ceph/src/seastar/include/seastar/core/thread_impl.hh

   1 /*
   2  * This file is open source software, licensed to you under the terms
   3  * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
   4  * distributed with this work for additional information regarding copyright
   5  * ownership.  You may not use this file except in compliance with the License.
   6  *
   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,
  12  * software distributed under the License is distributed on an
  13  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14  * KIND, either express or implied.  See the License for the
  15  * specific language governing permissions and limitations
  16  * under the License.
  17  */
  18
  19 /*
  20  * Copyright (C) 2016 ScyllaDB.
  21  */
  22
  23 #pragma once
  24 #include <seastar/core/preempt.hh>
  25 #include <setjmp.h>
  26 #include <ucontext.h>
  27 #include <chrono>
  28 #include <seastar/util/std-compat.hh>
  29
  30 namespace seastar {
  31 /// Clock used for scheduling threads
  32 using thread_clock = std::chrono::steady_clock;
  33
  34 /// \cond internal
  35 class thread_context;
  36 class scheduling_group;
  37
  38 struct jmp_buf_link {
  39 #ifdef SEASTAR_ASAN_ENABLED
  40     ucontext_t context;
  41     void* fake_stack = nullptr;
  42     const void* stack_bottom;
  43     size_t stack_size;
  44 #else
  45     jmp_buf jmpbuf;
  46 #endif
  47     jmp_buf_link* link;
  48     thread_context* thread;
  49 public:
  50     void initial_switch_in(ucontext_t* initial_context, const void* stack_bottom, size_t stack_size);
  51     void switch_in();
  52     void switch_out();
  53     void initial_switch_in_completed();
  54     void final_switch_out();
  55 };
  56
  57 extern thread_local jmp_buf_link* g_current_context;
  58
  59 namespace thread_impl {
  60
  61 inline thread_context* get() {
  62     return g_current_context->thread;
  63 }
  64
  65 inline bool should_yield() {
  66     if (need_preempt()) {
  67         return true;
  68     } else {
  69         return false;
  70     }
  71 }
  72
  73 scheduling_group sched_group(const thread_context*);
  74
  75 void yield();
  76 void switch_in(thread_context* to);
  77 void switch_out(thread_context* from);
  78 void init();
  79
  80 }
  81 }
  82 /// \endcond
  83
  84