| /* |
| * |
| * Copyright 2016 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. |
| * |
| */ |
| |
| #ifndef GRPC_CORE_LIB_GPR_MPSCQ_H |
| #define GRPC_CORE_LIB_GPR_MPSCQ_H |
| |
| #include <grpc/support/port_platform.h> |
| |
| #include <grpc/support/atm.h> |
| #include <grpc/support/sync.h> |
| #include <stdbool.h> |
| #include <stddef.h> |
| |
| // Multiple-producer single-consumer lock free queue, based upon the |
| // implementation from Dmitry Vyukov here: |
| // http://www.1024cores.net/home/lock-free-algorithms/queues/intrusive-mpsc-node-based-queue |
| |
| // List node (include this in a data structure at the top, and add application |
| // fields after it - to simulate inheritance) |
| typedef struct gpr_mpscq_node { |
| gpr_atm next; |
| } gpr_mpscq_node; |
| |
| // Actual queue type |
| typedef struct gpr_mpscq { |
| // make sure head & tail don't share a cacheline |
| union { |
| char padding[GPR_CACHELINE_SIZE]; |
| gpr_atm head; |
| }; |
| gpr_mpscq_node* tail; |
| gpr_mpscq_node stub; |
| } gpr_mpscq; |
| |
| void gpr_mpscq_init(gpr_mpscq* q); |
| void gpr_mpscq_destroy(gpr_mpscq* q); |
| // Push a node |
| // Thread safe - can be called from multiple threads concurrently |
| // Returns true if this was possibly the first node (may return true |
| // sporadically, will not return false sporadically) |
| bool gpr_mpscq_push(gpr_mpscq* q, gpr_mpscq_node* n); |
| // Pop a node (returns NULL if no node is ready - which doesn't indicate that |
| // the queue is empty!!) |
| // Thread compatible - can only be called from one thread at a time |
| gpr_mpscq_node* gpr_mpscq_pop(gpr_mpscq* q); |
| // Pop a node; sets *empty to true if the queue is empty, or false if it is not |
| gpr_mpscq_node* gpr_mpscq_pop_and_check_end(gpr_mpscq* q, bool* empty); |
| |
| // An mpscq with a lock: it's safe to pop from multiple threads, but doing |
| // only one thread will succeed concurrently |
| typedef struct gpr_locked_mpscq { |
| gpr_mpscq queue; |
| gpr_mu mu; |
| } gpr_locked_mpscq; |
| |
| void gpr_locked_mpscq_init(gpr_locked_mpscq* q); |
| void gpr_locked_mpscq_destroy(gpr_locked_mpscq* q); |
| // Push a node |
| // Thread safe - can be called from multiple threads concurrently |
| // Returns true if this was possibly the first node (may return true |
| // sporadically, will not return false sporadically) |
| bool gpr_locked_mpscq_push(gpr_locked_mpscq* q, gpr_mpscq_node* n); |
| |
| // Pop a node (returns NULL if no node is ready - which doesn't indicate that |
| // the queue is empty!!) |
| // Thread safe - can be called from multiple threads concurrently |
| gpr_mpscq_node* gpr_locked_mpscq_try_pop(gpr_locked_mpscq* q); |
| |
| // Pop a node. Returns NULL only if the queue was empty at some point after |
| // calling this function |
| gpr_mpscq_node* gpr_locked_mpscq_pop(gpr_locked_mpscq* q); |
| |
| #endif /* GRPC_CORE_LIB_GPR_MPSCQ_H */ |