle_data->replacement); + if (replacement != NULL) { + grpc_server_retry_throttle_data_unref(replacement); + } + gpr_free(throttle_data); + } +} + +static grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_create( + int max_milli_tokens, int milli_token_ratio, + grpc_server_retry_throttle_data* old_throttle_data) { + grpc_server_retry_throttle_data* throttle_data = + (grpc_server_retry_throttle_data*)gpr_malloc(sizeof(*throttle_data)); + memset(throttle_data, 0, sizeof(*throttle_data)); + gpr_ref_init(&throttle_data->refs, 1); + throttle_data->max_milli_tokens = max_milli_tokens; + throttle_data->milli_token_ratio = milli_token_ratio; + int initial_milli_tokens = max_milli_tokens; + // If there was a pre-existing entry for this server name, initialize + // the token count by scaling proportionately to the old data. This + // ensures that if we're already throttling retries on the old scale, + // we will start out doing the same thing on the new one. + if (old_throttle_data != NULL) { + double token_fraction = + (int)gpr_atm_acq_load(&old_throttle_data->milli_tokens) / + (double)old_throttle_data->max_milli_tokens; + initial_milli_tokens = (int)(token_fraction * max_milli_tokens); + } + gpr_atm_rel_store(&throttle_data->milli_tokens, + (gpr_atm)initial_milli_tokens); + // If there was a pre-existing entry, mark it as stale and give it a + // pointer to the new entry, which is its replacement. + if (old_throttle_data != NULL) { + grpc_server_retry_throttle_data_ref(throttle_data); + gpr_atm_rel_store(&old_throttle_data->replacement, (gpr_atm)throttle_data); + } + return throttle_data; +} + +// +// avl vtable for string -> server_retry_throttle_data map +// + +static void* copy_server_name(void* key, void* unused) { + return gpr_strdup((const char*)key); +} + +static long compare_server_name(void* key1, void* key2, void* unused) { + return strcmp((const char*)key1, (const char*)key2); +} + +static void destroy_server_retry_throttle_data(void* value, void* unused) { + grpc_server_retry_throttle_data* throttle_data = + (grpc_server_retry_throttle_data*)value; + grpc_server_retry_throttle_data_unref(throttle_data); +} + +static void* copy_server_retry_throttle_data(void* value, void* unused) { + grpc_server_retry_throttle_data* throttle_data = + (grpc_server_retry_throttle_data*)value; + return grpc_server_retry_throttle_data_ref(throttle_data); +} + +static void destroy_server_name(void* key, void* unused) { gpr_free(key); } + +static const gpr_avl_vtable avl_vtable = { + destroy_server_name, copy_server_name, compare_server_name, + destroy_server_retry_throttle_data, copy_server_retry_throttle_data}; + +// +// server_retry_throttle_map +// + +static gpr_mu g_mu; +static gpr_avl g_avl; + +void grpc_retry_throttle_map_init() { + gpr_mu_init(&g_mu); + g_avl = gpr_avl_create(&avl_vtable); +} + +void grpc_retry_throttle_map_shutdown() { + gpr_mu_destroy(&g_mu); + gpr_avl_unref(g_avl, NULL); +} + +grpc_server_retry_throttle_data* grpc_retry_throttle_map_get_data_for_server( + const char* server_name, int max_milli_tokens, int milli_token_ratio) { + gpr_mu_lock(&g_mu); + grpc_server_retry_throttle_data* throttle_data = + (grpc_server_retry_throttle_data*)gpr_avl_get(g_avl, (char*)server_name, + NULL); + if (throttle_data == NULL) { + // Entry not found. Create a new one. + throttle_data = grpc_server_retry_throttle_data_create( + max_milli_tokens, milli_token_ratio, NULL); + g_avl = gpr_avl_add(g_avl, (char*)server_name, throttle_data, NULL); + } else { + if (throttle_data->max_milli_tokens != max_milli_tokens || + throttle_data->milli_token_ratio != milli_token_ratio) { + // Entry found but with old parameters. Create a new one based on + // the original one. + throttle_data = grpc_server_retry_throttle_data_create( + max_milli_tokens, milli_token_ratio, throttle_data); + g_avl = gpr_avl_add(g_avl, (char*)server_name, throttle_data, NULL); + } else { + // Entry found. Increase refcount. + grpc_server_retry_throttle_data_ref(throttle_data); + } + } + gpr_mu_unlock(&g_mu); + return throttle_data; +} |