brpc/src/bthread/task_group.cpp at master · apache/brpc · GitHub

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// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements. See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership. The ASF licenses this file

// to you 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.

// bthread - An M:N threading library to make applications more concurrent.

// Date: Tue Jul 10 17:40:58 CST 2012

#include <sys/types.h>

#include <stddef.h> // size_t

#include <gflags/gflags.h>

#include "butil/compat.h" // OS_MACOSX

#include "butil/macros.h" // ARRAY_SIZE

#include "butil/scoped_lock.h" // BAIDU_SCOPED_LOCK

#include "butil/fast_rand.h"

#include "butil/unique_ptr.h"

#include "butil/third_party/murmurhash3/murmurhash3.h" // fmix64

#include "butil/reloadable_flags.h"

#include "bthread/errno.h" // ESTOP

#include "bthread/butex.h" // butex_*

#include "bthread/sys_futex.h" // futex_wake_private

#include "bthread/processor.h" // cpu_relax

#include "bthread/task_control.h"

#include "bthread/task_group.h"

#include "bthread/timer_thread.h"

#include "bthread/bthread.h"

#ifdef __x86_64__

#include <x86intrin.h>

#endif // __x86_64__

#ifdef __ARM_NEON

#include <arm_neon.h>

#endif // __ARM_NEON

namespace bthread {

// Global span function pointers for bthread lifecycle tracing.

// These are set by brpc layer via bthread_set_span_funcs().

void* (*g_create_bthread_span)() = nullptr;

void (*g_rpcz_parent_span_dtor)(void*) = nullptr;

void (*g_end_bthread_span)() = nullptr;

static const bthread_attr_t BTHREAD_ATTR_TASKGROUP = {

BTHREAD_STACKTYPE_UNKNOWN, 0, nullptr, BTHREAD_TAG_INVALID, {0} };

DEFINE_bool(show_bthread_creation_in_vars, false, "When this flags is on, The time "

"from bthread creation to first run will be recorded and shown in /vars");

BUTIL_VALIDATE_GFLAG(show_bthread_creation_in_vars, butil::PassValidate);

DEFINE_bool(show_per_worker_usage_in_vars, false,

"Show per-worker usage in /vars/bthread_per_worker_usage_<tid>");

BUTIL_VALIDATE_GFLAG(show_per_worker_usage_in_vars, butil::PassValidate);

DEFINE_bool(bthread_enable_cpu_clock_stat, false,

"Enable CPU clock statistics for bthread");

BUTIL_VALIDATE_GFLAG(bthread_enable_cpu_clock_stat, butil::PassValidate);

BAIDU_VOLATILE_THREAD_LOCAL(TaskGroup*, tls_task_group, nullptr);

// Sync with TaskMeta::local_storage when a bthread is created or destroyed.

// During running, the two fields may be inconsistent, use tls_bls as the

// groundtruth.

BAIDU_VOLATILE_THREAD_LOCAL(LocalStorage, tls_bls, BTHREAD_LOCAL_STORAGE_INITIALIZER);

// defined in bthread/key.cpp

extern void return_keytable(bthread_keytable_pool_t*, KeyTable*);

// [Hacky] This is a special TLS set by bthread-rpc privately... to save

// overhead of creation keytable, may be removed later.

BAIDU_VOLATILE_THREAD_LOCAL(void*, tls_unique_user_ptr, nullptr);

const TaskStatistics EMPTY_STAT = { 0, 0, 0 };

AtomicInteger128::Value AtomicInteger128::load() const {

#ifdef __x86_64__

(void)_mutex;

(void)_seq;

__m128i value = _mm_load_si128(reinterpret_cast<const __m128i*>(&_value));

return {value[0], value[1]};

#elif defined(__ARM_NEON)

(void)_mutex;

(void)_seq;

int64x2_t value = vld1q_s64(reinterpret_cast<const int64_t*>(&_value));

return {value[0], value[1]};

#elif defined(__riscv) && __riscv_xlen == 64

(void)_mutex;

// RISC-V: Seqlock-based atomic 128-bit load.

int64_t v1, v2;

uint64_t seq0, seq1;

do {

__asm__ volatile(

"ld %0, %1\n\t"

: "=r"(seq0)

: "m"(_seq)

: "memory"

);

if (seq0 & 1) continue;

__asm__ volatile("fence r, rw\n\t" ::: "memory");

__asm__ volatile(

"ld %0, %2\n\t"

"ld %1, %3\n\t"

: "=r"(v1), "=r"(v2)

: "m"(_value.v1), "m"(_value.v2)

: "memory"

);

__asm__ volatile("fence r, rw\n\t" ::: "memory");

__asm__ volatile(

"ld %0, %1\n\t"

: "=r"(seq1)

: "m"(_seq)

: "memory"

);

} while (seq0 != seq1);

return {v1, v2};

#else

BAIDU_SCOPED_LOCK(const_cast<FastPthreadMutex&>(_mutex));

return _value;

#endif

}

void AtomicInteger128::store(Value value) {

#ifdef __x86_64__

(void)_seq;

__m128i v = _mm_load_si128(reinterpret_cast<__m128i*>(&value));

_mm_store_si128(reinterpret_cast<__m128i*>(&_value), v);

#elif defined(__ARM_NEON)

(void)_seq;

int64x2_t v = vld1q_s64(reinterpret_cast<int64_t*>(&value));

vst1q_s64(reinterpret_cast<int64_t*>(&_value), v);

#elif defined(__riscv) && __riscv_xlen == 64

(void)_mutex;

// RISC-V: Seqlock-based atomic 128-bit store.

uint64_t old_seq;

__asm__ volatile(

"ld %0, %1\n\t"

: "=r"(old_seq)

: "m"(_seq)

: "memory"

);

uint64_t new_seq = old_seq + 1;

__asm__ volatile(

"fence w, w\n\t"

"sd %1, %0\n\t"

: "=m"(_seq)

: "r"(new_seq)

: "memory"

);

__asm__ volatile("fence w, w\n\t" ::: "memory");

__asm__ volatile(

"sd %2, %0\n\t"

"sd %3, %1\n\t"

: "=m"(_value.v1), "=m"(_value.v2)

: "r"(value.v1), "r"(value.v2)

: "memory"

);

__asm__ volatile("fence w, w\n\t" ::: "memory");

new_seq++;

__asm__ volatile(

"sd %1, %0\n\t"

: "=m"(_seq)

: "r"(new_seq)

: "memory"

);

#else

BAIDU_SCOPED_LOCK(const_cast<FastPthreadMutex&>(_mutex));

_value = value;

#endif

}

int TaskGroup::get_attr(bthread_t tid, bthread_attr_t* out) {

TaskMeta* const m = address_meta(tid);

if (m != nullptr) {

const uint32_t given_ver = get_version(tid);

BAIDU_SCOPED_LOCK(m->version_lock);

if (given_ver == *m->version_butex) {

*out = m->attr;

return 0;

}

errno = EINVAL;

return -1;

}

void TaskGroup::set_stopped(bthread_t tid) {

TaskMeta* const m = address_meta(tid);

if (m != nullptr) {

const uint32_t given_ver = get_version(tid);

BAIDU_SCOPED_LOCK(m->version_lock);

if (given_ver == *m->version_butex) {

m->stop = true;

}

bool TaskGroup::is_stopped(bthread_t tid) {

TaskMeta* const m = address_meta(tid);

if (m != nullptr) {

const uint32_t given_ver = get_version(tid);

BAIDU_SCOPED_LOCK(m->version_lock);

if (given_ver == *m->version_butex) {

return m->stop;

}

// If the tid does not exist or version does not match, it's intuitive

// to treat the thread as "stopped".

return true;

}

bool TaskGroup::wait_task(bthread_t* tid) {

do {

#ifndef BTHREAD_DONT_SAVE_PARKING_STATE

if (_last_pl_state.stopped()) {

return false;

}

_pl->wait(_last_pl_state);

if (steal_task(tid)) {

return true;

}

#else

const ParkingLot::State st = _pl->get_state();

if (st.stopped()) {

return false;

}

if (steal_task(tid)) {

return true;

}

_pl->wait(st);

#endif

} while (true);

}

static double get_cumulated_cputime_from_this(void* arg) {

return static_cast<TaskGroup*>(arg)->cumulated_cputime_ns() / 1000000000.0;

}

int64_t TaskGroup::cumulated_cputime_ns() const {

CPUTimeStat cpu_time_stat = _cpu_time_stat.load();

// Add the elapsed time of running bthread.

int64_t cumulated_cputime_ns = cpu_time_stat.cumulated_cputime_ns();

if (!cpu_time_stat.is_main_task()) {

cumulated_cputime_ns += butil::cpuwide_time_ns() - cpu_time_stat.last_run_ns();

}

return cumulated_cputime_ns;

}

void TaskGroup::run_main_task() {

bvar::PassiveStatus<double> cumulated_cputime(

get_cumulated_cputime_from_this, this);

std::unique_ptr<bvar::PerSecond<bvar::PassiveStatus<double> > > usage_bvar;

TaskGroup* dummy = this;

bthread_t tid;

while (wait_task(&tid)) {

sched_to(&dummy, tid);

DCHECK_EQ(this, dummy);

DCHECK_EQ(_cur_meta->stack, _main_stack);

if (_cur_meta->tid != _main_tid) {

task_runner(1/*skip remained*/);

}

if (FLAGS_show_per_worker_usage_in_vars && !usage_bvar) {

char name[32];

#if defined(OS_MACOSX)

snprintf(name, sizeof(name), "bthread_worker_usage_%" PRIu64,

pthread_numeric_id());

#else

snprintf(name, sizeof(name), "bthread_worker_usage_%ld",

(long)syscall(SYS_gettid));

#endif

usage_bvar.reset(new bvar::PerSecond<bvar::PassiveStatus<double> >

(name, &cumulated_cputime, 1));

}

// Don't forget to add elapse of last wait_task.

current_task()->stat.cputime_ns +=

butil::cpuwide_time_ns() - _cpu_time_stat.load_unsafe().last_run_ns();

}

TaskGroup::TaskGroup(TaskControl* c)

: _control(c) {

CHECK(c);

}

TaskGroup::~TaskGroup() {

if (_main_tid) {

TaskMeta* m = address_meta(_main_tid);

CHECK(_main_stack == m->stack);

#ifdef BUTIL_USE_ASAN

_main_stack->storage.bottom = nullptr;

_main_stack->storage.stacksize = 0;

#endif // BUTIL_USE_ASAN

return_stack(m->release_stack());

return_resource(get_slot(_main_tid));

_main_tid = 0;

}

#ifdef BUTIL_USE_ASAN

// Returns the **highest** address of the calling pthread's stack and its

// total size, matching brpc's `StackStorage::bottom` convention (see comment

// in bthread/stack.h: "Assume stack grows upwards"). Note that on Linux

// `pthread_attr_getstack(3)` returns the lowest address of the region, so

// we have to translate it; on macOS `pthread_get_stackaddr_np(3)` already

// returns the stack base (highest address), so we use it as-is.

int PthreadAttrGetStack(void*& stack_addr, size_t& stack_size) {

#if defined(OS_MACOSX)

stack_addr = pthread_get_stackaddr_np(pthread_self());

stack_size = pthread_get_stacksize_np(pthread_self());

return 0;

#else

pthread_attr_t attr;

int rc = pthread_getattr_np(pthread_self(), &attr);

if (0 != rc) {

LOG(ERROR) << "Fail to get pthread attributes: " << berror(rc);

return rc;

}

void* stack_lowest = nullptr;

rc = pthread_attr_getstack(&attr, &stack_lowest, &stack_size);

if (0 != rc) {

LOG(ERROR) << "Fail to get pthread stack: " << berror(rc);

} else {

// Translate lowest -> highest to match StackStorage::bottom.

stack_addr = (char*)stack_lowest + stack_size;

}

pthread_attr_destroy(&attr);

return rc;

#endif // OS_MACOSX

}

#endif // BUTIL_USE_ASAN

int TaskGroup::init(size_t runqueue_capacity) {

if (_rq.init(runqueue_capacity) != 0) {

LOG(FATAL) << "Fail to init _rq";

return -1;

}

if (_remote_rq.init(runqueue_capacity / 2) != 0) {

LOG(FATAL) << "Fail to init _remote_rq";

return -1;

}

#ifdef BUTIL_USE_ASAN

void* stack_addr = nullptr;

size_t stack_size = 0;

if (0 != PthreadAttrGetStack(stack_addr, stack_size)) {

return -1;

}

#endif // BUTIL_USE_ASAN

ContextualStack* stk = get_stack(STACK_TYPE_MAIN, nullptr);

if (nullptr == stk) {

LOG(FATAL) << "Fail to get main stack container";

return -1;

}

butil::ResourceId<TaskMeta> slot;

TaskMeta* m = butil::get_resource<TaskMeta>(&slot);

if (nullptr == m) {

LOG(FATAL) << "Fail to get TaskMeta";

return -1;

}

m->sleep_failed = false;

m->stop = false;

m->interrupted = false;

m->about_to_quit = false;

m->fn = nullptr;

m->arg = nullptr;

m->local_storage = LOCAL_STORAGE_INIT;

m->cpuwide_start_ns = butil::cpuwide_time_ns();

m->stat = EMPTY_STAT;

m->attr = BTHREAD_ATTR_TASKGROUP;

m->tid = make_tid(*m->version_butex, slot);

m->set_stack(stk);

#ifdef BUTIL_USE_ASAN

stk->storage.bottom = stack_addr;

stk->storage.stacksize = stack_size;

// No guard size required for ASan.

#endif // BUTIL_USE_ASAN

_cur_meta = m;

_main_tid = m->tid;

_main_stack = stk;

CPUTimeStat cpu_time_stat;

cpu_time_stat.set_last_run_ns(m->cpuwide_start_ns, true);

_cpu_time_stat.store(cpu_time_stat);

_last_cpu_clock_ns = 0;

return 0;

}

#ifdef BUTIL_USE_ASAN

void TaskGroup::asan_task_runner(intptr_t) {

// This is a new thread, and it doesn't have the fake stack yet. ASan will

// create it lazily, for now just pass nullptr.

internal::FinishSwitchFiber(nullptr);

task_runner(0);

}

#endif // BUTIL_USE_ASAN

void TaskGroup::task_runner(intptr_t skip_remained) {

// NOTE: tls_task_group is volatile since tasks are moved around

// different groups.

TaskGroup* g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

#ifdef BRPC_BTHREAD_TRACER

TaskTracer::set_running_status(g->tid(), g->_cur_meta);

#endif // BRPC_BTHREAD_TRACER

if (!skip_remained) {

while (g->_last_context_remained) {

RemainedFn fn = g->_last_context_remained;

g->_last_context_remained = nullptr;

fn(g->_last_context_remained_arg);

g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

}

#ifndef NDEBUG

--g->_sched_recursive_guard;

#endif

}

do {

// A task can be stopped before it gets running, in which case

// we may skip user function, but that may confuse user:

// Most tasks have variables to remember running result of the task,

// which is often initialized to values indicating success. If an

// user function is never called, the variables will be unchanged

// however they'd better reflect failures because the task is stopped

// abnormally.

// Meta and identifier of the task is persistent in this run.

TaskMeta* const m = g->_cur_meta;

if (FLAGS_show_bthread_creation_in_vars) {

// NOTE: the thread triggering exposure of pending time may spend

// considerable time because a single bvar::LatencyRecorder

// contains many bvar.

g->_control->exposed_pending_time() <<

(butil::cpuwide_time_ns() - m->cpuwide_start_ns) / 1000L;

}

// Not catch exceptions except ExitException which is for implementing

// bthread_exit(). User code is intended to crash when an exception is

// not caught explicitly. This is consistent with other threading

// libraries.

void* thread_return;

try {

thread_return = m->fn(m->arg);

} catch (ExitException& e) {

thread_return = e.value();

}

if (m->attr.flags & BTHREAD_INHERIT_SPAN) {

if (g_end_bthread_span) {

g_end_bthread_span();

}

// TODO: Save thread_return

(void)thread_return;

// Logging must be done before returning the keytable, since the logging lib

// use bthread local storage internally, or will cause memory leak.

// FIXME: the time from quiting fn to here is not counted into cputime

if (m->attr.flags & BTHREAD_LOG_START_AND_FINISH) {

LOG(INFO) << "Finished bthread " << m->tid << ", cputime="

<< m->stat.cputime_ns / 1000000.0 << "ms";

}

// Clean up span if it exists. This must be done before keytable cleanup

// because span cleanup may use bthread local storage (e.g. logging,

// which allocates bthread-local stream arrays via bthread_setspecific).

// If span cleanup ran after keytable cleanup, such allocations would

// re-populate the keytable and never be reclaimed, causing memory leak.

LocalStorage* tls_bls_ptr = bthread::tls_bls_ptr();

if (tls_bls_ptr->rpcz_parent_span && g_rpcz_parent_span_dtor) {

g_rpcz_parent_span_dtor(tls_bls_ptr->rpcz_parent_span);

tls_bls_ptr = bthread::tls_bls_ptr();

tls_bls_ptr->rpcz_parent_span = nullptr;

m->local_storage.rpcz_parent_span = nullptr;

}

// Clean tls variables, must be done before changing version_butex

// otherwise another thread just joined this thread may not see side

// effects of destructing tls variables.

KeyTable* kt = tls_bls_ptr->keytable;

if (kt != nullptr) {

return_keytable(m->attr.keytable_pool, kt);

// After deletion: tls may be set during deletion.

tls_bls_ptr = bthread::tls_bls_ptr();

tls_bls_ptr->keytable = nullptr;

m->local_storage.keytable = nullptr; // optional

}

// During running the function in TaskMeta and deleting the KeyTable in

// return_KeyTable, the group is probably changed.

g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

// Increase the version and wake up all joiners, if resulting version

// is 0, change it to 1 to make bthread_t never be 0. Any access

// or join to the bthread after changing version will be rejected.

// The spinlock is for visibility of TaskGroup::get_attr.

#ifdef BRPC_BTHREAD_TRACER

bool tracing = false;

#endif // BRPC_BTHREAD_TRACER

{

BAIDU_SCOPED_LOCK(m->version_lock);

#ifdef BRPC_BTHREAD_TRACER

tracing = TaskTracer::set_end_status_unsafe(m);

#endif // BRPC_BTHREAD_TRACER

if (0 == ++*m->version_butex) {

++*m->version_butex;

}

butex_wake_except(m->version_butex, 0);

#ifdef BRPC_BTHREAD_TRACER

if (tracing) {

// Wait for tracing completion.

g->_control->_task_tracer.WaitForTracing(m);

}

g->_control->_task_tracer.set_status(TASK_STATUS_UNKNOWN, m);

#endif // BRPC_BTHREAD_TRACER

g->_control->_nbthreads << -1;

g->_control->tag_nbthreads(g->tag()) << -1;

g->set_remained(_release_last_context, m);

ending_sched(&g);

} while (g->_cur_meta->tid != g->_main_tid);

// Was called from a pthread and we don't have BTHREAD_STACKTYPE_PTHREAD

// tasks to run, quit for more tasks.

}

void TaskGroup::_release_last_context(void* arg) {

TaskMeta* m = static_cast<TaskMeta*>(arg);

if (m->stack_type() != STACK_TYPE_PTHREAD) {

return_stack(m->release_stack()/*may be nullptr*/);

} else {

// it's _main_stack, don't return.

m->set_stack(nullptr);

}

return_resource(get_slot(m->tid));

}

int TaskGroup::start_foreground(TaskGroup** pg,

bthread_t* __restrict th,

const bthread_attr_t* __restrict attr,

void * (*fn)(void*),

void* __restrict arg) {

if (__builtin_expect(!fn, 0)) {

return EINVAL;

}

const int64_t start_ns = butil::cpuwide_time_ns();

const bthread_attr_t using_attr = (attr ? *attr : BTHREAD_ATTR_NORMAL);

butil::ResourceId<TaskMeta> slot;

TaskMeta* m = butil::get_resource(&slot);

if (BAIDU_UNLIKELY(nullptr == m)) {

return ENOMEM;

}

CHECK(m->current_waiter.load(butil::memory_order_relaxed) == nullptr);

m->sleep_failed = false;

m->stop = false;

m->interrupted = false;

m->about_to_quit = false;

m->fn = fn;

m->arg = arg;

CHECK(m->stack == nullptr);

m->attr = using_attr;

m->local_storage = LOCAL_STORAGE_INIT;

if (using_attr.flags & BTHREAD_INHERIT_SPAN) {

if (g_create_bthread_span) {

m->local_storage.rpcz_parent_span = g_create_bthread_span();

} else {

m->local_storage.rpcz_parent_span = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_bls).rpcz_parent_span;

}

m->cpuwide_start_ns = start_ns;

m->stat = EMPTY_STAT;

m->tid = make_tid(*m->version_butex, slot);

TaskGroup* g = *pg;

m->priority_index = g->_cur_meta->priority_index;

m->attr.tag = g->tag();

*th = m->tid;

if (using_attr.flags & BTHREAD_LOG_START_AND_FINISH) {

LOG(INFO) << "Started bthread " << m->tid;

}

g->_control->_nbthreads << 1;

g->_control->tag_nbthreads(g->tag()) << 1;

#ifdef BRPC_BTHREAD_TRACER

g->_control->_task_tracer.set_status(TASK_STATUS_CREATED, m);

#endif // BRPC_BTHREAD_TRACER

if (g->is_current_pthread_task()) {

// never create foreground task in pthread.

g->ready_to_run(m, using_attr.flags & BTHREAD_NOSIGNAL);

} else {

// NOSIGNAL affects current task, not the new task.

RemainedFn fn = nullptr;

auto& cur_attr = g->_cur_meta->attr;

if (g->_control->_enable_priority_queue && cur_attr.flags & BTHREAD_GLOBAL_PRIORITY) {

fn = priority_to_run;

} else if (g->current_task()->about_to_quit) {

fn = ready_to_run_in_worker_ignoresignal;

} else {

fn = ready_to_run_in_worker;

}

ReadyToRunArgs args = {

g->tag(), g->_cur_meta, (bool)(using_attr.flags & BTHREAD_NOSIGNAL)

};

g->set_remained(fn, &args);

sched_to(pg, m->tid);

}

return 0;

}

template <bool REMOTE>

int TaskGroup::start_background(bthread_t* __restrict th,

const bthread_attr_t* __restrict attr,

void * (*fn)(void*),

void* __restrict arg) {

if (__builtin_expect(!fn, 0)) {

return EINVAL;

}

const int64_t start_ns = butil::cpuwide_time_ns();

const bthread_attr_t using_attr = (attr ? *attr : BTHREAD_ATTR_NORMAL);

butil::ResourceId<TaskMeta> slot;

TaskMeta* m = butil::get_resource(&slot);

if (BAIDU_UNLIKELY(nullptr == m)) {

return ENOMEM;

}

CHECK(m->current_waiter.load(butil::memory_order_relaxed) == nullptr);

m->sleep_failed = false;

m->stop = false;

m->interrupted = false;

m->about_to_quit = false;

m->fn = fn;

m->arg = arg;

CHECK(m->stack == nullptr);

m->attr = using_attr;

m->local_storage = LOCAL_STORAGE_INIT;

if (using_attr.flags & BTHREAD_INHERIT_SPAN) {

if (g_create_bthread_span) {

m->local_storage.rpcz_parent_span = g_create_bthread_span();

} else {

m->local_storage.rpcz_parent_span = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_bls).rpcz_parent_span;

}

m->cpuwide_start_ns = start_ns;

m->stat = EMPTY_STAT;

m->tid = make_tid(*m->version_butex, slot);

m->priority_index = _cur_meta->priority_index;

*th = m->tid;

if (using_attr.flags & BTHREAD_LOG_START_AND_FINISH) {

LOG(INFO) << "Started bthread " << m->tid;

}

m->attr.tag = tag();

_control->_nbthreads << 1;

_control->tag_nbthreads(tag()) << 1;

#ifdef BRPC_BTHREAD_TRACER

_control->_task_tracer.set_status(TASK_STATUS_CREATED, m);

#endif // BRPC_BTHREAD_TRACER

if (REMOTE) {

ready_to_run_remote(m, (using_attr.flags & BTHREAD_NOSIGNAL));

} else {

ready_to_run(m, (using_attr.flags & BTHREAD_NOSIGNAL));

}

return 0;

}

// Explicit instantiations.

template int

TaskGroup::start_background<true>(bthread_t* __restrict th,

const bthread_attr_t* __restrict attr,

void * (*fn)(void*),

void* __restrict arg);

template int

TaskGroup::start_background<false>(bthread_t* __restrict th,

const bthread_attr_t* __restrict attr,

void * (*fn)(void*),

void* __restrict arg);

int TaskGroup::join(bthread_t tid, void** return_value) {

if (__builtin_expect(!tid, 0)) { // tid of bthread is never 0.

return EINVAL;

}

TaskMeta* m = address_meta(tid);

if (BAIDU_UNLIKELY(nullptr == m)) {

// The bthread is not created yet, this join is definitely wrong.

return EINVAL;

}

TaskGroup* g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

if (g != nullptr && g->current_tid() == tid) {

// joining self causes indefinite waiting.

return EINVAL;

}

const uint32_t expected_version = get_version(tid);

while (*m->version_butex == expected_version) {

if (butex_wait(m->version_butex, expected_version, nullptr) < 0 &&

errno != EWOULDBLOCK && errno != EINTR) {

return errno;

}

// Ensure all memory writes made by the joined bthread are visible to

// the joining thread after join returns. This matches the semantic

// guarantee provided by pthread_join() across supported architectures.

butil::atomic_thread_fence(butil::memory_order_acquire);

if (return_value) {

*return_value = nullptr;

}

return 0;

}

bool TaskGroup::exists(bthread_t tid) {

if (tid != 0) { // tid of bthread is never 0.

TaskMeta* m = address_meta(tid);

if (m != nullptr) {

return (*m->version_butex == get_version(tid));

}

return false;

}

TaskStatistics TaskGroup::main_stat() const {

TaskMeta* m = address_meta(_main_tid);

return m ? m->stat : EMPTY_STAT;

}

void TaskGroup::ending_sched(TaskGroup** pg) {

TaskGroup* g = *pg;

bthread_t next_tid = 0;

// Find next task to run, if none, switch to idle thread of the group.

#ifndef BTHREAD_FAIR_WSQ

// When BTHREAD_FAIR_WSQ is defined, profiling shows that cpu cost of

// WSQ::steal() in example/multi_threaded_echo_c++ changes from 1.9%

// to 2.9%

const bool popped = g->_rq.pop(&next_tid);

#else

const bool popped = g->_rq.steal(&next_tid);

#endif

if (!popped && !g->steal_task(&next_tid)) {

// Jump to main task if there's no task to run.

next_tid = g->_main_tid;

}

TaskMeta* const cur_meta = g->_cur_meta;

TaskMeta* next_meta = address_meta(next_tid);

if (next_meta->stack == nullptr) {

if (next_meta->stack_type() == cur_meta->stack_type()) {

// Reuse the stack of the current ending task.

// also works with pthread_task scheduling to pthread_task, the

// transfered stack is just _main_stack.

next_meta->set_stack(cur_meta->release_stack());

} else {

#ifdef BUTIL_USE_ASAN

ContextualStack* stk = get_stack(

next_meta->stack_type(), asan_task_runner);

#else

ContextualStack* stk = get_stack(next_meta->stack_type(), task_runner);

#endif // BUTIL_USE_ASAN

if (stk) {

next_meta->set_stack(stk);

} else {

// stack_type is BTHREAD_STACKTYPE_PTHREAD or out of memory,

// In latter case, attr is forced to be BTHREAD_STACKTYPE_PTHREAD.

// This basically means that if we can't allocate stack, run

// the task in pthread directly.

next_meta->attr.stack_type = BTHREAD_STACKTYPE_PTHREAD;

next_meta->set_stack(g->_main_stack);

}

sched_to(pg, next_meta);

}

void TaskGroup::sched(TaskGroup** pg) {

TaskGroup* g = *pg;

bthread_t next_tid = 0;

// Find next task to run, if none, switch to idle thread of the group.

#ifndef BTHREAD_FAIR_WSQ

const bool popped = g->_rq.pop(&next_tid);

#else

const bool popped = g->_rq.steal(&next_tid);

#endif

if (!popped && !g->steal_task(&next_tid)) {

// Jump to main task if there's no task to run.

next_tid = g->_main_tid;

}

sched_to(pg, next_tid);

}

extern void CheckBthreadScheSafety();

void TaskGroup::sched_to(TaskGroup** pg, TaskMeta* next_meta) {

TaskGroup* g = *pg;

#ifndef NDEBUG

if ((++g->_sched_recursive_guard) > 1) {

LOG(FATAL) << "Recursively(" << g->_sched_recursive_guard - 1

<< ") call sched_to(" << g << ")";

}

#endif

// Save errno so that errno is bthread-specific.

int saved_errno = errno;

void* saved_unique_user_ptr = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_unique_user_ptr);

TaskMeta* const cur_meta = g->_cur_meta;

int64_t now = butil::cpuwide_time_ns();

CPUTimeStat cpu_time_stat = g->_cpu_time_stat.load_unsafe();

int64_t elp_ns = now - cpu_time_stat.last_run_ns();

cur_meta->stat.cputime_ns += elp_ns;

// Update cpu_time_stat.

cpu_time_stat.set_last_run_ns(now, is_main_task(g, next_meta->tid));

cpu_time_stat.add_cumulated_cputime_ns(elp_ns, is_main_task(g, cur_meta->tid));

g->_cpu_time_stat.store(cpu_time_stat);

if (FLAGS_bthread_enable_cpu_clock_stat) {

const int64_t cpu_thread_time = butil::cputhread_time_ns();

if (g->_last_cpu_clock_ns != 0) {

cur_meta->stat.cpu_usage_ns += cpu_thread_time - g->_last_cpu_clock_ns;

}

g->_last_cpu_clock_ns = cpu_thread_time;

} else {

g->_last_cpu_clock_ns = 0;

}

++cur_meta->stat.nswitch;

++ g->_nswitch;

// Switch to the task

if (__builtin_expect(next_meta != cur_meta, 1)) {

g->_cur_meta = next_meta;

// Switch tls_bls

cur_meta->local_storage = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_bls);

BAIDU_SET_VOLATILE_THREAD_LOCAL(tls_bls, next_meta->local_storage);

// Logging must be done after switching the local storage, since the logging lib

// use bthread local storage internally, or will cause memory leak.

if ((cur_meta->attr.flags & BTHREAD_LOG_CONTEXT_SWITCH) ||

(next_meta->attr.flags & BTHREAD_LOG_CONTEXT_SWITCH)) {

LOG(INFO) << "Switch bthread: " << cur_meta->tid << " -> "

<< next_meta->tid;

}

if (cur_meta->stack != nullptr) {

if (next_meta->stack != cur_meta->stack) {

CheckBthreadScheSafety();

#ifdef BRPC_BTHREAD_TRACER

g->_control->_task_tracer.set_status(TASK_STATUS_JUMPING, cur_meta);

g->_control->_task_tracer.set_status(TASK_STATUS_JUMPING, next_meta);

#endif // BRPC_BTHREAD_TRACER

{

BTHREAD_SCOPED_ASAN_FIBER_SWITCHER(next_meta->stack->storage);

jump_stack(cur_meta->stack, next_meta->stack);

}

// probably went to another group, need to assign g again.

g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

#ifdef BRPC_BTHREAD_TRACER

TaskTracer::set_running_status(g->tid(), g->_cur_meta);

#endif // BRPC_BTHREAD_TRACER

}

#ifndef NDEBUG

else {

// else pthread_task is switching to another pthread_task, sc

// can only equal when they're both _main_stack

CHECK(cur_meta->stack == g->_main_stack);

}

#endif

} /* else because of ending_sched(including pthread_task->pthread_task). */

#ifdef BRPC_BTHREAD_TRACER

else {

// _cur_meta: TASK_STATUS_FIRST_READY -> TASK_STATUS_RUNNING.

TaskTracer::set_running_status(g->tid(), g->_cur_meta);

}

#endif // BRPC_BTHREAD_TRACER

} else {

LOG(FATAL) << "bthread=" << g->current_tid() << " sched_to itself!";

}

while (g->_last_context_remained) {

RemainedFn fn = g->_last_context_remained;

g->_last_context_remained = nullptr;

fn(g->_last_context_remained_arg);

g = BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group);

}

// Restore errno

errno = saved_errno;

// tls_unique_user_ptr probably changed.

BAIDU_SET_VOLATILE_THREAD_LOCAL(tls_unique_user_ptr, saved_unique_user_ptr);

#ifndef NDEBUG

--g->_sched_recursive_guard;

#endif

*pg = g;

}

void TaskGroup::destroy_self() {

if (_control) {

_control->_destroy_group(this);

_control = nullptr;

} else {

CHECK(false);

}

void TaskGroup::ready_to_run(TaskMeta* meta, bool nosignal) {

#ifdef BRPC_BTHREAD_TRACER

_control->_task_tracer.set_status(TASK_STATUS_READY, meta);

#endif // BRPC_BTHREAD_TRACER

push_rq(meta->tid);

if (nosignal) {

++_num_nosignal;

} else {

const int additional_signal = _num_nosignal;

_num_nosignal = 0;

_nsignaled += 1 + additional_signal;

_control->signal_task(1 + additional_signal, _tag);

}

void TaskGroup::flush_nosignal_tasks() {

const int val = _num_nosignal;

if (val) {

_num_nosignal = 0;

_nsignaled += val;

_control->signal_task(val, _tag);

}

void TaskGroup::ready_to_run_remote(TaskMeta* meta, bool nosignal) {

#ifdef BRPC_BTHREAD_TRACER

_control->_task_tracer.set_status(TASK_STATUS_READY, meta);

#endif // BRPC_BTHREAD_TRACER

_remote_rq._mutex.lock();

while (!_remote_rq.push_locked(meta->tid)) {

flush_nosignal_tasks_remote_locked(_remote_rq._mutex);

LOG_EVERY_SECOND(ERROR) << "_remote_rq is full, capacity="

<< _remote_rq.capacity();

::usleep(1000);

_remote_rq._mutex.lock();

}

if (nosignal) {

++_remote_num_nosignal;

_remote_rq._mutex.unlock();

} else {

const int additional_signal = _remote_num_nosignal;

_remote_num_nosignal = 0;

_remote_nsignaled += 1 + additional_signal;

_remote_rq._mutex.unlock();

_control->signal_task(1 + additional_signal, _tag);

}

void TaskGroup::flush_nosignal_tasks_remote_locked(butil::Mutex& locked_mutex) {

const int val = _remote_num_nosignal;

if (!val) {

locked_mutex.unlock();

return;

}

_remote_num_nosignal = 0;

_remote_nsignaled += val;

locked_mutex.unlock();

_control->signal_task(val, _tag);

}

void TaskGroup::ready_to_run_general(TaskMeta* meta, bool nosignal) {

if (BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group) == this) {

return ready_to_run(meta, nosignal);

}

return ready_to_run_remote(meta, nosignal);

}

void TaskGroup::flush_nosignal_tasks_general() {

if (BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group) == this) {

return flush_nosignal_tasks();

}

return flush_nosignal_tasks_remote();

}

void TaskGroup::ready_to_run_in_worker(void* args_in) {

ReadyToRunArgs* args = static_cast<ReadyToRunArgs*>(args_in);

return BAIDU_GET_VOLATILE_THREAD_LOCAL(tls_task_group)->

ready_to_run(args->meta, args->nosignal);

}

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brpc/src/bthread/task_group.cpp at master · apache/brpc · GitHub

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