Mark D. Roth | 764cf04 | 2017-09-01 09:00:06 -0700 | [diff] [blame] | 1 | /* |
| 2 | * |
| 3 | * Copyright 2017 gRPC authors. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | #include "src/core/lib/iomgr/call_combiner.h" |
| 20 | |
| 21 | #include <grpc/support/log.h> |
| 22 | |
| 23 | grpc_tracer_flag grpc_call_combiner_trace = |
| 24 | GRPC_TRACER_INITIALIZER(false, "call_combiner"); |
| 25 | |
| 26 | static grpc_error* decode_cancel_state_error(gpr_atm cancel_state) { |
| 27 | if (cancel_state & 1) { |
| 28 | return (grpc_error*)(cancel_state & ~(gpr_atm)1); |
| 29 | } |
| 30 | return GRPC_ERROR_NONE; |
| 31 | } |
| 32 | |
| 33 | static gpr_atm encode_cancel_state_error(grpc_error* error) { |
| 34 | return (gpr_atm)1 | (gpr_atm)error; |
| 35 | } |
| 36 | |
| 37 | void grpc_call_combiner_init(grpc_call_combiner* call_combiner) { |
| 38 | gpr_mpscq_init(&call_combiner->queue); |
| 39 | } |
| 40 | |
| 41 | void grpc_call_combiner_destroy(grpc_call_combiner* call_combiner) { |
| 42 | gpr_mpscq_destroy(&call_combiner->queue); |
| 43 | GRPC_ERROR_UNREF(decode_cancel_state_error(call_combiner->cancel_state)); |
| 44 | } |
| 45 | |
| 46 | #ifndef NDEBUG |
| 47 | #define DEBUG_ARGS , const char *file, int line |
| 48 | #define DEBUG_FMT_STR "%s:%d: " |
| 49 | #define DEBUG_FMT_ARGS , file, line |
| 50 | #else |
| 51 | #define DEBUG_ARGS |
| 52 | #define DEBUG_FMT_STR |
| 53 | #define DEBUG_FMT_ARGS |
| 54 | #endif |
| 55 | |
| 56 | void grpc_call_combiner_start(grpc_exec_ctx* exec_ctx, |
| 57 | grpc_call_combiner* call_combiner, |
| 58 | grpc_closure* closure, |
| 59 | grpc_error* error DEBUG_ARGS, |
| 60 | const char* reason) { |
| 61 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 62 | gpr_log(GPR_DEBUG, |
| 63 | "==> grpc_call_combiner_start() [%p] closure=%p [" DEBUG_FMT_STR |
| 64 | "%s] error=%s", |
| 65 | call_combiner, closure DEBUG_FMT_ARGS, reason, |
| 66 | grpc_error_string(error)); |
| 67 | } |
| 68 | size_t prev_size = |
| 69 | (size_t)gpr_atm_full_fetch_add(&call_combiner->size, (gpr_atm)1); |
| 70 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 71 | gpr_log(GPR_DEBUG, " size: %" PRIdPTR " -> %" PRIdPTR, prev_size, |
| 72 | prev_size + 1); |
| 73 | } |
| 74 | if (prev_size == 0) { |
| 75 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 76 | gpr_log(GPR_DEBUG, " EXECUTING IMMEDIATELY"); |
| 77 | } |
| 78 | // Queue was empty, so execute this closure immediately. |
| 79 | GRPC_CLOSURE_SCHED(exec_ctx, closure, error); |
| 80 | } else { |
| 81 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 82 | gpr_log(GPR_INFO, " QUEUING"); |
| 83 | } |
| 84 | // Queue was not empty, so add closure to queue. |
| 85 | closure->error_data.error = error; |
| 86 | gpr_mpscq_push(&call_combiner->queue, (gpr_mpscq_node*)closure); |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | void grpc_call_combiner_stop(grpc_exec_ctx* exec_ctx, |
| 91 | grpc_call_combiner* call_combiner DEBUG_ARGS, |
| 92 | const char* reason) { |
| 93 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 94 | gpr_log(GPR_DEBUG, |
| 95 | "==> grpc_call_combiner_stop() [%p] [" DEBUG_FMT_STR "%s]", |
| 96 | call_combiner DEBUG_FMT_ARGS, reason); |
| 97 | } |
| 98 | size_t prev_size = |
| 99 | (size_t)gpr_atm_full_fetch_add(&call_combiner->size, (gpr_atm)-1); |
| 100 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 101 | gpr_log(GPR_DEBUG, " size: %" PRIdPTR " -> %" PRIdPTR, prev_size, |
| 102 | prev_size - 1); |
| 103 | } |
| 104 | GPR_ASSERT(prev_size >= 1); |
| 105 | if (prev_size > 1) { |
| 106 | while (true) { |
| 107 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 108 | gpr_log(GPR_DEBUG, " checking queue"); |
| 109 | } |
| 110 | bool empty; |
| 111 | grpc_closure* closure = (grpc_closure*)gpr_mpscq_pop_and_check_end( |
| 112 | &call_combiner->queue, &empty); |
| 113 | if (closure == NULL) { |
| 114 | // This can happen either due to a race condition within the mpscq |
| 115 | // code or because of a race with grpc_call_combiner_start(). |
| 116 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 117 | gpr_log(GPR_DEBUG, " queue returned no result; checking again"); |
| 118 | } |
| 119 | continue; |
| 120 | } |
| 121 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 122 | gpr_log(GPR_DEBUG, " EXECUTING FROM QUEUE: closure=%p error=%s", |
| 123 | closure, grpc_error_string(closure->error_data.error)); |
| 124 | } |
| 125 | GRPC_CLOSURE_SCHED(exec_ctx, closure, closure->error_data.error); |
| 126 | break; |
| 127 | } |
| 128 | } else if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 129 | gpr_log(GPR_DEBUG, " queue empty"); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | void grpc_call_combiner_set_notify_on_cancel(grpc_exec_ctx* exec_ctx, |
| 134 | grpc_call_combiner* call_combiner, |
| 135 | grpc_closure* closure) { |
| 136 | while (true) { |
| 137 | // Decode original state. |
| 138 | gpr_atm original_state = gpr_atm_acq_load(&call_combiner->cancel_state); |
| 139 | grpc_error* original_error = decode_cancel_state_error(original_state); |
| 140 | // If error is set, invoke the cancellation closure immediately. |
| 141 | // Otherwise, store the new closure. |
| 142 | if (original_error != GRPC_ERROR_NONE) { |
Mark D. Roth | 66f3d2b | 2017-09-01 09:02:17 -0700 | [diff] [blame^] | 143 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 144 | gpr_log(GPR_DEBUG, |
| 145 | "call_combiner=%p: scheduling notify_on_cancel callback=%p " |
| 146 | "for pre-existing cancellation", |
| 147 | call_combiner, closure); |
| 148 | } |
Mark D. Roth | 764cf04 | 2017-09-01 09:00:06 -0700 | [diff] [blame] | 149 | GRPC_CLOSURE_SCHED(exec_ctx, closure, GRPC_ERROR_REF(original_error)); |
| 150 | break; |
| 151 | } else { |
| 152 | if (gpr_atm_full_cas(&call_combiner->cancel_state, original_state, |
| 153 | (gpr_atm)closure)) { |
Mark D. Roth | 66f3d2b | 2017-09-01 09:02:17 -0700 | [diff] [blame^] | 154 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 155 | gpr_log(GPR_DEBUG, "call_combiner=%p: setting notify_on_cancel=%p", |
| 156 | call_combiner, closure); |
| 157 | } |
| 158 | // If we replaced an earlier closure, invoke the original |
| 159 | // closure with GRPC_ERROR_NONE. This allows callers to clean |
| 160 | // up any resources they may be holding for the callback. |
| 161 | if (original_state != 0) { |
| 162 | closure = (grpc_closure*)original_state; |
| 163 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 164 | gpr_log(GPR_DEBUG, |
| 165 | "call_combiner=%p: scheduling old cancel callback=%p", |
| 166 | call_combiner, closure); |
| 167 | } |
| 168 | GRPC_CLOSURE_SCHED(exec_ctx, closure, GRPC_ERROR_NONE); |
| 169 | } |
Mark D. Roth | 764cf04 | 2017-09-01 09:00:06 -0700 | [diff] [blame] | 170 | break; |
| 171 | } |
| 172 | } |
| 173 | // cas failed, try again. |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | void grpc_call_combiner_cancel(grpc_exec_ctx* exec_ctx, |
| 178 | grpc_call_combiner* call_combiner, |
| 179 | grpc_error* error) { |
| 180 | while (true) { |
| 181 | gpr_atm original_state = gpr_atm_acq_load(&call_combiner->cancel_state); |
| 182 | grpc_error* original_error = decode_cancel_state_error(original_state); |
| 183 | if (original_error != GRPC_ERROR_NONE) { |
| 184 | GRPC_ERROR_UNREF(error); |
| 185 | break; |
| 186 | } |
| 187 | if (gpr_atm_full_cas(&call_combiner->cancel_state, original_state, |
| 188 | encode_cancel_state_error(error))) { |
| 189 | if (original_state != 0) { |
| 190 | grpc_closure* notify_on_cancel = (grpc_closure*)original_state; |
| 191 | if (GRPC_TRACER_ON(grpc_call_combiner_trace)) { |
| 192 | gpr_log(GPR_DEBUG, |
| 193 | "call_combiner=%p: scheduling notify_on_cancel callback=%p", |
| 194 | call_combiner, notify_on_cancel); |
| 195 | } |
| 196 | GRPC_CLOSURE_SCHED(exec_ctx, notify_on_cancel, GRPC_ERROR_REF(error)); |
| 197 | } |
| 198 | break; |
| 199 | } |
| 200 | // cas failed, try again. |
| 201 | } |
| 202 | } |